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  • Comment on “Measurement of the elastic properties of swelling clay minerals using the digital image correlation method on a single macroscopic crystal”, by S. Hedan, F. Hubert, D. Prêt, E. Ferrage, V. Valle, P. Cosenza [Applied Clay Science 116–117 (2015), 248–256, doi: 10.1016/j.clay.2015.04.002]
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2016-10-12
    Shengmin Luo, Dongwei Hou, Guoping Zhang

    Hedan et al. (2015) recently reported an interesting method for determining the elastic modulus of vermiculite, a representative swelling clay mineral. A platy natural macrocrystal of vermiculite was used in the study. The technique combining mechanical compression and digital image correlation (DIC) appears plausible. However, a fundamental issue related to the reported testing method, particularly the experimental setup and specimen geometry constraints, arises and is worth re-examination and discussion, because it may make the reported modulus inappropriate or inaccurate. In this short discussion, the stress distribution of a thin plate such as the tested vermiculite macrocrystal under uniaxial compression is analyzed, and the reported results are re-interpreted. It appears that the reported Young's modulus of 32.3 GPa is too high for the studied vermiculite.

    更新日期:2018-06-03
  • Selective loading of 5-fluorouracil in the interlayer space of methoxy-modified kaolinite for controlled release
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-05-02
    Daoyong Tan, Peng Yuan, Faqin Dong, Hongping He, Shiyong Sun, Zongwen Liu

    Methoxy-modified kaolinite was used as a novel carrier for anticancer drug 5-fluorouracil (5FU). The selective loading of 5FU into the interlayer space of methoxy-modified kaolinite was achieved because the weakly bonded 5FU on the external surface was removed off by facile water rinse. The intercalated 5FU has strong affinity (electrostatic force and hydrogen bonding) with the interlayer surface of kaolinite, and its release was controlled because of the diffusion restriction of the kaolinite lamellar layers and the strong affinity between 5FU and kaolinite. The controlled release of 5FU from methoxy-modified kaolinite in simulated colonic fluid (pH 5.5) makes it be of potential use to administer an oral formulation of 5FU for colon specific delivery.

    更新日期:2018-06-03
  • Self-supporting thin films of imogolite and imogolite-like nanotubes for infrared spectroscopy
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-06-16
    Yuanyuan Liao, Pierre Picot, Jean-Blaise Brubach, Pascale Roy, Sophie Le Caër, Antoine Thill

    Due to their narrow and well-defined structure, single wall nanotube, aluminosilicate nanotubes (imogolites) are excellent candidates to study how water is modified by either confinement or by the interface nature. A protocol is provided here to produce imogolite films that are ideally suited for infrared studies. Two types of imogolites were selected: a hydrophilic imogolite (IMO-OH) with inner surface fully covered with Si–OH hydrophilic groups and a hybrid imogolite (IMO-CH3) with inner surface fully covered with hydrophobic Si–CH3 groups. Films with different thicknesses were characterized by Small Angle X-ray Scattering (SAXS). The initial water content and the porosity of the films were estimated from ThermoGravimetric Analysis (TGA). Infrared spectroscopy was used to deduce the molar absorption coefficient of the bending mode that is significantly modified in confined water as compared to bulk water. Moreover, the interest of these films which allow avoiding extra-absorption features from the salt matrix or the supporting wafer is illustrated by an infrared study of the processes occurring in the IMO-OH film when it is heated from room temperature up to 350 °C. The evolution of the IR bands while heating shows the dehydration/dehydroxylation processes.

    更新日期:2018-06-03
  • Solvothermal evolution of red palygorskite in dimethyl sulfoxide/water
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-06-19
    Zhifang Zhang, Wenbo Wang, Guangyan Tian, Qin Wang, Aiqin Wang

    Red clay deposit with palygorskite (Pal) as the main component is abundant on the earth, but it is not yet fully utilized in industrial fields because of its deep color. In this paper, we employed a facile one-step solvothermal process to treat red Pal using water, dimethyl sulfoxide (DMSO) and DMSO/water as solvents and studied the effect of this process on the structure, physico-chemical characteristics and color of red Pal. It was revealed that the brick-red Pal still remain its color unchanged after solvothermal reaction in water or DMSO solvent, but it converted to white after reaction in dimethyl sulfoxide (DMSO)/water mixture. When the volume ratio of DMSO to water is 2:1, the product has the best whiteness of 83.3%. The associated minerals such as quartz, feldspar and muscovite did not change significantly and the rod-like crystalline morphology of Pal still remains intact after solvothermal reaction. The leaching of Fe(III) in Pal, the dissolution of α-Fe2O3 and the reduction of Fe(III) by the dimethyl sulfide (the reaction product of DMSO with water) to Fe(II) contributed to the conversion of red Pal to white one. The conversion of brick-red Pal to white would lay a foundation for the applications of deep-colored clay minerals in the fields of chemical industries and composite materials.

    更新日期:2018-06-03
  • Tracked changes of dolomite into Ca-Mg-Al layered double hydroxide
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-07-03
    Ning Mao, Chun Hui Zhou, John Keeling, Saverio Fiore, Hao Zhang, Liang Chen, Gui Chen Jin, Ting Ting Zhu, Dong Shen Tong, Wei Hua Yu

    Dolomite is a widespread carbonate mineral that has been investigated extensively over the past two centuries. Despite the high level of investigation, aspects of the environmental conditions of crystallization, diagenesis and dissolution remain elusive and the transformation of dolomite into other value-added products is still challenging. This work shows a novel, cleaner method to dissolve dolomite by taking advantage of the acidity from the hydrolysis of Lewis acid AlCl3 and as such the mineral can be efficiently converted into Ca-Mg-Al layered double hydroxide (LDH). The dolomite and the resulting Ca-Mg-Al LDH samples were characterized by powder X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composition of the products was measured by energy dispersive spectrometer-mapping (EDS-mapping), X-ray fluorescence (XRF) and atomic absorption spectroscopy (AAS). Particle sizes of the products were measured by a dynamic light scattering method. It is documented, for the first time, that dissolution of dolomite in AlCl3 aqueous solution is facilitated by hydrothermal treatment. Well-crystallized Ca-Mg-Al LDH crystals are achieved under (Ca + Mg): Al molar ratio = 1:1, pH = 10.5 via a simple co-precipitation method. The maximum utilization efficiencies of Ca2+, Mg2+ from dolomite to LDH are 36.3% and 95.5%, respectively. The possible mechanisms of LDH formation were: 1) the dolomite dissolved in the strong acid solution due to the hydrolysis of AlCl3 and thus provided Ca2+ and Mg2+; 2) with addition of NaOH, Al3+ cations precipitated to form Al(OH)3 (at 8.3 ≤ pH ≤ 9.3) and then part of the Al(OH)3 reacted with Ca2+ and Mg2+ to form the Ca-Mg-Al LDH; 3) at pH = 10.5, the Al(OH)3 was transformed as [AlO(OH)] and meanwhile Ca2+, Mg2+ and Al3+ took part in the formation of Ca-Mg-Al LDH; 4) when pH = 10.6, [AlO(OH)] reacted with NaOH to dissolve into [Al(OH)4]− and the [Al(OH)4]− finally co-precipitated with Ca2+ and Mg2+ to form the Ca-Mg-Al LDH during heating for drying.

