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  • Representative Domain Size for the Simulation of Coalescence Filtration in Nonwoven and Foam Media
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-23
    S. Abishek, A.J.C. King, J. Schuler, G. Kasper, H-J. Schmid, B.J. Mullins
    更新日期:2018-06-25
  • A Comprehensive Review on Recently developed Carbon based nanocomposites for Capacitive Deionization: From Theory to Practice
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Jimoh Oladunni, Jerina Zain, Abdul Hai, Fawzi Banat, G. Bharath, Emad Alhseinat

    A comprehensive review through few decades of capacitive deionization (CDI) ever since discovery of Carbon aerogel, including a brief theory and factors influencing along with detailed focus on various electrode materials explored till now is done. The importance ofpore structure, high surface area, good wettability, high conductivity and quantitatively adsorb ionic components are discussed for optimal desalination performance. Specifically, porous carbon bassed materials are extensively explored as electrode materials in CDI setup, attributable to their availability, low cost and stability. This review mainly discusses the current state of the art in carbon based materials for enhanced desalination performance. Also, in this review, various carbon-based composite electrode materials, including porous carbon, porous carbon–metal oxide, carbon–polymer and carbon–polymer–metal oxide nanocomposites, are systematically investigated. Moreover, a brief outlook on the challenges and new research directions in the CDI area is also presented for researchers toward designing the high performance carbon based CDI device.

    更新日期:2018-06-22
  • A durable and antifouling monovalent selective anion exchange membrane modified by polydopamine and sulfonated reduced graphene oxide
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-20
    Yali Jin, Yan Zhao, Huimin Liu, Arcadio Sotto, Congjie Gao, Jiangnan Shen
    更新日期:2018-06-22
  • Permselectivity and ion-conductivity of grafted cation-exchange membranes based on UV-oxidized polymethylpenten and sulfonated polystyrene
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-21
    D.V. Golubenko, G. Pourcelly, A.B. Yaroslavtsev

    In the present study the properties of novel cation-exchange membranes based on UV-oxidized polymethylpentene (PMP) with grafted sulfonated polystyrene are described. A correlation between the composition of the grafted copolymer (grafting degree, cross-linking degree) and transport properties (Na+-conductivity, permselectivity, diffusion permeability) of resulted membranes are discussed. It is shown that with increasing of grafting degree (GD) and lowering of cross-linking degree (CD) the concentration of inner solution and permselectivity decrease, while ionic conductivity increases. The obtained membranes have the GD ranging from 29 to 120 % and CD from 0 to 5 %. The superior membranes have ionic surface resistance of 0,3-0,6 Ω cm2 in 0.5M NaCl, apparent cation transport numbers of 0.870-0.998 and NaCl diffusion permeability of 4.60∙10−8-5.5∙10−7 cm2 s−1, as well as satisfactory mechanical performance. A comparison of the obtained membranes with a number of commercial and experimental samples according to the conductivity and cation transport number criteria is made. It is noted that some of the obtained samples are at the level of the superior perfluorinated homogeneous membranes in terms of the ratio of conductivity and cation transport numbers. High ionic conductivity and permselectivity make the prepared membranes promising candidates for possible applications in electrodialysis, dialysis, reverse electrodialysis, Red-Ox flow batteries and other membrane processes.

    更新日期:2018-06-22
  • Solubility and fractionation of Indulin AT kraft lignin in ethanol-water media
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-21
    Werner Marcelo Goldmann, Juha Ahola, Marja Mikola, Juha Tanskanen

    Lignin solubility is a varying property, as depending on the type of lignin and its origin, its solubility in different solvents will differ. This is due to the highly heterogeneous nature of lignin. Solubilizing lignin could improve its potential valorization by making it more conducive to chemical reactions. Solvent fractionation could be utilized as the first step in lignin refining to adjust some of its properties before further processing. It is known that kraft lignin is completely soluble in alkaline solvents such as aqueous NaOH. The purpose of this study was to assess the solubility of Indulin AT lignin in aqueous ethanol solvents and to determine the useful properties of the resulting fractions: namely, molar mass distribution and phenolic hydroxyl groups. The highest concentration of lignin was achieved in 60 wt% ethanol solution with 235.89 g/L at a solid-to-liquid ratio of 300 gLignin/LSolvent. The original lignin had a mass average molar mass of 4.7 kDa. When only water was utilized, the average molar mass of the dissolved fraction was between 1-2 kDa and the molecular size distribution was mostly between 0.1-1 kDa. When using pure ethanol, the molecular size distribution ranged from 0.1 kDa to 10 kDa, with a mass average molar mass between 1-1.3 kDa. With an ethanol content in the solvent higher than 90 wt%, the bigger molar mass molecules (>10kDa) could be separated as the insoluble fraction. Additionally, the polydispersity of both fractions decreased with an ethanol concentration above 80 wt%. The hydroxyl group content of the insoluble fraction was higher when fractionating with less than 20 wt% ethanol, whereas with 20 wt% ethanol and higher, the soluble fraction retained most of the phenolic hydroxyls. Fractionating lignin prior to use or further processing may be potentially beneficial if the lower molar mass molecules can be used as they are, leaving only the higher molar mass molecules to be further processed or burned for energy.

    更新日期:2018-06-22
  • 更新日期:2018-06-22
  • Removal of COD from landfill leachate by advanced Fenton process combined with electrolysis
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Zhe Wang, Jiangbo Li, Weihua Tan, Xiaogang Wu, Heng Lin, Hui Zhang

    Zero-valent iron (ZVI) was used as the iron source for the advanced Fenton treatment of landfill leachate in an electrochemical cell. In this process, Fe0 was dissolved from the surface of ZVI powder and then the generated Fe2+ would activate the added H2O2 to produce hydroxyl radical (•OH), which is a strong oxidant and can lead to the removal of COD from landfill leachate. The effect of initial pH, H2O2 dosage, Fe0 dosage, current density and inter-electrode gap on the COD removal of landfill leachate was investigated. The results indicate that COD removal followed pseudo-second order kinetic model. The rate constant and COD removal efficiency increased with Fe0 dosage being increased from 0.524 to 1.745 g/L, but decreased when initial pH rose from 2 to 4. The optimal conditions of H2O2 dosage, current density and inter-electrode gap were determined to be 0.187 mol/L, 20.6 mA/cm2 and 1.8 cm, respectively. The humic acid-like organics in the leachate were effectively degraded and over 70% of COD could be removed from the leachate, showing high efficiency of the electro-advanced Fenton process.

    更新日期:2018-06-19
  • Association of fibrous filters for aerosol filtration in predominant Brownian diffusion conditions
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Augustin CHARVET, Stéphanie PACAULT, Soleiman BOURROUS, Dominique THOMAS

    In order to improve the dust retention capacity of air filters and increase their lifetime, the filtration performance of associations of fibrous filters has been investigated. This study highlighted the interest of the addition of a medium or coarse filter, composed of microfibers, upstream of a HEPA filter. Collecting nanostructured particles in the depth of this upstream filter, rather than directly on the surface of a HEPA filter, permits to significantly reduce the pressure drop increase while maintaining a global mass collection efficiency close to the unit. On the one hand, the association of a medium filter and a HEPA filter induces a real energy gain, compared to the implementation of a single HEPA filter. On the other hand, the implementation of a coarse filter, presenting a too low initial collection efficiency, upstream of a HEPA filter leads to mixed results.

