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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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    Enhanced photocatalytic O2 activation by the synergy of efficient oxygen adsorption and interfacial charge separation: A case of Bi3O4Br/rGO van der Waals heterojunction

    Hu J.Chen F.Mu K.Lu J....
    13页
    查看更多>>摘要：? 2022 Elsevier B.V.Herein, a novel 2D/2D van der Waals (VDW) heterojunction of oxygen-vacancy-rich Bi3O4Br load reduced graphene oxide (rGO) (Bi3O4Br/rGO) was used to reveal the synergy of efficient oxygen adsorption and interfacial charge separation. The performance of Bi3O4Br/rGO was evaluated by degrading tetracycline (TC), ciprofloxacin (CIP), 2,4-dichlorophenoxyacetic acid (2,4-D) and ranitidine hydrochloride (RAN) under visible light, which were 2.3, 2.6, 2.5 and 4 times higher than that of Bi3O4Br, respectively. Furthermore, Bi3O4Br/rGO displayed 4 times enhanced [rad]O2? production ability than Bi3O4Br. The improvement of photocatalytic efficiency could be ascribed to the better chemisorbed oxygen and lower recombination rate of photogenerated electron-holes. More importantly, its interfacial charge migration pathway was unraveled: The electrons are efficiently transferred from Bi3O4Br to rGO through VDW heterojunction interface thus resulting in more photogenerated carriers participating in reactions. This work may provide a feasible strategy to study on improving the molecular O2 activation efficiency for VDW heterojunction.
      原文链接:
    • NSTL
    • Elsevier

    Ingenious design of ternary hollow nanosphere with shell hierarchical tandem heterojunctions toward optimized Visible-light photocatalytic reduction of U(VI)

    Zeng D.Cheng Z.Wang Y.Cao X....
    13页
    查看更多>>摘要：? 2022 Elsevier B.V.TiO2 based photocatalytic reduction has been regarded as a promising technology for flexibility of uranium recovery from seawater, however, the use of sacrificing agents and protection gas are two major challenges for practical application. Herein, a ternary hybrid TiO2@CdS@Au hollow nanosphere (TCA) was designed and synthesized for highly efficient photocatalytic reduction of U(VI). The designed ternary hollow nanosphere is composed of double heterojunctions: type-Z heterojunction generated between TiO2 with CdS and metal–semiconductor junction between CdS and Au NPs, which is contributive for the spatial separation and diffusion of photogenerated charges. Therefore, compared with loaded Pt or GOQDs, the superior photocatalytic reduction efficiency of TCA2 (Au NPs content of 0.8%) for U(VI) achieves 99.7% within 25 min and remains unchanged after five cycles in the presence of 3 mmol·L-1 NaHCO3 under air condition. Its photoreduction rate constant is 5.7 and 4.1 times as much as the CdS and hollow TiO2@CdS nanosphere. Additionally, in the absence of any protective gases and holes sacrificial agent, the soluble U(VI) adsorbed on the photocatalyst is reduced to insoluble α-U3O8 by photogenerated electrons and superoxide radical, which has been recognized as one of the most effective strategy for the separation and recovery U(VI) from polluted environment.
      原文链接:
    • NSTL
    • Elsevier

    Extra-thin composite nanofiltration membranes tuned by γ-cyclodextrins containing amphipathic cavities for efficient separation of magnesium/lithium ions

