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  • Deterioration of anion-adsorption abilities of layered double hydroxides synthesized in agarose gel
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-10
    Toshiyuki Hibino

    With the goal of improving solid–liquid separability in wastewater treatment, Mg-Al layered double hydroxides (LDH) were synthesized in agarose gel, and the resulting LDH-containing hybrid hydrogels were dried. The anion-adsorption abilities of the dried hydrogels were compared with those of LDH synthesized by means of a conventional constant-pH coprecipitation method at low supersaturation. A surprising result was found: the adsorption abilities of the dried hybrid hydrogels decreased with storage time, whereas the adsorption abilities of the LDH synthesized by the conventional method remained essentially constant. Further investigation revealed that the adsorption abilities of LDH synthesized by rapid mixing of aqueous Mg-Al and aqueous NaOH at high supersaturation (i.e., a method similar to that used to prepare the hybrid hydrogel) also decreased over time. Therefore, only LDH synthesized by coprecipitation at high supersaturation showed deterioration during storage time in anion-adsorption abilities. Observed results that accompanied the deterioration suggest that the decrease was due to the formation of pockets of mutually adjacent Al-occupied cation sites in the metal hydroxide layers of the Mg-Al LDH as a result of rapid mixing of the starting solutions. The presence of mutually adjacent Al-occupied sites is thought to be in instability due to mutual repulsion. This instability may have led to gradual decomposition of hydroxide moieties containing mutually adjacent Al-occupied sites together with interlayer anions of OH– and Cl− to form aluminum hydroxide or basic aluminum chloride, as well as to separation of nearby Mg(OH)2 moieties from LDH structure.

    更新日期:2020-01-21
  • Synthesis of CuNiSn LDHs as highly efficient Fenton catalysts for degradation of phenol
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-20
    Hao Wang; Zeng Zhang; Mengmeng Jing; Song Tang; Yan Wu; Wenshi Liu
    更新日期:2020-01-21
  • Effects of metakaolin on the mechanical and anticorrosion properties of epoxy emulsion cement mortar
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-11
    Jiandong Zuo; Huabing Li; Biqin Dong; Lei Wang

    Different sizes of Metakaolin (MK) were introduced into epoxy resin emulsion concrete mortar (EECM) to improve mechanical and anticorrosion properties. The effects of MK contents and sizes on the mechanical property, water absorption and chloride diffusion coefficient of EECM were studied respectively. Electrochemical tests were used to measure corrosion rate of samples. The results showed MK could greatly enhance the mechanical properties of EECM and more content MK obtained higher strength. The smaller size MK caused a slight decrease in strength due to poor dispersion in EECM. The water absorption and chloride diffusion coefficient of EECM both decreased significantly after adding MK. The smaller size of MK with 400-mesh and 1250-mesh made the water absorption reduced approximately 51%. The chloride diffusion coefficient of EECM also reduced with the increasing of MK content, especially the largest decline 73.1% corresponds to 1250-mesh MK. The data in polarization curves and EIS curves coincide with the above conclusion. The larger size of MK had the better anticorrosion effect on steel bar than that with smaller size. The corrosion situation on the surface of steel bars in mortar supplied the realistic anticorrosion effect.

    更新日期:2020-01-21
  • Can halloysite nanotubes be used to remediate zinc and lead-contaminated marine clay? A solidification/stabilization approach
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-14
    Endene Emmanuel; Lee Li Yong; Vivi Anggraini; Pooria Pasbakhsh

    This paper presents details of an experimental study employing the solidification/stabilization (S/S) technique to treat zinc (Zn) and lead (Pb) contaminated marine clay using two types of halloysite nanotubes [Matauri Bay (MB-Hal) and Dragonite (DG-Hal)]. To this end, an extensive laboratory-testing matrix was developed to investigate the effects of MB-Hal and DG-Hal contents (2, 4, 6, and 8% by mass of dry clay) and Zn and Pb concentrations (0.5, 1, and 2% by mass of dry clay) on the engineering properties of the clay, including, grading characteristics, Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), and secant modulus. Furthermore, X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were performed to gain an insight into the mechanisms responsible for the changes in engineering properties of the contaminated-stabilized clay. In addition, descriptive statistics were employed to better assess the effect of MB-Hal and DG-Hal treatments on the strength development. The findings reveal that 6% MB-Hal and DG-Hal content was optimal in improving the UCS for the uncontaminated clay. The level of Zn and Pb concentrations were found to have considerable influence on the engineering properties and microstructural characteristics of the stabilized clay. MB-Hal and DG-Hal improve the UCS of the contaminated clay up to 1% Zn and Pb concentrations; beyond that, the UCS decreased. A comparison of the two treatment materials reveals that DG-Hal treatment is more effective than MB-Hal treatment in improving the strength properties of the contaminated clay. SEM analysis further shows that the stabilization process modified the porous network of the clay as the pores of the clay were filled by the halloysite nanoparticles. The findings suggest that both MB-Hal and DG-Hal can be effectively used as sustainable S/S agents for contaminated soft soils.

    更新日期:2020-01-21
  • One-pot synthesis of the reduced-charge montmorillonite via molten salts treatment
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-14
    Qiuzhi He; Runliang Zhu; Qingze Chen; Yanping Zhu; Yixuan Yang; Jing Du; Jianxi Zhu; Hongping He
    更新日期:2020-01-21
  • Microstructural and mechanical properties of poly(sialate-siloxo) networks obtained using metakaolins from kaolin and halloysite as aluminosilicate sources: A comparative study
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-17
    Hervé K. Tchakouté; Sorelle J.K. Melele; Aubin T. Djamen; Cyriaque R. Kaze; Elie Kamseu; Charles N.P. Nanseu; Cristina Leonelli; Claus H. Rüscher

