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Separation and Purification Technology
Elsevier Science B.V.
Separation and Purification Technology

Elsevier Science B.V.

1383-5866

Separation and Purification Technology/Journal Separation and Purification TechnologySCIEIISTP
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    S-scheme heterojunction g-C3N4/Ag/AgNCO for efficient tetracycline removal in a photo-assisted peroxymonosulfate system

    Hongjun FangYing HanXinzhen Feng
    15页
    查看更多>>摘要：Photo-assisted peroxymonosulfate(PMS)activation process is emerging as an effective and eco-friendly technology for sewage purification.Herein,a g-C3N4-based S-scheme heterostructure(g-C3N4/Ag/AgNCO)was fabricated by a facile chemical-deposition and photo-reduction method.Because of intensive hetero-interface contact and synergistic effect between g-C3N4 and Ag/AgNCO,the assembled heterojunction exhibits enhanced light absorption,rapid charge separation/transport and impressive catalytic performance.Tetracycline(TC)degradation efficiency of 98% with a rate constant of 0.2995 min~(-1)can be accomplished over 40%-g-C3N4/Ag/AgNCO/PMS/light system within 12 min,3.05 and 4.86 times better than that obtained over g-C3N4/PMS/light and AgNCO/PMS/light system,respectively.The quenching/ESR investigation suggested that the active species function syngenetically in TC degradation and the significance follows the order of h~+>SO_4~(·-)-~·O_2~(·-)>~O_2>~·OH.The cyclic test proved the excellent stability of the current catalyst system.The involved degradation routes,intermediates,and toxicity assessment have been studied in detail.The current research may serve as a versatile tactic for designing the g-C3N4-based functionalized catalytic material for wastewater purification through the photocatalysis/sulfate-mediated advanced treatment process.
      原文链接:
    • NSTL

    High-efficiency separation of CO2 from CO2-CH4 gas mixtures via gas hydrates under static conditions

    Weiguo LiuShaohua LiZucheng Cheng
    12页
    查看更多>>摘要：Hydrate technology with high gas storage capacity and excellent safety features has attracted much attention for capturing CO2 from biogas to produce purified CH4.When considering operational efficiency,it is desirable to overcome technical barriers such as slow hydrate generation and low separation efficiency.Therefore,based on the properties of surfactant-enhanced hydrate generation kinetics,this work first systematically evaluated the performance of 500 ppm SDS on the separation efficiency of 40 mol% CO2 and 60 mol% CH4 simulated biogas.The experimental results show a significant increase in gas capture at higher driving forces,with the rise being dominated by the CH4 component,indicating that larger driving forces reduce hydrate selectivity to CO2-CH4 and weaken gas separation efficiency,with a maximum CO2 recovery of 84.24 ± 1.19% at 275.15 K and 8 MPa.Interestingly,hydrate growth mainly occurred in the liquid phase,leading to the separation factor being positively correlated with the induction time with sufficient CO2 dissolution.In comparison,the gas capture per unit volume of solution could be improved by more than a factor of 2 at higher gas-liquid ratios.The best separation factor of 7.84 ± 0.73 was achieved,and separation factors in general gradually decreased with increasing gas-liquid ratio;however,there was high-pressure failure behavior.Furthermore,the impact of the defoamer on separation efficiency was deeply investigated for SDS decomposition foaming,with results showing that the defoamer would alleviate hydrate decomposition foaming behaviour while having no significant effect on hydrate generation kinetics and separation efficiency.
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    • NSTL

    Recent advancements in carbonic anhydrase immobilization and its implementation in CO2 capture technologies:A review