    Zhao Y.Li N.Shi J.Zhu B....
    10页
    查看更多>>摘要：? 2022 Elsevier B.V.Although nanofiltration (NF) membrane as a new frontier technique had made significant progress in the field of lithium extraction from salt lakes, they still suffered from the conventional permeability–selectivity trade-off effect. In this study, γ-cyclodextrins(CDs) containing amphipathic cavities and polyethyleneimine (PEI) acted as the aqueous phase monomer, which was carried out interfacial polymerization with the trimesoyl chloride (TMC) as the organic phase monomer to fabricate thin film composite (TFC) NF membranes with the extra-thin active layer. The hydrophilic surface and hydrophobic cavity of γ-CDs enhanced the hydrophilicity of the membrane surface and the water flux of the nanofiltration membrane. Moreover, the cavity size of γ-CDs also effectively screened magnesium and lithium ions to a certain extent. Under the best preparation conditions, the permeation flux of the PEI/γ-CDs-TMC nanofiltration membrane was 4.86 L?m?2?h?1?bar?1, SLi, Mg was 10.8. It was noteworthy that we used the molecular dynamics simulation method to confirm that the participation of γ-CDs led to the diffusion rate of the water phase monomers during the interfacial polymerization reaction slowed down. Thus, the thickness of the active layer of the nanofiltration membrane formed was also significantly reduced from 110.16 nm to 52.84 nm. This PEI/γ-CDs-TMC membrane provided a new strategy for preparing nanofiltration membranes with excellent overall magnesium-lithium separation performance.
      原文链接:
    • NSTL
    • Elsevier

    Rapid oxidation of 4-cholorphenol in the iron-based Metal–Organic frameworks (MOFs)/H2O2 system: The ignored two-steps interfacial single-electron transfer

    Han Y.Huang M.Xiang W.Wang C....
    9页
    查看更多>>摘要：? 2022 Elsevier B.V.Fe-based metal–organic frameworks (MOFs) are popular in activating oxidants e.g·H2O2 and persulfate (PS) for degrading recalcitrant organic substances, generally regarded with a simple interfacial efficient iron cycle. This study has revealed that a novel two-steps single-electron transfer mechanism would occur initially to activate the rapid degradation 4-chlorophenol (4-CP) in the MIL-88B(Fe)/H2O2 system (88B/H2O2 system). The degradation of 4-CP was acidic favorable (pH0 ≤ 6.0) and could be divided into two reaction stages, i.e., initial lag phase (0–10 min) and following rapid decay phase (10–50 min). In the first stage, H2O2 was slowly activated on the surface of 88B to form superoxide radical (O2?–), which would lead to the accumulation of the key intermediate hydroquinone (HQ) through reducing 4-CP. Afterwards, HQ could reductively dissolve iron ions which would lead to the subsequent efficient homogeneous Fenton reaction for the rapid oxidation of 4-CP by hydroxyl radical (?OH) in the following rapid decay phase. It was interesting to note that specific aromatic compounds, which would form reductive benzenediols intermediates by O2?–, could be efficiently degraded in the 88B/H2O2 system. The result of this study is expected to provide a new insight for understanding the catalytic oxidation process based on MOFs, and its application if possible.
      原文链接:
    • NSTL
    • Elsevier

    Recovery of bio-based medium-chain fatty acids with membrane filtration

    McDowall S.C.Braune M.Nitzsche R.
    10页
    查看更多>>摘要：? 2022 Elsevier B.V.Medium-chain fatty acids (MCFAs) are promising platform chemicals for biorefineries in the circular economy. An efficient and sustainable process for their recovery from biomass, however, remains elusive. This work aimed to develop a separation cascade for MCFA recovery from fermentation broth (FB) using membrane filtration. This technical-scale process consisted of a filter-press, thermal-pretreatment, ultrafiltration (UF), and nanofiltration (NF). While solid–liquid separation and UF were efficient, NF fluxes declined rapidly due to membrane fouling, limiting MCFA separation and concentration. Thermal pretreatment and UF membrane pore size had a negligible effect on filtration performance and diafiltration trials in NF proved ineffective. While process feasibility is presently constrained by membrane fouling in NF, characterization, and reduction of foulants could make the process readily viable. Overall, the membrane filtration cascade yielded a product, the NF retentate, with an MCFA concentration approximately 230% greater than that of the feedstock with an average overall recovery of 84%. Furthermore, although the concentration of MCFAs (C4-C8, 12.9 g L–1) may be inadequate for direct use, this product, being clarified and enriched, could serve as an improved feedstock for MCFA purification by alternative methods.
      原文链接:
    • NSTL
    • Elsevier