    更新日期:2018-06-19
  • Simulation on performance of a demulsification and dewatering device with coupling double fields: swirl centrifugal field and high-voltage electric field
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Haifeng Gong, Bao Yu, Fei Dai, Ye Peng, Jiaru Shao

    Demulsification and dewatering of emulsion oil are common in petroleum and chemical industries. For waste lubricating oil, as a common W/O emulsion, with high water content and complex construction, the multi-field coupling or integration technology can satisfactorily accomplish oil and water separation which cannot be realized by using a single technological method. A coupling device integrated swirl centrifugal and high-voltage electric fields are proposed. Water-droplet coalescence in emulsified oil under the high-voltage electric field can enlarge the droplet size, and the swirl centrifugal field can rapidly and efficiently achieve water-droplet separated from emulsified oil. In this study, the performance of the coupling device was investigated by using numerical simulation and experimental methods. The numerical results were in agreement with the values obtained by experimental methods. And the numerical results show that the dewatering and deoiling rates of overflow and outflow orifices increased by 4.5% and 6.2%, respectively, when voltage amplitude 10 kV increases to 11 kV. Moreover, when inlet velocity increased from 8 m·s−1 to 12 m·s−1, the separation efficiency gradually decreased. In conclusion, the results demonstrate that the double-field coupling device has a greatly performance at 11 kV and 8 m·s−1.

    更新日期:2018-06-19
  • Preparation of 3D TiO2 nanotube arrays photoelectrode on Ti mesh for photoelectric conversion and photoelectrocatalytic removal of pollutant
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Longyu Qiu, Qingyao Wang, Zhiyuan Liu, Qianqian Zhao, Xiaoyu Tian, Huili Li, Shanmin Gao
    更新日期:2018-06-19
  • Effects of AlB2/AlP phase and electromagnetic stirring on impurity B/P removal in the solidification process of Al-30Si alloy
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Qingchuan Zou, Ning Han, Zhangfeng Shen, Jinchuan Jie, Tingju Li

    To enhance the understanding of impurities B and P removal in the solidification purification process of the Al-30Si alloy, series of experiments were carried out to study the roles of AlB2 and AlP in the nucleation of primary Si and the effect of electromagnetic stirring on the segregation behaviors of B and P. The results showed that the formed AlB2 phase does not act as the nucleation site for the primary Si and tends to distribute in the eutectic Al-Si, which would not pollute the primary Si. The P content (<68 ppmw) in metallurgical silicon is not sufficient to form AlP phase before the nucleation of primary Si, and thus the AlP phase can be removed effectively as it would be pushed to the front of the solid-liquid interface during the primary Si growth. It was also found electromagnetic stirring could effectively enhance the segregation behaviors of B and P during the growth of the primary Si, where the B and P contents in the primary Si were decreased with the increase of the magnetic field intensity. The effective segregation coefficients of B and P were reduced from 0.41 to 0.23 and 0.47 to 0.3, respectively, under 25 mT magnetic field compared that without electromagnetic stirring.

    更新日期:2018-06-19
  • Cationic kraft lignin-acrylamide as a flocculant for clay suspensions: 1) molecular weight effect
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Agha Hasan, Pedram Fatehi

    Currently, kraft lignin is burned in the recovery cycle of the kraft pulping process; despite its high potential to be extracted and converted into value-added products. In this work, kraft lignin (KL) was copolymerized with acrylamide (AM) and 2-[(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) to produce cationic copolymers. Copolymers with two different molecular weights of 168,200 g/mol (KAD-1) and 103,000 g/mol (KAD-2), but with a similar charge density of 1.15 meq/g, were selected and the flocculation efficiency of the copolymers in two different clay suspensions was investigated. Suspension pH affected the adsorption of the copolymers on clay particles and the removal of the particles from the suspension. At a 8 mg/g dosage, KAD-1 adsorbed more than KAD-2 as it was larger and thus developed more bridging with clay particles. The size of particles raised from 4.7 for kaolin to 16.3 μm for kaolin/KAD-1 flocs and 15.1 μm for kaolin/KAD-2 flocs, and it increased from 6.1 for bentonite to 18.97 μm for bentonite/KAD-1 flocs and 15.35 μm for bentonite/KAD-2 flocs in the presence of 8 mg/g of copolymers, respectively. The adsorption, zeta potential and flocculation analyses confirmed that KAD-1 was a more effective flocculant than KAD-2. The evidence for the agglomeration of clay particles via bridging and electrostatic patch mechanisms was also discussed in this work.

    更新日期:2018-06-19
  • New strategy of grafting hydroxyethyl acrylate (HEA) via γ ray radiation to modify polyvinylidene fluoride (PVDF) membrane: thermodynamic mechanisms of the improved antifouling performance
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-19
    Liguo Shen, Hongzhan Wang, Yicheng Zhang, Renjie Li, Bucyibaruta Fabien, Genying Yu, Hongjun Lin, Bao-Qiang Liao
    更新日期:2018-06-19
  • Reactive Separation of Protocatechuic Acid Using Tri-n-octyl amine and Di-(2-ethylhexyl) phosphoric acid in Methyl isobutyl ketone
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-18
    Fiona Mary Antony, Kailas L. Wasewar

    Protocatechuic acid is used extensively in pharmacological and related industries which can also be obtained by fermentation. Reactive separation by means of reactive extractant is a favourable alternative to recover carboxylic acids from the aqueous dilute streams and the fermentation broth. In this paper, the reactive separation of protocatechuic acid were performed by D2EHPA (Di-(2-ethylhexyl) phosphoric acid) and TOA (tri-n-octyl amine) dissolved in MIBK (Methyl isobutyl ketone) at 298 K. Distribution coefficients, degree of extraction, complexation constants and loading ratio were estimated. The equilibrium for protocatechuic acid−extractant−diluent system was represented using Langmuir model, mass action law and relative basicity model. Results obtained from model were found to be close to experimental data. TOA was found more effective than D2EHPA for the recovery of protocatechuic acid having 5.39 as maximum distribution coefficient and 84.36 % efficiency at 0.01 mol.L-1 and 1.1437 mol.L-1 concentration of protocatechuic acid and TOA respectively.

    更新日期:2018-06-18
  • Effects of different secondary biological treatment processes followed by flocculation and sand-filtration on subsequent DBPs control from sewage treatment plants
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-15
    Weixiao Qi, Hua Zhang, Ruiping Liu, Huijuan Liu, Jiuhui Qu

    The nature and chlorine reactivity of dissolved organic matter (DOM) in reclaimed water from sewage treatment plants (STPs) are quite important for assessing the risk of wastewater reuse. Elucidating relation between DOM and its fractions characterization with different treatment processes is quite important for selection of treatment processes focusing on disinfection by-products (DBPs) control. In this study, four classical STPs in Beijing (A∼D) with different secondary biological treatment processes but all with flocculation and sand-filtration as advanced treatment process were selected to investigate DBPs formation potentials and DOM characterization variation during these processes and their relation. Chloroform, trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) dominated among four trihalomethanes (THMs) and nine haloacetic acids (HAAs) formation potentials respectively during chlorination of both secondary and sand-filtration effluents with the order of TCAA>chloroform>DCAA. Both THMs and HAAs formation potentials were positively related with DOC percentage for the hydrophobic fractions in the DOM. The bromine incorporation in THMs was obviously higher than that in HAAs. The especially higher bromine incorporation in D STP was probably due to the higher SUVA value in this STP with SBR as secondary biological treatment process comparing to those in the other three STPs. DOC and bromide removal, SUVA decrease were important elements for selecting secondary treatment process considering DBPs control. Flocculation and sand-filtration performed not well in removing DBPs precursors especially for chloroform and DCAA except for C STP, which had higher hydrophobic fraction percentage removal and molecular weight decreasing during the advanced treatment process. FTIR analysis revealed that flocculation and sand-filtration probably removed more aliphatic structures than aromatic or COO- structures. The absorption ratio of aromatic C=C, COO-/aliphatic CH3 peaks in D STP was the highest among the four STPs, which was consistent with the highest bromine incorporation in this STP.

