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  • Direct Z-scheme Ag3PO4/Bi4Ti3O12 heterojunction with enhanced photocatalytic performance for sulfamethoxazole degradation
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-26
    Chenlu Liu; Jingjing Xu; Junfeng Niu; Mindong Chen; Yonghui Zhou

    This paper introduces a Z-scheme Ag3PO4/Bi4Ti3O12 heterojunction composite photocatalyst prepared by an in-situ growth method. The photocatalytic properties of the prepared samples under visible light irradiation were studied by degrading sulfamethoxazole (SMX). The results of photocatalytic experiments and cycle experiments showed that Ag3PO4/Bi4Ti3O12-20% composite exhibited much better photocatalytic activity and stability than pure Ag3PO4 and pure Bi4Ti3O12. The capture experiment results showed that h+ is the main active substance in the process of SMX degradation. In addition, we proposed a possible photocatalytic mechanism based on the results of experiment and characterization. The formation of a direct Z-Scheme photocatalytic system promoted the separation of carriers, thereby improving the stability and activity of the composite samples.

    更新日期:2020-01-26
  • Enhanced peroxymonosulfate activation by supported microporous carbon for degradation of tetracycline via non-radical mechanism
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-25
    Jia Li; Jialu Zhu; Lizhu Fang; Yulun Nie; Na Tian; Xike Tian; Liqiang Lu; Zhaoxin Zhou; Chao Yang; Yong Li
    更新日期:2020-01-26
  • Enhanced nano-aerosol loading performance of multilayer PVDF nanofiber electret filters
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-25
    Qiangqiang Sun; Wallace Woon-Fong Leung

    Aerosol loading behavior of PVDF nanofiber electret filters using neutrally charged nano- and submicron aerosols was investigated experimentally for the first time. The loading behavior include variations of filtration efficiency and pressure drop and distribution of deposited aerosols in the filters all having the same fiber basis weight (3.060 gsm). Through the filtration efficiency variations of uncharged/charged, single-/multi-layer filters with aerosol loading, it was observed that mechanical PVDF filters had continuously increasing filtration efficiency, while PVDF electret filters had initially decreasing and subsequently increasing filtration efficiency until reaching 100% due to diminishing electrostatic effect and enhancing mechanical effect. By combining the pressure drop evolution of different filters during aerosol loading and detailed SEM images of the loaded filters, we have demonstrated that multilayer PVDF filters, especially the electret ones, could significantly slow down the pace of filter clogging (skin effect) and elevate the aerosol holding capacity during depth filtration. Generally, the multilayer filters received the most aerosol deposit during depth filtration, whereas the single-layer filters received the most deposit during cake filtration. The multilayer nanofiber filters had approximately 70% aerosol deposit in the filter during depth filtration fully utilizing the full filter thickness, especially for the electret filters that had charged fibers, and only 30% deposit in the cake. On the contrary, the single-layer uncharged/charged nanofiber filters were exactly the reverse due to persistency of the skin effect with only 30% deposit in the filter mostly located in the upstream layer, yet 70% deposit in the cake. During depth filtration, the pressure drop per added mass deposit for the multilayer electret filter was very low at 11 Pa gsm-1, which was at least twice below any other nanofiber filters. This was all attributed to the uniform capture of aerosols by electrostatic effect across the entire filter depth from the upstream to downstream layers of the multilayer electret filter. The above conclusion was confirmed by the detailed SEM images taken across the different filter layers for the multilayer filter configuration. The 4-layer electret nanofiber filter with a 3.060-gsm basis weight has 4 times more aerosol holding capacity than the single uncharged/charged nanofiber filter with the same fiber basis weight in depth filtration. Based on the standpoint of highest efficiency and capacity with maximum pressure drop 800 Pa imposed on the filtration operation, the 4-layer electret was the best among all 4 filters. It had 52% more aerosol holding capacity than the single layer uncharged filter and 38% more capacity than the charged single-layer and the uncharged multilayer nanofiber filters. The multilayer PVDF electret filters have excellent filtration performance for long-term aerosol filtration and also great potential applications in the fields of personal health care and environmental protection.

    更新日期:2020-01-26
  • Visible light-induced activation of peroxymonosulfate in the presence of ferric ions for the degradation of organic pollutants
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-25
    Najmul Hasan; Saewung Kim; Min Sik Kim; Nguyen Thi Thao Nguyen; Changha Lee; Jungwon Kim
    更新日期:2020-01-26
  • Chemical Conditioning for Wet Magnetic Separation of Printed Circuit Board Dust Using Octyl Phenol Ethoxylate
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-25
    Oluwayimika Olasunkanmi OLUOKUN; Iyiola Olatunji OTUNNIYI

    Magnetic separation of ferromagnetic particles from fine dust recovered from airbag during printed circuit board (PCB) comminution appears quite rational, but under magnetic field, dust particle separation is problematic due to diverse particle morphology, electrostatics, induced magnetism and does not wet. These effects frustrate PCB dust magnetic separation, wet or dry. Chemical conditioning of the PCB dust pulp with octyl phenol ethoxylate (OPE) was conceived to combat these effects by altering the surface tension of water to wet and disperse the dust particles for efficient wet magnetic separation. At optimum OPE concentration used, which gave 56 dynes/cm solution, Fe and Ni recoveries in the 150 – 212 µm dust, were 97 and 94 %, respectively, under wet high intensity magnet (3150 Gauss); these dropped to 92 and 85 %, under low intensity magnet (1370 Gauss) , but misplacement of paramagnetic elements such as gold, copper reduced from 22 % to 5.4 % Au and 5.4 % to 2.2% Cu. The best Separation Efficiency, considering the major economic elements, is up to 83 % in a single roughing step under the low intensity wet magnetic separation. With evolution in PCB dust complex material streams for beneficiation, chemical conditioning has appeared as a vital factor to make wet magnetic separation effective.

