查看更多>>摘要：? 2022Tetracycline (TC) is a widely used pharmaceutical and personal care product (PPCP), and considering its biotoxicity in aquatic systems, the metabolism and stimulation of TC in wastewater purification processes are still deserving of concern. This study reveals the stimulation of TC biodegradation by acetate in bioelectrochemical systems (BESs). Attributed to the abundance of exoelectrogens Geobacter (mainly G. sulfurreducens) and putative TC-degraded bacteria (PTDB) in the electroactive biofilm samples, 94% of 100 mg/L TC decomposed within 48 h. Limited acetate (0.1 g/L, AC-0.1) as a cosubstrate enhanced the removal efficiency of TC by 44% when compared to abundant acetate (1 g/L, AC-1) and controls. This resulted from the enhancement of PTDB and the stability of the Geobacter population under limited acetate stimulation. With the differentiation of the microbial community, ubiquinone and other terpenoid-quinone biosynthesis and histidine metabolism were significantly upregulated in AC-0.1 but downregulated in AC-1, another factor that enhanced the removal efficiency of TCs. Here, we concluded that limited acetate could partially relieve the selective pressure of TC and improve the biodegradation of TC, and the catabolism pathways, as well as the main metabolites, were stimulated by acetate and its concentration.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, polyvinylpyrrolidone (PVP) modified magnetic rGO/CoFe2O4 (PVP/rGO/CFO) composites are successfully synthesized by a simple hydrothermal method. The addition of PVP effectively changes the morphology of the PVP/rGO/CFO composites. When the mass ratio of PVP to rGO is 1:1 during the preparation of the composites (named as sample S3), a unique sandwich structure is formed through the self-assembly behavior between rGO nanosheets and CoFe2O4 nanoparticles with the aid of PVP. The adsorption capacity of the as-synthesized samples for different dyes is investigated. Here, it is noted that, owing to the specific microstructure, sample S3 exhibits superior adsorption properties, where, in terms of Langmuir isotherm model, the maximum adsorption capacities for MB, RhB and CR are 333.3, 558.7 and 355.9 mg g?1, respectively. Because of the typical magnetic characteristics, the adsorbents can be easily separated by a magnet. The adsorption kinetics accords well with the pseudo-second-order model. It is demonstrated that the excellent adsorption performance of cationic dyes MB and RhB is attributed to the synergistic effect of π-π conjugation interactions and electrostatic interaction, while the adsorption of anionic dyes CR is mainly due to the interaction between its functional groups and the lactam group in PVP. This study provides a new route to develop graphene-based magnetic adsorbents to simultaneously remove cationic and anionic dyes in the wastewater.
查看更多>>摘要：? 2022 Elsevier B.V.Remove of trace Al3+ from rare earth solutions is a challenging task. In the present study, an aluminum ion imprinted polymer (Al (III)-IIP) has been fabricated by surface-imprinting method. Al (III)-IIP was obtained by grafting silica gel with aminopropyl triethoxysilane and acrylic acid (AA). The structure and morphology of the polymer were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The densification degree and the number of grafted functional groups were regulated by changing the synthesis conditions, and the optimal synthesis conditions are obtained as template ion: functional monomer: crosslinker = 1:8:8, and the optimal synthesis temperature is 333.15 K. The adsorption performance and selectivity properties of Al (III)-IIP were also investigated. The results show that at 298.15 K, the optimal pH for Al3+ adsorption is 4. The maximum adsorption capacity is 106.0 mg·g?1 at an Al3+ ion concentration of 1000 mg·L?1, which is 50% higher than that of reported recently. In addition, the adsorption process reaches equilibrium within 180 min. Furthermore, among many adsorption models and isothermal models, pseudo-second-order (PSO) adsorption model and Langmuir isothermal model are more suitable for the adsorption process. The selectivity coefficient of the Al3+ ion in binary mixtures of Nd3+, Ca2+ or Mg2+ are 17.76, 16.72 and 11.09, respectively. In addition, the adsorption mechanism of Al3+ is most probably caused by the formation of ionic bond between the Al3+ ions and the carboxyl functional groups on Al (III)-IIP and template effect. Results show that Al (III)-IIP has a great potential for a selective separation of aluminum ions from rare earth solutions.