    This work focuses on the comparison between the mechanical and microstructural properties of poly(sialate-siloxo) networks based on metakaolins from halloysite and kaolin. Poly(sialate-siloxo) networks were prepared using three metakaolins as aluminosilicate sources. Sodium waterglass from rice husk ash and commercial sodium waterglass were used as chemical reagents. The obtained results showed that metakaolins from kaolins have plate shapes with coarse particle sizes whereas the one from halloysite has a spherical morphology and smaller particle sizes. The IR spectra of poly(sialate-siloxo) networks from calcined halloysite indicate the higher value of the wavenumber of the main band. The XRD patterns of all poly(sialate-siloxo) networks show the broad hump structure with higher intensity between 18 and 40°(2θ). The XRD patterns of poly(sialate-siloxo) networks show the band of the unreacted metakaolin at about 20.45°(2θ). This band is more pronounced on the XRD patterns of geopolymer cements from calcined halloysite. The obtained poly(sialate-siloxo) networks based on metakaolins from halloysite and kaolin have a compact, homogenous and denser microstructures. The compressive strength values of the poly(sialate-siloxo) networks using calcined kaolin are ranging from 58.43 to 66.52 MPa whereas those using calcined halloysite are between 72.29 and 88.50 MPa. The compressive strength values of poly(sialate-siloxo) networks using calcined halloysite are higher compared to those from calcined kaolin. The higher compressive strength values of the geopolymer cements from calcined halloysite could be attributed to the fine and spherical particle sizes of calcined halloysite. This implies that the shape and the fine particle sizes of the raw materials influence the properties of the poly(sialate-siloxo) networks. Metakaolin from halloysite can be used as an aluminosilicate source for producing poly(sialate-siloxo) network with higher mechanical properties.

    更新日期:2020-01-21
  • Optical properties of the europium (II) and (III) ions doped metal oxides obtained from sintering layered double hydroxides, and their fine structures
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-15
    Noriyuki Sonoyama; Keita Takagi; Satoshi Yoshida; Tomoki Ota; Patrick Dedetemo Kimilita; Yoshitaka Ogasawara
    更新日期:2020-01-21
  • State of compacted bentonite inside a fractured granite cylinder after infiltration
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-15
    Xia Bian; Yu-Jun Cui; Ling-Ling Zeng; Xiao-Zhao Li

    A small-scale mock-up test was carried out on a fractured hollow granite cylinder with compacted MX80 bentonite inside, to study the interaction between engineered barrier (compacted bentonite) and natural barrier (host rock with the presence of rock fracture). The swelling pressure and relative humidity of bentonite were monitored with respect to the position of the rock fracture during 349 days of infiltration. Herein, the variation of water content, dry density, suction and microstructure along bentonite column after dismantling were reported, focusing on the changes in the vicinity of the rock fracture, to evaluate the effect of the rock fracture on the swelling behaviour of compacted bentonite. Results showed that the presence of rock fracture disturbed the water content distribution, with a lower water content at a position closer to the fracture. A significant decrease in dry density was also observed in the vicinity of the rock fracture; the closer the positions to the fracture the larger the decrease of dry density. This decrease coincided with the reduction of swelling pressure recorded by the pressure sensors, suggesting the occurrence of rock fracture filling-up by bentonite. Further examination showed that when the soil suction was higher than 9 MPa, the decrease in dry density in the near field of rock fracture was mainly attributable to the increase in large pore porosity (>2 μm). This suggests that at this suction the mechanism involving intrusion of bentonite into the rock fracture with fracture width higher than the size of bentonite gains was related to the pushing effect under the swelling of bentonite behind. By contrast, when the suction became lower than 9 MPa, the bentonite gel formed from the exfoliation of clay particles might fill up the rock fracture with smaller aperture width.

    更新日期:2020-01-21
  • Effect of the acid activation on a layered titanosilicate AM-4: The fine-tuning of structural and physicochemical properties
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-15
    Maria N. Timofeeva; Galina O. Kalashnikova; Kristina I. Shefer; Elena A. Mel'gunova; Valentina N. Panchenko; Anatoliy I. Nikolaev; Antonio Gil
    更新日期:2020-01-21
  • AFM measurements of Hofmeister effects on clay mineral particle interaction forces
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-15
    Bo Feng; Hanyi Liu; Yingli Li; Xinmin Liu; Rui Tian; Rui Li; Hang Li
    更新日期:2020-01-21
  • Theoretical and experimental investigation on the intercalation of metformin into layered clay minerals
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-18
    Ediana Paula Rebitski; Margarita Darder; C. Ignacio Sainz-Diaz; Raffaele Carraro; Pilar Aranda; Eduardo Ruiz-Hitzky
    更新日期:2020-01-21
  • Adsorption of humic acid from aqueous solution by magnetic Zn/Al calcined layered double hydroxides
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-17
    Shaoxiu Li; Yuhe Yang; Su Huang; Zhifeng He; Changhui Li; Dongmei Li; Bohan Ke; Chan Lai; Qiuyi Peng
    更新日期:2020-01-21
  • Methane hydrate formation in the stacking of kaolinite particles with different surface contacts as nanoreactors: A molecular dynamics simulation study
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-09
    Yun Li; Meng Chen; Hongzhe Song; Peng Yuan; Dong Liu; Baifa Zhang; Hongling Bu
    更新日期:2020-01-11
  • Tuning the swelling and rheological attributes of bentonite clay modified starch grafted polyacrylic acid based hydrogel
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-08
    Suranjana Datta Chaudhuri; Arup Mandal; Ayan Dey; Debabrata Chakrabarty
    更新日期:2020-01-08
  • Hydrothermal synthesis of 11 Å tobermorite – Effect of adding metakaolin to the basic compound
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-08
    J. Schreiner; F. Goetz-Neunhoeffer; J. Neubauer; D. Jansen

    Different amounts and types of metakaolin were analyzed and applied for the hydrothermal synthesis of 11 Å tobermorite. All synthesized samples were investigated by means of powder XRD combined with Rietveld refinement. Al-substituted 11 Å tobermorite was successfully synthesized on the basis of a broad range of compounds characterized by a varying content of metakaolin. Katoite was present depending on the amount of supplied Al3+, which was determined by the dosage of metakaolin. Minor crystalline components included in the two types of metakaolin sources varied greatly in their reactivity under hydrothermal conditions. Despite a different degree of purity, the two types of metakaolin showed corresponding effects at moderate dosages but contrary effects at higher dosages as for the synthesis of 11 Å tobermorite. The domain morphology of tobermorite could be associated with Al3+ incorporation for low dosages of metakaolin represented by up to 2 wt.-% Al2O3 in the dry mix. By contrast, Al3+ affected tobermorite lattice parameters at equivalent and even at higher dosages with c reaching 22.95 Å at 12 wt.-% Al2O3 in the dry mix.