    更新日期:2018-06-03
  • Effect of acid activation of palygorskite on their toluene adsorption behaviors
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-07-26
    Jianxi Zhu, Ping Zhang, Yuebo Wang, Ke Wen, Xiaoli Su, Runliang Zhu, Hongping He, Yunfei Xi

    In this paper, acid-activated palygorskite (APalx) samples were prepared by a facile acid treatment method with different concentrations of HCl (0.5, 1, 3, 5 and 7 mol/L). The dynamic toluene adsorption performances of APalx were evaluated and the relevant adsorption mechanism was discussed. The prepared adsorbents were characterized using X-ray diffraction (XRD), elemental analysis, transmission electron microcopy (TEM), nitrogen adsorption-desorption isotherms and Fourier-transform infrared spectroscopy (FTIR). The results show that the palygorskite has a good resistant ability to acid attack, the structure still remains when the acid concentration is as high as 7 mol/L. Acid activation could significantly enhance the surface area (228, 250, 271, 273, 329 and 308 for Pal, APal0.5, APal1, APal3, APal5 and APal7, respectively) and porosity of palygorskite. APal5 has the best toluene adsorption capacity (90.4 mg/g) due to its highest SBET (329 m2/g) and Vmicro (0.055 cm3/g). The adsorption performance in terms of dynamic toluene adsorption capacities follows the order of Pal (44.6 mg/g) < APal0.5 (63.5 mg/g) < APal1 (71.3 mg/g) < APal7 (74.2 mg/g) < APal3 (75.1 mg/g) < APal5 (90.4 mg/g). APal5 can be readily regenerated by thermal desorption and has exhibited steady reproducibility after 6 cycles. These results have demonstrated that acid activation is a feasible and effective method for the structure and surface optimizing of palygorskite, enabling the APalx to become a promising candidate for the adsorption of volatile organic compounds in practical applications.

    更新日期:2018-06-03
  • Discussion of “Optimization of carpet waste fibers and steel slag particles to reinforce expansive soil using response surface methodology” by M. Shahbazi, M. Rowshanzamir, S.M. Abtahi, S.M. Hejazi [Appl. Clay Sci., doi:10.1016/j.clay.2016.11.027]
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-08-01
    Amin Soltani

    Shahbazi et al. (2017) adopted the response surface methodology (RSM) technique to evaluate the combined efficiency of slag treatment and fiber reinforcement in the stabilization of an expansive soil mixture. The swell percent (Sp), swelling pressure (Ps), and unconfined compressive strength (qu) were represented as a function of three independent variables (i.e. slag content, fiber content, and fiber aspect ratio) by the second-order polynomial regression model, and ANOVA analysis was adopted to allocate a contribution percentage to each component of the regression model. It was noticed that the reported fitting parameters for Sp and Ps provided ambiguous predictions, and thus were recalculated to avoid any misleading information for readers. The statistical technique proposed by the authors is limited to allocating contribution factors to regressional components rather than evaluating the net favorable impact of each independent variable on the desired dependent variable. Therefore, the partial derivative sensitivity analysis approach was proposed as a simple and practical alternative to address the aforementioned uncertainty. The new approach presented in this discussion not only provides a unique contribution factor for each independent variable but also accounts for the combined favorable contribution offered by all three independent variables.

    更新日期:2018-06-03
  • Variable charges of a red soil from different depths: Acid-base buffer capacity and surface complexation model
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-08-10
    Ying Wang, Pengfei Cheng, Fangbai Li, Tongxu Liu, Kuan Cheng, Jinling Yang, Ying Lu

    The soil variable charges play a unique role in many soil geochemical processes, particularly soil acidification. However, due to the complicated nature of soil particles, a fundamental understanding of the acid-base buffer capacities and mechanisms is still lacking. In the present study, red soil samples from different depths were examined. The element compositions, crystal structures, and surface groups were characterized by X-ray fluorescence, X-ray diffraction, and Fourier transform infrared spectroscopy, respectively. Thermogravimetric analysis was further conducted to examine the soil compositions and the organic matter content. Kaolinite, quartz, and hematite were identified as the dominant mineral components. As the depth of the soils increased, the contents of hematite and kaolinite increased, while the contents of quartz decreased. The weight loss of the soil samples from 200 to 400 °C indicated that the organic matter decreased substantially with increasing soil depth. Based on the potentiometric titration, the pHpzc was determined to range from 4.4 to 5.0. The surface complexation model (SCM) was used to further evaluate the acid-base properties of the soils by assuming two pKa for one surface site of the bulk soil. The results showed that the values of the model-derived pHpzc were well matched with those from the titration experiments; therefore, it is feasible to apply the SCM in examining the variable charges of the bulk soils. The calculated surface site concentration Hs, representing the soil buffer capacity, was positively correlated with the contents of the organic matter, implying that the organic matter of the soil plays an important role in the soil acid-base buffer capacity. From the extrapolated pHpzc, it can be proposed that kaolinite was the major soil mineral controlling the pHpzc of soils. This study would provide a quantitative approach for the soil acid-base buffer properties and a fundamental understanding of the underlying mechanisms.

    更新日期:2018-06-03
  • Surface organo-functionalization of palygorskite nanorods with γ-mercaptopropyltrimethoxysilane
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-08-16
    Peng Liu, Hongxing Wang, Changou Pan

    Palygorskite (Pal) nanorods have attracted more and more interests in polymer-based nanocomposites. Surface modification with silane is the main approach to improve their dispersibility in organic matrices. In the present work, the functionalization of Pal nanorods with silane was optimized in detail, aiming to the high dispersibility in organic matrices, including the reaction condition (temperature and time) and feeding ratio of silane (e.g. γ-mercaptopropyltrimethoxysilane, MPS). The morphology of the products was analyzed with TEM technique. Based on the characterization results and the sedimentation phenomena of their dispersions in toluene, the microstructure of the organo-functionalized palygorskite (OPAL) was established, in which locking effect and welding effect of silane were proposed.

    更新日期:2018-06-03
  • Investigation of adsorption of 5-Chlorouracil onto montmorillonite: An IR and Raman spectroscopic study
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-08-23
    Sevim Akyuz, Tanil Akyuz

    In this study, the adsorption of 5-Chlorouracil (5-ClU) on natural montmorillonite from Anatolia was investigated using FT-IR and Raman spectroscopy. The 5-ClU is a thymine antagonist and has some antitumor properties. The comparison of the vibrational spectra of the adsorbed 5-ClU with those of the free molecule provided data on the nature and characteristics of the clay organic complexes. The intercalation of 5-ClU within montmorillonite has been shown by X-ray diffraction to increase the interlayer spacing. Vibrational spectroscopy indicates that adsorbed 5-ClU molecules on montmorillonite are coordinated to exchangeable cations, directly or indirectly through water bridges.

    更新日期:2018-06-03
  • Synthesis of palygorskite-supported Mn1 − xCexO2 clusters and their performance in catalytic oxidation of formaldehyde
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-08-31
    Can Wang, Haibo Liu, Tianhu Chen, Chengsong Qing, Xuehua Zou, Jingjing Xie, Xiaori Zhang

    Nano-scale Mn1 − xCexO2 catalysts supported on palygorskite (PG) with different dopant fractions were prepared by the co-precipitation method and applied in the catalytic oxidation of formaldehyde (HCHO). The obtained samples were characterized using BET, XRD, Raman spectroscopy, TEM, EDS, and H2-TPR to illustrate the physicochemical properties of the catalysts. After the introduction of cerium, the growth of manganese oxide was inhibited. However, an increase of the Ce/(Ce + Mn) ratio from 0.1 to 0.5 increased the particle size from 2.87 to 6.86 nm. A remarkable interface (grain boundaries) between MnO2 and CeO2 was observed, especially for low cerium molar fractions (0.1–0.4). The doping of cerium significantly enhanced the activity of manganese oxide for HCHO oxidation at 100–180 °C. The Mn0.9Ce0.1/PG catalyst exhibited the best activity, and HCHO was completely converted to CO2 and H2O at 160 °C. The characterization results indicated that smaller particle size, surface-adsorbed oxygen species and abundant oxygen vacancies accounted for the high catalytic activity of the Mn0.9Ce0.1/PG catalyst for HCHO conversion. In addition, the Mn0.9Ce0.1/PG catalyst also displayed high stability in lifetime testing and excellent water-resistant performance. The experimental results suggest that palygorskite-supported Mn0.9Ce0.1 is a promising catalyst for the catalytic oxidation of formaldehyde at low temperatures.

