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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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    Type-II surface heterojunction of bismuth-rich Bi4O5Br2 on nitrogen-rich g-C3N5 nanosheets for efficient photocatalytic degradation of antibiotics

    Ji, HaodongLiu, WenHuang, YiningFu, Jie...
    12页
    查看更多>>摘要：A novel g-C3N5/Bi4O5Br2 surface heterojunction was developed via in-situ growth of Bi-rich Bi4O5Br2 on g-C3N5 nanosheets. The optimal composite achieved 3.6- and 16.0- times of sulfathiazole (STZ) degradation activity when compared with pristine Bi4O5Br2 and g-C3N5. The interlayer stacking morphology and extra nitrogen in triazine units significantly narrowed the conduction band of g-C3N5, which greatly promoted its visible utilization; while the bismuth-rich property of Bi4O5Br2 prolonged the excited charge carrier lifetime. Both photoluminescence and electrochemical impedance spectroscopy analysis demonstrated that the type-II surface heterojunction (g-C3N5/Bi4O5Br2) offered remarkable charge transfer and separation due to the matched energy band structure. The STZ degradation mechanism and pathways were proposed based on experiments and density functional theory calculation, and the contribution of reactive species for STZ degradation followed the order of O-2(center dot-) > h(+) > (OH)-O-center dot. Moreover, the toxicity evolution of STZ was evaluated, suggesting that sufficient mineralization is required to ensure safe discharge. The Box-Behnken experimental design methodology study revealed that g-C3N5/Bi4O5Br2 exhibited high reactivity for antibiotics degradation under different water matrix. This study suggested that g-C3N5/Bi4O5Br2 has great application potential for cost-effective remediation of persistent organic contaminants by using solar light.
      原文链接:
    • NSTL
    • Elsevier

    A novel strategy of pulsed electro-assisted pyrite activation of peroxymonosulfate for the degradation of tetracycline hydrochloride

    Chen, XiaojiaoZhao, NaHu, Xiaomin
    8页
    查看更多>>摘要：In order to overcome the complexity and high cost of preparation of iron-based modified catalyst, a novel process of natural pyrite (FeS2) superimposed pulsed electro-assisted activation peroxymonosulfate (PMS) for contamination treatment was developed. Tetracycline hydrochloride (TCH) was selected as the target pollutant because of its persistence and high drug-resistance toxicity. Firstly, the optimum parameters (pulse current intensity, duty cycle, pH, PMS concentration) were determined by different conditional experiments. Then, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize pyrite before and after the reaction. And electron spin resonance (ESR) and quenching experiment were used to discern the active species in the reaction processes. The results showed that pyrite could effectively activate PMS to degrade into hydroxyl radicals (.OH) and sulfate radicals (SO4.- ) to treatment contamination. In addition, the pulsed electro-assisted addition could weaken concentration polarization, improve TCH removal efficiency to 93%, and reduce energy consumption. More importantly, pulsed current was better than the direct current for converting SO2-4 to SO.-4 . And Fe(III) can be converted to Fe(II) through the action of electrons and S22- in the pulse electro-assisted pyrite activation of PMS process. These findings provide new insights into PMS activation by iron-based catalyst and electrochemistry.
      原文链接:
    • NSTL
    • Elsevier

    MgO-supported CuO with encapsulated structure for enhanced peroxymonosulfate activation to remove thiamphenicol