    更新日期:2018-06-15
  • Enhanced treatment of pharmaceutical wastewater by combining three-dimensional electrochemical process with ozonation to in situ regenerate granular activated carbon particle electrodes
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-15
    Juhong Zhan, Zhaoxin Li, Gang Yu, Xuejun Pan, Jinlin Wang, Wei Zhu, Xia Han, Yujue Wang

    The treatment of a real pharmaceutical production wastewater by electrolysis using three-dimensional electrodes (3D electrolysis), ozonation, and their combined process (3D/O3) was investigated in this study. The pharmaceutical wastewater was characterized by a high organic concentration (total organic carbon (TOC) of 13475 mg/L) and high acute toxicity (100% inhibition of the luminescent bacterial Vibrio fischeri). After 6 h treatment, ∼23% and 43% of TOC could be removed from the pharmaceutical wastewater by individual ozonation and the 3D electrolysis process using granular activated carbon (GAC) as the particle electrodes, respectively. However, the acute toxicity of the wastewater was hardly reduced by the two individual processes. In comparison, by sparging the ozone generator effluent (oxygen and ozone gas mixture) in the three-dimensional electrode reactor, the 3D/O3 process considerably enhanced TOC abatement to ∼71% and reduced the inhibition of the luminescent bacterial to <70% in Microtox bioassays. These improvements can be mainly attributed to the enhanced hydroxyl radical (•OH) production in the 3D/O3 process via several reaction mechanisms, e.g., the reaction of sparged O3 with in situ generated H2O2, the electrochemical reduction of O3, and GAC catalyzed O3 decomposition, which in turn enhanced the oxidation of organics in the bulk and those adsorbed onto the GAC particle electrodes. The results of this study indicate that there exists a synergistic effect between 3D electrochemical process and ozonation for the degradation of toxic organics in the pharmaceutical wastewater. Compared with the two individual processes, the 3D/O3 process can thus provide a more effective option for the treatment of high-strength pharmaceutical wastewater.

    更新日期:2018-06-15
  • Pervaporation dehydration of aqueous solutions of various types of molecules via organosilica membranes: Effect of membrane pore sizes and molecular sizes
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-15
    Norihiro Moriyama, Hiroki Nagasawa, Masakoto Kanezashi, Toshinori Tsuru

    Organosilica membranes were developed and showed excellent stability in aqueous solutions, which raised expectation for applications to pervaporation dehydration. In order to investigate the properties of pervaporation through organosilica membranes, 1,2-(bistriethoxysilyl)ethane (BTESE)-derived membranes with different pore sizes (0.44 nm and 0.54 nm) were prepared by tuning the acid molar ratio in the sols, then applying the resultant membranes to the gas permeation of various single gases (He, H2, CO2, N2, CH4, CF4, and SF6) as well as to the pervaporation dehydration of aqueous solutions (methanol, ethanol, n-propanol, iso-propanol, n-butanol, tert-butanol, acetone, and n-methyl-2-pyrrolidone). Both membranes showed high levels of both water permeance (>10-6 mol/(m2 s Pa)) and separation factors for water/iso-propanol (500-6,000). Both the permeances in pervaporation and in gas permeation tended to decrease with an increase in the molecular size and a decrease in the pore size, which confirmed the contribution of the molecular sieving effect. Pervaporation performance was correlated with gas permeation performance.

    更新日期:2018-06-15
  • 更新日期:2018-06-15
  • Molecular dynamics simulation and experimental investigation of furfural separation from aqueous solutions via PEBA-2533 membranes
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-15
    Changlin Liu, Chuan Ding, Xiaogang Hao, Chuncheng Li, Xiaowei An, Peifen Wang, Beilei Zhang, Fengfeng Gao, Changjun Peng, Guoqing Guan
    更新日期:2018-06-15
  • Synthesis optimization of (h 0 h)-oriented silicalite-1 membranes for butane isomer separation
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-02-13
    Amei Wu, Congyong Tang, Shenglai Zhong, Bin Wang, Junjing Zhou, Rongfei Zhou

    Tubular oriented silicalite-1 membranes were prepared on the inner surface of α-alumina tubes by secondary (seeded) growth. Membrane microstructures including orientation, thickness and defect densities which affected membrane performance could be regulated by synthesis optimization for butane isomer separation. Synthesis parameters such as synthesis temperature, synthesis time and solution composition were modified. Membrane orientation was greatly affected by synthesis temperature. Two typical membranes of highly (h 0 h)-oriented and mixed (h 0 h)&c-oriented membranes were obtained after synthesis optimization. Four highly (h 0 h)-oriented silicalite-1 membranes prepared under optimized synthesis conditions showed ideal H2/SF6 selectivities of 1325 ± 35, which was much higher than that of mixed (h 0 h)&c-oriented membrane M3 (3 0 0), indicating that the former membranes had fewer boundary defects. These highly (h 0 h)-oriented membranes displayed n-butane permeances and separation factors were (2.26 ± 0.23) × 10−7 mol (m2 s Pa)−1 and 32.7 ± 2.5 for an equimolar n-butane/i-butane mixture at 333 K, respectively. The low deviations in permeance and selectivity indicate that membrane synthesis had a good reproducibility. This average n-butane permeance for these highly (h 0 h)-oriented membranes was 4 times higher than that of mixed (h 0 h)&c-oriented membrane M3. Both kinds of highly (h 0 h)- and (h 0 h)&c- silicalite-1 membranes displayed the similar trend with test temperature and pressure.

    更新日期:2018-06-15
  • A water-based mixing process for fabricating ZIF-8/PEG mixed matrix membranes with efficient desulfurization performance
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-02-15
    Xiaolong Han, Tingting Hu, Ye Wang, Huiyong Chen, Yuqi Wang, Ruiqing Yao, Xiaoxun Ma, Jiding Li, Xifei Li

    In this article, ZIF-8 nanoparticles were synthesized in water and directly added to a polyethyleneglycol (PEG) aqueous solution (water-based mixing process) to prepare ZIF-8/PEG mixed matrix membranes (MMMs) for pervaporation desulfurization. The structure and properties of ZIF-8 particles were characterized by Fourier Transform-Infrared Spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and BET analysis. The surface composition and structural morphology of all ZIF-8/PEG MMMs were systematically investigated by FT-IR and SEM. The effect of ZIF-8 content on the pervaporation performance of ZIF-8/PEG membranes was investigated. Versus pure PEG membranes, both the total flux and the sulfur enrichment factor of the ZIF-8/PEG MMMs were remarkably increased. This phenomenon is attributed to the good compatibility between PEG and ZIF-8 particles and the high thiophene selective sorption of ZIF-8 particles (confirmed by molecular simulation). Optimal pervaporation performance was achieved at a 4 wt% loading of ZIF-8 particles with the flux of 1.96 kg/(m2 h) and the sulfur enrichment factor of 8.93. These increased by 397.46% and 18.75% versus pristine PEG membrane, respectively. In addition, the effect of operation temperature and feed sulfur content on membrane performance were also systematically investigated.

    更新日期:2018-06-15
  • Enhanced performance of superhydrophobic polypropylene membrane with modified antifouling surface for high salinity water treatment
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-02-19
    Yingqi Wang, Gaohong He, Yushan Shao, Daishuang Zhang, Xuehua Ruan, Wu Xiao, Xiangcun Li, Xuemei Wu, Xiaobin Jiang

    In this work, the superhydrophobic polypropylene (PP) composite membranes with modified surface were successfully fabricated by loading the SiO2 nanoparticles and attaching low surface energy 1H,1H,2H,2H-perfluorodecyltriethoxysilane. The impact of deposited nanoparticle size on the surface roughness, heterogeneous nucleation barrier and critical nucleus size versus the loaded nanoparticle size (d∗nuclear/d) was simulated by the model combining the surface roughness and superhydrophobility with the critical nucleation energy. The optimized loaded nanoparticles size maintained the proper roughness and d∗nuclear/d to ensure the desired performance of antifouling. The improved superhydrophobic surface enhanced the anti-wetting ability of the membrane for vacuum membrane distillation (VMD) purpose. The resulting modified membrane possessed good anti-wetting ability and stable anti-fouling performance during long-term continuous and batch operation of VMD treating high salinity water system. The fouling rate of the fabricated membrane was decreased to 20% of the one of the original membrane under 15 wt% high salinity feed condition.