    更新日期:2018-06-03
  • Photocatalytic microreactors based on nano TiO2-containing clay colloidosomes
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-09-01
    Sen Lin, Shiyong Sun, Kexuan Shen, Daoyong Tan, Hongping Zhang, Faqin Dong, Xiaoxin Fu

    Photocatalytic microcompartments have attracted increasing interests in the field of photocatalytic degradation. This work focused on the construction and characterization of a novel photocatalytic microsystem comprising polydopamine-modified TiO2 nanoparticles (NPs) dispersed in clay-based colloidosomes, utilizing partially hydrophobic montmorillonite particles as building blocks for colloidosome membrane assembly. Assessment of photocatalytic activity was performed by photocatalytic degradation of methylene blue and rhodamine B, with the small molecule dyes decomposing within the compartmentalized microsystems. Encapsulation of TiO2 NPs within the clay colloidosomes enhanced the efficiency of photocatalytic degradation. The results showed a selective degradation of methylene blue in the presence of rhodamine B, with associated λMB/λRhB of 2.04. The present study indicates that photocatalytic semiconductor NPs encapsulated in clay colloidosomes form a promising microsystem with great potential for application in environmental remediation.

    更新日期:2018-06-03
  • Effects of charge density on the hydration of siloxane surface of montmorillonite: A molecular dynamics simulation study
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-09-18
    Wei Shen, Lin Li, Huijun Zhou, Qing Zhou, Meng Chen, Jianxi Zhu

    The physicochemical properties of clay minerals strongly depend on their hydration characteristics which therefore have drawn great concerns from different research communities. In the present work, the effects of charge density of montmorillonite (Mt) on the hydration characteristics of its interlayer spaces, particularly the siloxane surface, were studied using classical molecular dynamics (MD) simulations. Four Mt. models with various octahedral charges are established, and these charges are compensated with tetramethylammonium cation (TMA). The simulation results showed that water molecules within the hydration layer of siloxane surface will donate hydrogen atoms to form H-bond with the surface oxygen atoms, while those surrounding TMA only slightly have their oxygen atoms point towards TMA. In addition, water molecules prefer to first hydrate the siloxane surface and then the TMA as the water content increases. These findings indicate that water molecules have stronger hydration interaction with siloxane surface than with TMA, and TMA can be ideal counterbalance cation in terms of studying the hydration characteristics of siloxane surface. Charge density can significantly influence the hydration of TMA-Mt. Although increasing charge density will not lead to the formation of stronger H-bond (i.e., no obvious reduction of H-bond length) between water molecules and siloxane surface, water molecules are more likely to be drawn to the siloxane surface and form more H-bonds between them. Subsequently, the hydration energy increases and the mobility of water molecules decreases as the charge density rises. These findings show that charge density can evidently influence the hydrophobicity of siloxane surface, which may further influence its interaction with organic species, e.g., the adsorption of organic contaminants.

    更新日期:2018-06-03
  • Assessment of the effect of mineralogy on the geotechnical parameters of clayey soils: A case study for the Orta County, Çankırı, Turkey
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-09-19
    Haluk Akgün, Asuman Günal Türkmenoğlu, Arzu Arslan Kelam, Karim Yousefi-Bavil, Gökalp Öner, Mustafa Kerem Koçkar

    The purpose of this study is to investigate and relate the geotechnical parameters with the mineralogical properties of the Miocene and Plio-Quaternary (Pliocene to Quaternary) lacustrine and fluvial sediments, particularly clayey soils in the Orta County, Çankırı. The study area is located about 110 km northeast of Ankara which is the capital city of the Republic of Turkey and Orta is a small county of Çankırı. The study area is a structural depression in the northern part of the Orta plain which is filled by fault-controlled continental sedimentation. In order to correlate the geotechnical and mineralogical characteristics and to establish a relation between these properties, comprehensive geotechnical laboratory studies have been performed. For correlation purposes, disturbed and undisturbed soil samples were collected from twenty-two locations of the study area. On these samples, mineralogical (i.e., methylene blue absorption, specific surface area determination, X-ray powder diffraction (XRD) and scanning electron microscope (SEM-EDAX)) analysis and geotechnical (i.e., sieve analysis, hydrometer, Atterberg (consistency) limits, oedometer and swelling) tests were implemented. By the aid of the statistical analysis, cross-correlation of the soil properties was established by the regression analyses performed. In particular, the plasticity index was correlated with cation exchange capacity, specific surface area, clay content, percent of fines, smectite and smectite/kaolinite ratio (SKR). There was a direct relationship between PI and smectite percentage as well as between PI and SKR. Additionally, the liquid limit was correlated with the clay content and the effect of the specific surface area on the swelling characteristics was studied. The effects of the mineralogical properties of the Orta clays together with the geological history on geotechnical parameters were investigated by considering the relationships mentioned. The results of the study revealed that the mineralogical characteristics had a significant effect on the geotechnical behavior of clayey soils of the Orta County which was demonstrated by regression analyses. Finally it was identified that the geotechnical properties of clayey soils can be approximated and more reliably determined if the mineralogical character and composition of clay is accurately investigated and well developed.

    更新日期:2018-06-03
  • Adsorption of ammonium by different natural clay minerals: Characterization, kinetics and adsorption isotherms
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-11-11
    Aref Alshameri, Hongping He, Jianxi Zhu, Yunfei Xi, Runliang Zhu, Lingya Ma, Qi Tao

    This research presented six natural clay minerals (NCM) evaluated for the effectiveness of NH4+ adsorption from aqueous solution. For the first time, the NH4+ adsorption capacities of kaolinite, halloysite, montmorillonite, vermiculite, palygorskite, and sepiolite were examined and compared in the same study. All the NCM were fully characterized by XRD, SEM/EDS, XRF,FTIR, CEC, zeta potential and nitrogen adsorption-desorption isotherms to better understand the adsorption mechanism-property relationship. Adsorption kinetics showed that the adsorption behavior followed the pseudo-second-order kinetic model. The adsorption isotherms fitted by the Langmuir model illustrated that among all the NCM studied, vermiculite (50.06 mg/g) and montmorillonite (40.84 mg/g) showed the highest ammonium adsorption capacities. Our results revealed that the cation exchange is the main mechanism for the NH4+ adsorption. Additionally, negatively charged surface, water absorption process and surface morphology of NCM might also contribute to the high adsorption capacity for the NH4+. The maximum adsorption capacities for all NCM were rapidly obtained within 30 min with a dosage of 0.3 g/25 mL at pH of 7. The results illustrated that the NCM have significant potential as economic, safe and effective adsorbent materials for the NH4+ adsorption from the aqueous solution.

    更新日期:2018-06-03
  • 更新日期:2018-06-03
  • Preparation and characterization of a granular bentonite composite adsorbent and its application for Pb2+ adsorption
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2017-12-29
    Wei Mo, Qiuzhi He, Xiujuan Su, Shaojian Ma, Jinpeng Feng, Zhenli He

    Bentonite is an important clay for preparation of adsorbents for potential treatment of industrial effluents. However, due to its natural occurrence as fine particles and swelling after moisture absorption, bentonite is difficult to be separated from the liquid for regeneration purpose, which limits its application in effluent treatment. In this study, two different bentonite-polypropylene composites were synthesized, i.e., with and without pore-enlarging treatment. They both showed strong ability to resist hydraulic agitation damage with a small breakage rate in water. The obtained results from SEM and XRD characterization revealed that the compounding of bentonite with the polypropylene was a physical process, and the structural characteristics of bentonite particles were maintained in the new products. The granular composite adsorbents were effective in removing Pb2+ in aqueous solution. The suggested pore-enlarging treatment was verified as a successful operation to increase greatly the adsorption rate of contaminants on the granular bentonite composite.

    更新日期:2018-06-03
  • Evaluation of a sand bentonite mixture as a shaft/borehole sealing material
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-01-05
    Haluk Akgün, Mustafa K. Koçkar

    The mechanical and hydrological characteristics of compacted sand bentonite mixtures with bentonite contents ranging from 5 to 40% were investigated in the laboratory in order to assess their use as a waste isolation material and to select an optimum sand bentonite mixture. Laboratory tests included compaction, compaction permeability, unconfined compression and direct shear tests which led to a recommendation to select a mixture with a bentonite content of 30% for the isolation of underground geological waste disposal repositories. This study complements the previous studies of the authors of this manuscript by determining the mechanical and hydrological properties of sand bentonite mixtures that possess bentonite contents > 30% to determine the geotechnical properties (i.e., unconfined compressive strength, Young's modulus, cohesion and angle of internal friction) and the mechanical behavior of these relatively high levels of bentonite mixtures for the first time in the literature.