    更新日期:2020-01-08
  • The effect of benzothiazolium surfactant modified montmorillonite content on the properties of polyamide 6 nanocomposites
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-07
    Mohamed El Mehdi Mekhzoum; Marya Raji; Denis Rodrigue; Abou el kacem Qaiss; Rachid Bouhfid
    更新日期:2020-01-07
  • A novel multifunctional adsorbent synthesized by modifying acidified organo-montmorillonite with iron hydroxides
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-07
    Yixuan Yang; Runliang Zhu; Qingze Chen; Haoyang Fu; Qiuzhi He; Jianxi Zhu; Hongping He
    更新日期:2020-01-07
  • 更新日期:2020-01-07
  • A facile fabrication of Ag2O-Ag/ZnAl-oxides with enhanced visible-light photocatalytic performance for tetracycline degradation
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2020-01-03
    Jia-Chao Shen; Hong-Yan Zeng; Chao-Rong Chen; Sheng Xu

    A facile and low-cost method to prepare novel Ag2O-Ag/LDO photocatalysts was demonstrated, where the Ag2O/Ag nanoparticles were decorated on the ZnAl oxide (LDO) supports. The LDO supports were obtained by calcining their ZnAl layered double hydroxide precursor (LDH) at different temperatures. The structure, composition, morphology and optical and electrochemical properties of the as-prepared Ag2O-Ag/LDO were characterized using various techniques. Under visible light irradiation, the Ag2O-Ag/LDO showed higher photoactivity and stability of tetracycline (TC) degradation than pure Ag2O-Ag. Especially, the Ag2O-Ag/LDO5 (Ag2O-Ag/LDO calcined at 500 °C) had the most excellent photoactivity with the highest rate constant k (0.0242 min−1), suggesting that the photocatalytic activity depended on the calcination temperature. The enhancement of the photocatalytic performance was attributed to the formation of the heterostructure between Ag2O/Ag and ZnO, the strong visible-light absorption and outstanding separation efficiency of photoinduced electron-hole pairs under visible light irradiation.

    更新日期:2020-01-04
  • Growth of metastable phases during brick firing: Mineralogical and microtextural changes induced by the composition of the raw material and the presence of additives
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-30
    Giuseppe Cultrone; Francisco Javier Carrillo Rosua

    This paper studies the mineralogical and textural changes that take place during the firing in an electric kiln at 800, 950 and 1100 °C of brick samples made with or without additives. Samples were made with a clayey raw material which was mixed with either halite or calcined diatomite sludge and then fired. These samples were then compared with control samples made without additives. Different analytical techniques (X-ray fluorescence, thermogravimetric and differential scanning calorimetric analyses, X-ray diffraction, polarized optical microscopy and scanning electron microscopy) were used to reconstruct the changes that took place inside the bricks from a mineralogical and textural point of view, changes that are similar to those that take place in nature during pyrometamorphism. The carbonates decomposed and reacted with silicates to form gehlenite, diopside and wollastonite; the plagioclase was enriched in calcium and the quartz concentration fell; the clay minerals favoured the melting of the matrix and the appearance of mullite, and K-feldspar changed from microcline to sanidine. The extent of vitrification increased in line with the increase in the firing temperature. When halite was added, new silicates appeared earlier at lower firing temperatures and molysite was formed, while the most important mineralogical difference in the bricks made with added calcined diatomite sludge was the presence of cristobalite, a component of the sludge. It is interesting to observe that the newly-formed phases contain certain chemical elements that are not normally found in their standard chemical composition.

    更新日期:2019-12-31
  • Effects of halloysite content on the thermo-mechanical performances of composite bioplastics
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-28
    Lorenzo Lisuzzo; Giuseppe Cavallaro; Stefana Milioto; Giuseppe Lazzara

    The aim of this study is the design and preparation of Mater-Bi/halloysite nanocomposite materials that could be employed as bioplastics alternative to the petroleum derived products. The biocomposite materials at variable halloysite content (from 0 to 30 wt%) were prepared by using the solvent casting method. We investigated the mechanical behaviour and the thermal properties of the prepared nanocomposites in order to estimate their suitability as biocompatible packaging materials. The thermo-mechanical characteristics were correlated to the nanocomposites' morphologies, which were studied by Scanning Electron Microscopy (SEM). As a general result, the physico-chemical performances of Mater-Bi were improved by the presence of small amounts of nanotubes, which evidenced a homogenous distribution in the polymer matrix. The strongest enhancements of the thermal stability and tensile properties were achieved for Mater-Bi/halloysite 10 wt%. A further addition of nanotubes determined the worsening of both thermal stability and mechanical behaviour. The attained knowledge represents the starting step for the development of packaging films composed by Mater-Bi and halloysite nanotubes.

    更新日期:2019-12-29
  • A split-combination method for estimating the thermodynamic properties (Gfo and Hfo) of multicomponent minerals
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-26
    Xiaobin Li; Liqun Yang; Qiusheng Zhou; Tiangui Qi; Guihua Liu; Zhihong Peng

    To resolve the lack of Gibbs free energy and enthalpy thermodynamic data for multicomponent minerals, the concepts of cage and cage effect along with a split-combination estimation method are proposed in this paper. A ternary or greater complex oxide is completely split into free simple oxides, and then the oxides are combined stepwise by preliminary combination and advanced combination according to the principle of maximum energy change. A major cage forms in the preliminary combination, and the complex oxide reforms in advanced combinations by shared cage combination and/or invaded cage combination. Based on only the relative data of simple and binary oxides, the energy change in advanced combination can be estimated through cage effects, and the total energy change from simple oxides to the complex oxide can thus be obtained as the total of the energy changes for all of the individual steps. Compared with the thermodynamic data available for 60 minerals reported in references, the average relative errors of the estimated values are 0.33% and 0.39% for Gfo and Hfo, respectively. Therefore, the split-combination method seems to give reliable results for most cases, and it might be used to predict the standard Gibbs free energy and enthalpy of multicomponent minerals when those are unavailable.

    更新日期:2019-12-27
  • Clay and alunite-rich materials in painting grounds of prominent Italian masters – Caravaggio and Mattia Preti
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-20
    David Hradil; Janka Hradilová; Giancarlo Lanterna; Monica Galeotti; Katarína Holcová; Victory Jaques; Petr Bezdička

    Recently, the fine arts' research is increasingly carried out by non-invasive techniques, which do not require any sampling. However, some questions cannot be answered in this way. A typical example is the provenance analysis of the natural materials used in historical paintings. Another question is how much the provenance of the material is related to the provenance of the artwork itself (because of trade with pigments, painters' migration and their artistic preferences). Often, only painter's preference and intention are mentioned, and not economic factors and regional availability of the raw material. This is also the case of clay-based preparatory layers (grounds) on Caravaggio's paintings. In order to prove a connection of the ground composition with the place of the painting's creation, the painting grounds used by two prominent Baroque Masters Caravaggio and Mattia Preti have been investigated using X-ray powder micro-diffraction and Fourier transform infrared micro-spectroscopy in combination with micro-palaentological analysis. It was found that grounds applied by the same painter, but in two closely related regions – Italy and Malta, differ. While pottery clays were used in Italy, weathered Globigerina limestones were applied in Malta in combination with alunite-hematite material. It is the first time ever that such material has been identified as a main component in painting grounds.