    更新日期:2018-06-15
  • ZIF-8 heterogeneous nucleation and growth mechanism on Zn(II)-doped polydopamine for composite membrane fabrication
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-02-27
    Xuehua Ruan, Xinfang Zhang, Ziyuan Zhou, Xiaobin Jiang, Yan Dai, Xiaoming Yan, Gaohong He

    Continuous ZIF-8 membranes have showed great potential for gas separation. The prospect is subjected to two pivotal issues: shorten the time to construct the ZIF-8 selective layer and tightly bond ZIF-8 layer onto the substrate. In our previous work, Zn(II)-doped polydopamine (Zn-PDA) linkage layer was proposed and effectual to solve these problems. In this research, the mechanism likely to support the improvements is studied intensively. The dominant factor is that Zn(II) ions can be chelating and depositing sufficiently in the linkage layer. The strongly alkaline condition for dopamine polymerization is also beneficial to Zn(II) chelation and deposition, which has been confirmed by DFT simulation, together with characterization tests, e.g., XPS, FTIR, and Zn(OH)2 precipitation for Zn(II)–O coordination. Phenolic hydroxyl groups are deprotonated in the strongly alkaline environment with high Mulliken charge (−0.515 & −0.524 e) and become strong chelation sites to Zn(II). Subsequently, Zn(II) clusters extensively filled in the PDA linkage layer are acting as the starting sites for ZIF-8 heterogeneous nucleation and growth. The correspondence between Zn(II) clusters probed by EDX and nascent ZIF-8 crystals visualized by FE-SEM can support this phenomenon clearly. On the whole, the abundant starting sites in Zn-PDA enhanced ZIF-8 growth, and ZIF-8 growth from the rooting-in Zn(II) clusters created an indented and hinged boundary for tightly bonding ZIF-8 layer onto the substrate.

    更新日期:2018-06-15
  • Effect of the electrolyte on the electrolysis and photoelectrolysis of synthetic methyl paraben polluted wastewater
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-06
    D. Dionisio, A.J. Motheo, C. Sáez, M.A. Rodrigo

    In this work, the electrochemical oxidation of methyl paraben (MeP) with diamond electrodes is studied. Results point out that this preservative can be easily removed from wastewater, either in sulfate or chloride media. Pollutant removal is faster in chloride media due to the chlorination of the molecule. However, mineralization is faster in sulfate media. Current density does not have a clear influence on the efficiency, explained by a mediated oxidation control of the process. Irradiation by UV light produces a synergistic effect on the process, which is greater in sulfate than in chloride media, a behavior that could be initially understood in terms of the formation of sulfate and chloride radicals. However, chemical tests showed that persulfate is not active for the oxidation of MeP neither in dark conditions nor under UV irradiation and that hypochlorite is active in the chlorination of the MeP molecule but not in the mineralization. Consequently, these results can be better explained considering the oxidizing effect of ozone and hydrogen peroxide, which are produced during the electrolysis on the surface of diamond, and that within the reaction conditions undertaken, are unstable and decompose to hydroxyl radicals. Regarding electrolysis in chloride media, although chlorates or perchlorates are produced, UV light significantly delays the appearance of both species.

    更新日期:2018-06-15
  • Synergy of combined adsorption and electrochemical degradation of aqueous organics by granular activated carbon particulate electrodes
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-12
    Nikoline Loklindt Pedersen, Mahdi Nikbakht Fini, Peter Krisztian Molnar, Jens Muff

    Electrochemical oxidation (EO) and activated carbon (AC) adsorption are, despite difference in maturation and market dissemination, both well-proven water treatment principles for the abatement of micropollutants. Both technologies suffer some drawbacks as mass transfer limitations (in case of EO) and poor adsorption affinity of some compounds (in case of AC). Granular active carbon may, when placed within an electric field, be polarized generating particulate reactive microelectrodes in bulk solution increasing the overall active electrode area, a concept known as 3D electrochemistry. In this paper, a potential synergy by combining EO and AC was studied in a potentiostatic batch setup at different applied electric field strengths (25–500 V/m), using boron-doped diamond (BDD) as active anode and the hydroxyl radical probe compound p-nitrosodimethylaniline (RNO) and the groundwater contaminants 2-methyl-4-chlorophenoxy acetic acid (MCPA), 2-methyl-4-chlorophenoxy propionic acid (MCPP or mecoprop) and 2,6-benzamide (BAM) as target model contaminants. Synergy was assessed based on comparison of the 3D process with removal kinetics in conventional 2D electrochemical process and pure AC adsorption. In demineralized water model solutions, synergies of 121–126% was found for RNO, MCPA and MCPA at 375 V/m electric field strength and w/w AC:organic ratio of 5:1. For BAM, the synergy was 192%, primarily due to stronger AC adsorption affinity. The study showed interesting perspectives of this treatment concept that needs to be pursued and studied in matrices of higher complexity.

    更新日期:2018-06-12
  • Oxygen vacancy of CeO2 improved efficiency of H2O2/O3 for the degradation of acetic acid in acidic solutions
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-09
    Yalei Ding, Jiejie Wang, Shanshan Xu, Kun-Yi Andrew Lin, Shaoping Tong

    In order to completely mineralization of contaminants, it is necessary to develop new methods which can effectively degrade final products of chemical oxidation. Acetic acid (HAc) has been considered one of the typical end products of chemical oxidation of pollutants and thus chosen as a representative target pollutant in the study. Nano-cerium oxide (CeO2), an environment-friendly rare-earth material, was prepared to catalytic ozonation of HAc in acidic solutions. Experimental results show that the prepared CeO2 could greatly enhance efficiency of H2O2/O3, and also have good stability and recyclability. The Raman spectra indicate that H2O2 interacts with oxygen vacancies of CeO2 to form peroxide-like species, which could effectively initiate the decomposition of ozone to produce hydroxyl radicals. A mechanism is proposed to explain the activity of peroxide-like species for the decomposition of ozone. The effects of different parameters such as initial pH value, catalyst dosage, and the concentration of H2O2 are also investigated. The results indicate that the CeO2/H2O2/O3 may provide a convenient and effective method for degrading refractory organic pollutants in acidic wastewaters.

    更新日期:2018-06-10
  • Scaling problems and control technologies in industrial operations: Technology Assessment
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-08
    Constanza Cruz, Luis A. Cisternas, Andrzej Kraslawski

    Calcium and magnesium ions are the major components of scaling in different water sources, especially seawater. Calcium and magnesium scale causes problems in various industrial operations such as reverse osmosis unit, heating unit of multi-stage flash distillation, concentration operation of copper-molybdenum mining industry, cooling water system of power generation industry, and water injection operation of oil and gas production. In general terms, scaling affects the operation performance that leads to increased production, as well as maintenance costs. The pH control, scale inhibitors, and nanofiltration membrane have been implemented by industrial operations to control scale. However, the drawbacks of these technologies may force to seek alternative technologies which could be potential alternatives for scale control.This paper discusses the problems of calcium and magnesium scale affecting various industrial operations when seawater is used. It presents current technologies for scale control such as pH control, scale inhibitors, and nanofiltration. Moreover, the technology assessment (TA) was made to evaluate existing and emerging scale control approaches in the case of reverse osmosis (RO) process. The identification of the emerging technologies of scale control has been performed using bibliometric analysis. The comparison of the technologies was made using House of Quality (HOQ) matrix. The identified emerging technologies are: bioelectrochemical system, biomineralization, biosorbent, microbial desalination cells, step by step deposition and extraction technique, carbon dioxide as a precipitator, gas hydrate, ultrasonic crystallization, and capacitive deionization. The comparison of the technologies has shown that nanofiltration, as a common technology, could be an appropriate approach to ensure feasibility and efficiency of RO process, while emerging technology, microbial desalination cells, could become a potential alternative in the future.