    更新日期:2018-06-03
  • Preparation and characterization of the eco-friendly chitosan/vermiculite biocomposite with excellent removal capacity for cadmium and lead
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-01-05
    Liya Chen, Pingxiao Wu, Meiqing Chen, Xiaolin Lai, Zubair Ahmed, Nengwu Zhu, Zhi Dang, Yingzhi Bi, Tongyun Liu

    The chitosan/vermiculite biocomposite (CTS-VMT) was synthesized successfully with epichlorohydrin (ECH) cross-linking agent and used to remove cadmium and lead from the aqueous solution. CTS-VMT was characterized by FTIR, SEM, BET, TG-DTG, zeta potential and XPS. The effects of critical parameters including solution pH, contact time, initial heavy-metal concentration and adsorbent regeneration were investigated. Besides, adsorption mechanisms were also researched. The results indicated that chitosan molecule cannot intercalate into the interlayer space but cross link on the external surface of VMT. The maximum adsorption capacities for Cd(II) and Pb(II) were 58.48 mg g− 1 and 166.67 mg g− 1 at pH 4, respectively. The adsorption process fitted well the pseudo-second-order model and the adsorption isotherms could be correctly simulated by the Langmuir isotherm model. The zeta potential analyses put forward that electrostatic attraction existed in the adsorption process between the metal cations and CTS-VMT. However, the principal mechanism for adsorption on CTS-VMT was chelation according to the kinetic study and XPS analyses. Moreover, the desorption experiments revealed the prepared adsorbent tended to be regenerated by using HCl and the removal rations for four cycles were all > 90%. Therefore, the synthesized CTS-VMT in this study has the potential to be utilized as an eco-friendly adsorbent for removing Cd(II) and Pb(II).

    更新日期:2018-06-03
  • Comparison of organo-sepiolite modified by different surfactants and their rheological behavior in oil-based drilling fluids
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-01-06
    Jianle Weng, Zhijin Gong, Libing Liao, Guocheng Lv, Jianjie Tan

    Sepiolite modified by surfactants has been used in adsorption, catalysts, etc. While few studies focus on organo-sepiolite (OSep) which is used in oil-based drilling fluid. In this paper, a kind of cationic-anionic organo-sepiolite (CA-OSep) was prepared to be applied in oil-based drilling fluids. The structure and properties of OSep were characterized by X-ray diffraction, FTIR spectrum, thermal analysis and surface contact angle (SCA) analysis. The effect of dosage and chain length of surfactants, and the ratio of cationic to anionic surfactants on OSep were discussed as well as the rheological properties of OSep/diesel system. Cationic surfactant of long chains had better adhesion to the surface of sepiolite than surfactants of short chains. Compared with cationic organo-sepiolite (C-OSep), CA-OSep has an advantage in thermal stability. The apparent viscosity, plastic viscosity and yield value of oil-based drilling fluids with OSep as additives were further studied at different temperatures. Results indicated that organic surfactants had been adsorbed on the surface of sepiolite, and the CA-OSep had higher surface polarity and better thermal stability in 5# diesel oil than C-OSep. CA-OSep presented a new kind of potential rheological control additive for oil-based drilling fluids, and would exhibit excellent thermal stability.

    更新日期:2018-06-03
  • Adsorption of linuron by an Algerian palygorskite modified with magnetic iron
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-24
    Lala Setti Belaroui, Affaf Ouali, Abdelkader Bengueddach, Alberto Lopez Galindo, Aránzazu Peña
    更新日期:2018-06-03
  • 更新日期:2018-05-31
  • An experimental investigation on the effect of thixotropic aging on primary and secondary compression of reconstituted dredged clays
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-05-30
    Azmayeen Rafat Shahriar, Rowshon Jadid

    Dredged clay is often undesirable as a foundation soil layer since it undergoes large deformation with time. In addition, the space constraint due to ever-growing population might require to utilize the dredged-fill reclaimed lands. As such, an effort has been taken in this study to characterize the deformation behavior of dredged clay. To this end, the one-dimensional incremental load oedometer tests were administered on three reconstituted dredged clays. Samples were prepared at a moisture content ranging from 0.54–1.27 times the corresponding liquid limits. To observe the effect of thixotropic aging, prepared samples were subjected to three aging periods, such as 10 days, 30 days and 90 days. At a particular moisture content, with the increase of aging period, yield stress was observed to be increased. A unique relationship was established between yield stress ratio and initial moisture content incorporating the aging time. Compression index, Cc increases linearly as the void ratio at yield stress increases. However, Cc decreases as the yield stress increases, the decrease being rapid when the yield stress is below 7.5 kPa. Secondary compression index, Cα increases as the consolidation pressure increases, reaches a peak value and decreases thereafter. At higher initial moisture content, the secondary compressibility of dredged clays increases. Irrespective of the type of the clay, the relationship between Cα and Cc is linear in the considered stress range and time. The slope of the linear relationship (Cα/Cc) is higher for thixotropically aged clays compared to the unaged ones, indicating high secondary compressibility due to thixotropic effects.

    更新日期:2018-05-31
  • Alteration of olivine in vulcanic rocks from Trindade Island, South Atlantic
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-05-07
    A.C.C. Mateus, A.F.D.C. Varajão, F.S. Oliveira, C.E. Schaefer

    The alteration of olivine (forsterite) phenocrysts in three soil profiles that were developed on similar pyroclastic rocks from Trindade Island, at different altitudes and degree of development, were investigated in this study. Optical microscopy, Electron Probe Microanalysis (EPMA), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Differential Thermal and Thermogravimetric Analysis (DTA-TGA) were used to determine the mineralogical, micromorphological and geochemical transformations resulting from the alteration process. Micromorphological analyses showed fractured phenocrysts of colorless olivines with high relief at plane polarized light. These crystals are euhedral and irregularly shaped, and distributed in a dark reddish brown matrix constituted by pyroxenes, magnetites, ilmenites, kaolinite, hematite and anatase. At crossed polarized light, the olivine phenocrysts display a rim of reddish brown material in the fractures and in the borders that extinguishes parallel to their extinction direction. This reddish brown material appears to invade the crystal progressively until a complete replacement towards the top of the soil profile of higher altitude and degree of development. The olivine was identified as forsterite type and the reddish brown material has a chemical composition of Si, Fe, Mg, Al, Ca, Na, K, Mn and Ti, with predominant and variable contents of Fe, Si and Mg. The chemical composition and optical features are consistent with that found in iddingsites which may form through the incipient alteration of olivines due to the oxidation of ferrous iron to ferric iron, and with the coordination of magnesium with hydroxyl groups. The microscopic features of olivine did not allow us to identify any previous alteration by either deuteric or hydrothermal processes. However, the advance of the alteration towards the soil profile, leaving only relicts of olivine crystals or reaching their total transformation in the upper horizons, shows that weathering is the main process of iddingsite formation. This finding is corroborated by the presence of greater alteration of olivine crystals in the topmost soil at the highest altitude on the same lithology.