    Dan, JiabinRao, PinhuaWang, QiongfangDong, Lei...
    14页
    查看更多>>摘要：Copper-base catalysts with high load content of CuO were commonly utilized to activate peroxymonosulfate (PMS) for removal of contaminants but limited catalytic efficiency and increased risk of copper ion leaching restricted their use. In this paper, Cu-Mg mixed metal oxides with highly dispersed minute quantities of CuO were successfully prepared by one-pot synthesis for efficiently activating PMS to remove thiamphenicol (TAP), which was economical and environmentally friendly. The catalytic activities of catalysts with different molar ratios of Cu and Mg for PMS and their characteristics were evaluated, illustrating the optimal molar ratio of Cu and Mg (1:15, named CuMg-MMO) in the catalyst. For the CuMg-MMO catalyst, MgO widely dispersed and wrapped CuO nanoparticles, minimized the copper ion leaching and promoted the generation of Cu-OH complex and non-radical species. In the CuMg-MMO/PMS system, the influence factors for TAP degradation were analyzed, including different systems, catalyst dosages, PMS concentrations, temperatures, initial pH values, TAP concentrations, anions (NO3-, HCO3-, Cl-, HPO42-, and H2PO4-) and natural organic matter (NOM) concentrations. Under the optimal conditions (i.e., [catalyst]: 75 mg/L, [PMS]: 0.3 mM, temperature: 30 degrees C and initial pH: 6.5), TAP removal efficiency obtained by this system was 99.9%. SO4 center dot-, center dot O-2(-) and O-1(2) played more important roles than HO center dot in TAP degradation. Four successive repeated experiments indicated that CuMg-MMO possessed good reusability and stability. PMS decomposition, mineralization of TAP, the activation mechanism of PMS and possible degradation pathways of TAP were analyzed.
      原文链接:
    • NSTL
    • Elsevier

    Co-N-C@SiO2 core@shell architectures enhanced stability to activate peroxymonosulfate (PMS) for efficient sulfamethoxazole degradation

    Feng, YijieSang, WenjiaoDeng, ZhiyiZhang, Shiyang...
    11页
    查看更多>>摘要：Co-N-C@SiO2 with Co, N doped carbon as core and SiO2 as shell was successfully synthesized by template method, and SiO2 shell was about 43 wt%. Impressively, the SiO2 shell increased the active sites of the core in CoN-C@SiO2 preparation, and reduced the loss of active sites during use. Co-N-C@SiO2/PMS was a O-1(2) dominated non-radical reaction, which was less interfered by solution pH and water constituents. In addition, Co-N-C@SiO2 possessed better cycling performance compared with Co-N-C. Finally, the possible SMX degradation pathways were presented based on the identified intermediate products.
      原文链接:
    • NSTL
    • Elsevier

    SPIONs self-assembly and magnetic sedimentation in quadrupole magnets: Gaining insight into the separation mechanisms

    Wu, XianGomez-Pastora, JeniferZborowski, MaciejChalmers, Jeffrey...
    10页
    查看更多>>摘要：Superparamagnetic iron oxide nanoparticles (SPIONs) are currently popular materials experiencing rapid development with potential application value, especially in biomedical and chemical engineering fields. Examples include wastewater management, bio-detection, biological imaging, targeted drug delivery and biosensing. While not exclusive, magnetically driven isolation methods are typically required to separate the desired entity from the media in specific applications and in their manufacture and/or quality control. However, due to the nano-size of SPIONs, their magnetic manipulation is affected by Brownian motion, adding considerable complexities. The two most common methods for SPION magnetic separation are high and low gradient magnetic separation (HGMS and LGMS, respectively). Nevertheless, the effect of specific magnetic energy fields on SPIONs, such as horizontal (perpendicular to gravity), high fields and gradients (higher than LGMS) on the horizontal magnetophoresis and vertical sedimentation of SPIONs has only recently been suggested as a way to separate very small particles (5 nm). In this work, we continue those studies on the magnetic separation of 5-30 nm SPIONs by applying fields and gradients perpendicular to gravity. The magnetic field was generated by permanent magnets arranged in quadrupolar configurations (QMS). Different conditions were studied, and multiple variables were evaluated, including the particle size, the initial SPIONs concentration, the temperature, the magnetic field gradient and the magnetic exposure time. Our experimental data show that particles are subjected to horizontal magnetic forces, to particle agglomeration due to dipole-dipole interactions, and to vertical sedimentation due to gravity. The particle size and the type of separator employed (i.e. different gradient and field distribution acting on the particle suspension) have significant effects on the phenomena involved in the separation, whereas the temperature and particle concentration affect the separation to a lesser extent. Finally, the separation process was observed to occur in less than 3 mins for our experimental conditions, which is encouraging considering the long operation time (up to days) necessary to separate particles of similar sizes in LGMS columns that also employ permanent magnets.
      原文链接:
    • NSTL
    • Elsevier

    Synthesis and properties of Polymeric ionic liquids (PILs) bearing hydrophilic PEO groups: Evaluation of gas and water vapor separation performance