    Hannaneh RasouliKaven NguyenMaria C.Iliuta
    23页
    查看更多>>摘要：Currently,amine-based solutions are considered as benchmark absorbents for CO2 capture.However,there are severe environmental concerns as well as high energy consumption.A viable option is CO2 capture utilising water as absorbent,via a biomimetic approach by the enzyme carbonic anhydrase(CA),with high selectivity,upmost performance,and environmental friendliness.However,the employment of the free form of CA in industrial applications is not rational due to the considerable amounts of enzyme required,instability and non-reusability.The immobilization of CA has attained significant interest,appearing as a promising approach to solve the problems associated with free CA.In this context,different immobilization strategies and supports have been developed to ameliorate the activity,stability,and reusability of CA enzyme,lowering the cost and increasing the process efficiency in large-scale applications.CO2 capture has been studied using immobilized CA in various technologies such as absorption columns,selective membranes,and membrane contactors.In this state-of-the-art review,the scientific literature regarding the immobilization of CA and carbon capture technologies using immobilized CA are analyzed,highlighting the benefits,issues,and limitations of processes.Moreover,modelling approaches describing the absorption of CO2 in packed-bed and membrane bioreactors with immobilized CA are presented,as well as the impact of operating parameters on bioreactors performance.The techno-economic analyses carried out on enzymatic capture processes are reviewed as well,to assess their feasibility in an industrial context.Finally,concluding remarks are made with a recommended perspective on open challenges and research priorities.
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    • NSTL

    Highly efficient Li~+/Mg~(2+)separation of monovalent cation permselective membrane enhanced by 2D metal organic framework nanosheets

    Lu TaoXiaojuan WangFadong Wu
    9页
    查看更多>>摘要：Monovalent cation permselective membranes(MCPMs)manifest remarkable effectiveness and potential in lithium extraction whereas facing the challenge to achieve high permselectivity and high Li~+ permeability simultaneously.In this work,Zn-TCPP,a kind of two-dimensional nanosheet with abundant negative charges,was successfully synthesized via surfactant-assisted method and introduced into surface cross-linked SPES membrane to fabricate MCPMs.The physicochemical properties,electrochemical properties and Li~+/Mg~(2+)separation performance of resulted MCPMs were systematically estimated.As ions passing through the membrane,dense PVA/GA crosslinked layer separated Li~+ and Mg~(2+)by pore-size sieving effect.Afterwards,uniformly distributed Zn-TCPP nanosheets with rich negative charges and physically adsorbed water molecules elevated the charge density and water content in the membrane and thus expedited Li~+ transporting.Therefore,high Li~+/Mg~(2+)permselectivity(P_(Mg~(2+)~(Li~+))= 8.99)and Li~+ permeation flux(J_(Li~+)= 9.12 × 10~(-9)mol cm~(-1)·s~(-1))were obtained.Furthermore,membrane surface resistance was reduced from 108.99 Ω.cm~2 to 24.12 Ω·cm~2.This study points out the feasibility of the new method for accelerating monovalent ion transport and alleviating the restriction between ion permeation and permselectivity in selective ion exchange membranes.
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    • NSTL

    Carbon nitride coupled with Fe-based MOFs as an efficient photoelectrocatalyst for boosted degradation of ciprofloxacin:Mechanism,pathway and fate

    Yiming QinShuai YangXinyu You
    15页
    查看更多>>摘要：This paper reports a heterostructure composites,g-C3N4/MIL-101(Fe),that was synthetized through effortless solvothermal method by g-C3N4 coupled with MIL-lOl(Fe)containing terephthalic acid(H2BDC)as organic linker.Eminent photoelectrocatalytic degradation effect was demonstrated by the heterojunctions coordinated with visible light and low current(PEC)for the treatment of ciprofloxacin(CIP)in model matrix and realistic water samples.Moreover,morphological,physicochemical and photocatalytic properties of the catalyst were appraised.Compared with g-C3N4,MIL-lOl(Fe)and the heterojunction in various systems,the CIP degradation was up to 87.55% by 0.5 g/L of g-C3N4/MIL101(Fe)addition along with 12 W LED lamp and 50 mA current in 240 min.The realization of PEC synergism for an intensified treatment effect to this organic molecule has mainly been implemented through electro-Fenton and visible light catalysis,which was based on circulation of the Fe~(II)/Fe~(IIO)along with a correct band structure between g-C3N4 and MIL-lOl(Fe).Active species capture and electron spin resonance(ESR)test uncovered that ·OH,>>02 and h+ contributed to the elimination of CIP.The degradation pathway and toxicity assessment of intermediates was conducted using LC-MS,DFT calculation and QSAR theory.Seventeen kinds of intermediates were detected,which showed a reduced toxicity.Findings of the paper provide incisive insights on the mechanism of the degradation of organic pollutants through PEC synergy over g-C3N4/MIL-101(Fe)heterojunction catalyst.Moreover,the results constitute a meritorious instance for preparing catalyst in this application field.
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    • NSTL