    更新日期:2018-05-08
  • Laboratory research on the influence of swelling clay on the quality of borehole cementing and evaluation of clay-cutting wellbore tool prototype
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-05-04
    Mateusz Kmieć, Bartłomiej Karpiński, Michał Antoszkiewicz, Marek Szkodo

    Swelling clay phenomenon is frequently observed during oil and gas drilling operations and has a significant impact on the quality of cementing procedure. Certain types of clayey minerals increase their volume in contact with water-based drilling fluids. After drilling is completed, borehole remains unsupported and filled with water-based drilling fluids for several hours, before a casing string is inserted and secured with cement. In the period of time between completing the drilling and inserting the casing string the clay can expand hindering proper cementing or blocking the casing string in a wellbore. Filling the annular space between a casing pipe and wellbore walls with cement is crucial for further exploitation of a well. An improper performance of displacement work (primary cementing) may cause both financial losses and environmental damage. The aim of this study is to describe the impact of distorted annular space geometry on cement sheath quality and to examine the possibility of improving the distorted geometry with a prototype wellbore tool. The tool was designed to be mounted as a first pipe section on the casing string (cementing shoe/reamer shoe). Two test stands were designed and constructed. The first one simulates the well cementing process, while the second one simulates the downward movement of the casing pipe in the well (run in hole process) drilled in expansive clay. Six distorted annular space sections were cemented using the first test stand. The sections were scanned with μXCT (computed micro-tomography) to locate discontinuities in the cement sheath. This research has confirmed an adverse influence of annular space obstructions on the cement sheath quality, thus the necessity of removing them before cementing. The obstructions can be removed by means of newly designed clay cutting wellbore tool. Therefore, the prototype of such a tool was tested on the second test stand. The experiment allowed to evaluate an influence of a swollen clay obstruction on the force needed to push the prototype tool through the obstruction. The same experiment was conducted with a standard cementing shoe in order to obtain comparative data. Hole geometry improvement, ability to fragment and remove clay cuttings have been observed. The research has confirmed that the prototype tool efficiently improves the borehole geometry and, consequently, improves the cement sheath quality.

    更新日期:2018-05-04
  • Adsorption of the tallow amine ethoxylate surfactant Ethomeen T/15 on montmorillonite
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-04-14
    Ana Borrego-Sánchez, Eulalia Gómez-Pantoja, Esmeralda Morillo, Tomás Undabeytia, C. Ignacio Sainz-Díaz

    The use of biocompatible surfactants is interesting to increase the properties of clay minerals in an environment-friendly process of charge capacity of organics. The adsorption of the surfactant Ethomeen T/15 in the interlayer space of montmorillonite was studied experimentally and computationally. Different proportions of surfactant, water and phyllosilicate were explored. Calculations at molecular level were performed using forcefields based on empirical interatomic potentials. The surfactant is likely to be adsorbed within the montmorillonite interlayer space forming hydrogen bonds between the H atoms of surfactant and the basal tetrahedral O atoms of the montmorillonite interlayer surface. These hydrogen bonds and the electrostatic interactions between cations and phyllosilicate surface are the main driving forces of the adsorption. Molecular dynamics simulations have indicated several possible conformations of the surfactant molecules in the interlayer space. The combination of molecular modeling, thermal analysis, Fourier transformed infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) has allowed the interpretation of this adsorption process.

    更新日期:2018-04-25
  • Mg-Zn-Al LDH: Influence of intercalated anions on CO2 removal from natural gas
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-27
    A.A.-E. Sakr, T. Zaki, O. Elgabry, M.A. Ebiad, S.M. El-Sabagh, M.M. Emara

    In this study, three components Mg-Zn-Al LDH were synthesized by microwave assisted homogenous precipitation using urea hydrolysis. The physicochemical properties of the prepared solids were evaluated using XRD, FTIR, elemental analysis, surface characterization measurements, and electron microscope. The results indicated the formation of the layered structure containing the three metals in one phase. By controlling the synthesis condition, carbonates as well as nitrogen containing anions were intercalated within the interlayer space of the LDH structure. The type of the nitrogenous species depended on the type and concentration of M (II) cation. The nitrogen adsorption-desorption isotherms were found to be type IV. The specific surface area decreased with increasing zinc content. However, the high specific surface area could be related to inter-particle agglomeration. The TEM images indicated the presence of nanoparticles. The particle size was affected by the concentration of zinc content. The particles of the smallest size (~14–25 nm) were detected in Mg-Zn-Al LDH (Mg:Zn molar ratio = 1:3). The amorphous mixed oxides (LDO) were obtained after the thermal treatment of the as-synthesized LDH at 550 °C. The abilities of the as-synthesized Mg-Zn-Al LDH materials and corresponded LDO to capture carbon dioxide from methane stream were tested using dynamic flow system technique at the ambient conditions of temperature and pressure. The results indicated that the presence of nitrogen containing anions in MgZn(25:75)Al LDH enhance the CO2 adsorption capacity (3.55 mmol/g) relative to its corresponded oxide (3.03 mmol/g).

    更新日期:2018-03-28
  • Study on viscoelastic behaviors of bentonite/nitrile butadiene rubber nanocomposites compatibilized by different silane coupling agents
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-15
    Xin Ge, Zhijian Zhang, Huitao Yu, Bangwen Zhang, Ur Ryong Cho

    The influences of bentonite and different silane coupling agents (SCA) on the viscoelastic properties of nitrile butadiene rubber were studied in this work. The silane coupling agents compatibilized bentonite/nitrile butadiene rubber nanocomposites were fabricated by a novel green method. The viscoelastic behaviors of the nanocomposites and their vulcanizates were explored using a rubber processing analyzer (RPA) in the modes of strain sweep and frequency sweep. Storage modulus (G′) and elastic torque (S′) of nitrile butadiene rubber increased significantly with the incorporation of bentonite. In the SCA applied in this work, mercaptopropyltrimethoxysilane (MPTMS) contributed to high storage modulus (G′) of the nanocomposites because of thorough exfoliation of bentonite and short sulfur bonds formed during curing process. Meanwhile, multi-sulfur bonds in bis-[3-(triethoxysilyl)propyl] tetrasulfide (TESPT) and reversible interactions from [3-(2-aminoethylamino)propyl] trimethoxysilane (AEAPTMS) resulted in lower storage modulus of the cured nanocomposites.

    更新日期:2018-03-16
  • Chemically modified kaolinite nanolayers for the removal of organic pollutants
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-14
    Qiang Zhang, Zhaoli Yan, Jing Ouyang, Yi Zhang, Huaming Yang, Deliang Chen
    更新日期:2018-03-15
  • Synthesis and characterization of PMMA and organic modified montmorilonites nanocomposites via in situ polymerization assisted by sonication
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-13
    Bruna Rosa Prado, Julio Roberto Bartoli

    A variety of organo-modified montmorillonite (OMMT) and poly(methylmethacrylate) (PMMA) nanocomposites (CPN) were synthetized by in situ polymerization in a chloroform solution under probe sonication at clay loadings of 3 mass%. A factorial experimental design was used to study the effects of the synthesis variables: Flory-Huggins (F-H) interaction parameters between PMMA and clay organomodifier (three grades of OMMT) and sonication energy (26.0 kJ, 30.3 kJ and 34.6 kJ), aiming clay dispersion at nanoscale levels into the polymeric matrix and improvements in CPN properties. The distinct surfactant side groups of commercial OMMT were: hydroxyl (C30B), aryl (C10A) or alkyl (C25A), considering their similar interlayer space. Multiple techniques of analysis to evaluate the level of clay dispersion were used. Small-amplitude oscillatory shear rheology (SAOS) indicated a high level of clay dispersion for the PMMA/C25A CPN and a tendency to form a percolated network structure from the low shear thinning exponent nω of complex viscosity, either at low (nω = −0.97) or high (nω = −0.83) sonication energy. However, the rheological results showed a low level of clay dispersion for PMMA/C10A (nω = −0.70) and PMMA/C30B (nω = −0.40). The F-H interaction parameter was the statistically significant factor for the shear thinning exponent nω response. X-ray diffraction (XRD) of CPN exhibited no discernible reflections for PMMA/C25A-26 kJ and PMMA/C10A-30.3 kJ CPN, suggesting that a high level of clay dispersion was achieved. Transmission electronic microscopy (TEM) images of PMMA/C25A-36.4 kJ and PMMA/C30B-26 kJ CPN showed exfoliated/intercalated and intercalated morphologies, respectively. Thermogravimetry presented a significant increase in PMMA chain scission temperature of up to 82 °C for all CPN when compared to pristine PMMA. The UV–visible transmittance of PMMA/C25A-26 kJ CPN showed to be around 4.5% lower in comparison with pristine PMMA. The CPN refractive index showed a slight reduction, which could even candidate them for new materials in optical electronic devices. The improvements in the verified properties for PMMA/C25A CPN were attributed to the lower F-H interaction parameter of C25A alkyl surfactant with chloroform when considering the others OMMT side groups. The chemical affinity of the alkyl chain to the chloroform could contribute to the diffusion of the solvent/monomer solution into the interlayer space of the clay, prior to polymerization, and then the polymer chain growth to push the layers apart.