    更新日期:2020-01-26
  • Phosphorus separation from metallurgical-grade silicon by magnesium alloying and acid leaching
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-25
    Mengyi Zhu; Alexander Azarov; Eduard Monakhov; Kai Tang; Jafar Safarian
    更新日期:2020-01-26
  • Enhanced photodegradation performance of Rhodamine B with g-C3N4 modified by carbon nanotubes
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-25
    Guohong Liu; Menglong Liao; Zhaohan Zhang; Hongyue Wang; Dahong Chen; Yujie Feng
    更新日期:2020-01-26
  • GWF-NH2 enhanced OSN membrane with trifluoromethyl groups in polyamide layer for rapid methanol recycling
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-25
    Sun-Jie Xu; Qian Shen; Yi-Hao Tong; Zhe-Qin Dong; Zhen-Liang Xu
    更新日期:2020-01-26
  • A Sustainable Strategy for Remediation of Oily Sewage: Clean and Safe
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-24
    Yunyan Peng; Yuan Liu; Jinyue Dai; Lijun Cao; Xiaoqing Liu
    更新日期:2020-01-24
  • Predictive models for determination of peptide fouling based on the physicochemical characteristics of filtration membranes
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-24
    Mathieu Persico; Gaétan Daigle; Sabita Kadel; Véronique Perreault; Genèvieve Pellerin; Jacinthe Thibodeau; Laurent Bazinet

    Peptide fouling of fifteen membranes with different physicochemical characteristics was estimated based on statistical redundancy analyses. The zeta-potential (ZP) and the roughness (Rz) parameters were highly correlated with the total fouling quantity (TFQ, RDA explanation of 86.6%), meaning that that fouling by peptides was mainly due to electrostatic interactions over rough surfaces. TFQ was predicted by a statistical model using the combined effect of both ZP and Rz membrane parameters, of the form: ln(TFQ) = 7.9546 + 0.1008.XRz + 0.03629.XZP (R2=0.8418). Concerning individual peptide and their own physicochemical properties, redundancy analyses showed that ZP, Rz, conductivity, contact angle and percentage of hydrophilic pores contributed significantly to the peptide fouling. Using the data of all 15 membranes, global predictive multivariate regression models were also established for each of the seven main peptides allowing the prediction of their specific fouling behavior on a wide range of membrane characteristics and properties. Finally, the models were validated by comparing them with experimental data of an extra membrane and consequently, peptide fouling can be well-estimated by using these relevant predictive models. Furthermore, based on the PES membranes, total fouling and individual peptide fouling were not affected by the membrane cut-off. However, based on the PVDF and PAN results, a combined effect of cut-off and material seemed to have an impact on both fouling: fouling decreased for these membranes when increasing their cut-off.

    更新日期:2020-01-24
  • Moving from lab to pilot scale in forward osmosis for pesticides rejection using aquaporin membranes
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-24
    Mahdi Nikbakht Fini; Henrik Tækker Madsen; Jens Laurids Sørensen; Jens Muff
    更新日期:2020-01-24
  • High-efficient removal of Tetrabromobisphenol A in aqueous by dielectric barrier discharge: Performance and degradation pathways
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-23
    Qi Wang; Tiecheng Wang; Guangzhou Qu; Ying Zhang; Qiuhong Sun; Xuetao Guo; Hanzhong Jia

    Brominated flame retardants are widely used in fire protection area, but also bring great threats to ecological environment and human health. In this study, the potential of brominated flame retardant removal in wastewater by dielectric barrier discharge (DBD) plasma was investigated, with Tetrabromobisphenol A (TBBPA) as a model pollutant. The experimental results showed that TBBPA could be effectively removed by the DBD plasma oxidation. Almost all of the TBBPA in wastewater could be successfully decomposed within 15 min’s oxidation treatment, and the decomposition process fitted well with the pseudo-first-order kinetic model. Relatively lower TBBPA initial concentration favored its decomposition; and the effect of solution pH value on the oxidation process was negligible in the selected pH range. Electron paramagnetic resonance analysis showed that •O2-, •OH, and 1O2 were produced in the DBD plasma process; and •O2- was the main reactive species for TBBPA decomposition, •OH and 1O2 also played important roles. The molecular structure of TBBPA was effectively destroyed, and some byproducts including bisphenol A, and dibromophenol were generated. The possible decomposition pathways for TBBPA degradation were proposed. Furthermore, the acute toxicity and bioaccumulation factor of intermediate byproducts were alleviated via the analysis of Toxicity Estimation Software Tool.

    更新日期:2020-01-24
  • Energy efficiency of membrane vs hybrid membrane / cryogenic processes for propane recovery from nitrogen purging vents: A simulation study
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-23
    Simon Picaud-Vannereux; Florence Lutin; Eric Favre; Denis Roizard

    When pure propane contained in pipelines or storage tankers has to be flushed out by nitrogen fluxes for maintenance purpose, propane recovery is obviously of interest both for environmental issue and for propane valorization. A low temperature condensation is generally used for that purpose and is attractive because it allows to recover propane under liquid state. However, the energy required is very important to reach a high recovery separation target. An alternate approach can be the combination of a nitrogen or propane permselective membrane with a conventional condensation step to improve the global efficiency of the separation process. The present work has been intended to investigate this approach and evaluate to which extent a hybrid process can bring an added value. This study shows first a map of membrane separation performance of propane over nitrogen from data of the open literature. Interestingly it shows that either N2-selective or conversely, propane-selective membranes can be used and also that propane –selective membrane will require higher area for atmospheric down-stream pressures (1 bar) compared to down-streams kept at lower pressures (0.1 bar). The selection of the most nitrogen and propane selective membrane is used in order to simulate hybrid processes where separations performances (purity of the propane condensed versus energy required) are compared to the baseline cryogenic standalone process. For low propane contents in the feed mixture (xin,C3H8= 0.5 and 5% mol/mol), it is shown that the use of a propane selective membrane module with a vacuum system seems to be the most energy efficient process while reaching a high purity (>98%). Based on rigorous process simulations, other hybrid processes cases were performed considering SSZ-13 zeolite membranes and the different separation performances are discussed. It is shown that a membrane/cryogenic process can indeed be less energy demanding to recover propane from N2-vents. However, according to the recovery target the choice of the membrane type can vary from an organic to a zeolite membrane.

    更新日期:2020-01-23
  • Characterisation of RomakonTM-PM pervaporation membranes for the separation of dilute aqueous alcohol mixtures
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-23
    D.A. Sapegin; G.N. Gubanova; S.V. Kononova; E.V. Kruchinina; N.N. Saprykina; A.Ya. Volkov; M.E. Vylegzhanina

    Thin-film composite pervaporation membranes with selective layer from pyromellitic dianhydride - 4,4’ oxydianiline polyimide on porous poly(amide-imide) support (RomakonTM-PM) for treatment of water/ethanol mixtures with exceeding water content (>50 wt% water) are characterised by the use of scanning electron microscopy, atomic force microscopy and X-ray diffraction. Membranes showed high values of flux, separation factor and PSI (up to 774) in the selected feed mixture composition range. The influence of the support and structural features of the polyimide in the coating layer on the transport properties is discussed. The membranes are successfully tested in terms of pervaporation dehydration of beer. The influence of the permeate temperature on the separation process performance is discussed.