    Ioannidi, A.Anastasopoulos, C.Vroulias, D.Kallitsis, J....
    13页
    查看更多>>摘要：New pyridinium based PILs containing PEO pendants were synthesized to be examined as CO2 and water selective membranes. A two-step synthetic procedure was followed including an N-methylation reaction of a precursor copolymer and a subsequent anion exchange metathesis to afford the corresponding PILs. The prepared PILs having different counter-anions form mechanically robust, flexible membranes, which exhibit high thermal stability and Tgs close to room temperature. It was examined the effect of anion nature on physicochemical as well as gas/water vapor separation properties. The conversion of the precursor copolymer to its corresponding PIL analogues led to Tg increase and thermal stability decrease of the latter. Surprisingly, the gas permeability for all PILs was decreased compared to precursor owing to the strong cation-anion interactions developed in the PIL structures which lead to a tighter polymer chain packing and consequently to gas diffusion hindering. The PIL containing the C(CN)(3)(-) anion (PIL750-C(CN)(3)) experiences the lowest CO2 permeability compared to TFSI- and MeSO4- which is accompanied by a very high CO2/CH4 selectivity value of 70 that is among the highest reported in the literature for PILs. This behavior can be attributed to its dense polymer chain packing and thus to its strong sieve-sieving ability associated with the diffusion-driven permeability decrease. Regarding water vapor permeability, it was evidenced that the PIL containing the MeSO4- anion (PIL750-MeSO4) showed the highest water vapor permeability (80,000 Barrer) compared to anions TFSI- and C(CN)(3)(-), which is attributed to MeSO4- increased hydrophilicity and higher hydrogen bond basicity. The high water permeability is accompanied by a very high H2O/CO2 and H2O/N-2 selectivity. The water vapor effect on gas permeation of PIL750-TFSI and PIL7(50)-MeSO4 under process gas streams conditions using two different mixtures with compositions 3% H2O:14.5% CO2:82.5 %N-2 and 3% H2O:48.5% CO2:48.5% CH4, respectively, was also investigated. The results demonstrate that gas permeability of all tested gases increased under humid conditions due to plasticization induced by water vapor. Accordingly, the separation factors decreased when compared with ideal selectivities in dry conditions for both PILs. However, PIL750-MeSO4 combines the high water vapor permeability with the high H2O/CO2 and HO2/N-2 separator factors highlighting its potential to be used in flue gas dehydration and air dehydration.
      原文链接:
    • NSTL
    • Elsevier

    Activation of peroxymonosulfate by nitrogen-doped porous carbon for efficient degradation of organic pollutants in water: Performance and mechanism

    Hu, YiChen, DezhiWang, ShoujunZhang, Rui...
    14页
    查看更多>>摘要：Carbon materials are becoming the first choice for activating persulfate due to their environmental friendliness, high chemical stability, and metal-free leaching. However, the preparation of efficient carbon catalyst and the indepth analysis for persulfate activation is still insufficient. Herein, N-doped porous carbons (NPCs) were prepared by the pyrolysis of polyacrylonitrile and used to trigger peroxymonosulfate (PMS) for degrading organic pollutants in water. The results showed that the optimized NPC-700, with large specific surface area, rich pore structure, high content of pyridinic N and graphitic N, as well as excellent oxygen-containing functional groups, possessed the best performance in activating PMS to degrade methylene blue (MB) with 99.15% degradation rate in 30 min. Furthermore, the NPC-700 delivered high stability under a wide pH from 3.51 to 11.15. The radical quenching experiments and electron paramagnetic resonance (EPR) spectroscopy revealed that center dot OH, O2 center dot-, SO4 center dot and 1O2 active species were involved in the catalytic oxidation of MB. Besides, the NPC-700/PMS system exhibited excellent degradation performance for various organic dyes, including rhodamine B, acid orange 7, and methyl orange. This study not only provides a promising metal-free catalyst for the removal of organic pollutant in water, but also promotes the sustainable development of carbon-based materials.
      原文链接:
    • NSTL
    • Elsevier