    更新日期:2018-03-13
  • Effect of optimum compaction moisture content formulations on the strength and durability of sustainable stabilised materials
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-09
    Mohamad Nidzam Rahmat, Norsalisma Ismail

    The achievement of Optimum Compaction Moisture Content (OCMC) of clay soil plays an important role in compaction as well as the durability and strength of compacted soil. This is due to its effect on the structure and orientation of the clay soil particles. Most researchers on stabilised systems involving soils and/or industrial waste by-product additives for applications in roads and buildings are faced with the problem of how to approach the establishment of OCMC, when the complex mixtures involved. This paper reports on the laboratory investigation of theoretical methods of two different approaches to establish the OCMC in the stabilisation of clay soil involving multi-binary binder in cementitious binder system. Furthermore, this research also explores the use of an industrial by-product, Pulverized Fuel Ash (PFA) as partial target material and ground granulated blastfurnace slag (GGBS), with a view to reducing the reliance on the traditional cementitious binders, such as lime and/or Portland Cement (PC), in stabilising Lower Oxford Clay (LOC) soil combining with PFA at 50:50 ratio. LOC + PFA was stabilised both in conventional manner using Lime and PC as control and using sustainable binders incorporating GGBS. The results show that there was no one particular approach to the establishment of the optimal compaction moisture content for best strength development and durability. The best approach being dependent on the period of curing, stabiliser content and whether GGBS was blended with Lime or with PC. Of the various stabilisers studied, the highest strength magnitudes were however recorded with LOC-PFA stabilised using the blended binders incorporating GGBS. For all 7, 28 and 56 days of curing periods, the PC-based stabilisers were observed to be less sensitive to the different approaches to compaction moisture content, relative to the lime-based systems.

    更新日期:2018-03-11
  • 更新日期:2018-03-11
  • Identifying the differences between clays used in the brick industry by various methods: Iron extraction and NMR spectroscopy
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-09
    Julie Peyne, Ameni Gharzouni, Isabel Sobrados, Sylvie Rossignol
    更新日期:2018-03-11
  • Reprint of ZnO/sepiolite heterostructured materials for solar photocatalytic degradation of pharmaceuticals in wastewater ☆ ☆☆
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-09
    M. Akkari, P. Aranda, C. Belver, J. Bedia, A. Ben Haj Amara, E. Ruiz-Hitzky
    更新日期:2018-03-11
  • Hyperspectral remote sensing for mapping and detection of Egyptian kaolin quality
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-06
    Mahmoud E. Awad, Reda Amer, Alberto López-Galindo, Mahmoud M. El-Rahmany, Luis F. García del Moral, César Viseras

    This study aims to use spectral analysis and hyperspectral Hyperion remote sensing images of the Egyptian Abu Zenima Carboniferous and Cretaceous kaolin deposits, located in West-Central Sinai Peninsula, for mapping the spatial distribution of their qualities determined by their mineralogical and geochemical parameters. Mineral quantification has been made by X-ray diffractometry and chemical analysis, and kaolinite structural order-disorder degree was measured by mean of the Hinckley (HI), Stoch (IK) and Liètard (R2) indices. The geochemical characteristics classified the studied samples into ferruginous and non-ferruginous deposits. The mineralogical composition discriminated the studied sample grades into kaolin (>75% kaolinite), silty kaolin (75–50% kaolinite) and kaolinitic siltstone (<50% kaolinite). Abu Zenima kaolin quality is mainly influenced by quartz and Fe-Ti minerals contents. The Carboniferous kaolin samples are characterized by ordered kaolinite (HI or R2 > 1 and IK < 0.7), while the Cretaceous kaolins exhibited mainly disordered kaolinite (HI or R2 < 1 and IK > 0.7). Five EO-1 Hyperion Level 1 GST radiometrically and geometrically corrected images of April and May 2011 were used to identify the spatial distribution of Carboniferous and Cretaceous kaolin grades and the structural characteristics of kaolinite. The position, depth, full-width-half-maximum and 22SP-Index of the absorption features were calculated for the continuum-removed spectra in the range 350–2500 nm. Prominent absorption features spectra occur around ~1400, ~1900, ~2200 and 2300 nm, and there are shifting and changes in their position and morphology with the kaolinite richness and the structural order-disorder degree. Spectral Angle Mapper (SAM) supervised classifications proved successfulness for identifying the kaolinite spatial distribution on the Hyperion images using the measured spectra of kaolins with different qualities and structural order-disorders.

    更新日期:2018-03-07
  • Microbially induced palygorskite-sepiolite authigenesis in modern hypersaline lakes (Central Spain)
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-03-03
    Pablo del Buey, Óscar Cabestrero, Xabier Arroyo, M. Esther Sanz-Montero
    更新日期:2018-03-06
  • Calcium adsorption on clays: Effects of mineralogy, pore fluid chemistry and temperature
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-26
    Chinchu Cherian, Nikhil John Kollannur, Sandeep Bandipally, Dali Naidu Arnepalli

    The present study describes the calcium adsorption behavior of clays exhibiting distinct mineralogical composition. The adsorption characteristics were determined using conventional batch-equilibrium sorption method, and different theoretical models were applied to describe the equilibrium sorption isotherms. The variation in calcium adsorption capacity was determined as a function of clay mineralogy, temperature and pore fluid chemistry. Further, the thermodynamic parameters were also calculated to describe the nature of adsorption mechanisms. Significant variation in calcium adsorption potential was observed among the clays, primarily attributed to their mineralogical diversities and related unique surface charge properties. The adsorption density escalated with rise in calcium concentration, temperature and pH of the adsorption system. These observations can be attributed to surface charge modifications and mineral dissolution properties of the clays, which in turn resulted in higher electro-negativity of the clay surface and thereby enhancing the affinity for calcium ions.

    更新日期:2018-02-27
  • Interactions between kaolinite and phosphinate-based flame retardant in Polyamide 6
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-22
    M.A. Batistella, R. Sonnier, B. Otazaghine, C.O. Petter, J.-M. Lopez-Cuesta

    The interactions between kaolinite and a commercially available phosphinate-based flame retardant (Exolit® OP1311) were evaluated as flame retardant systems in Polyamide 6 (PA6). The thermal degradation and flammability of PA6 composites were studied by TGA and cone calorimeter tests. Characterizations were conducted using FTIR, EDX and XRD. Cone calorimeter results showed a reduction in peak heat release rate (pHRR) as a function of filler loading and type with a greater reduction for OP1311 containing composites. Interestingly, OP1311 can be partially substituted by kaolinite without detrimental effect on peak of release rate (pHRR) measured by cone calorimeter. FTIR, EDX and XRD analysis of cone calorimeter residues showed that kaolinite may trap some phosphorous compounds in condensed phase leading to the formation of a glassy structure on sample residue. To assess possible interactions between kaolinite and phosphinate, a controlled thermal degradation was carried out on kaolinite, OP1311 and kaolinite/OP1311 (50:50) blends. The residues were analyzed by EDX and XRD. Results showed that almost all phosphorous present in the initial sample remains in residue for Kaolinite/OP1311 blend versus only about 60% for OP1311 alone. Also, XRD results showed that during combustion, new crystalline phases can be formed in the sample when kaolinite is combined with OP1311. These results suggest that some interactions between both components may occur and could explain the observed fire behavior of the composites containing kaolinite and phosphinate.