    更新日期:2020-01-23
  • Adsorbent Screening for CO2/CO Separation for Applications in Syngas Production
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2019-01-06
    Sean M.W. Wilson; Dean A. Kennedy; F.H. Tezel

    Single gas carbon dioxide (CO2) and carbon monoxide (CO) adsorption behaviour is investigated in detail with different adsorbents for the potential separation of syngas. In this study, 20 zeolites, 2 activated aluminas, 3 activated carbons, and 2 silica gels were investigated by determining pure gas isotherms of CO2 and CO at 30°C. The results were compared to literature to determine which adsorbents would be the most promising for CO2 separation from syngas at this temperature. Since CO2 concentrations vary in syngas based on the method of production, different adsorbents were selected for purification and bulk separation of CO2 from a syngas mixture. The individual adsorption capacities of CO2 and CO were analysed separately using a gravimetric system, modelled, and then compared for all of the adsorbents studied. CO2 is shown to be more favourably adsorbed compared to CO, with CO2 having higher adsorption capacities and heats of adsorption for all adsorbent samples studied. High-density silica gel and H-Y type zeolites were found to be promising adsorbents for the bulk separation of CO2 from syngas due to the shape of their isotherms, large CO2 adsorption capacities, their favourable adsorption capacity ratios for CO2 over CO. For the purification of syngas, Na+ exchanged FAU structured zeolites with their high CO2 adsorption capacity at low pressures, and favourable CO2 over CO adsorption capacity ratios was found to be the most promising adsorbent.

    更新日期:2020-01-23
  • Influence of laccase treatment on fouling layer formation in ultrafiltration of birch hot-water extract
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-22
    Tiina Virtanen; Jussi Lahti; Anna Kalliola; Tarja Tamminen; Mika Mänttäri; Mari Kallioinen
    更新日期:2020-01-22
  • Impact factors for flux decline in ultrafiltration of lignocellulosic hydrolysis liquor
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-22
    Shunli Li; Honglei Chen; Xin Zhao; Lucian A. Lucia; Chen Liang; Yu Liu

    Ultrafiltration (UF) is an effective approach for the separation and purification of organic components dissolved in lignocellulosic pre-hydrolysis liquor (PHL). However, flux decline has been a problem that restricts UF industrial applications. Here, the main impact factors for flux decline on UF processing of PHL are examined. Flux decline curves for four UF membranes having different molecular weight cut-offs (MWCOs) indicated that the largest MWCO UF membrane had a faster flux decline rate because of its better ability to concentrate PHL. Using a 10-kDa UF membrane, the normal UF procedure was modified three different ways to study the independent factors affecting flux, including retentate concentration, charge density, and membrane fouling. The results indicated that membrane fouling was a main impact factor causing flux decline in the early stages of UF, and then charge and concentration effects gradually intervened. Relative to the latter factors, membrane fouling displayed a more regular behavior, with a good linear relationship between flux and operating time. Micro-computed tomography, scanning electron microscopy, and atomic force microscopy were used to characterize fouled membranes. It was revealed that surface contamination plays a more dominant role in flux decline than does internal contamination.

    更新日期:2020-01-22
  • Enhancement of Pollutants Hydrocyclone Separation by Adjusting Back Pressure Ratio and Pressure Drop Ratio
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-22
    Jinyi Tian; Hualin Wang; Wenjie Lv; Yuan Huang; Pengbo Fu; Jianping Li; Yi Liu
    更新日期:2020-01-22
  • Synergy between membrane filtration and flocculation for harvesting microalgae
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-22
    Zhenyu Zhao; Yun Li; Koenraad Muylaert; Ivo F.J. Vankelecom
    更新日期:2020-01-22
  • Pre-deposition layers for alleviating ultrafiltration membrane fouling by organic matter: Role of hexagonally and cubically ordered mesoporous carbons
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-21
    Xiaoxiang Cheng; Weiwei Zhou; Daoji Wu; Congwei Luo; Ruibao Jia; Peijie Li; Lu Zheng; Xuewu Zhu; Heng Liang
    更新日期:2020-01-22
  • Grafting Copolymer of Thermo-Responsive and Polysaccharide Chains for Surface Modification of High Performance Membrane
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-21
    Shaohu Zhang; Pantrangi Manasa; Qi Wang; Dan Li; Xuechao Dang; XiaoqinNiu; Fen Ran
    更新日期:2020-01-22
  • Negative pressure cavitation based ultrasound-assisted extraction of main flavonoids from Flos Sophorae Immaturus and evaluation of its extraction kinetics
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2019-07-12
    Gen Wang; Qi Cui; Lu-Jun Yin; Ying Li; Ming-Zhu Gao; Yao Meng; Ji Li; Sun-Dong Zhang; Wei Wang
    更新日期:2020-01-22
  • Matchstick-like metal-organic framework-based superwetting materials for efficient multiphase liquid separation via filtration or adsorption
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-20
    Yuanyuan Hou; Mingming Liu; Liping Zhang; Min Li; Dong Wang; Jingyan Liu; Shaohai Fu
    更新日期:2020-01-21
  • Synergistic degradation of chloramphenicol by ultrasound-enhanced nanoscale zero-valent iron/persulfate treatment
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-20
    Tingting Zhang; Yanling Yang; Jingfeng Gao; Xing Li; Haikuan Yu; Nan Wang; Peng Du; Rui Yu; Hang Li; Xiaoyan Fan; Zhiwei Zhou
    更新日期:2020-01-21
  • Selective removal of chloride ions by bismuth electrode in capacitive deionization
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-20
    Junjun Chang; Yuping Li; Feng Duan; Chunlei Su; Yujiao Li; Hongbin Cao
    更新日期:2020-01-21
  • Design and control of a novel side-stream extractive distillation column for separating methanol-toluene binary azeotrope with intermediate boiling entrainer
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-20
    Chao Wang; Yu Zhuang; Linlin Liu; Lei Zhang; Jian Du; Zhishan Zhang

    It is innovative and important to perform complex binary azeotrope separation via single distillation column. In the article, design and control of a novel and simple side-stream extractive distillation (SSED) column with extraction and solvent recovery function is investigated for the separation of methanol and toluene binary azeotrope with intermediate boiling triethylamine (Et3N) as solvent. The steady-state design parameters of the novel SSED column are optimized and obtained with the objective of minimal total annual cost (TAC) via conventional sequential iterative procedure. On the basis of steady-state design, four single-end temperature control structures (STCS), four dual-temperature control structures (DTCS) and four dual-composition control structures (DCCS) are developed and established successively to overcome the operation and control challenges caused by the novel scheme. To seek the robust control, the dynamic performance analysis on account of the above control structures is conducted for the SSED column, which is evaluated for feed flowrates and composition disturbances. The results show that the control performance of DCCS is significantly superior to that of STCS and DTCS while the integral squared error (ISE) and energy-consuming effect are equivalent, and can take shorter time to bring the product purities back to the original steady state in coping with specified feed disturbances.