    更新日期:2018-06-08
  • 更新日期:2018-06-07
  • Yeast Flocculation aids the Performance of Yeast Dewatering using Mini-Hydrocyclones
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-06
    J.J. Cilliers, S.T.L. Harrison

    Conventionally, filtration and centrifugation are used to separate yeast from suspensions. Mini hydrocyclones (10 mm diameter) have previously been shown to achieve limited dewatering of non-flocculating Bakers’ yeast. This indicated the potential of the application of hydrocyclones to the concentration of naturally flocculating Bakers’ or Brewers’ yeast suspensions, where the effective particle size is larger. In this study, the effect of degree of flocculation on the concentration of flocculating Brewers’ yeast suspensions was investigated. The separation performance was determined when varying the floc size and feed concentration. Variation in yeast flocculation was achieved by reducing the pH with acetic acid, which produced narrow floc size distributions, with median sizes between 200 μm and 20 μm. The feed yeast concentration range investigated was between 0.6 and 14 g/L.Stable yeast flocs do not break on passage through the hydrocyclone. Separation improved significantly with increasing floc size. Flocculation allowed enhanced separation, as compared to results obtained for unicellular, non-flocculating Saccharomyces cerevisiae. Increasing the feed concentration decreased the recovery of yeast to the concentrated product and the concentration ratio between feed and product. This is in agreement with previous findings for single cellular yeast. An interaction between floc size and suspension concentration on the separation was found with separation performance maximised for concomitant increase in floc size and decrease in yeast concentration. Typical results indicate that the concentration can be doubled and some 70% to 85% of the yeast recovered in a single pass through the system.Furthermore, yeast quality and fermentation performance were not compromised by passage through the hydrocyclone.

    更新日期:2018-06-07
  • An overview of operating parameters and conditions in hydrocyclones for enhanced separations
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-05
    Jinyi Tian, Long Ni, Tao Song, James Olson, Jianing Zhao
    更新日期:2018-06-06
  • 更新日期:2018-06-06
  • 更新日期:2018-06-06
  • Chromatographic Fractionation of a Ternary Mixture with an SMB Cascade Process: The Effect of Ion Exchange Resin Cross-Linkage on Separation Efficiency
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-05
    Jari Heinonen, Markku Laatikainen, Tuomo Sainio

    In this study, the effect of cation exchange resin cross-linkage (4.8–8.0 wt.% of DVB) on separation efficiency in a fractionation of a ternary mixture with a two-step cascade simulated moving bed process was investigated experimentally and by simulations. The recovery of betaine and sucrose from sugar beet molasses containing sulfate salts was chosen as a case study. Betaine was recovered in the first step, and sucrose was recovered in the second step. The strong effect of cross-linkage on the separation efficiency in both steps was observed. In betaine recovery, the performance increased with increasing cross-linkage of the resin due to stronger ion and size exclusion. The increase of cross-linkage from 5.2 wt.% to 8.0 wt.% increased productivities of betaine and sucrose by 107 % and 61 %, respectively. Water consumption decreased simultaneously by 50 % and 58 %, respectively. No separation could be achieved with 4.8 wt.% cross-linked resin. In sucrose recovery, the decrease in cross-linkage from 8.0 wt.% to 5.2 wt.% was found to increase sucrose productivity by 180 % and decrease water consumption by 50 %. Further decrease of cross-linkage resulted in decreased separation efficiency. The results clearly demonstrate that the proper choice of separation material cross-linkage not only significantly improves the separation efficiency in fractionation of molasses, but also in other relevant separation cases as well. In the case of ternary separations, it is beneficial to optimize the resin cross-linkage for each separation step.

    更新日期:2018-06-06
  • Effect of coexisting ions on recovering lithium from high Mg2+/Li+ ratio brines by selective-electrodialysis
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-05
    Peng-Yuan Ji, Zhi-Yong Ji, Qing-Bai Chen, Jie Liu, Ying-Ying Zhao, Shi-Zhao Wang, Fei Li, Jun-Sheng Yuan

    Selective-electrodialysis (S-ED) is a booming technology for recovering lithium from salt lake brine and (concentrated) seawater, especially from high Mg2+/Li+ ratio brines. The coexisting ions in the solutions containing lithium can make some impact on the ion fractionation of lithium and magnesium in high Mg2+/Li+ brines. The effect of the concentration of coexisting cations (Na+, K+) and anions (SO42-, HCO3-) on the separation coefficient of magnesium and lithium (FMg-Li), recovery ratio of Li+ (RLi), current efficiency (η) and specific energy consumption (ESEC) was evaluated. The results show that an applied voltage of 6 V is more preferable for lithium ions recovery from high Mg2+/Li+ brines by S-ED. The separation of Mg2+/Li+ tends to unsatisfactory with increasing cation concentration (Na+, K+), and FMg-Li drops from 8.73 to 1.83 with the increase of Na+/Li+ from 1 to 5 and from 8.33 to 2.13 with the rise of K+/Li+ from 1 to 5. The strength of influence on the separation of Mg2+/Li+ is K+ > Na+, correlating with the order of their hydrated ion radiuses. However, FMg-Li rises from 7.99 to 14.66 with the increase of SO42-, reversing with the influence of cations concentration. As for HCO3-, the variation tendency of FMg-Li is opposite to RLi, probably ascribing to the appearance of MgHCO3+. These observations showed that S-ED has a wide adaptability for the ion fractionation of magnesium and lithium from brines.

    更新日期:2018-06-05
  • Silver vanadium oxide materials: controlled synthesis by hydrothermal method and efficient photocatalytic degradation of atrazine and CV dye
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-04
    Chiing-Chang Chen, Janah Shaya, Huan-Jung Fan, Yi-Kuo Chang, Han-Ting Chi, Chung-Shin Lu

    Silver vanadium oxides have received remarkable attention in recent years because of their stability, suitable band gaps, and relatively superior photocatalytic abilities. This study reports the synthesis of silver vanadates by the hydrothermal method and the investigation of their photocatalytic abilities for removing crystal violet (CV) and atrazine pollutants under visible-light irradiation. The as-prepared silver vanadates are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectra (DRS). Crystal violet and atrazine could be successfully degraded in the presence of the silver vanadate catalyst under visible-light irradiation. The obtained results show complete degradation of crystal violet after 24 h of treatment and over 97% degradation of atrazine after 72 h. The as-prepared silver vanadate materials show extremely high catalytic stability and maintain stable activity after three catalytic cycles. The scavenger studies indicate that •O2− radicals are the main active species in the degradations of CV and atrazine, while •OH and h+ play an assistant role in these processes. Liquid chromatography coupled with electrospray ionization mass spectrometry is used to analyze the samples obtained from the photocatalytic degradation of CV and atrazine. The degradation pathways of atrazine are evaluated suggesting two different routes including dechlorination–hydroxylation and alkylic-oxidation–de-alkylation. On the other hand, the degradation of the CV takes place via N-de-methylation in a stepwise manner generating the various N-de-methylated intermediate CV species. The excellent activity and photostability reveal that silver vanadates (including Ag4V2O7) are promising visible-light-responsive photocatalysts for water and wastewater treatment.

    更新日期:2018-06-05
  • Sonochemical and Photosonochemical Degradation of Endocrine Disruptor 2-phenoxyethanol in Aqueous Media
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-04
    Zineb Boutamine, Oualid Hamdaoui, Slimane Merouani

    2-Phenoxyethanol (PhE) has been shown to induce hepatotoxicity, renal toxicity, and hemolysis in subchronic and chronic studies in multiple species. It is one of the endocrine disrupting compounds, which are listed as priority emerging water contaminates. In this work, the removal of PhE at variable doses from water has been achieved using high frequency ultrasound (600 kHz) in batch mode. 100 min of irradiation was required for the complete disappearance of PhE (10 mg L−1) and for the removal of more than 60% of the initial solution COD. Several parameters were evaluated for the ultrasound application: the initial concentration of PhE (2−400 mg L−1), applied power (40–120 W), dissolved gas (air and N2), pH (2–10) and temperature (15−45 °C). Additionally, the effect of combining ultrasound with UV irradiation (15 mW cm−2, 253.7 nm) on the degradation of PhE was evaluated. The degradation rate increased notably with increasing initial PhE concentration and power, whereas pH and liquid temperature did not affect significantly the removal rate of the pollutant. Air atmosphere showed the best degradation yield than nitrogen. UV-assisted ultrasound (US) provided a significant enhancement in the oxidation of the organic matter. After 2 h of treatment, 94% of initial COD was removed using US/UV system, whereas 76 % was eliminated with UV and 65% with US alone.