查看更多>>摘要：? 2022 Elsevier B.V.Anaerobic treatment of wastewater from various sources is becoming increasingly popular as it can convert 73% of the chemical oxygen demand present in the wastewater to biogas. Methane in the biogas is the major contributor to produce energy in subsequent downstream processes. However, a significant amount of methane usually escapes to the environment through the treated effluent. This study proposes a model that can predict the recovery of dissolved methane and other performance parameters from the effluent of an anaerobic reactor using porous and dense hollow fiber membrane contactors (HFMCs) for the pilot- or large-scale application. The model introduced a distribution factor, m, to the liquid mass transfer coefficient to fit the experimental removal of dissolved methane and the methane desorption flux, JCH4, through the HFMCs. The factor m was found to have a linear relationship with the average JCH4. Further, it was found that a net energy gain of 0.34 MJ·m-3 (0.024 MJ·kg-1CH4 for 16 mg·L-1 dissolved methane in the feed) is achieved for an effluent flow rate of 11 m3·d-1, with a methane content of 35% recovered from the HFMC. A break-even payback period will be attained when multiple modules of HFMC are used. The model provides simplified investigation of the potential and effectiveness of the HFMCs for dissolved methane recovery from anaerobic effluent, with further verification using data from pilot- and large-scale systems.
查看更多>>摘要：? 2022 Elsevier B.V.Deep eutectic solvents (DESs) are environmentally friendly solvents with excellent affinity to acidic gases and have broad application prospect in the field of SO2 capture. In this work, four inexpensive DESs comprising of tetraethylammonium chloride (TEACl) and azoles (imidazole, pyrazole and tetrazole) were designed and prepared for highly efficient and reversible absorption of SO2. Physical properties and chemical structures of the prepared DESs were characterized. High SO2 capacity ranging from 0.756 to 1.251 g/g (3.610–7.231 mol/mol) were obtained at 20 °C and 1.0 bar. Surprisingly, owing to the accompanying phase transition, available SO2 capacity of TEACl-Im (1:3) reaches 0.438 g/g (2.532 mol/mol) at 2000 ppm and 20 °C, which is the highest value reported so far. The absorption mechanism and phase transition were further investigated using FTIR, NMR and XRD, revealing the generation and precipitation of SO2-imdazole adduct. In addition, no significant drop in SO2 absorption capacity was observed after five successive absorption–desorption cycles. Overall, TEACl-Im (1:3) exhibits good absorption performance especially for low-concentration SO2, providing potential alternatives for flue gas desulfurization.
查看更多>>摘要：? 2022 The AuthorsSurface modification of polysulfone (PSf) surface, via acrylic acid (AA) surface graft polymerization, induced by atmospheric pressure Air plasma (Air APP) surface treatment, was explored for imparting UF membrane fouling resistance and tuning its performance. PSf surface activation with Air APP and subsequent tethering of PAA chains resulted in a higher degree of surface hydrophilicity relative to the use of He and He/O2 plasmas. Surface-nano-structed (SNS) PSf membranes with tethered PAA chains were of increased surface hydrophilicity and the polar component of the surface energy by 14% and 556%, respectively, and had a greater negative zeta potential (by 26% at pH >～6) relative to the native-PSf membrane. Fouling filtration tests with bovine serum albumin (BSA) and sodium alginate demonstrated reduced fouling resistance, relative to the native-PSf membrane. Moreover, complete permeability recovery of the fouled SNS-PAA-PSf membrane was achieved, via simple water backwash, relative to 66%-81% permeability recovery for the native PSf membrane. Tethering the PSf UF surface with PAA chains was also enabled tuning of the membrane molecular weight cutoff (MWCO) and hydraulic permeability. It was shown that starting with the same PSf UF membrane a series of SNS-PAA-PSf membranes can be synthesized whereby performance tuning was achieved over a MWCO range of 5.5–11 kDa and a corresponding permeability range of 12.7–23.5 L·m?2·h?1·bar?1. The present approach of PSf UF membrane surface structuring with tethered PAA chains, employing Air APP for surface activation, was shown to be effective for UF membrane fouling reduction and performance tuning. Thus, the present study results suggest that there is merit in exploring its scalability given the utilization of air as a low cost plasma source gas.
查看更多>>摘要：? 2022 The AuthorsA downstream process for the purification and concentration of formic acid (FA) from FA/gluconic acid (GA) mixtures, obtainable by a coupled biocatalytic reaction of CO2 reduction and glucose oxidation, has been developed. The process involved two technologies: (i) a first nanofiltration (NF) step to separate FA and GA, and (ii) a second reactive liquid-liquid extraction (RLLE) step to concentrate FA. The NF process, using a Synder NFX membrane, consisted of three NF steps separated into two divergent lines, named permeate and retentate pathways. The first NF was common for both pathways, resulting in a permeate strongly enriched in FA and depleted in GA, and a retentate with opposite characteristics. In the permeate pathway, this first permeate was subjected to a second NF to obtain a 99.6% pure FA permeate. In the retentate pathway, an additional NF step on the first retentate resulted in a concentrated 99.4% pure GA retentate. The final diluted FA permeate was concentrated by RLLE using tri-N-octylamine as extractant in n-octanol, and a final back-extraction with NaOH. The optimized RLLE process involved a 100-fold volume decrease and resulted in a final FA solution (as sodium formate) of 174.5 g/L, 78 times more concentrated than the feed.