    Synergistic interplay between Aliquat 336 and organophosphorus extractants towards non-dispersive extraction of arsenic from petroleum produced water via hollow fiber membrane contactor

    Mohdee V.Woraboot C.Nootong K.Pancharoen U....
    14页
    查看更多>>摘要：? 2021This work presents the elimination of arsenic from petroleum produced water via hollow fiber membrane contactor (HFMC). Results demonstrate that the extractability of arsenic is successfully achieved through the blended extractants of Aliquat 336 + Cyanex 921 suggesting the occurrence of synergism. Under optimum conditions, the extraction and stripping of arsenic achieved 94.42% and 78.90%, respectively. Slope analysis is applied to determine the stoichiometric coefficients of synergistic interplay. Both kinetics and mathematical modelling are employed to describe the behaviors arising in the HFMC system. It is seen that chemical reactions proved to govern the transportation of arsenic across HFMC. Besides, a novel approach as regards reaction mechanisms in a binary system is adopted.
      原文链接:
    • NSTL
    • Elsevier

    A green desilication method from highly concentrated chromate solutions by Mg-Al-CO3 LDH

    Liu W.Luo L.Han Y.Zhang H....
    7页
    查看更多>>摘要：? 2022 Elsevier B.V.The Mg-Al-CO3 LDH was synthesized as a desilication agent to effectively and environmentally remove Si(IV) from Na2CrO4-NaAlO2-NaVO3-Na2SiO3-H2O solutions. It was observed that the changes of reaction parameters including temperature, NaOH concentration, time, the dosage of Mg-Al-CO3 LDH and NaAlO2 concentration significantly affected the desilication efficiency, while the effect of Cr(Ⅵ) and V(Ⅴ) concentration on the desilication was negligible. The results showed that 91.5% Si(IV) could be removed after desilication at 90 °C for 6 h with the additive of 4 g/L Mg-Al-CO3 LDH, without the formation of hazardous Cr(VI)-containing compounds. It could be concluded that the desilication mechanism was dominated by the synergistic effect between the ion exchange of Si(IV) and the formation of zeolite compounds. The method proposed in this study provides a new insight for Si(IV) removal from the highly concentrated Cr(VI) solutions in the chromate clean production.
      原文链接:
    • NSTL
    • Elsevier

    A water-stable Cd-MOF and corresponding MOF@melamine foam composite for detection and removal of antibiotics, explosives, and anions

    Lei M.Ge F.Ren S.Gao X....
    12页
    查看更多>>摘要：? 2022 Elsevier B.V.Water pollution has become one of the most worrisome environmental problems due to its harmful to human health and environmental safety. Thus, the design and development of robust and porous materials for detection and removal of pollutants from wastewater is extremely significant. Herein, a water-stable urea-containing 3D Cd-based metal-organic framework (MOF), {[Cd(L)0.5(bpe)0.5(H2O)]·x(solv)}n (MOF-1) (H4L = 5,5′-(((1,4-phenylenebis(azanediyl))bis(carbonyl))bis(azanediyl))diisophthalic acid) was prepared using urea-functionalized tetracarboxylate H4L ligand. The activated MOF-1 (MOF-1a) showed fast, sensitive, selective, and recyclable discrimination of nitrofurazone (NFZ) and nitrofurantoin (NFT) antibiotics, 2,4,6-trinitrophenol (TNP) explosive, as well as Cr2O72? by strong luminescence quenching and obvious red-shift of maximum emission. Unfortunately, MOF-1a has low adsorption capacity for the above pollutants owing to its small pore. To improve this disadvantage, MOF-1 crystals were in situ grown on the macroporous melamine foam (MF) by a facile one-pot solvothermal method, generating a MOF-1@MF composite with stability and high voids. The MOF-1@MF exhibited rapid, enhanced, and recyclable adsorption capacity toward NFZ, NFT, TNP, and Cr2O72? in water or even aqueous solutions with different pH values. Combination of the accessible functional sites in MOF-1 and macroporous structure of MF makes MOF-1@MF composite stand out as an excellent adsorbent in wastewater treatment. This work not only presents a water-stable MOF for selective recognition of NFZ, NFT, TNP, and Cr2O72?, but also provides a facile one-pot strategy to prepare MOF-based composites for high-performance removal of above pollutants from water, promoting their practical application in water quality monitoring and wastewater purification.
      原文链接:
    • NSTL
    • Elsevier