    更新日期:2018-06-04
  • Coupling electrokinetic remediation with phytoremediation for depolluting soil with petroleum and the use of electrochemical technologies for treating the effluent generated
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-07
    I.M.V. Rocha, K.N.O. Silva, D.R. Silva, C.A. Martínez-Huitle, E.V. Santos

    This work aims to investigate the enhancement of the efficiency of phytoremediation (phytoR) by electrokinetic remediation (ER) by using graphite electrodes to depollute soil contaminated with petroleum. It was focused on the effects of electric fields (by applying direct current (DC) of reversal polarity (RP)) as well as the growth of sunflower plants after soil remediation. In this case, five experimental setups were used, phytoR, ER and electro-phytoremediation (ER-PhytoR) by supplying DC (ER-PhytoR-DC) or RP (ER-PhytoR-RP). Regarding the total petroleum hydrocarbon (TPH) removal, it was more efficient for the ER-phytoR-RP carried out at 1 V cm−1 after 20 d where microbial degradation in the rhizosphere and organic compounds transport through the soil associated to the RP (contributing to avoid the acidity and alkaline fronts in the soil), were the key operating parameters. Results clearly showed that the application of RP favoured the germination, growth of plants and high TPH removal after 20 d. It was also demonstrated by higher biomass production achieved at different treatments; 5.22 g for phytoR, 1.137 g for ER-phytoR-DC and 5.89 g for phytoR-ER. Finally, two diamond based-electrochemical technologies (anodic oxidation (AO-H2O2) and electro-Fenton (EF)) have been used for treating the effluents generated by soil decontamination to eliminate the dissolved organic matter.

    更新日期:2018-06-03
  • Thermodynamic study on carbon dioxide absorption in aqueous solutions of choline-based amino acid ionic liquids
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-16
    Biao Li, Yifeng Chen, Zhuhong Yang, Xiaoyan Ji, Xiaohua Lu

    Five choline-based amino acid ionic liquids ([Cho][AA]s) are prepared by neutralization between choline hydroxide and amino acids with different molecular weight and alkalinity. Solubility of CO2 in 30 wt% aqueous solutions of these five [Cho][AA]s has been measured at temperatures from 303.15 to 333.15 K and pressures up to 7 bar. Based on the zwitterion mechanism, the solubility of CO2 in aqueous [Cho][AA]s solutions is correlated with a reaction equilibrium thermodynamic model (RETM). The corresponding thermodynamic parameters, such as Henry’s law constants, reaction equilibrium constants, and enthalpy of physical dissolution and chemical reaction are all calculated and compared to evaluate the CO2 absorption performance in aqueous solutions of five [Cho][AA]s. Meanwhile, the recyclability of the aqueous solution with 30 wt% [Cho][Lys] has been also investigated.

    更新日期:2018-06-03
  • Cold incineration of 1,2-dichlorobenzene in aqueous solution by electrochemical advanced oxidation using DSA/Carbon felt, Pt/Carbon felt and BDD/Carbon felt cells
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-16
    Hicham Zazou, Nihal Oturan, Mutlu Sönmez Çelebi, Mohamed Hamdani, Mehmet A. Oturan

    This study reports on the electrochemical degradation and mineralization of 1,2-dichlorobenzene, called also ortho-dichlorobenzene (o-DCB) in aqueous solution, using an undivided electrochemical reactor for the application of electro-Fenton (EF) process. The o-DCB was chosen as model pollutant because of its high toxicity and persistence in the environment. Among the different parameters influencing process efficiency, the effect of different anode materials such as DSA, BDD and Pt on the production of hydroxyl radicals (OH) was investigated. These radicals were generated concomitantly from the oxidation of water on the anode surface and from electrochemically generated Fenton’s reagent in bulk of solution. The effects of current, supporting electrolyte and the nature of the anode material on degradation kinetic and mineralization efficiency were studied. The absolute rate constant for oxidation of o-DCB by OH was determined as (1.61 ± 0.02) × 109 M−1 s−1 by using the competition kinetic method. Mineralization of o-DCB aqueous solution was monitored using total organic carbon (TOC) analysis. Under optimum conditions, i.e., 500 mA current, BDD anode and CF cathode, treatment of o-DCB solution containing 50 mM Na2SO4 and 0.1 mM Fe2+ at pH = 3.0 conducted to more than 90% TOC removal in 3 h electrolysis. Oxidative degradation products formed during the treatment (aromatic intermediates and short-chain carboxylic acids) or end-products (inorganic ions) were identified and quantified by using HPLC and ion chromatography techniques respectively, and based on the identified products a degradation pathway for mineralization of o-DCB was proposed.

    更新日期:2018-06-03
  • Electrochemical oxidation of crystal violet using a BDD anode with a solid polymer electrolyte
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-21
    Nizar Klidi, Davide Clematis, Maria Paola Carpanese, Abdellatif Gadri, Salah Ammar, Marco Panizza

    This paper explores the applicability of an innovative electrochemical cell with a solid polymer electrolyte (SPE) with mesh electrodes for the electrochemical oxidation of a low conductivity solution (0.022 mS/cm) containing crystal violet (CV) dye compound as model pollutant in a range concentration of 25–100 mg/L. The system anode/membrane/cathode is formed by Nafion membrane sandwiched between a Ti/RuO2 cathode and a BDD anode. The dependence of applied current, stirring rate, supporting electrolyte and temperature has been investigated. The experimental results showed that the electrochemical cell with SPE is suitable for the treatment of solution with a very low conductivity since the CV solution was completely mineralized with an energy consumption of about 60 kWh m−3. Furthermore, the process was under charge transfer control for low applied current, becoming mass transfer control around 1 A. The addition of supporting electrolyte as Na2SO4 (0.6 and 1 g/L) and NaHCO3 (1 g/L) to the solution decreased the removal rate due to the presence of competitive reaction and scavengers media. The evolution of nitrogen compounds during the electrolysis shows that at the end of the process the 80% of initial N has been converted in nitrate and ammonium, indicating the formation of volatile compound.

    更新日期:2018-06-03
  • Comparison of microcrystalline and ultrananocrystalline boron doped diamond anodes: Influence on perfluorooctanoic acid electrolysis
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-22
    Beatriz Gomez-Ruiz, Nazely Diban, Ane Urtiaga

    This work aims to study the effect of the distinctive chemical and structural surface features of boron doped diamond (BDD) anodes on their electrochemical performance for perfluorooctanoic acid (PFOA) degradation. Commercial BDD anodes were compared: (i) a microcrystalline (MCD) coating on silicon; and (ii) an ultrananocrystalline (UNCD) coating on niobium. MCD gave rise to the complete PFOA (0.24 mmol L−1) degradation in 4 h, at any applied current density in the range 1–5 mA cm−2. On the contrary, only 21% PFOA removal was achieved when using UNCD at 5 mA cm−2 under comparable experimental conditions. Similarly, the total organic carbon (TOC) was reduced by 89% using MCD, whereas only 13% TOC decrease was obtained by UNCD. In order to explain the dissimilar electrochemical activities, the morphological and chemical characterization of the electrode materials was developed by means of FESEM microscopy, XPS and Raman spectroscopy. The UNCD anode surface showed characteristic ultrananocrystalline grain size (2–25 nm), higher boron doping and greater content of H-terminated carbon, whereas the MCD anode was less conductive but contained higher sp3 carbon on the anode surface. Overall, the MCD electrode features allowed more efficient PFOA electrolysis than the UNCD anode. As a result of their distinctive performance, the energy needed for the maximum PFOA degradation (after 4 h) using MCD anode was only 1.4 kWh m−3, while the estimated energy consumption for the UNCD anode would be 37-fold higher. It is concluded that the use of the MCD anode involves considerable energy costs savings.