    更新日期:2020-01-21
  • Evaluation of electrostatic properties of electret filters for aerosol deposition
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-20
    Maximilian Kerner; Kilian Schmidt; Stefan Schumacher; Vanessa Puderbach; Christof Asbach; Sergiy Antonyuk
    更新日期:2020-01-21
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  • Treatment of laundry wastewater containing residual surfactants using combined approaches based on ozone, catalyst and cavitation
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-18
    Vishal V. Patil; Parag R. Gogate; Akash P. Bhat; Pushpito K. Ghosh

    The present work investigates the treatment of wastewater by degrading detergents and residual surfactants using individual and combined approaches based on ozone, catalyst and cavitation. The intensification of ozonation has been investigated by the addition of solid ZnO and CuO catalysts. The extent of degradation increased with catalytic ozonation as compared to non-catalytic ozonation. In comparison, the combination with cavitation did not yield any beneficial results. The study of the effect of initial pH of the solution and effect of different catalyst loadings in catalytic ozonation with ZnO established that the maximum degradation as 89.3 % was obtained at initial pH of 9 and 0.1 g L-1 of catalyst loading respectively. It was also demonstrated that the reaction followed first order kinetics with rate constant as 0.067 min-1. BOD analysis at optimized conditions demonstrated that catalytic ozonation efficiently converts non-biodegradable harmful surfactants in wastewater to easily digestible compounds, which means that this can be a complimentary process to biological oxidation. Overall the work has clearly demonstrated the efficacy of catalytic ozonation approach for treating the laundry wastewater.

    更新日期:2020-01-21
  • Salting-out extraction of acetoin from fermentation broths using hydroxylammonium ionic liquids as extractants
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-18
    Yan Li; Jian-Ying Dai; Zhi-Long Xiu

    The salting-out extraction (SOE) systems based on ionic liquids (ILs) have attracted extensive attention in the separation of bio-based products, in which imidazolium ILs were widely studied. However, the high cost and toxicity have hindered their further industrial application. Hydroxylammonium ILs have the characteristics of cheap raw material, simple synthesis process and low toxicity, but are rarely used in the SOE systems. In this work, five hydroxylammonium ILs (2 cations and 4 carboxylate anions) were synthesized and used in SOE of bio-chemicals. The phase forming abilities of ILs with K3PO4 and H2O were affected by the hydrophilicity of anions and cations. With the increase of carbon chain length, phase forming abilities of ILs increased, while the temperature had little influence. The partition behaviors of acetoin, ILs and 2,3-butandiol, and the selectivity of acetoin to organic acids were investigated and compared at different concentrations of ethanolammonium butyrate (EOAB) and K3PO4. In a SOE system consisted of 6% EOAB-38% K3PO4 (w/w), the recovery of acetoin, IL and 2,3-butandiol was 92.7%, 76.0% and 86.0%, respectively, and the selectivity of acetoin to lactic acid and acetic acid was 16.46 and 3.85, respectively. The ATR-IR spectra showed the hydrogen bonds formed between acetoin and O-H, N-H, -COO- of hydroxylammonium IL played an important role in the efficient extraction of acetoin from fermentation broths.

    更新日期:2020-01-21
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  • Fouling resistance of 3-[[3-(trimethoxysilane)-propyl] amino] propane-1-sulfonic acid zwitterion modified poly (vinylidene fluoride) membranes
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-18
    Wentao Zhai; Mengliang Wang; Jianfeng Song; Lin Zhang; Xue-Mei Li; Tao He

    Zwitterion polymer modified membranes have demonstrated fouling resistance in wide applications. The ubiquitous success in scientific progress, however, has not yet brought significant breakthrough in the application of such membranes in wastewater treatment. Limitation of zwitterion materials in membrane is seldomly discussed. In this paper, we aimed to bring an engineering view on the pros-and-cons of zwitterion modified microfiltration membrane in treating solutions containing humic acid (HA) and bovine serum albumin (BSA). A 3-[[3-(trimethoxysilane)-propyl] amino] propane-1-sulfonic acid (TMAPS) grafted zwitterionic PVDF membrane was selected as a model membrane. The membranes were prepared via a two-step “hydroxylation-grafting” method; surface modified PVDF membrane was transformed from hydrophobic to hydrophilic with significant improvement in pure water flux. An 87% increase was obtained in the stable flux for the grafted membrane when treating HA, but very similar flux pattern to the pristine one was found when treating BSA. The membrane resistance model showed that cake layer was the main fouling factor for both foulants. For HA, the cake layer blocking model predicted the membrane flux well; but for BSA, the intermediate blocking model fits best the experimental results. Zwitterion grafted surface failed to show improvement in the fouling resistance even at very low BSA feed concentration. Adsorption experiment indicated that the interaction of BSA to membrane is significantly stronger than HA and membranes independent from the surface characteristics. Present work clarified the limitation of zwitterion modified membranes in treating solutions containing HA-like and protein matters.

    更新日期:2020-01-21
  • Carbon Nanotubes in-situ Cross-linking the Activated Carbon Electrode for High-performance Capacitive Deionization
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-18
    Jiangzhou Xie; Jinxing Ma; Linlin Wu; Min Xu; Wei Ni; Yi-Ming Yan
    更新日期:2020-01-21
  • Preparation of electrolyte for vanadium redox flow battery from sodium-polyvanadate precipitated wastewater
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-18
    Cong Liu; Tao Liu; Yimin Zhang; Zilin Dai; Yadong Yang

    In order to reduce pollution from wastewater and recycle the valuable metal in the vanadium precipitation process, sodium polyvanadate precipitated wastewater was utilized to prepare an electrolyte for the vanadium redox flow battery after two-stage purification via solvent extraction, which removed most of the impurities, especially Mn. The concentration of impurity ions was less than 10 ppm, as obtained by using inductively coupled plasma-optical emission spectroscopy, and the electrolyte obtained from the wastewater complied with the Chinese national standard. The method applied herein can simplify the preparation process compared to the conventional method and avoid ammonia nitrogen pollution. Electrochemical analysis showed that the properties of the prepared electrolyte were similar to those of the standard electrolyte. From the charge/discharge test, the energy efficiency and coulombic efficiency of the electrolyte reached nearly 90% of those of the standard electrolyte, which indicates that the electrolyte prepared from wastewater has the potential for commercial applications.