    更新日期:2019-12-20
  • Polyol intercalation in copper substituted zinc hydroxide acetate and evaluation of its adsorptive role towards Congo red dye
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-20
    Sanjay Kumar Saroj; Sachin Pal; Rajamani Nagarajan

    The extent of incorporation of Cu2+for Zn2+ in layered zinc hydroxide acetate to convert it to a hydroxy double salt carried out following titrimetric experiments with KOH solution. The reflections present in the powder X-ray diffraction pattern became broad suggestive of incorporation of copper for zinc. Well defined weight-loss steps, in the thermogravimetric trace of zinc hydroxide acetate, became diffused with the inclusion of copper. The intercalation of various polyols (ethylene glycol, diethylene glycol, and propylene glycol)was performed successfully, exploiting the organophilic character of ZnCu hydroxide acetate. The interlayer spacing expanded for polyol intercalated samples, as indicated by their powder X-ray diffraction patterns.The FT-IR and Raman spectra of polyol intercalated samples confirmed their presence in the interlayer, and the samples showed enhancement in thermal stability. These samples showed mesoporosity and reasonably high surface area (128.6 m2/g). The role of ethylene glycol intercalated ZnCu hydroxy double salt as an adsorbent to remove harmful and carcinogenic CR dye molecules from aqueous solutions investigated. The physisorption process was majorly responsible for the effective removal of CR dye, following a pseudo-second-order kinetics.

    更新日期:2019-12-20
  • Clay/PVP nanocomposites enriched with Syzygium aromaticum essential oil as a safe formulation against Aedes aegypti larvae
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-20
    Adriana J. Santos; Lícia T.S. Pina; Juliana G. Galvão; Gabriela G.G. Trindade; Rafaela K.V. Nunes; Jeferson S. Santos; Cochiran P. Santos; Joyce Kelly M.C. Gonsalves; Ana Amélia M. Lira; Sócrates C.H. Cavalcanti; Roseli L.C. Santos; Victor H.V. Sarmento; Rogéria S. Nunes

    Clay-polymer composites represent the possibility to stabilize, protect volatile and easily oxidized compounds such as essential oils. Thus, the aim of this study was to develop an eco-friendly formulation based on bentonite/PVP nanocomposites to incorporate Syzygium aromaticum essential oil (SAEO) in for controlling Aedes aegypti larvae. The bentonite/PVP nanocomposites were prepared with different ratios 1:2, 1:1, 2:1 in both absence (INano) or presence of SAEO (NanoSAEO), and evaluated by X-ray diffraction (XRD), small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). Finally, larvicidal activity was performed. XRD indicated an intercalated structure because of the displacement of reflections at low angle range and an increase in INano interlayer space (d). After SAEO incorporation, the interlayer space (d) did not changed, therefore suggesting that SAEO may be associated to the nanocomposite-intercalated layers. SAXS also demonstrated the composite intercalated structure that in presence of SAEO induced a reflection displacement and change in the curve profile suggesting a structure transition to accommodate SAEO. This structure transition after SAEO incorporation was enough to shift the nanocomposite endothermic peak to lower temperatures (Tpeak = 68 °C) in DSC analysis. NanoSAEO demonstrated a LC50 of 27.34 ppm, while eugenol and SAEO presented 48.19 ppm and 40.74 ppm, respectively. Furthermore, SAEO incorporated in the nanocomposite was not harmful to non-target organisms, being not toxic up to 1000 ppm. Thus, bentonite/PVP nanocomposites containing SAEO is a promising formulation for controlling Aedes aegypti larvae.

    更新日期:2019-12-20
  • Clays and carbon nanotubes as hybrid nanofillers in thermoplastic-based nanocomposites – A review
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-18
    Olawale Monsur Sanusi; Abdelkibir Benelfellah; Nourredine Aït Hocine
    更新日期:2019-12-19
  • Adsorption of an iron(III)porphyrin onto a 2:1 Zn/Al-CO3 layered double hydroxide and its use as an oxidation catalyst with different counter ions: An experimental and DFT study
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-19
    Sérgio R. Tavares; Charles Carvalho; Karen M. Mantovani; Fernando Wypych; Shirley Nakagaki; Alexandre A. Leitão

    DFT calculations were employed in order to gain insight about the mechanism of the oxidation reaction catalyzed by anionic iron(III) porphyrin ([Fe(TSPP)Cl]4−) with different counter ions (H+ and Na+) immobilized onto Zn4Al2(OH)12(CO3).4H2O layered double hydroxide. The immobilization of these porphyrinates was modelled by the construction of a LDH slab and the CI-NEB method was used to obtain the reaction path of the H2O2 cleavage and the subsequent formation of the oxoiron species. The computational simulations predicted that the counter ion affects the energy barriers of the oxoiron species formation. On the experimental side, the solid catalysts were synthesized and their catalytic performances were tested for the oxidation reaction of cyclohexane. The experiments showed that the immobilization process of the catalysts led to a selectivity of alcohol formation compared to the catalysis in homogeneous media. Furthermore, the reaction yield of the iron(III) porphyrin with H+ was higher, confirming that the consideration of the counter ion for the catalyst is important for oxidation reactions.

