查看更多>>摘要：? 2022Efficient CH4/N2 separation is necessitated for obtaining purified methane from natural gas. Aluminum-based metal–organic frameworks (Al-MOFs) have potential for industrial separation applications due to their structure-tunable, low-cost, and scalable features. Intrigued by the impressive selectivity of a recently reported Al-MOF (Al-CDC) toward CH4 over N2, we herein further study the potential of Al-MOFs as adsorbent for CH4/N2 separation, mainly considering the effects of pore geometry and linker polarity. Utilization of two bent ligands and two linear ligands with different polarity afforded two one-dimensional square-shaped Al-MOFs i.e., CAU-10-H, MIL-160, and two rhombic-shaped counterparts i.e., Al-Fumarate (Al-Fum), MIL-53(Al)), respectively. Afterward, pure CH4 and N2 adsorption experiments were conducted at 273–313 K for assessing the CH4/N2 separation performance. The results indicated that all the Al-MOFs exhibited superior affinity toward CH4 over N2, and the CH4 uptake followed the sequence of Al-Fum > CAU-10-H > MIL-53(Al) > MIL-160. Exhilaratingly, Al-Fum exhibited unprecedented CH4/N2 selectivity (17.2) and high CH4 uptake at 273 K and 1.0 bar. The mechanism underlying the disparity of Al-MOFs affinity toward CH4 was deciphered via theoretical simulation, suggesting that the synergetic effects of accessibility of strong affinity sites (μ2-OH) on AlO6 chains and polar pore surface induced by varying linkers highly promoted the CH4 uptake. Furthermore, the results of cyclic adsorption–desorption experiments and binary breakthrough tests validated the feasibility of Al-Fum for practical application.
查看更多>>摘要：? 2022 Elsevier B.V.Liquid-liquid extraction (LLE) was investigated for mineral acid (H2SO4) recycling from membrane distillation (MD) concentrate treating gold mining wastewater. Five extractants (Alamine 336, Aliquat 336, Cyanex 923, TEHA, and Versatic Acid) were preferably diluted in kerosene or 1-decanol (30 vol%) in extraction experiments conducted at 60 °C. Cyanex 923 extracts the mineral acid mainly by solvation of the neutral species, whereas the mechanisms for amine-based extractants involve an ion-pair formation. An important outcome was the temperature contribution to extraction efficiency. The endothermic nature of extraction would be advantageous to acid recovery and the integration of MD with LLE considering that the MD concentrated is produced at ～ 60 °C. If stripping is considered, Aliquat 336 (diluted in 1-decanol), Cyanex 923, and TEHA (diluted in 1-decanol) become the most appropriate organic phases for mineral acid recycling given the greater efficiency for acid recovery (>90%) after a single contact stage. The results for extraction efficiency, selectivity, stripping efficiency, and costs demonstrated that TEHA (30 vol% in 1-decanol) was the most cost-effective (US$ 0.57/kg) alternative for mineral acid recycling. It would be possible to recover 4.8 kg of mineral acid per cubic meter of MD concentrate as an acid solution (concentration: 25 mmol/L). Overall, LLE was a feasible alternative to enhance gold mining wastewater exploitation and MD concentrate management. From a broader perspective, acid recycling would imply environmental gains, economical savings given the lower requirements of neutralizing agents for mining wastewater treatment and residual sludge disposal, or additional incomes by its commercialization.
查看更多>>摘要：? 2022 The Authors“Green” protein purification/immobilization processes based on low-cost, earth-abundant, and eco-friendly affinity matrices are highly desirable. Unmodified silica matrices fit well these demands. Since histidine-rich silica-binding peptides are frequently isolated in biopanning experiments, this work aimed at assessing the viability of using bare silica as an alternative matrix for the purification/immobilization of His-tagged proteins. Adsorption and desorption studies with a purified His6-tagged EGFP shown that binding to bare silica particles of different size and porosity occurred under the conditions tested, and that elution could be accomplished with eco-friendly eluants containing L-arginine/L-lysine. Non-tagged EGFP did not bind to these matrices. Small-scale batch purification schemes using silica gel Davisil grade 643 or 646 as affinity matrices and a Tris-buffered saline eluant containing 0.5 M L-arginine (pH 8.5) allowed purifying His6-EGFP from Escherichia coli lysates with a purity of up to 96% and a recovery yield of ～70% after just one elution step. EGFP tagged with the silica-binding peptide Car9 was recovered with comparable purity and yield. Other His-tagged proteins could also be purified to similar purity levels. The scale of this batch purification scheme was shown to be extendable. These results demonstrate that unmodified silica matrices can be used to effectively purify His-tagged proteins. Since the recovery of double tagged His6-EGFP-Car9 was only of 30–55%, the combination of tags revealed to be advantageous for immobilization purposes.