    更新日期:2018-06-03
  • Membrane preconcentration as an efficient tool to reduce the energy consumption of perfluorohexanoic acid electrochemical treatment
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-24
    Álvaro Soriano, Daniel Gorri, Ane Urtiaga

    One of the key points for the large-scale implementation of electrochemical water treatment technologies lies in the need of reducing the energy consumption. The present work analyzes the removal of persistent perfluorohexanoic acid (PFHxA, 204 mg L−1) from industrial process waters using a strategy that combines membrane pre-concentration followed by electrooxidation of the concentrate. A mathematical model describing the nanofiltration (NF) system was developed and complemented with new and background experimental data of PFHxA and ion species rejections and total permeate flux through the NF270 and NF90 membranes. Similarly, the kinetics of PFHxA electrolysis on boron doped diamond anodes was determined at laboratory scale. Later, the model was used to simulate the NF-ELOX integrated process, where a commercial spiral wound unit (membrane area 7.6 m2) was implemented and the electrooxidation unit was scaled-up to pilot plant (anode area 1.05 m2). The obtained energy savings depended on a combination of the target PFHxA removal ratio at the end of the treatment train, the separation performance of the commercial membrane and the reduction of the electrolyte ohmic resistance in the electrooxidation stage, that was attained as a result of the increase of salts content in the concentrate. Only the tight NF90 membrane allowed to achieve high (99%) PFHxA removal ratios in the integrated NF-ELOX process, and the specific energy consumption was estimated at 11.6 kWh m−3, 59.2% less than when electrolysis alone was applied. Still, the electrolysis is the most energy demanding step, with 85.9% contribution to the total energy consumption. The strategy of combining membrane pre-concentration with electrochemical degradation could be extended to the treatment of other highly persistent organic compounds.

    更新日期:2018-06-03
  • Bio-inspired fabrication of superhydrophilic nanocomposite membrane based on surface modification of SiO2 anchored by polydopamine towards effective oil-water emulsions separation
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-26
    Jiuyun Cui, Zhiping Zhou, Atian Xie, Minjia Meng, Yanhua Cui, Siwei Liu, Jian Lu, Shi Zhou, Yongsheng Yan, Hongjun Dong

    A new PVDF@pDA@SiO2 nanocomposite membrane was fabricated by virtue of the surface modification of polydopamine anchored SiO2 on PVDF membrane through a facile and eco-friendly preparation process. It possessed the superior superhydrophilicity/underwater superoleophobicity properties and presented the outstanding antifouling oil performance and high-efficiency separation ability for oil-water emulsions, which mainly resulted from its special surface micro-nano structure and pore induced capillarity phenomenon. Furthermore, the PVDF@pDA@SiO2 nanocomposite membrane also exhibited the splendid separation performance, regeneration ability and universality for various oil-water emulsions separation. In addition, the oil-water emulsion separation mechanism was discussed in depth. This work might provide a significant guidance for large-scale production and application of this nanocomposite membrane in the fields of wastewater recovery and drinking water treatment.

    更新日期:2018-06-03
  • Deoiling of Oil-coated Catalyst using High-speed Suspending Self-rotation in Cyclone
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-27
    Dai Shi, Yuan Huang, Hualin Wang, Wei Yuan, Pengbo Fu

    Disposal of waste catalysts has posed considerable threat to the environment and biological health. It has been confirmed that the self-rotation of particles in a hydrocyclone can enhance the efficiency of removing pollutants in catalyst particles. This paper presented the high-speed suspending self-rotation of catalyst particles in cyclone with the help of microfluidic technology and high-speed camera test. The oil-removal efficiency can be improved further by controlling the self-rotation speed and suspending time. Results showed that under the inlet flux of 35 m3/h, catalyst particles had a self-rotation speed of more than 14000 rad/s in cyclone, 80 times as that of the revolution speed under the same operating condition. The self-rotation speed and suspending time of catalyst particles can be enhanced by the increase of inlet flux and cone angle. The coating oil is removed under the periodic resultant centrifugal force when the suspending time is prolonged, and the oil content can be reduced from 36.17% to less than 4% within 100 s in cyclone under 25 °C. This finding is highly significant to non-thermal purification of waste catalyst under gas–solid environment.

    更新日期:2018-06-03
  • Nafion/PEG hybrid membrane for CO2 separation: Effect of PEG on membrane micro-structure and performance
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-27
    Zhongde Dai, Hesham Aboukeila, Luca Ansaloni, Jing Deng, Marco Giacinti Baschetti, Liyuan Deng

    In the present work, PEGDME with different molecular weight (Mn ∼ 250 and 500 g/mol) was added into Nafion-based membranes as CO2-philic additive, aiming at improving their CO2 capture performance. The physical, chemical and morphological characteristics of the hybrid membranes were thoroughly investigated using different techniques, including TGA, XRD, SEM and FTIR. The gas transport properties were studied by means of mixed gas permeation tests at different relative humidity conditions. CO2 permeability is greatly enhanced upon the addition of the PEGDME. The addition of 40 wt% PEGDME 250 into the Nafion matrix shows a CO2 permeability of 57.4 Barrer at the dry state, which is 36 folds higher than the pristine Nafion. The presence of water vapor in the gaseous streams further enhances the CO2 permeability and CO2/N2 selectivity, reaching a value of 446 Barrer and 37, respectively, under fully saturated conditions. However, the further increase of the PEGDME content in the Nafion matrix leads to undesirable micro phase separation (defects were observed from the morphological analysis), causing serious loss of the selectivity. Finally, in order to improve the theoretical understanding of the transport mechanism, a modified Maxwell model was successfully applied to describe the separation performances of the resulted Nafion/PEGDME hybrid membrane. The model results suggest that an interconnected CO2-philic structure is obtained upon the addition of PEGMDE and water to the ionomer matrix, forming preferential pathways for gas permeation able to enhance the membrane performance.

    更新日期:2018-06-03
  • Absorption of SO2 with calcium-based solution in a rotating packed bed
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-29
    Liangliang Zhang, Shuying Wu, Yue Gao, Baochang Sun, Yong Luo, Haikui Zou, Guangwen Chu, Jianfeng Chen

    In this work, the absorption performance of SO2 into calcium-based solution was studied in a rotating packed bed (RPB). Experiments were carried out to examine the effect of various operating parameters on the desulfurization efficiency, such as absorbent pH value, gravity level of RPB, gas-liquid ratio, gas treatment amount and inlet SO2 concentration. It was found that the SO2 removal efficiency increased with the increasing of absorbent pH value and RPB gravity level, and decreased with the increasing of the gas-liquid ratio and inlet SO2 concentration. SO2 removal efficiency was about 88% for the metal packing and 82% for the plastic packing under the optimal operating conditions when the SO2 inlet concentration was 900 mg/m3. Moreover, volumetric mass transfer coefficient (KGa) in RPB of this absorption process was calculated. It was found that KGa was 7.83–19.34 s−1 in RPB, almost 1 order of magnitude higher than that in packed tower and impinging stream gas-liquid reactor.

    更新日期:2018-06-03
  • A multifunctional chromatographic material modified with aminopolycarboxylic acid agent
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-03-31
    Ning Zhang, Bin Chen, Rong Li, Chen Li, An Fan, Fei Huang

    A novel chromatographic material, aminopolycarboxylic-modified silica, was developed by two different synthetic routes, followed by characterization of the prepared material. The methods were compared and discussed based on binding capacity of ligand, chromatographic experiments and metal ion-chelating capacity of the material. Versatility of this chromatographic material including ion-exchange and affinity behaviors for proteins as well as chelating property for metal ions were investigated. The results showed that the material was prepared successfully, and synthetic method II was more favorable to the preparation of the material. This novel chromatographic material displayed good chromatographic behaviors for the separation of proteins, as well as outstanding chelating property for metal ions. Versatility of the material can effectively expand the applications of this functional material in different research fields.