    更新日期:2020-01-21
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  • Comb-shaped amphiphilic triblock copolymers blend PVDF membranes overcome the permeability-selectivity trade-off for protein separation
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-18
    Junqiang Zhao; Qiqi Wang; Jing Yang; Yi Li; Zhongyun Liu; Luqing Zhang; Yiping Zhao; Shuxiang Zhang; Li Chen
    更新日期:2020-01-21
  • Recovery of ammonium nitrogen from human urine by an open-loop hollow fiber membrane contactor
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-17
    Junhui Zhang; Mengfei Xie; Xin Tong; Su Liu; Dan Qu; Shuhu Xiao
    更新日期:2020-01-17
  • Comprehensive experimental study of acid gases removal process by membrane-assisted gas absorption using imidazolium ionic liquids solutions absorbent
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-17
    Artem A. Atlaskin; Sergey S. Kryuchkov; Nail R. Yanbikov; Kirill A. Smorodin; Anton N. Petukhov; Maxim M. Trubyanov; Vladimir M. Vorotyntsev; Ilya V. Vorotyntsev

    For the first time the comprehensive study of a unique hybrid technique – membrane-assisted gas absorption (MAGA) for the acid gases removal was performed. As a case study, the influences of the presence of imidazolium ionic liquids in the methyldiethanolamine (MDEA) absorbent solutions on process separation efficiency were evaluated on the example of separation of two binary methane-based gases mixtures containing impurities of carbon dioxide or hydrogen sulfide. It was shown, that the addition of small amount (5 vol.%) of ionic liquids provides the significant increase on the process separation efficiency in a comparison with pure MDEA performance, which was taken as a reference. Also, the proposed technique was compared with a conventional single-stage membrane gas separation method and it was shown, that membrane-assisted gas absorption provides much higher separation efficiency in a whole observed range of processes productivity. The achieved purity of target component (methane) using absorbent solutions containing imidazolium ionic liquids exceeds the pure MDEA results more when 6 vol.% and equals to 90.2 vol.% in case of CH4/CO2 separation. In case of hydrogen sulfide removal (the initial content in the mixture is 5 vol.%) using a sorbent containing an ionic liquid, the methane purity is 99.87 vol.%, which exceeds the purity of methane achieved by using pure MDEA by 1.8 vol.%. Moreover, as an important part of process study the dynamics of establishing the steady state under a closed-mode operation was studied and the most efficient operational time regions and ultimate separation performance of a process was observed.

    更新日期:2020-01-17
  • The selective chlorination of nickel and copper from low-grade nickel-copper sulfide-oxide ore: mechanism and kinetics
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-17
    Fuhui Cui; Wenning Mu; Yuchun Zhai; Xueyi Guo

    On account of the complex occurrence of valuable metals in a large amount of low-grade nickel sulfide ore, obstacles have been caused by using the existing metallurgical method. Therefore, we are reporting a new selective chlorination roasting and water leaching process to treat complex nickel sulfide ore. Anhydrous aluminum chloride was firstly used as the solid chlorination agent to sulfide ore. The chlorination mechanism for metals in nickel-copper sulfide ore were determined by thermodynamic calculation and experiment. The thermodynamic analysis showed that the predominant matter contributing to the chlorination of talc, lizardite, and magnetite were AlCl3 (both solid or gas) and the generated HCl, however, the chlorination of metal sulfide (pentlandite, chalcopyrite, and pyrite) were mostly contributed by the generated Cl2. The effect of roasting temperature, the roasting time, the mass ratio of AlCl3 to the ore, the content of O2 in the roasting atmosphere and the particle size of ore were investigated. The orthogonal experiments results showed that the optimal conditions of the chlorination roasting process were the roasting time of 3 h, the roasting temperature of 450°C, the mass ratio of AlCl3 to ore of 1.5:1, the content of O2 of 20%, and particle size of the ore of 96-80 μm, under this condition, an extraction rate of nickel, copper, iron, and magnesium of 91.6%, 88.5%, 28.4%, and 16.4% was obtained. The chlorination mechanism is that, in the chlorination roasting process, nickel and copper were transferred into their corresponding metal chlorides, while most of the iron and magnesium were transferred into ferric oxide and magnesia-alumina silicates, respectively. TAK (thermal analytic kinetics) were used to clarify the chlorination kinetics, the results showed that the apparent activation energy calculated from DSC data was 70.4 kJ·mol-1, while calculated from TG data was 86.5 kJ·mol-1 (average) by using the FWO method, one of the most probable mechanism function of the chlorination process was G(α)=0.8701[1-(1-α)0.8701](integral form) and f(α)=(1-α)1.8701(differential form). The chlorination selectivity for metals could give guidance to the extraction of metals (especially for valuable metals) either in nickel sulfide ore or other minerals with a complex metal occurrence.

    更新日期:2020-01-17
  • Enhanced Separation of Benzene and Cyclohexane by Homogeneous Extractive Distillation using Ionic Liquids as Entrainers
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-17
    Miguel Ayuso; Andrés Cañada-Barcala; Marcos Larriba; Pablo Navarro; Noemí Delgado-Mellado; Julián García; Francisco Rodríguez

    The worldwide production of cyclohexane is mainly carried out through the hydrogenation of benzene. Unreacted benzene is separated from produced cyclohexane, being one of the most challenging processes in the petrochemical industry due to their extremely close boiling points and the presence of an azeotrope. In this work, an experimental screening of seven ionic liquids has been done in order to check the suitability of the extractive distillation with ionic liquids. The vapor-liquid or vapor-liquid-liquid equilibria (VLE/VLLE) of {cyclohexane/benzene + ionic liquid} binary systems and {cyclohexane + benzene + ionic liquid} ternary systems have been determined by Headspace-Gas Chromatography technique. The Non-Random Two Liquids (NRTL) thermodynamic model has been used to fit the experimental VLE/VLLE accurately. Although all the selected ionic liquids enhanced the cyclohexane/benzene relative volatility (α1,2) in comparison with conventional solvents, the [4bmpy][TCM] was chosen and implemented in Aspen Plus to simulate the extractive distillation process of benzene from cyclohexane with ionic liquids. The associated operating costs and the energy savings in comparison with conventional process, using N-methyl-2-pyrrolidone (NMP) as solvent, show that the extractive distillation with the [4bmpy][TCM] ionic liquid improves the conventional process, standing as an enhancer technology in the field.