查看更多>>摘要：? 2022 Elsevier B.V.It is a great challenge to selectively translating a pollutant into a valuable product from multi-component organic pollutants for waste treatment. Herein, we design and then fabricate a novel thermo-responsive bilayer composite membrane realizing the selective separation, catalytic transformation and in situ product separation from two-component pollutants in a one-step. This bilayer membrane systematically characterized by FTIR, XPS, SEM and AFM and the other techniques, comprises a top semi- interpenetrating polymer network(semi-IPN) coating layer and a bottom poly(vinylidene fluoride) @Pd catalytic layer. In a continuous cross-flow filtration process, the pollutant BSA is directly separated by the membrane, while the pollutant p-nitrophenol controllably penetrates through the top semi-IPN layer and then reacts in the catalytic layer; subsequently, the product p-aminophenol is in situ separated and collected. The reactant is purified before reaction, further, any unexpected reactions on membrane surface are avoided by isolating reactants from the catalysts via the top layer, preventing the interference of the unexpected pollutants and products for the catalytic transformation. The transformation efficiency can be strengthened by adjusting temperature and an maximum conversion of 99.74% can be obtained for a p-nitrophenol solution of 10 mg/L at a flux of 27.0 L?m?2?h?1?bar?1 and a temperature of 30℃.
查看更多>>摘要：? 2022 Elsevier B.V.Efficient removal of pollutants based on porous adsorbents is a research hotspot now. Triazine herbicides (TRZHs), a class of broad-spectrum, low-cost pesticides, have become an environmental concern owing to the widespread use and abuse these chemicals. In this study, an ionic liquid (IL)-functionalized porous m-aminophenol formaldehyde polymer (IL-PMAPFP) used to adsorb four TRZHs (simazine, cyanazine, atrazine, and terbuthylazine) in environmental water was synthesized. The role of the ethylene oxide/propylene oxide block copolymer (F127) and IL in pore formation was confirmed by microscopic morphology and specific surface area analysis of IL-PMAPFP. The specific surface area of IL-PMAPFP increased 13-fold after adding F127 and the IL. The adsorption of TRZHs on IL-PMAPFP conformed to the pseudo-second-order kinetic and Freundlich isotherm models. The adsorption process is spontaneous, endothermic, and has a strong anti-interference ability. The adsorption equilibrium of IL-PMAPFP could be reached within 1 h, and the adsorption capacities of the four TRZHs are 4.26, 4.82, 5.21, and 8.53 mg/g, respectively, which were higher than many reported adsorbents. Theoretically, the ability of the adsorbent to treat TRZH-contaminated water is 450–900 L/g. IL-PMAPFP is a powerful adsorbent owing to its large surface area, high adsorption amount, fast mass transfer, and good regeneration capability (>eight cycles). IL-PMAPFP combined with dispersive solid phase extraction/miniaturized pipette tip solid phase extraction-high performance liquid chromatography is expected to accurately quantify TRZHs. In addition, the synergistic pore formation strategy of F127 and IL present a new method for preparing of porous polymer. This study provides a new perspective for developing efficient purification techniques to monitor and remove pollutants.
查看更多>>摘要：? 2022 Elsevier B.V.Organic solvent nanofiltration (OSN) has become an emerging green and efficient technique for the separation and purification of organic solvents. The key of the industrial application of this technique is OSN membrane. Till now, current OSN membranes still have relatively low solvent permeance due to the high hydraulic resistance of the dense structure of the OSN barrier layer. Herein, a thin-film composite (TFC) polyamide-polyarylate OSN membrane containing polymers of intrinsic microporosity (PIMs) structure was successfully prepared via interfacial polymerization (IP) using a kind of hydrophilic monomer with rigid twisted structure as aqueous co-monomer together with m-phenylenediamine (MPD). The added co-monomer remarkably enhanced the perm-selectivity of the prepared OSN membrane, with an increase of more than 1.5 times for ethanol permeance, while maintaining the rejection of rhodamine B (RDB, 479 Da) above 99% under the optimal conditions. Moreover, the prepared OSN membrane has a much high permeance to polar solvents, e.g., 110.5, 112.6 and 95.8 L m?2h?1 MPa?1, for ethyl acetate, methanol and DMF, respectively. The most exciting aspect of the prepared OSN membrane is its superior solvent resistance in strong polar organic solvent. It maintained an essentially unchanged solute rejection during 63 d immersion in DMF at 80 °C, and during 120 h continuous cross-flow filtration of the RB-DMF solution at room temperature, which is superior over most of the state-of-the-art literature works, indicating its broad application prospects for separation and purification of polar organic solvent systems.
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