    Myrica Rubra-like MnFe2O4 Microsphere: A high efficiency microwave reduction catalyst for Cr(VI) removal from water

    Yuan G.Li K.Zhang J.Wang H....
    9页
    查看更多>>摘要：? 2022 Elsevier B.V.Aqueous hexavalent chromium (Cr(VI)) is easy to enter the biological system, causing serious threat to human and aquatic environment health. In this paper, a myrica rubra-like MnFe2O4 catalyst with average diameter of 200–300 nm were prepared by a simple solvothermal method. Benefiting from the knobby surface and the considerable microwave absorption ability, the as-prepared MnFe2O4 microsphere exhibited excellent microwave catalytic reduction ability for Cr(VI) in water, and the catalysts dosage, initial Cr(VI) concentration, solution pH value and temperature showed crucial effect on the catalytic reduction process. When the pH value of the solution was 2, the amount of catalysts was 2 g/L, and the temperature was 100 ℃, the myrica rubra-like MnFe2O4 catalysts could remove as high as 96% of Cr(VI) from a 50 mg/L aqueous solution only after 10 min microwave irradiation, which is much higher than the commercial one. The enhanced catalysis performance could be ascribed to the surface “knob” with a size of ～ 17 nm, which accelerated the generation of e– under microwave irradiation, finally promoted the catalytic reduction performance. The microwave catalytic reduction strategy is a hopeful alternative for ultrafast reduction of Cr(VI) in sewage with high efficiency.
      原文链接:
    • NSTL
    • Elsevier

    Simultaneous removal of aniline and antimony (Sb(V)) from textile wastewater using amidoxime-PAN/PLA nanofiber microsphere supported TiO2

    Tu Y.Ren L.-F.Shao J.He Y....
    7页
    查看更多>>摘要：? 2022 Elsevier B.V.Removal of organic aniline and antimony (Sb(V)) in textile wastewater was usually studied individually in cost-ineffective way. In this study, novel amidoxime-PAN/PLA nanofiber sphere (NFS) supported TiO2 (TiO2@NFS) was fabricated to remove aniline and Sb(V) simultaneously. Results of scanning electron microscope (SEM), fourier infrared spectrometer (FTIR), X-ray diffractometer (XRD) and photoluminescence spectrometer (PL) demonstrated that TiO2 nanoparticles were uniformly dispersed and immobilized on NFS. With 6 h of UV light exposure, aniline and Sb(V) reductions of TiO2@NFS were 86.3% and 78.5%, respectively, both of which were higher than those of plain commercial TiO2 (48.6% and 6.3%). This was attributed to that numerous mesopores in TiO2@NFS could facilitate “dark reaction” adsorption prior to photodegradation for aniline and abundant amidoxime groups could increase adsorption sites for Sb(V). Kinetics for aniline and Sb(V) removal could be well modeled by Langmuir-Hinshelwood and pseudo-second-order equation, respectively, according to high correlation coefficients (R2 greater than 0.90). In addition, TiO2@NFS could well deposit after 10 min of standing, indicating excellent sedimentation performance. Recycling experiment showed good recycling stability of TiO2@NFS. These findings indicated that aniline and Sb(V) were promising to be simultaneously removed from textile wastewater by novel TiO2@NFS via photodegradation coupled with adsorption technology.
      原文链接:
    • NSTL
    • Elsevier