    更新日期:2020-01-17
  • Novel nitrogen-rich g-C3N4 with adjustable energy band by introducing triazole ring for Cefotaxime removal
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-17
    Boru Gao; Jin Wang; Mengmeng Dou; Xue Huang; Xiaoxia Yu

    Graphitic carbon nitride (g-C3N4) possesses promising photocatalytic abilities due to its graphene-phase framework, distinct electronic structure, and optical performance. Nevertheless, the low visible light absorption capacity, rapid photoexcited electron-hole pairs recombination and transient electron lifetime have limited its extensive applications. In this study, nitrogen-rich triazole ring was introduced into conventional g-C3N4 structure to yield N-rich g-C3N4 (g-C3N4-N). Compared to traditional g-C3N4, the photocatalytic degradation efficiency of g-C3N4-N towards cefotaxime (CFX) was improved by 3-fold. Meanwhile, the mineralization rate rose to 51.3% with respect to 29.2%. The photocatalytic mechanism was then analyzed by various techniques, such as XPS, elemental analysis, FT-IR, and DFT calculations. The data revealed that introduction of triazole ring with mild electrophilicity on LUMO shifted the electron from melem to triazole ring. The change in electron structure shortened the bandgap of the catalyst and produced midgap state, thereby increasing the visible light absorption region of the catalyst. The PL, photocurrent density and EIS analyses suggested that midgap state could temporarily capture electrons and promote the separation of photoexcited electron-holes. In sum, the proposed novel one-step synthetic route of modified g-C3N4 material looks promising for future environmental remediation applications.

    更新日期:2020-01-17
  • Scaling up of defect-free flat membrane with ultra-high gas permeance used for intermediate layer of multi-layer composite membrane and oxygen enrichment
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Songlin Dong; Zhi Wang; Menglong Sheng; Zhihua Qiao; Jixiao Wang

    Multi-layer composite membrane has attracted more and more attention in the field of gas separation, especially for CO2 separation, and the intermediate layer (or gutter layer) has a significant influence on the performance of the multi-layer composite membrane. However, due to low gas permeance, current commercial gas separation membranes cannot be used as the intermediate layers with which to fabricate multi-layer composite membranes with high gas permselectivity. Aiming at oxygen enrichment application and developing proper large-area intermediate layer for multi-layer composite membrane, the scaling-up process of the flat membrane with ultra-high permeance was investigated in detail by using the most common material for intermediate layer and a substrate with extremely high gas permeance. In the lab-scale, through simply adjusting the relative humidity and prepolymer concentration, the coating solution with an appropriate cross-linking degree could be successfully prepared in 10 minutes. In view of the low viscosity of the coating solution, a consecutive membrane fabrication machine with the dip-blade coating unit was specifically designed to scale up the membrane. Using a firstly proposed wet-dry combined coating method, the defect-free flat membrane with a width of 1 m was successfully prepared, which had uniform performance in both the transverse and longitudinal directions. The O2 and CO2 permeance of the prepared large-area membrane could reach 2000 and 10000 GPU respectively, which was the highest among the reported membranes prepared with similar materials.

    更新日期:2020-01-17
  • Synthesizing Co3O4-BiVO4/g-C3N4 heterojunction composites for superior photocatalytic redox activity
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Yile Wang; Dan Yu; Wei Wang; Pin Gao; Shan Zhong; Lishan Zhang; Qiangqiang Zhao; Baojiang Liu
    更新日期:2020-01-17
  • Chemically tunable DILs: physical properties and highly efficient capture of low-concentration SO2
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Dan Li; Yong Kang; Jie Li; Zongchi Wang; Zhinan Yan; Kai Sheng

    As a successive work towards exploring suitable IL-based absorbents for SO2 absorption from flue gas, we developed a species of new dicationic ionic liquids (DILs) with the combination of ether-functionalized dication and N-heterocyclic anions. These dual-functionalized DILs possessed high thermal stability, low vapour pressure, and high SO2 capacity. The solubilities of SO2 in the DILs increased with declining of the temperature and elevating of the SO2 concentration. Notably, the available loading capacity of SO2 in DIL4 was up to 0.267 g SO2·(g DIL)-1 at 313.2 K when the concentration of SO2 in the feed gas was 2000 ppm, which was exceedingly significant for trapping SO2 from the flue gas with low content of SO2. The regeneration experiments demonstrated that the absorption capacities of SO2 in DIL4 kept unchanged after six successive cycles of absorption/desorption. The absorption mechanisms based on the results of 1H NMR, FTIR analysis and quantum chemical calculations indicated that both physical and chemical interactions between the SO2 molecules and DIL4 could be found in spite of different concentrations of SO2.

    更新日期:2020-01-17
  • Permeability dependencies on the carrier concentration and membrane viscosity for Y(III) and Eu(III) transport by using liquid membranes
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    S. Pavón; A. Fortuny; M.T. Coll; M. Bertau; A.M. Sastre

    The recovery of Y(III) and Eu(III) from fluorescent lamp leachates via supported liquid membranes using Cyanex 923 as a carrier has been studied. The results reveal that the transport process is mainly controlled by the diffusion or the viscosity of the organic phase depending on the carrier concentrations. Furthermore, this paper compares the transport model for flat sheet supported liquid membranes and hollow fibre renewal liquid membranes regarding both REEs in nitrate media. The model allows foreseeing the permeability coefficients for these REEs as a function of the organic phase variables. This study reveals furthermore, that the difference on the permeability coefficients between both membranes correlates to their structural characteristics, e.g. tortuosity, thickness and porosity.