    更新日期:2018-06-03
  • 更新日期:2018-06-03
  • Influenza DNA vaccine purification using pHEMA cryogel support
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-02
    Tiago Santos, Andreia Brito, Renato Boto, Pedro Sousa, Paulo Almeida, Carla Cruz, Cândida Tomaz

    Influenza virus is a huge financial and social burden for health care systems over the world. Currently, traditional approaches are not effective in the fight of the epidemy and new alternatives like DNA vaccines have been developed. However, the downstream process of DNA vaccines is a constant challenge in the biotechnology industry. Cryogels has several advantages over traditional supports and have been tested as stationary phase in chromatographic separations. In this work, a method based on poly(2-hydroxyethyl methacrylate) cryogel was used to purify the plasmid NTC7482-41H-VA2 HA, which express the Influenza hemagglutinin gene. For this purpose, the cryogel was synthesized by cryo-polymerization of 2-hydroxyethyl methacrylate and characterized by scanning electron microscopy. The purification of supercoiled isoform of the plasmid NTC7482-41H-VA2 HA from a clarified lysate sample was achieved in a two-step experiment using NaCl and the dynamic binding capacity of pHEMA cryogel was determined. The assessment of DNA vaccine allowed to conclude that the level of contaminants such as proteins, genomic DNA, RNA and endotoxins are in accordance with FDA agency.

    更新日期:2018-06-02
  • 更新日期:2018-06-02
  • 更新日期:2018-06-02
  • Recent Developments in Biofouling Control in Membrane Bioreactors for Domestic Wastewater Treatment
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-02
    Muhammad Aslam, Rizwan Ahmad, Jeonghwan Kim
    更新日期:2018-06-02
  • The use of membrane based reactive extraction for the recovery of carboxylic acids from thin stillage
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-06-01
    Kristien De Sitter, Linsey Garcia-Gonzalez, Claudia Matassa, Lorenzo Bertin, Heleen De Wever

    Within the carboxylate platform, carboxylic acids are seen as important building-blocks for the chemical industry, but their recovery is challenging. Membrane based reactive extraction (MBRE) was evaluated for the recovery of these acids from a fermentor in which a mixed culture is converting biorefinery wastewater to carboxylates. Both off-line and in-line experiments were performed. The off-line experiments were promising and extraction efficiencies of 15 (acetic acid) to almost 100 % (caproic acid) were reached. The in-line experiments confirmed the selective and near complete extraction of carboxylates with longer chain length. However the overall extraction rates were lower than in off-line tests and the total carboxylate production rate was also decreasing. This was probably caused by limited but repeating contact between organic phase and fermentation broth via the membrane interface.

    更新日期:2018-06-01
  • 更新日期:2018-05-31
  • Fabrication and characterization of BiOBr:Yb3+,Er3+/g-C3N4 p-n junction photocatalysts with enhanced visible-NIR-light-driven photoactivities
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-05-30
    Shuhui Liang, Manman He, Jingjing Guo, Jie Yue, Xipeng Pu, Bo Ge, Wenzhi Li

    The BiOBr:Yb3+,Er3+/g-C3N4 (BYE/CN) p-n junction photocatalysts were successfully fabricated by a stepwise method. Experimental results show that Er3+/Yb3+ were successfully doped into BiOBr lattice. As-obtained BYE/CN exhibited strong NIR light absorption and upconversion emission from NIR to UV-visible due to the upconversion transition of Er3+. The p-n junction was constructed due to the appropriate alignment band structure of BYE and g-C3N4, which distinctly suppresses the recombination rate of electron-hole pairs. Compared with pure BYE and CN, as-synthesized BYE/CN samples exhibit distinctly improved photoactivities under the irradiation of visible or NIR light, which can be attributed to the upconversion effect of Er3+ and the construction of p-n junction. This result may provides a promising system for efficient harvest of the NIR light, which will contribute to the utilization of solar energy in the future.

    更新日期:2018-05-31
  • Study of the degradation of an organophosphorus pesticide using electrogenerated hydroxyl radicals or heat-activated persulfate
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-05-30
    Yassine Aimer, Omar Benali, Karine Groenen Serrano

    The use of pesticides and their release into the natural environment constitutes a direct threat for the environment and the living beings especially the human health. Consequently, the development of technics to detoxify the pesticide residues to reduce at least areas and contaminated matrix is needed. In the present work, a comparative study was performed on the chemical oxidation of an organophosphorus compound, the dimethoate (DIM), with sulfate radicals and hydroxyl radicals. Both oxidants are generated in situ, the sulfate radicals were produced by heat-activation of persulfate (PS) and hydroxyl radicals were generated by water electrooxidation using a boron doped diamond anode (BDD). For both cases, the target molecule has disappeared but the selective reaction of sulfate radicals with organics led to the production of intermediates which are less biodegradable than DIM since the ratio between the biological oxygen demand (BOD5) and the chemical oxygen demand (COD) has been divided by 2 within the first hour of the process. Whereas the BOD5/COD ratio during the electrochemical oxidation of DIM via hydroxyl radicals showed that it was possible to render the solution biodegradable without reaching a complete mineralization. However, it has been shown that the presence of chlorides in the solution must be avoided because of the formation of undesired organochlorides during the process.

    更新日期:2018-05-31
  • 更新日期:2018-05-31
  • Enhanced pervaporation performance of SA-PFSA/ceramic hybrid membranes for ethanol dehydration
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-05-30
    Hao-Ran Xie, Chen-Hao Ji, Shuang-Mei Xue, Zhen-Liang Xu, Hu Yang, Xiao-Hua Ma

    In this study, sodium alginate (SA)-perfluorinated sulfonic acid (PFSA)/ceramic hybrid membranes were successfully prepared by dip-coating method. The contorted rigid structure of PFSA immobilized the loose structure of SA as well as improved the interconnectivity so as to demonstrated high separation factors. Meanwhile, the ion clusters formed by –SO3H groups of PFSA possessed high affinity for water, resulting in high water flux. The viscosity of blend solution, structures and properties of the hybrid membranes were investigated by viscometry, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), water contact angle meter and pervaporation dehydration. The effects of SA-PFSA ratio, PFSA content, feed composition and temperature on the separation performances of the hybrid membranes were investigated. The hybrid membrane fabricated by 2.0 wt.% SA and 2.0 wt.% PFSA demonstrated a high flux of 1155 g m−2 h−1 coupled with separation factor of 1149 by dehydration of 15 wt.% water content ethanol-water mixture at 75 °C, reflecting superior pervaporation processing capacity.

    更新日期:2018-05-31
  • Potentiality of polymeric membranes in aromatherapy: application to bergamot essential oil
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-05-30
    A. Figoli, T. Marino, F. Galiano, E. Blasi, E.L. Belsito, A. Liguori, A. Leggio, L. Rombolà, L.A. Morrone
    更新日期:2018-05-31
  • A hybrid method for the removal of fluoride from drinking water: Parametric study and cost estimation
    Sep. Purif. Technol. (IF 3.359) Pub Date : 2018-05-30
    M. Changmai, M. Pasawan, M.K. Purkait

    A hybrid technique (electrocoagulation followed by microfiltration) was utilized for an efficient defluoridation of contaminated drinking water. Three samples of drinking water with an initial fluoride concentration of 7.89, 4.79 and 1.78 mg/L were collected from a hand tube well located in Karbi Anglong district of Assam, India. Effects of different operational parameters such as initial fluoride concentration, current density and pH on the removal of fluoride were extensively investigated in the electrocoagulation chamber. For a current density of 15 A/m2 and an electrode distance of 0.005 m, an efficient removal of 0.0097, 0.335 and 0.656 mg/L was observed for initial fluoride concentration of 1.78, 4.79 and 7.89 mg/L, respectively. The uptake of fluoride was the highest at pH = 7.9 with a final fluoride concentration of 0.43 mg/L. Filtration studies were performed using indigenously prepared membrane. An increase in flux from 7.98 × 10-5 to 19.19 × 10-5 m3/m2.s was observed with an increase in transmembrane from 196 to 509 kPa. Produced flocs were scraped from the membrane surface, dried and characterized to confirm the presence of fluoride. The proposed hybrid technique was able to lower the concentration of fluoride from contaminated drinking water within the permissible limit as per WHO of 1.5 mg/L.

    更新日期:2018-05-31
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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