    更新日期:2018-02-22
  • 更新日期:2018-02-22
  • Durable and fluorine-free superhydrophobic coatings from palygorskite-rich spent bleaching earth
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-22
    Penglin Zhang, Shuantao Dong, Bucheng Li, Xudong Wei, Junping Zhang
    更新日期:2018-02-22
  • Effective removal of emulsified oil from oily wastewater using surfactant-modified sepiolite
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-21
    Yunfei Li, Maoxin Wang, Dejun Sun, Yujiang Li, Tao Wu
    更新日期:2018-02-21
  • Mineral abundances quantification to reveal the swelling property of the black cotton soil in Kenya
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-20
    Shiding Miao, Jianzhou Shi, Yanbin Sun, Peng Zhang, Zhaopu Shen, Hongen Nian, Jinqiu Huang, Xueqiu Wang, Peiping Zhang
    更新日期:2018-02-21
  • Behavior of talc and mica in copper ore flotation
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-16
    Saeed Farrokhpay, Bulelwa Ndlovu, Dee Bradshaw

    Talc and mica are major gangue minerals in many base metal ores including sulfide ores. Talc is a naturally hydrophobic mineral, and therefore it is easily floatable. There have been many studies to overcome this problem, and depress talc with various reagents. In this study the flotation of a copper ore in the presence of talc and muscovite was studied. It was found that talc can affect copper flotation mainly via froth phase. The copper grade and recovery were affected in the presence of only 7% talc. On the other hand, muscovite influenced the pulp phase via affecting the pulp rheology. The copper flotation grade was reduced in the presence of high amount (30%) of muscovite due to the entrainment, but its effect on the copper recovery was negligible.

    更新日期:2018-02-16
  • Effect of surface property of halloysite on the crystallization behavior of PBAT
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-16
    Xujuan Li, Daoyong Tan, Lan Xie, Hongjuan Sun, Shiyong Sun, Ganji Zhong, Penggang Ren
    更新日期:2018-02-16
  • Anionic surfactant induced desorption of a cationic surfactant from mica
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-16
    Finian J. Allen, Chris L. Truscott, Rebecca J.L. Welbourn, Stuart M. Clarke

    The adsorption and desorption of a cationic surfactant, didodecyldimethylammonium bromide, from water onto a mica surface have been investigated using neutron reflectivity. The surfactant was observed to adsorb strongly as a bilayer that was tenacious to a sustained water wash, but on the addition of an anionic surfactant, sodium dodecyl sulfate, at its critical micelle concentration complete desorption was observed.

    更新日期:2018-02-16
  • Preparation of nanocomposites for the removal of phenolic compounds from aqueous solutions
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-16
    Karina Abigail Hernández-Hernández, Javier Illescas, María del Carmen Díaz-Nava, Sonia Martínez-Gallegos, Claudia Muro-Urista, Rosa Elena Ortega-Aguilar, Efraín Rodríguez-Alba, Ernesto Rivera
    更新日期:2018-02-16
  • Origin and paleoenvironmental significance of Fe single bond Mn nodules in the Holocene perialpine sediments of Geneva Basin, western Switzerland
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-15
    Branimir Šegvić, Stéphanie Girardclos, Giovanni Zanoni, Carlos Arbiol González, Tara Steimer-Herbet, Marie Besse
    更新日期:2018-02-16
  • 更新日期:2018-02-15
  • Influence of ZnO on the activation of kaolinite-based coal waste: Pozzolanic activity and mineralogy in the pozzolan/lime system
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-14
    R. García-Giménez, R. Vigil de la Villa, S. Martínez-Ramírez, L. Fernández-Carrasco, M. Frías

    One inconvenience presented by the thermal activation of kaolinite-based wastes is their low content of metakaolinite, a highly pozzolanic product listed in current standards for the manufacture of commercial cements. The addition of a chemical activator during the thermal activation process is a priority line of research to increase the reactivity of the recycled metakaolinite. In this paper, an additional chemical activator, ZnO, is studied and its effect on both pozzolanic properties and the evolution of mineralogical phases in the thermal activation of coal waste with a reaction time of up to 90 days in the pozzolan/lime system. To do so, activation temperatures of between 550 °C/650 °C were selected and additions of chemical activator (ZnO) in percentages of between 0.0% and 3.0% by weight of coal waste, because it is an activator with a positive effect on a 100% natural kaolinite. The results showed that the incorporation of ZnO inhibited the reactivity of the recycled metakaolinite and in consequence, the capacity of the metakaolinite to react with the surrounding lime; even more so when the content of added chemical activator was raised, albeit with some exceptions, in the samples activated at 550 °C and 650 °C with 0.5% of chemical activator. In none of the cases under analysis was the chemical activator able to improve the properties of the metakaolinite in comparison with the properties of the reference sample activated only with temperature. The hydrated phases that appeared in the pozzolanic reaction were tetracalcium aluminate hydrate, stratlingite, monosulfoaluminate hydrate and LDH (phyllosilicate/carbonate).

    更新日期:2018-02-15
  • Alginate clay hybrid composite adsorbents for the reclamation of industrial lean methyldiethanolamine solutions
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-14
    Anjali Achazhiyath Edathil, Priyabrata Pal, Fawzi Banat

    Alginate based clay hybrid composites were used as adsorbents for the removal of total organic acid anions (TOA) as heat stable salt (HSS) and heavy metal ions (chromium and iron) from industrial lean methyldiethanolamine (MDEA, 50 wt%) solvents. Spherical calcium alginate based hybrid (CAH) composites were prepared using three different filler clays such as sepiolite, montmorillonite and bentonite. To overcome the inherent iron leaching problem associated with clay minerals, an appropriate clay treatment method was utilized before preparing the hydrogel composite. The structure of the clay (before and after modification) and composites was characterized by XRD, whereas the sorption mechanism of the CAH hydrogel composites was conferred in combination with the results obtained from SEM, EDX and FTIR analyses. The effect of quantitative contributions of polymer, bead size, agitation speed, cross linker concentration, reaction time and filler weight% were studied using batch adsorption. The initial experiments confirmed that all the hybrid composites could superiorly separate HSS and heavy metal ions from lean MDEA solvents. 2.0 wt% clay containing composite hydrogels prepared by using 1 mm dropper in a CaCl2 solution of 1.5 M was found to have highest adsorption capacity. Thus, calcium alginate hybrid (CAH) composites showed efficient adsorption capacity for removing all the contaminants present in lean MDEA.

    更新日期:2018-02-14
  • A facile preparation of superhydrophobic halloysite-based meshes for efficient oil–water separation
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-13
    Danyi Guo, Jiahui Chen, Kun Hou, Shouping Xu, Jiang Cheng, Xiufang Wen, Shuangfeng Wang, Chaoyun Huang, Pihui Pi

    A superhydrophobic halloysite-based mesh was facilely prepared by spraying epoxy/hexadecyltrimethoxysilane-halloysite nanotubes (HDTMS-HNTs) on stainless steel mesh. The as-prepared mesh was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical contact angle meter (OCA). The HNTs modified by HDTMS not only enhanced surface roughness, but also endowed hydrophobicity of the mesh. The mesh, with a static water contact angle of 154° and a sliding angle of 1.5°, was applied to separate a series of oil-water mixtures, such as n-hexane-water, isooctane-water and petroleum ether-water, with high separation efficiency of over 98%. The mesh still kept separation efficiency approximately 98.5% even after 25 separation cycles for n-hexane-water mixture separation. More importantly, the mesh is durable enough to withstand heat, chemical and mechanical challenges, such as hot water, strong alkaline, strong acid and sand abrasion, and high hydrostatic pressure. The as-prepared mesh will be a promising material in oil-water separation, because of the simple, economical and easily scalable preparation method and the excellent separation performance in radical oil-water separation.