    更新日期:2020-01-17
  • Purification of concentrated nickel sulfuric liquors via synergistic solvent extraction of calcium and magnesium using mixtures of D2EHPA and Cyanex 272
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Alexandre Silva Guimarães; Lucas Andrade Silva; Alexandre Moni Pereira; Julio Cesar Guedes Correia; Marcelo Borges Mansur

    A synergistic solvent extraction circuit consisting of D2EHPA and Cyanex 272 was applied to purify a concentrated Ni sulfuric solution ([Ni] = 88 g.L-1, [Mg] = 3.1 g.L-1, [Ca] = 0.5 g.L-1) similar to the MHP industrial liquors that feed the electrowinning step. The temperature was identified as a key parameter to optimize Mg extraction as well as to promote the selective recovery of co-extracted Ni in the extraction stages and make the stripping of Ca feasible using HCl as a stripping agent. Ca was crowded out by Ni from the loaded D2EHPA + Cyanex 272 solution and limited the operating pH range between 2 and 4. Under optimum conditions, 98.0% Ca and 98.4% Mg were simultaneously extracted in two and three theoretical stages by D2EHPA (0.30 M) + Cyanex 272 (0.32 M) mixture (pH 4, A/O ratio = 0.7 and 50°C). Co-extracted Ni was selectively recovered (99.7%) from the loaded D2EHPA + Cyanex 272 using [H2SO4] = 0.063 M in three stages (O/A ratio = 1 and 50°C). Ca and Mg can be completely stripped out from the loaded D2EHPA + Cyanex 272 at 50°C in only 1 ([HCl] = 3 M, O/A ratio = 5) or two theoretical stages ([H2SO4] = 1 M, O/A ratio = 2). The purified liquor containing 80 g.L-1 Ni (99.9% purity) can be directed for the electrowinning step to produce Ni cathodes. Extraction and stripping kinetics are rapid (equilibrium reached within 5 minutes). Thermodynamic analysis was done to support the synergism/antagonism trends observed experimentally.

    更新日期:2020-01-17
  • Two-dimensional Metal-Organic Framework nanobelts for Selective Fe3+ Removal from Aqueous Solution with High Adsorption Capacity
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Wen-Wen Fan; Xiao-Lan Liu; Yi Cheng; Yu Qin; Shao-Xiong Yang; Zhi-Xiang Lu; Yan-Xiong Liu; Qiu-E Cao; Li-Yan Zheng
    更新日期:2020-01-17
  • ZnAl2O4/BiPO4 composites as a heterogeneous catalyst for photo-Fenton treatment of textile and pulping wastewater
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Qingwen Tian; Miao Ran; Guigan Fang; Laibao Ding; Aixiang Pan; Kuizhong Shen; Yongjun Deng

    ZnAl2O4/BiPO4 heterostructures were successfully obtained via co-precipitation and hydrothermal method. The photocatalytic efficiency of ZnAl2O4/BiPO4 composites were improved and seriously influenced by the loading content of ZnAl2O4 under UV light. Photocatalytic tests showed that the kinetic constant of 1 wt% ZnAl2O4/BiPO4 composites for methylene blue degradation under UV irradiation were 0.959 h-1, which is 2.47 and 18.10 times as large as that of pure ZnAl2O4 and BiPO4, respectively. The enhanced photocatalytic performance of ZnAl2O4/BiPO4 heterojunctions was ascribed to effective separation of photo-generated electron–hole pairs. The photogenerated holes (h+) and •OH were the primary reactive species in the MB degradation over ZnAl2O4/BiPO4 composites. Photo-Fenton-like reaction was initiated with H2O2 addition, which significantly improved the photocatalytic activity of ZnAl2O4/BiPO4. The CODCr and color removals of textile wastewater over ZnAl2O4/BiPO4/H2O2 under UV irradiation were 76.74% and 83.22%, and the CODCr and color removals of eucalyptus chemimechanical pulp wastewater (ECMPW) over ZnAl2O4/BiPO4/H2O2 under UV irradiation were 73.98% and 84.54%, respectively. This work provides a new insight for constructing efficient flexible heterogeneous photocatalysts for wastewater purification.

    更新日期:2020-01-17
  • Dynamic Control Analyses of Eco-efficient Partially Heat-integrated Side-stream Pressure-swing Distillation Processes
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Qingjun Zhang; Aiwu Zeng; Youguang Ma; Xigang Yuan; Jun Gao

    Dynamic control behavior analysis for the new partially heat-integrated side-stream pressure-swing distillation arrangement is performed with the demonstrating examples of separating a minimum-boiling ethyl-acetate/ethanol azeotrope and a maximum-boiling ethylenediamine/water azeotrope. The snowball effect is observed in these systems. The contribution of this paper is to develop some novel robust and effective control schemes to eliminate or attenuate this effect for these processes. The stable regulatory control is achieved with the dual-product composition held close to their steady-state design specifications when handling the large step changes in throughput and feed composition. The feature control loops of these novel control schemes are that the flowrate in the azeotropic recycle loop from high-pressure column is, respectively, used to control the level in reflux drum and column base of low-pressure column for the minimum- and maximum-boiling azeotropes.

    更新日期:2020-01-16
  • Preparation of Polydimethylsiloxane-SiO2/PVDF-HFP Mixed Matrix Membrane of Enhanced Wetting Resistance for Membrane Gas Absorption
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-16
    Moau Jian Toh; Pei Ching Oh; Thiam Leng Chew; Abdul Latif Ahmad

    Membrane gas absorption (MGA) has been widely used to separate CO2 from gas mixture attributed to its high interfacial area. In order to secure high absorption flux, the pores of the membrane need to be non-wetted. Currently, hydrophobic membrane suffers from severe pore wetting over prolonged periods of operation. This has called for the enhancement of membrane hydrophobicity to suppress the tendency of pore wetting. In this work, highly hydrophobic PVDF-HFP membrane was synthesized using solvent additive i.e. polydimethylsiloxane-grafted-silica (PGS) via non-solvent induced phase separation. Results showed that mixed matrix membranes (MMMs) exhibited hierarchical structure composed of polymer spherulites due to delayed phase inversion. The embedment of nanoparticles in membrane matrix also contributed to the reduction of membrane’s surface energy. As a result, MMMs achieved an improvement in wetting resistance with a water contact angle up to 149.87° at 3wt% of PGS nanoparticles. The CO2 absorption test using MEA as liquid absorbent showed that MMMs exhibited an enhancement in gas absorption flux owing to higher hydrophobicity. The CO2 absorption flux of pristine and MMMs was declined about 37% and 22%, respectively during 150 h of operation.

    更新日期:2020-01-16
  • Aluminum Sludge thickening: Novel helical pipes for aggregation by dual flocculation and thickening by filtration applied to water treatment plants
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-14
    Manoel Maraschin; Keila Fernanda Soares Hedlund Ferrari; Andressa Paolla Hubner da Silva; Elvis Carissimi
    更新日期:2020-01-15
  • Catalytic degradation of methylene blue through activation of bisulfite with CoO nanoparticles
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-14
    Ruyan Dou; Hao Cheng; Jianfeng Ma; Yong Qin; Yong Kong; Sridhar Komarneni

    A novel catalytic system was developed by activating NaHSO3 with CoO nanoparticles for methylene blue (MB) degradation. The CoO nanoparticles were synthesized by a facile one-pot hydrothermal method followed by calcination. The crystallinity, morphology and elemental valence of the CoO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. MB degradation rates of 91.5% in one minute and 99.4% in six minutes were obtained using the CoO/NaHSO3 system, which may provide a more cost-effective and efficient way for decomposition of dye pollutants. The well-known classical quenching tests were used to investigate the free radicals involved in MB degradation along with electron paramagnetic resonance (EPR) spectra, the latter further confirmed the types of free radicals. Sulfate and hydroxyl radicals were proposed to be responsible for the excellent dye degradation achieved with the new CoO/NaHSO3 system.