    更新日期:2019-12-19
  • A new generation low-cost biochar-clay composite ‘biscuit’ ceramic filter for point-of-use water treatment
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-17
    Nhamo Chaukura; Robert Chiworeso; Willis Gwenzi; Machawe M. Motsa; Wisdom Munzeiwa; Welldone Moyo; Innocent Chikurunhe; Thabo T.I. Nkambule
    更新日期:2019-12-18
  • 更新日期:2019-12-13
  • Combined impact of selected material properties and environmental conditions on the swelling pressure of compacted claystone/bentonite mixtures
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-11
    M. Middelhoff; O. Cuisinier; F. Masrouri; J. Talandier; N. Conil

    Mixtures composed of 70% crushed Callovo-Oxfordian claystone and 30% MX80-bentonite are considered as materials, that could be used for backfilling a future radioactive waste repository in deep sedimentary rock formations. Their characterization is of interest, as the replacement of fractions of crushed claystone by bentonite enhances the chemo-hydro-mechanical performance of backfill. The materials are envisaged to be installed directly in the drifts and shafts by means of conventional compaction techniques. The hydro-mechanical behavior of materials containing expansive mineral phases, and especially their swelling behavior, is known to be significantly affected by the initial material properties and environmental and stress conditions. The present study aimed to assess the combined impact of variations in the material properties and environmental conditions, particularly the grain size distribution, dry density and saturating solution chemistry, on the swelling pressure of the mixtures, by conducting a comprehensive laboratory experimental program. The results revealed that the adjustment of the grain size distribution of employed bentonite enhanced the compaction behavior and, in turn, the swelling behavior of the mixtures. Generally, swelling pressures of mixtures were less affected by the employed saline and alkaline solutions than those of crushed claystone. The measured swelling pressures were exponentially related to the initial dry density of the expansive mineral phase, regardless of the grain size distribution. Based upon the finding that the expansive mineral phase being present in crushed claystone contributed to measured swelling pressures, a new approach was introduced to calculate the dry density of the expansive mineral phase in bentonites and their mixtures with non-expansive or less-expansive materials.

    更新日期:2019-12-13
  • Adsorption of iodate on nanosized tubular halloysite
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-12
    Wenbin Yu; Huifang Xu; Daoyong Tan; Yihang Fang; Eric E. Roden; Quan Wan

    Naturally occurring porous minerals as adsorbents for the remediation of environmental pollution has been one of the hot topics in environmental science and material science. In this study, the adsorption of iodate (IO3−) on two nanosized tubular halloysite samples (HBHal and SCHal, from Hubei and Sichuan Province, China, respectively) were investigated for the first time. To evaluate the impact of nanopore of halloysite on the adsorption of IO3−, chemically similar platy kaolinite was used for comparative studies in the batch experiments. The adsorption of IO3− on HBHal reached equilibrium within 36 h, and the adsorption kinetics and isotherm fitted the pseudo-second-order and Langmuir equation well, respectively. Both HBHal and SCHal exhibited high adsorption capability to IO3−, with distribution coefficients (Kd's) of 131.6 ± 14.6 and 126.6 ± 3.1 mL/g, respectively, which were >30 times higher than that for kaolinite (4.2 ± 2.3 mL/g). The specific surface area normalized Kd values on halloysite samples were >13.5-fold higher than that on kaolinite. In addition, halloysite had high selectivity to IO3−, and the adsorption capacities on the two halloysite samples were slightly affected by the concurrent anions, such as SO42−, NO3−, or ClO3−. It was proposed that the curved octahedral sheet caused geometry match between three oxygen atoms in the iodate and three OH above the vacant site of the octahedral sheet. This work also gave insight into the potential application of halloysite on the adsorption of radioactive iodate in natural and engineering environments.

    更新日期:2019-12-13
  • Influence of layer charge on hydration properties of synthetic octahedrally-charged Na-saturated trioctahedral swelling phyllosilicates
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-11
    Doriana Vinci, Baptiste Dazas, Eric Ferrage, Martine Lanson, Valérie Magnin, Nathaniel Findling, Bruno Lanson
    更新日期:2019-12-11
  • Excellent flame retardant and thermal insulated palygorskite/wood fiber composite aerogels with improved mechanical properties
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-10
    Xinyu Zhou, Huiran Jin, Tingting Xu, Jinbo Wang, Yong Zhu, Shijie Ding, Tao Hu, Shan Yun, Jing Chen

    Clay aerogels have many attractive properties, such as low thermal conductivities, good thermal stabilities and low flammability. But the generally weak mechanical property severely restrains their practical applications. Incorporation of polymers into clay aerogel could achieve desirable strength, unfortunately, the fire resistance or insulating properties were sacrificed to some extent. In this work, fire-resistant palygorskite/wood fiber composite aerogels with low densities were prepared by an eco-friend freeze-drying method. In the aerogels, palygorskite contents were up to 80 wt% while only a small amount of wood fiber were used as reinforced filler. The composite aerogel had an array of porous structure with intertwined palygorskite fibers as pore walls, which resulted in a low thermal conductivity of 0.033 W/mK. In addition, the composite aerogel exhibited good mechanical strength with the Young's modulus up to 4.7 MPa while the density was lower than 0.08 g/cm3. Overall, an outstanding combination of excellent machinability, thermal stability, high limiting oxygen index, and prominent flame-retardant properties has been achieved in the composite aerogels. This work represents a significant progress of porous materials development and makes the practical applications of clay-based aerogel insulators realistic.

    更新日期:2019-12-11
  • Chemical and biological evaluation of cross-linked halloysite-curcumin derivatives
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-09
    Marina Massaro, Paola Poma, Carmelo G. Colletti, Anna Barattucci, Paola M. Bonaccorsi, Giuseppe Lazzara, Giuseppe Nicotra, Filippo Parisi, Tania M.G. Salerno, Corrado Spinella, Serena Riela
    更新日期:2019-12-09
  • Palygorskite supported rare earth fluoride for photocatalytic nitrogen fixation under full spectrum
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-09
    Chengli He, Xiazhang Li, Xiaofan Chen, Sujuan Ma, Xiangyu Yan, Yuying Zhang, Shixiang Zuo, Chao Yao
    更新日期:2019-12-09
  • 更新日期:2019-12-06
  • A new catalytic composite of bentonite-based bismuth ferrites with good response to visible light for photo-Fenton reaction: Application performance and catalytic mechanism
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-06
    Guangtao Wei, Yanjuan Yang, Yunshang Li, Linye Zhang, Zongwu Xin, Zhongmin Li, Lili Huang
    更新日期:2019-12-06
  • 更新日期:2019-12-06
  • Failure modes for hydrated bentonite plugs used in well decommissioning operations
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-04
    Brian Towler, Duncan Hywel-Evans, Mahshid Firouzi

    This paper aims to theoretically investigate and characterize the failure mechanism of hydrated bentonite plugs, when used as a sealing material in wellbores. Using the proposed theoretical models, it was determined that when hydrated bentonite plugs failed due to friction at the walls, created by internal swelling pressure or through internal shear failure, the resulting failure pressure was linear with the plug height (H), coefficient of friction or internal shear strength, and inversely proportional to plug diameter (D). On the other hand, if the friction at the walls was created by plug weight then the failure pressure was a function of H2/D. However, in this case, the frictional strength increased parabolically with height, and, at reasonable plug heights, the frictional strength became greater than shear strength, and resulted in failure due to internal shear failure, which also made the failure pressure a function of H/D. This suggests that plug strength is usually a linear function of H/D. Moreover, the coefficient of friction and internal shear strength are dependent on final moisture content of the hydrated plug, the salinity of the hydration water, pressure, temperature and hydration time. The strength of a bentonite plug is inversely proportional the total volume by which it expands during hydration and takes in excess of 185 days to achieve this state. Plug strength decreased in saline water, although even at elevated concentrations sufficient strength remained to produce and adequate seal.From very limited data, shown here, Queensland bentonite, from the 5D zone of Amcol's Gurulmundi mine, appeared to have similar plugging strength as Wyoming bentonite.