    Separation of cobalt and nickel via solvent extraction with Cyanex-272:Batch experiments and comparison of mixer-settlers and an agitated column as contactors for continuous counter-current extraction

    Isadora R.RodriguesClio DefermKoen Binnemans
    10页
    查看更多>>摘要：The separation of cobalt and nickel was carried out via solvent extraction using the commercial extractant bis(2,4,4-trimethylpentyl)phosphinic acid(Cyanex-272).Solvent extraction experiments were performed on a batch scale to optimize the extractant concentration,saponification degree,equilibration time,organic-to-aqueous phase ratio(O/A),and stripping conditions.High selectivity of cobalt over nickel was obtained at an extractant concentration as low as 0.2 M(or 20% v/v),with a saponification degree of 40% and a phase ratio 0/A of 1/1.Furthermore,eleven diluents,covering different aliphatic-aromatic compositions were tested to evaluate their effect on the separation of cobalt and nickel.Cobalt extraction efficiencies were not significantly impacted by the nature of the diluent.However,the co-extraction of nickel was approximatively 10% higher when toluene was used as a diluent in comparison with the aliphatic diluent Shell GS270.The process was validated in continuous mode using a battery of mixer-settlers and an agitated Klihni column.High recovery of cobalt and negligible co-extraction of nickel were achieved in both cases.The specificities,advantages,and challenges of the operation of both types of liquid-liquid extraction equipment were further discussed.
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    • NSTL

    Electrocoagulation process for greywater treatment:Statistical modeling,optimization,cost analysis and sludge management

    Pushpraj PatelShubhi GuptaPrasenjit Mondal
    13页
    查看更多>>摘要：The present study investigates the removal of greywater pollutants such as COD,BOD,nitrate,and phosphate using the electrocoagulation treatment process.The influence of operating parameters such as current density(CD)(1-5 A/m~2),contact time(CT)(10-90 min),and initial pH(3-11)of the solution was investigated using aluminum electrode.The results demonstrate that 70% COD removal,87.5% BOD removal,82.7% nitrate removal,and 84.7% phosphate removal is achieved at optimum operating condition(CD = 3 A/m~2,CT = 60 min,and pH = 7,energy consumption = 0.153 kWhm~(-3),and operating cost = 0.114 US$m~(-3)).The kinetics study analysis confirms that the electrocoagulation process follows pseudo-first-order kinetics model.The combination of response surface methodology(RSM)and artificial neural network(ANN)based statistical models were employed to optimize the electrocoagulation process parameters as well as to accomplish the individual limitations.The correlation coefficient value closer to ~ 1 and lower error governs the feasibility of the developed models.The results exhibited that,the ANN model had a higher R~2 and a lower MSE value than the RSM model,indicating that ANN is better at predicting process output than RSM,although RSM appropriately predicts process parameter interaction and its relevance.The study found that using a combinational approach to represent the electrocoagulation process for greywater treatment is more effective.
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    • NSTL

    Novel 0D-1D-2D nanostructured MCN/NCDs recyclable composite for boosted peroxymonosulfate activation under visible light toward tetracycline degradation