    更新日期:2020-01-15
  • Enantioseparation of 4-Nitrophenylalanine using (S)-SDP-metal complex as chiral extractant
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-13
    Xiong Liu; Shuhuan Chen; Yu Ma; Wenjie Xiao

    The development of new and efficient chiral extractant is of great concern in the field of chiral extraction. Axial chiral diphosphine, such as (S)-BINAP, has been proved to be effective chiral extractant. However, the stereoselectivity of chiral diphosphine with novel structure has been rarely investigated in chiral extraction. (S)-SDP, a famous spiro diphosphine used in asymmetric synthesis, was firstly employed to separate 4-Nitrophenylalanine enantiomers in this study. The influences of metal precursors, pH, extractant concentration and temperature on extraction were investigated. Separation factor (α), enantiomeric excess (ee) and performance factor (pf) were adopted to evaluate the efficiency of enantioseparation. (S)-SDP-Pd was suitable for separation of 4-Nitrophenylalanine enantiomers with the highest α of 3.32. L-4-Nitrophenylalanine was preferentially recognized by (S)-SDP-Pd in extraction. The extraction process was systematically optimized by response surface method. The optimum extraction condition was pH of 7.1, (S)-SDP-Pd concentration of 2.2 mmol/L and temperature of 14.0°C. At this optimum condition, the maximum pf was 0.08536. In addition, the possible chiral recognition mechanism was discussed.

    更新日期:2020-01-13
  • Gelatin-based mesoporous hybrid materials for Hg2+ ions removal from aqueous solutions
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-13
    Hem Suman Jamwal; Sunita Ranote; Dharamender Kumar; Ghanshyam S. Chauhan; Monica Bansal

    High toxicity and bioaccumulation are the two major features that make mercury as the most dangerous heavy metal for the living organisms and mandates its removal from the contaminated water bodies. Keeping this in view, a new gelatin-based mesoporous hybrid material, with SiO2 as the inorganic and gelatin as the biopolymeric component, was synthesized via the sol-gel process. The material was characterized by FTIR, SEM, SEM-EDS, TEM and BET studies. The synthesized hybrid material containing Gelatin/SiO2, has high surface area of 675.92 m2g-1. It was evaluated as an adsorbent of Hg2+ ions from their aqueous solutions. Parametric study of the factors affecting adsorption process was carried out to find the optimum adsorption conditions. Different kinetic and isotherms models were applied to the data obtained and adsorption was found to follow pseudo-second order kinetics and Langmuir isotherm model. The highest partition coefficient value of 7.13 mg g-1 µM-1 was obtained at the lowest initial Hg2+ ions concentration (50 ppm) studied alongwith an adsorption capacity of 43.85 mg/g while for the highest initial concentration of 225 ppm the respective values were 0.876 mg g-1 µM-1 and 105.075 mg/g. Cumulative adsorption capacity of the hybrid material from reusability studies in seven cycles was found to be 315.6 mg g.−1

    更新日期:2020-01-13
  • Fabrication and characterization of a novel hydrophobic polystyrene membrane using electroblowing technique for desalination by direct contact membrane distillation
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-13
    Amirhossein Sadeghzadeh; Saeed Bazgir; Mohammad Mahdi A. Shirazi

    In this work, a new hydrophobic membrane with nanofibrous structure was prepared from polystyrene using the electroblowing technique, for the first time, for desalination experiments. Using this technique, the injection rate for the dope solution increased up to 117 µL/min. This means faster and considerably higher fiber productivity as compared to the typical electrospinning. The membrane was treated via a hot-press post treatment. The new membrane was analyzed for the surface morphology and topography, and was then evaluated for desalination using DCMD process. The results for the new membrane compared to a commercial PTFE membrane with 0.22 µm pore size. Larger mean pore size (0.562 µm) was observed for the new membrane. However, the membrane porosity for the nanofibrous membrane was comparable with the PTFE one (∼75%). The fabricated membrane was thinner and therefore it produced higher permeate flux. Both fabricated and commercial membranes showed ˃99% salt rejections for lower range of feed flow rate (≤0.48 L/m). Most importantly, the new membrane fabricated using a cheap and available polymer via a fast technique for DCMD desalination. The hot-pressed, nanofibrous membrane showed higher surface hydrophobicity (154.52o) than the commercial membrane (124.61o). The superhydrophobic state of the new membrane prevented the liquid encroachment into the membrane pores. This consequently improved not only the permeate flux, but also the average salt rejection. Overall, the new fabricated membrane showed a reasonable desalination performance.

    更新日期:2020-01-13
  • 更新日期:2020-01-13
  • A Thermodynamic Model for Reactive Extraction of Macro Amounts of Zirconium and Hafnium with TBP
    Sep. Purif. Technol. (IF 5.107) Pub Date : 2020-01-13
    M.V.S.R. Ravi Kanth; S. Pushpavanam; Shankar Narasimhan; B. Narasimha Murty

    Pure component thermodynamic models are developed for solvent extraction involving ionic reaction equilibrium for distribution of macro concentrations of zirconium and hafnium between an aqueous phase containing HNO3 and an organic solvent phase containing diluted TBP. The concentration range considered is 10-03 to 100 M. A framework based on chemical speciation calculation is used for the purpose. Experimental procedures adopted to obtain the required solvent extraction data for modeling and validating these models are detailed. Measured equilibrium concentrations of total zirconium, total HNO3, total nitrate in the aqueous phase and total zirconium in the organic phase are used to obtain the thermodynamic parameters such as equilibrium constants and activity coefficient model parameters for zirconium and hafnium extraction systems. The novel framework is useful for computing equilibrium concentrations of all the species present in the respective systems. It is also demonstrated that the pure component models developed for extraction of zirconium and hafnium are effective over a wide range of concentrations. These pure component models can be used to simulate and optimize industrial scale zirconium – hafnium separation process.

    更新日期:2020-01-13
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