    更新日期:2019-12-05
  • Peculiarities of the 5-fluorouracil adsorption on porous aluminosilicates with different morphologies
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-05
    Olga Yu Golubeva, Yulia A. Alikina, Elena Yu Brazovskaya, Valery V. Ugolkov
    更新日期:2019-12-05
  • 更新日期:2019-12-04
  • Catalytic activity of SAPO-34 molecular sieves prepared by using palygorskite in the synthesis of light olefins via CO2 hydrogenation
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-03
    Haifeng Tian, Jihui Yao, Fei Zha, Lu Yao, Yue Chang

    Palygorskite was used as a silicon and partial aluminum source to prepare SAPO-34 molecular sieves using diethylamine, triethylamine, morpholine and tetraethylammonium hydroxide as templates. The synthesized SAPO-34 molecular sieves were characterized by using the methods of XRD, SEM, EDS, BET, FT-IR, NH3-TPD, H2-TPR and TG. Composite catalysts of CuO-ZnO-Al2O3/SAPO-34 were prepared by mechanically mixing SAPO-34 molecular sieves with CuO-ZnO-Al2O3 and were used in the direct synthesis of light olefins via CO2 hydrogenation. The results showed that SAPO-34 molecular sieves prepared by acid-treated palygorskite using tetraethylammonium hydroxide as a template had a higher specific surface area, a greater CO2 conversion rate and higher light olefin selectivity. The CO2 conversion rate reached 53.5%, the light olefin selectivity reached 62.1%, and the yield reached 33.2% when the reaction conditions were as follows: reaction temperature 673 K, reaction pressure 3.0 MPa, volume ratio of CO2/H2 1:3 and 0.5 g composite catalyst.

    更新日期:2019-12-03
  • Kinetic determination of sedimentation for GMZ bentonite colloids in aqueous solution: Effect of pH, temperature and electrolyte concentration
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-03
    Zhen Xu, Yalou Sun, Zhiwei Niu, Yang Xu, Xiaoyan Wei, Ximeng Chen, Duoqiang Pan, Wangsuo Wu
    更新日期:2019-12-03
  • Water microbial disinfection via supported nAg/Kaolin in a fixed-bed reactor configuration
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-30
    Lütfiye Yıldız Ozer, Ahmed Yusuf, Joao M. Uratani, Belén Cabal, Luis A. Díaz, Ramón Torrecillas, José S. Moya, Jorge Rodríguez, Giovanni Palmisano

    In this paper we have investigated and demonstrated the antimicrobial capabilities of nano-silver-4 wt%-kaolin (nAg-4-Kn) composite supported on borosilicate glass beads (BGB). Tests have been conducted in a fixed bed reactor on effluent from the secondary clarifier of a conventional wastewater treatment plant (WWTP) in Abu Dhabi, United Arab Emirates (UAE). The prepared BGB with immobilized nAg-4-Kn (nAg-4-Kn/BGB) were characterized using the RAMAN spectroscopy, TEM equipped with EDX and Focus Ion Beam Scanning Electron Microscope (FIB-SEM) techniques. The rate of disinfection was assessed through Luria-Bertani (LB)-agar plate cell counting technique. The results showed complete disinfection after few hours, which was preserved even after several days in repeated runs. The nAg-4-Kn/BGB was reused, demonstrating that the immobilization of nAg-4-Kn was stably achieved, and the activity and integrity of the composites on the BGB were preserved. First order disinfection kinetic constants were estimated to be 2.76 cm h−1 and 2.56 cm h−1 in two consecutive runs. Analyses of the beads after the experiments showed minor losses of nAg from the kaolin matrix thereby corroborating reusability of these materials.

    更新日期:2019-12-02
  • Synthesis and characterization of conducting aniline and o-anisidine nanocomposites based on montmorillonite modified clay
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-12-02
    Abdelbassat Kenane, Aurelian-Catalin Galca, Elena Matei, Ahmed Yahyaoui, Aicha Hachemaoui, Ali Mustapha Benkouider, Cristina Bartha, Marian Cosmin Istrate, Magdalena Galatanu, Oana Rasoga, Anca Stanculescu
    更新日期:2019-12-02
  • Thermophysical properties of three-dimensional palygorskite based composite phase change materials
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-29
    Yi Wang, Yanhui Song, Shuang Li, Ting Zhang, Deyi Zhang, Pengran Guo

    In order to enhance the loading capacity of palygorskite (Pal) and further understand the relationship between pore size of carrier and thermal properties of mineral-based phase change materials (PCMs), series of three-dimensional palygorskite carriers and corresponding composite PCMs (CPCMs) were fabricated. The morphology, structural characteristics and thermal properties of the support and composite PCMs were determined by various techniques. The effects of support microstructure on the thermo physical properties of CPCMs were also discussed. The results revealed that the isocyanate functionalized palygorskite can be covalently bonded by dihydric alcohol to form three-dimensional Pal-based carrier. The pore diameter of the carrier varies with the chain length of dihydric alcohol. Since covalent bonding and surface functionalization can prevent the agglomeration of palygorskite crystals, thermal energy storage performance of stearic acid/three-dimensional palygorskite is increased by 67.4% to 100.7% within the scope of the study compared with that of stearic acid/palygorskite. The phase change temperature and latent heat of the composite phase change material have a linear correlation with pore size of support. This study is expected to be helpful for designing mineral-based porous carrier and providing guidance for optimizing CPCMs.