    Chiral polymeric membranes: Recent applications and trends

    Vedovello, PriscilaParanhos, Caio MarcioFernandes, CarlaTiritan, Maria Elizabeth...
    16页
    查看更多>>摘要：The development and marked growth of chiral compounds is primarily due to the increased demand for pharmaceutical applications, but it has been also extended to other sectors like agrochemicals, food, flavours, fragrances and material science. The pure enantiomers can present higher efficacy, potency and are considered safer than racemate or even achiral compounds. Enantiomerically pure compounds can be obtained by stereoselective synthesis and by post-synthesis separation through chiral separation methodologies. The use of solid polymeric membranes has become promising for enantiomeric separation, due to the low cost and energy consumption, continuous operability and variety of materials. This review aims to present the advances in research of chiral separation, using the enantioseparation technique based on solid polymeric membranes. Theoretical fundamentals and applications of solid polymeric enantioselective membranes in the last ten years is presented. The review also provides relevant information on the performance of this type of membranes for future applications and improvement in chiral separation field.
      原文链接:
    • NSTL
    • Elsevier

    Nanoscale tailoring on thin bimetallic organo-oxide membranes for H-2/CO2 separation

    Mirza, E. SimalTopuz, Berna
    8页
    查看更多>>摘要：The design of tailored novel membrane networks with excellent hydrothermal stability allowing gas sieving is highly desired to take them a step closer to large scale commercialization for energy efficient separation. Bistriethoxysilylmethane (BTESM) containing Si-C-Si bonds was used as a precursor for the fabrication of Tiincorporated BTESM organosilica membranes on a macroporous ceramic support with a mesoporous intermediate layer. The precise engineering on the sol-gel parameters allowed the formation of bimetallic clusters with 2-4 nm size range in the clear organo-oxide sols. XPS analyses indicated the development of Si-O-Ti connections in the organo-oxide membrane network. A high H-2 permeance of 6.3 x 10(-7) mol/m(2)sPa and attractive ideal selectivities of 10, 10, 119 and 222 for H-2/N-2, H-2/CH4, H-2/C3H6 and H-2/C3H8, respectively are attained from an exceptionally thin BTESM membrane. H-2/CO2 ideal selectivity increases from 4 to 8 upon incorporation of 15 mol% Ti into membrane network while selectivities increase to 32 for H-2/N-2, 44 for H-2/CH4, and 246 for H-2/C3H8 with 1.25-fold increase in H-2 permeance. H-2/CO2 ideal selectivity of 24 was achieved with moderate H-2 permeance of 1.7 x 10(7) mol/m(2)sPa after hydrothermal treatment for 45 h for BTESM15 membrane as thin as 65 nm. This is the one of the thinnest ceramic supported organosilica membrane reported having acceptable H-2 permeance after hydrothermal treatment.
      原文链接:
    • NSTL
    • Elsevier

    Constructing MOF-doped two-dimensional composite material ZIF-90@C3N4 mixed matrix membranes for CO2/N-2 separation

    Jiang, XiaobinHe, GaohongXiao, WuGuo, Fei...
    9页
    查看更多>>摘要：Two-dimensional nanomaterials have the characteristics of high aspect ratio and high space utilization, which has huge potential advantages in gas separation. In this work, g-C3N4 two-dimensional nanosheets with sieving pore structure were selected as templates and combined with ZIF-90 to construct a 0-dimensional/2-dimensional composite material ZIF-90@C3N4 (ZCN). The complete two-dimensional g-C3N4 nanosheets were stripped under acid etching conditions at 25 degrees C. ZIF-90 was distributed in an orderly manner on the two-dimensional nano-sheets, and the nanosheets were spread out due to the growth of ZIF-90 to provide more free volume. The gas permeation experiment proved that the ZCN has a better CO2/N-2 separation performance. The ZCN/Pebax mixed matrix membrane (MMM) with the optimized 8.0 wt% ZCN loading showed an improved CO2 permeability of 110.5 Barrer and a CO2/N-2 selectivity of 84.4, surpassing the Robeson upper bound (2008). The results demonstrated that the designed composite filler with 2D nanosheets is an effective strategy to enhance gas separation performance of MMMs and verified the application potential in gas purification industry.
      原文链接:
    • NSTL
    • Elsevier