    Kaibang XiaoZhang LiuXueding Jiang
    14页
    查看更多>>摘要：In this study,a novel nitrogen modified carbon quantum dots(NCDs)decorated graphite carbon nitride/molybdenum(Mo)heterojunction photocatalyst(MCN/NCDs)was obtained by in-situ calcination and physical deposition,and applied as peroxymonosulfate(PMS)activators for tetracycline(TC)removal under visible light.It was found that the MCN/NCDs as PMS activation catalyst exhibited outstanding removal efficiency under visible light assistance and nearly 98.4% of TC was degraded within 60 min.The analysis data of photochemistry demonstrated that the introduction of NCDs could significantly improve the visible-light utilization,narrow the band gap and increase the separation of photogenerated electron-hole pairs.The results of radical capture experiment and electron spin resonance test(ESR)suggested that the order of active species contributing to TC degradation in vis/PMS/MCN/NCDs system was O_2~(·-)>h~+>·OH>~1O_2>SO_4~(·-)Moreover,the MCN/NCDs composite exhibited excellent stability with over 98% activity retention for 5 cycles and superior catalytic efficiency in four real water matrix.Finally,the underlying degradation mechanism and toxicity assessment were proposed in detail.This work provided a new perspective on the design of excellent activity g-CsN4 composite catalysts and elucidated a promising potential strategy for efficient contaminated water treatment via PMS activation process.
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    • NSTL

    External optimization of Zr-MOF with mercaptosuccinic acid for efficient recovery of gold from solution:Adsorption performance and DFT calculation

    Chao XiongXusheng ZhangChen Wang
    10页
    查看更多>>摘要：A novel sulfhydryl-modified MOF(UiO-66-MSA)was prepared by externally optimizing UiO-66-NH2 with mercaptomalic acid(MSA)and its capacity in selective recovering of Au(III)from solution was examined.Tests indicated that external modification of UiO-66-NH2 by MSA increased its theoretical maximal adsorption capacity at pH 5 by 24.57% from 578.0 to 720.0 mg/g.Simulation of the kinetics data revealed that Au(III)binding on both UiO-66-MSA and UiO-66-NH2 followed the pseudo-second-order model,with the former material having significantly higher kinetics.In the existence of competing ions,Au(III)recovery by sulfydryl-modified UiO-66-NH2(UiO-66-MSA)was increased from 72.06% to 98.59% at an initial Au(III)concentration of 56.9 mg/L.This material also had a fairly good reusability.At 5 times of regeneration,it was still able to capture 99.42% Au(III)from solution.Analysis of the changes in XPS patterns and the electrokinetic properties of UiO-66-MSA suggested that Au(III)binding on this MSA-modified MOF was complex.The electrostatic interaction,reduction and chelation may have all actively participated in the adsorption process.DFT calculation revealed that Au(III)binding was attributed to the-SH,-NH and G=0 functional groups residing on the repeating unit of UiO-66-MSA,with its sulfhydryl functional group being the strongest binding site.
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    • NSTL

    Bio-Inspired phosphate adsorption by Copper-Decorated weak base anion exchanger

    Biplab K.MahataSue-min ChangPurnendu Bose
    13页
    查看更多>>摘要：Hybrid-based phosphate adsorbents have high adsorption ability but are challenged with regeneration because of strong bonding.Inspired by phosphate-binding proteins(PBPs)which reached a trade-off between high adsorption and regeneration ability by binding phosphate species with multiple hydrogen bonds,a weak-base anion(WBA)exchange resin was decorated with Cu~(2+)ions to develop an alternative advanced phosphate adsorbent.Different from the role of metal species in the promoted adsorption of existing hybrid-based adsorbents,the Cu~(2+)ions mainly drove phosphate diffusion from the liquid to the resin and then induced the phosphate species to bond with multiple-NH_2~+/-NH groups.Such adsorption exhibited a high entropy(AS0 = 132.47 J/mol-K)and was highly exergonic(ΔG~0 =-16.83 ~-20.14 kJ/mol).Moreover,it enhanced the phosphate selectivity because the driving force for the sorption process originated from the complexation.During the regeneration,the Cu~(2+)-to-Cu-O~-transformation could occur under weak alkaline conditions and repelled the adsorbed phosphate species to facilitate desorption.Therefore,the Cu-WBA resin not only exhibited high phosphate adsorptions(31.94 to 61.03 mg-P/g)and high competing-anion tolerance but also was successfully recovered with a diluted NaOH solution(0.05 N).Detailed adsorption behaviors under different pHs,temperatures,and interference of competing anions were examined,and the mechanisms were elucidated.
      原文链接:
    • NSTL