    更新日期:2019-11-30
  • Mechanical and compressibility characteristics of a soft clay stabilized by slag-based mixtures and geopolymers
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-30
    Mahdi Salimi, Ali Ghorbani

    In the present study, industrial wastes such as Granulated Blast Furnace Slag (GBFS) and Basic Oxygen Furnace Slag (BOFS) activated with calcium oxide (CaO) and medium reactive magnesia (MgO) are used for chemical stabilization of a soft clay. This environmentally friendly approach can eliminate the hazards associated with improper waste disposal and reduce greenhouse gas emissions generated by cement production. To this end, various amounts of additives (ranging from 2.5 to 20%) with the activator:slag ratio of 1:3 are added to kaolinite clay and cured at two temperatures of 20 and 45°C. A series of laboratory tests, including pH, Electrical Conductivity (EC), one-dimensional consolidation, Unconfined Compressive Strength (UCS), are conducted on the stabilized samples. The increasing temperature causes a faster formation of cementitious products and a higher UCS value, as confirmed by the SEM micrographs and XRD analysis, particularly in the case of MgO-BOFS (MB) and CaO-BOFS (CB) samples with the UCS values of 4 and 4.7 MPa after 90 days of curing, respectively. Furthermore, the MB- and CB-stabilized clay samples show a better compressibility characteristic compared to the MgO-GBFS (MG) and CaO-GBFS (CG) blends. To further enhance the activity of the additives and to prepare a slag-clay based geopolymers, two types of alkaline solutions at various Na2SiO3:NaOH ratios are added to the mixtures at the final step. In addition, the energy absorption capacity (Eu) and the secant modulus (E50) of the optimum blends are determined to assess the toughness and stiffness of the samples. The results indicate that the UCS values of the MB and CB samples increase up to 7.41 MPa and 8.44 MPa after 90 days of curing, respectively, when the Na2SiO3:NaOH ratio is 80:20. Generally, the use of slag-clay based geopolymers, particularly BOFS, is very effective to address the problems associated with the soft soil and the optimum mixtures are successful in decreasing settlements and enhancing compressive strength of the soft soil, which can be considered for use as a pavement base material.

    更新日期:2019-11-30
  • 更新日期:2019-11-30
  • The effect of ammonium polyphosphate on the mechanism of phosphorous-containing hydrotalcite synergism of flame retardation of polypropylene
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-29
    Sheng Xu, Min Zhang, Si-Yu Li, Hong-Yan Zeng, Jin-Ze Du, Chao-Rong Chen, Kun Wu, Xian-Yao Tian, Yong Pan
    更新日期:2019-11-30
  • A new material based on montmorillonite and Cu(II)-phenanthroline complex for effective capture of ammonia from gas phase
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-28
    Elena Castellini, Daniele Malferrari, Fabrizio Bernini, Beatrice Bighi, Adele Mucci, Ignacio Claro Sainz-Díaz, Aida Serrano, German R. Castro, Maria Franca Brigatti, Marco Borsari
    更新日期:2019-11-29
  • 更新日期:2019-11-28
  • The role of clays, clay minerals and clay-based materials for nitrate removal from water systems: A review
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-26
    C.V. Lazaratou, D.V. Vayenas, D. Papoulis

    Excessive use of nitrogenous fertilizers has led to increased nitrate concentrations in groundwater that pose a threat to human health, via nitrate-contaminated potable water, and contribute to eutrophication. The elimination of nitrate from water systems has been thoroughly examined; however, unconventional and low-cost technologies are greatly needed. Clays and clay minerals are widely-used for environmental applications, mostly due to their non-toxicity, worldwide abundance, low cost and physicochemical properties (high surface area, ion exchange capacity, high sorption and catalytic properties). Most are used for the degradation of cationic pollutants, nevertheless, they can be equally efficient at anionic decontamination, depending on the modification process they have undergone, or the materials they are combined with. This review aims to assemble the available literature research on the application of clays and clay minerals as well as the mechanisms that lead to successful removal of nitrate from water. The main characteristics of clays and clay minerals in nitrate uptake are evaluated and the known shortcomings of their application discussed, leading to suggestions for further research.

    更新日期:2019-11-27
  • Catalytic conversion of cellulose to reducing sugars over clay-based solid acid catalyst supported nanosized SO42−-ZrO2
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-26
    Haiyan Yang, Yang Zhou, Dongshen Tong, Miao Yang, Kai Fang, Chunhui Zhou, Weihua Yu
    更新日期:2019-11-27
  • Cytocompatibility and cellular uptake of alkylsilane-modified hydrophobic halloysite nanotubes
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-26
    Elvira Rozhina, Abhishek Panchal, Farida Akhatova, Yuri Lvov, Rawil Fakhrullin
    更新日期:2019-11-27
  • The hydration of bentonite buffer material revealed by modeling analysis of a long-term in situ test
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-24
    Liange Zheng, Hao Xu, Jonny Rutqvist, Matthew Reagan, Jens Birkholzer, María Victoria Villar, Ana María Fernández

    The hydration of a bentonite barrier in the early stage of a geologic nuclear waste repository with a bentonite buffer is a critical issue for its long-term performance and safety because bentonite might be permanently altered and subsequently affect the function of bentonite barrier. Large scale in situ testing integrated with modeling analysis is an effective way to study the key processes affecting the hydration of a bentonite barrier. In this paper, through the comparison between coupled thermal, hydrological, mechanical, and chemical (THMC) models and data from a long term in situ test, we attempt to pinpoint the importance of non-Darcian flow, thermal osmosis, and hydro-mechanical coupling (porosity and permeability change due to swelling) to the hydration rate of the bentonite barrier under heating conditions. We found that a TH model equipped with non-Darcian flow severely underestimates the relative humidity and water content measured in the bentonite. Calibration of the parameters associated with relative permeability overshadows the contribution of non-Darcian flow, and non-Darcian flow under unsaturated conditions is not yet fully understood. An empirical relationship between saturated permeability and dry density was found to work better than a saturated permeability that is the function of effective stress in matching the relative humidity, water content data, and the chloride concentration in pore water. We also found that chemical data are actually helpful in calibrating the THM model. A question regarding the relevance of thermal osmosis to the hydration process, in terms of matching models and data, remains unanswered. Although a THMC model with thermal osmosis matches all THMC data nicely, similar goodness-of-fit can also be achieved by a THMC model without thermal osmosis but with lower permeability. We learned that the robustness of the model could be increased if the model is tested against long-term data and multiple types of data, and given that non-uniqueness is inevitable, more independent measurements of key parameters and multi-scale and multi-physics tests may help approximate the right model for evaluating the safety of the repository.