    更新日期:2018-02-13
  • Hydrothermal synthesis of zeolites using sanitary ware waste as a raw material
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-09
    Fátima García-Villén, Eduardo Flores-Ruíz, Cristóbal Verdugo-Escamilla, F. Javier Huertas

    Zeolites are extensively produced by hydrothermal treatment of different raw materials, such as kaolin. Sanitary ware (SW) is a kaolin-based ceramic ware usually found in sinks, urinals and bathtubs whose production is led by Spanish domestic clay product industry. SW production generates approximately 8% of solid waste in Spain, which increases landfills sizes and pose economic, social and technical problems. This study aims to evaluate the feasibility of solid waste of SW industry to produce zeolites once subjected to a conventional hydrothermal treatment during different times and temperatures. Ground SW was subjected to dissolution in a highly basic medium (NaOH 5 M) inside a Teflon-lined stainless steel reactors, at temperatures of 100, 150 and 200 °C for 1 to 30 days. X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize both the raw material and resultant mineral phases. Quartz and mullite present in SW transform into zeolites, as temperature and time increase. Mineral assemblage at 100 °C includes zeolite P, Na-faujasite and sodalite as major component and analcime, natrolite, and zeolite A as minor, which behave as metastable phases and their relative abundance depends on aging time. Analcime and cancrinite crystallization is favored by high temperature (150 °C to 200 °C) and increasing aging time produces analcime disappearance. Cancrinite is the dominant mineral after 30 days. Conventional SW waste is an optimal raw material for zeolites synthesis under high alkaline hydrothermal conditions. Combining time and temperature it is possible to drive crystallization towards a target phase.

    更新日期:2018-02-10
  • Smectite in bentonite: Near infrared systematics and estimation of layer charge
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-02
    C. Tsiantos, V. Gionis, G.D. Chryssikos
    更新日期:2018-02-04
  • Water adsorption and its impact on the pore structure characteristics of shale clay
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-01
    Dong Feng, Xiangfang Li, Xiangzeng Wang, Jing Li, Fengrui Sun, Zheng Sun, Tao Zhang, Peihuan Li, Yu Chen, Xu Zhang

    Water is considered ubiquitous within the shale reservoirs and mainly stored in the hydrophilic clay minerals. The water distribution characteristics and its effect on pore structure are important for the gas-in-place of shale systems. In this work, water vapor adsorption on montmorillonite (Mt), kaolinite (Kaol) and illite (Il) were performed to investigate the behaviors of water adsorption on shale clay. Subsequently, the moisture-equilibrated samples were conducted with N2 gas-adsorption techniques to investigate the effect of adsorbed water on pore structure characteristics, such as apparent pore size distribution (APSD), N2 BET specific surface area (N2-BET SSA) and pore volume (PV). The results show that the water uptake isotherms of our samples have the sigmoidal-shaped profiles and GAB model provides a good fit for the adsorption behavior. In addition, The APSD curves under different relative humidity (RH) conditions have validated the condensation effect and indicated that the small pores (approximately smaller than 5 nm) are blocked by the capillary water and will disappear on the APSD curves at RH of 98% while the large nanopores (> 5 nm) are covered with water film, these effects will lead dramatically decrease of N2-BET SSA. Taking Mt and Il samples as the examples, the N2-BET SSA has declined to 33.51% and 33.66% compared with the dry conditions when Sw approaches to 50%. Meanwhile, these effects also indicate that the gas storage for clay minerals is massively overestimating under dry condition, the contribution to methane adsorption might be negligible in the actual shale reservoir.

    更新日期:2018-02-02
  • 更新日期:2018-02-02
  • Rheological and filtration properties of clay-polymer systems: Impact of polymer structure
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-01
    Hafiz Mudaser Ahmad, Muhammad Shahzad Kamal, Mamdouh A. Al-Harthi

    In this study, the effect of polymer structure, the degree of hydrolysis, chemical structure of monomer in the backbone, and charge distribution of monomer groups on rheological and filtration properties of Bentonite (Bent)/polymer dispersions were assessed. Two different water-soluble polymers were employed to investigate the rheological and filtration properties of Bent/polymer dispersions. The polymers evaluated are a copolymer of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid (AM-AMPS) (P1) and a terpolymer of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and N-Vinylpyrrolidone (AM-AMPS-NVP) (P2). The objective of this work was to study the rheological and filtration properties of Bent/polymer dispersions in deionized and salt water at different temperatures (25 °C and 85 °C). The steady shear rheological data was fitted to Herschel-Bulkley model to compute rheological parameters like yield stress, consistency index, and flow behavior index. The incorporation of polymers in Bent dispersions improved the rheological properties of the Bent dispersions. Addition of electrolyte in Bent/polymer dispersions led to a slight decrease in the rheological properties of all developed dispersions. The Bent/P2 dispersion revealed superior rheological properties compared to the other Bent and Bent/polymer dispersions in both deionized and salt water. TEM analysis of Bent/polymer dispersions was carried out to study the morphology of dispersions. LP/LT and HP/HT filtration experiments were performed in deionized and salt water at 25 °C and 85 °C, respectively, and results showed that Bent/P2 dispersion had minimum filtrate volume and filter cake thickness compared to the Bent dispersion. The permeability of filter cakes was determined using Darcy's law and filter cake morphologies were studied using SEM analysis. The excellent rheological and filtration properties of Bent/P2 dispersion was attributed to the presence of NVP monomer group in P2 polymer, which is stable towards elevated temperatures and high salinity environments. The exceptional filtration and rheological properties of P2 polymer make it a suitable candidate for the development of high-performance drilling fluids.

    更新日期:2018-02-02
  • Halloysite nanotubes as a fine grained material for heavy metal ions removal in tropical biofiltration systems
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-01
    Andreas Aditya Hermawan, Jia Wei Chang, Pooria Pasbakhsh, Frank Hart, Amin Talei

    Biofiltration systems are landscape depressions or shallow basins used to slow and treat on-site stormwater runoff and are considered as one of the important components of a sustainable drainage system. Biofilters generally consist of two components: a filtration media which is sand-dominant and a top vegetated soil layer. The efficiency of a biofiltration system is normally assessed by two key parameters namely hydraulic conductivity and percentage removal of pollutants. In tropical areas like Malaysia where rainfall intensity is normally high, hydraulic conductivity of the biofiltration systems needs to be high enough to prevent ponding and possible flooding of the system. To date, several studies have been done on development and maintenance of such systems; however, few have studied such systems under tropical climates with heavy and intense rainfall which needs high hydraulic conductivity. The present study aims to identify proper soil filter media that not only can remove heavy metal ions efficiently but also has reasonably high hydraulic conductivity. For this, a soil column experimental set up was developed and the effectiveness of adding different fine grained materials such as fly ash, halloysite nanotubes (Hals) from two different origins (Imerys from NZ and HalloPure from I-Minerals, Idaho), and zeolite in sand-based soil media was assessed. To assure the validity of the results for each proposed filter media three replicates were prepared. The performance in removing heavy metal ions Fe(III), Mn(II), Cu(II), Zn(II), Ni(II), and Pb(II) was then evaluated for each soil composition using Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) test. Synthesized stormwater was used to provide consistency of pollutant concentration in experiments. The watering dosage was calculated based on hydrological data of a Malaysian catchment. Infiltration rate of each soil composition was also measured for further comparison. Results showed that increasing the percentage of fine materials can improve the heavy metal ions removal; however, the drawback would be significant decrease in infiltration rate. In general, Hals were found to fulfill the requirements for both high percentage removal and high infiltration rate compared to zeolite and fly ash. Moreover, the effect of aspect ratio, surface area, particle size and chemical composition of each fine material on its efficiency in heavy metal ions removal and infiltration rate were compared.

    更新日期:2018-02-02
  • 更新日期:2018-02-02
  • Novel Cu-Zn-Al catalysts obtained from hydrotalcite-type precursors for middle-temperature water-gas shift applications
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-02-01
    C. Lucarelli, C. Molinari, R. Faure, G. Fornasari, D. Gary, N. Schiaroli, A. Vaccari
    更新日期:2018-02-02
  • Functionalized halloysite nanotubes: Efficient carrier systems for antifungine drugs
    Appl. Clay. Sci. (IF 3.641) Pub Date : 2018-01-19
    Marina Massaro, Ambra Campofelice, Carmelo Giuseppe Colletti, Giuseppe Lazzara, Renato Noto, Serena Riela
    更新日期:2018-01-19
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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