    更新日期:2019-11-26
  • Geopolymerization of halloysite via alkali-activation: Dependence of microstructures on precalcination
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-23
    Baifa Zhang, Haozhe Guo, Peng Yuan, Yun Li, Qiang Wang, Liangliang Deng, Dong Liu

    Halloysite has a chemical composition very similar to that of kaolinite, but it possesses a special nanotubular structure and surface reactivity. This work focuses on the geopolymerization of halloysite via alkali-activation, and investigates the effects of precalcination temperatures ranging from 450 °C to 1000 °C on the microstructures and mechanical properties of halloysite-based geopolymer. The products obtained were characterized using a combination of techniques including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, N2 physisorption analysis, and nuclear magnetic resonance. The results show that halloysite underwent minimal structural changes when calcined at 450 °C, and its alkali-activation product showed poor mechanical properties due to the formation of hydrosodalite with a porous structure. The dehydroxylation that occurred at calcination temperatures between 650 °C and 850 °C could improve the reactivity of halloysite with alkaline solution. The formation of geopolymer with a compact structure resulted in increased compressive strength. When halloysite was calcined at 1000 °C, geopolymerization also occurred, but to a lesser extent because of the formation of nanosized γ-Al2O3. This resulted in a decreased compressive strength in the product. These results indicate that the microstructures and properties of halloysite-based geopolymers are greatly dependent upon the precalcination of halloysite and that the optimal temperature is around 750 °C to ensure a high degree of dehydroxylation with high reactivity, which is favorable for geopolymerization.

    更新日期:2019-11-26
  • Inhibition performance of amidocyanogen silanol in water-based drilling fluid
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-23
    Qi Chu, Junlin Su, Ling Lin

    In this study, a series of amidocyanogen silanols (HASes) modified by methacryloxy propyl trimethoxyl silane (MPS) with polyethylene polyamine was introduced as potential shale inhibitors, thus providing the development and application of high-temperature resistant shale inhibitors in water-based drilling fluids. One shale inhibitor was selected based on cuttings dispersion tests. The results indicated that the shale inhibitor prepared with tetraethylenepentamine and MPS with the mole ratio of 1:2 (named HAS-8) was the best. The inhibition performance of HAS-8 was evaluated with the cuttings dispersion test, linear swelling test, and bentonite inhibition test, and was compared with the performance of currently available polyamine inhibitors. The results indicated that HAS-8 can effectively inhibit the hydration swelling and dispersion of clay, and that its temperature resistance is significantly better than that of polyamine inhibitors. The inhibition mechanism of HAS-8 was investigated with X-ray diffraction, adsorption measurement, and thermogravimetric and transmission electron microscope analysis. The mechanism is the adsorption on the clay surface and the intercalation of the interlayer, which inhibited the surface hydration and osmotic hydration of the clay. In field application of Bei 9 well, the HAS-8 effectively inhibits the hydration of water-sensitive cuttings and maintains the wellbore stability of the shale formation, providing a guarantee for safe and fast drilling.

    更新日期:2019-11-26
  • Evolution of the crystallographic structure and physicochemical aspects of rectorite upon calcination
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-23
    Weimin Xie, Jie Wang, Liangjie Fu, Qi Tan, Xiumin Tan, Huaming Yang

    Rectorite (Rec) with exchangeable cations has a wide range of potential applications, including adsorbents, catalyst supports, high-temperature binders, and flame retardant additives. The understanding of the variation of rectorite upon thermal treatment is vital for exploiting its application potential. This paper reports on the thermal decomposition and structural evolution of Rec in the temperature range of 25–1200 °C. Thermogravimetric (TG) analysis, in-situ X-ray diffraction (XRD), and in-situ Fourier transform infrared (FTIR) spectroscopy were used to trace real-time variations in rectorite upon calcination. Then, pristine rectorite and its calcined samples were systematically characterized by 29Si and 27Al magic-angle sample spinning nuclear magnetic resonance (MAS NMR), Brunauer-Emmet-Teller (BET), Zeta potential, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The results showed that Rec went through the following four stages after thermal treatment: dehydration at room temperature (RT) to 300 °C, dehydroxylation at 500–700 °C, structural collapse at 1000 °C, and formation of a new phase above 1100 °C. Furthermore, SiO4 tetrahedral units and AlO6 octahedral units in Rec were distorted around 1000 °C, so that the maximum contents of active SiO2 and Al2O3 could be simultaneously obtained. The atomic-level structural evolution mechanism of Rec upon calcination is proposed.

    更新日期:2019-11-26
  • Vulcanization, interfacial interaction, and dynamic mechanical properties of in-situ organic amino modified kaolinite/SBR nanocomposites based on latex compounding method
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-22
    Yongjie Yang, Hao Zhang, Kenan Zhang, Lihui Liu, Leibo Ji, Qinfu Liu

    With the help of soluble amino modifiers, the vulcanization delay of kaolinite/SBR composites is investigated to shorten the optimum curing time of the filled rubber system based on the latex compounding method (LCM). Compared to the traditional dry blending method, the LCM had better kaolinite dispersion in the rubber matrix. The two different amino modifiers, i.e., quaternary ammonium salt ((CH3)3-N-CH2-) and amino silane (H2N–(CH2)2–NH–(CH2)2–NH–(CH2)3–) were selected in the in-situ modification through two different routes: physical adsorption and chemical bonding. The Moving Die Rheometer revealed that the curing process with the amino group could accelerate the crosslinking reaction, and the kaolinite grafted KH892 nanocomposite showed the best vulcanization performance. An improvement in the curing rate and mechanical properties of kaolinite/SBR composite is ascribed to the outstanding distribution and chemical bonding of nanokaolinite lamellae in the vulcanizate. Furthermore, SEM, HR-TEM, and DMA results demonstrated that both the dispersion of kaolinite in the vulcanizate and the wet skid resistance of the kaolinite/SBR hybrid materials are superior to the composite made by the dry blending method.

    更新日期:2019-11-22
  • Euganean therapeutic mud (NE Italy): Chlorophyll a variations over two years and relationships with mineralogy and geochemistry
    Appl. Clay. Sci. (IF 3.890) Pub Date : 2019-11-21
    A. Calderan, A. Carraro, C. Honisch, A. Lalli, P. Ruzza, F. Tateo
    更新日期:2019-11-22
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