查看更多>>摘要：? 2022 Elsevier B.V.Photocatalytic remediation of explosive wastewater pollution gradually attracts our attention owing to strict environmental protection requirements. In this study, visible light driven photocatalytic degradation of ammonium dinitramide (ADN) over the novel solvothermal-synthesized 2D/2D g-C3N4(CN)/BiOBr(BB) heterostructure nanosheets was carried out. Multiple characterization techniques confirm the successful formation of tight contact interface between BiOBr and CN nanosheets. 30CN/BB composite exhibits the superior photocatalytic activity with degradation efficiency of 95.0 %, attributing to larger effective electrochemical surface area (ECSA), expanded light capture range and efficient S-scheme charge transfer ability. Besides, the main active species were determined as e? and ?O2?, and generation level of free radicals was detected by EPR technique. Moreover, the reactive sites and possible degradation mechanism of ADN were analyzed by DFT calculation.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, the cellulose nanocrystal (CNC) heat-treated in an air atmosphere at 300 °C shows the enhanced piezo-catalytic performance in Rhodamine B (RhB) dye decomposition. Under 180 min ultrasonic vibration with the power of 180 W and the frequency of 40 kHz, the piezo-catalytic decomposition ratio of the heat-treated CNC for RhB (5 mg/L) can reach ～ 96.65%, far exceeding the 34.58% of the raw CNC. The improvement of the piezo-catalytic performance of the heat-treated CNC is attributed to the introduction of oxygen vacancy defects, which can cause the destruction of crystal structure symmetry and promote the carrier separation, resulting in the enhancement of piezoelectric effect of the heat-treated CNC. The free radical scavenger experiments confirm that the main active specie involved in piezo-catalysis is superoxide radical. Three recycling utilization results show that the decomposition ratio of RhB dye remains about 95% without significant loss, indicating that the heat-treated CNC possesses the good durability and high efficiency in piezo-catalysis. The introduction of oxygen vacancy defects into CNC to obtain the marvelous piezo-catalytic performance is expected to show broad application prospects in the catalytic treatment of dye wastewater.
查看更多>>摘要：? 2022Electrochemically switched ion exchange (ESIX) technology has been proved as a promising valid method for separation of valued-added ions in diluted solutions. Herein, to promote industrial application of the ESIX technology, a general theoretical framework based on the electroactive site concentration (ESC) is proposed to describe the rigorous mechanism of ESIX process with electroactive ion exchange material (EIXM) coated electrodes. In particular, the pseudocapacitive ion adsorption process is modeled by modifying the electrochemical potential of the electroactive sites of EIXM. The proposed ESIX model reveals that the constant current density operation should be more suitable than the constant cell voltage operation for the ESIX process. It is found that the increasing of operating current density and the initial ion concentration can improve the average ion adsorption rate. For the ESIX process with the electroactive bismuth oxybromide (BiOBr) film coated electrode for bromine ions (Br?) separation, the simulation results are in good agreement with the dynamic experiment data. It is confirmed that the modeling of ESIX process based on the ESC provides an effective way to elucidate the ion separation mechanism in pseudocapacitive adsorption process and to predict the effect of various operating parameters on the ESIX process performance conveniently.
查看更多>>摘要：? 2022Highly efficient elimination of oils or petroleum pollutions in water is of great importance for both human health and society sustainability. In this work, we report the fabrication of oleophilic porous carbon loading with microbials (OPC-M), which was prepared through a carbonization of pitch followed by a multi-step doping of the microbials into the as-prepared carbon, for selective absorption and efficient degradation of petroleum pollutions. Thanks to its abundantly porous structure and oleophilic wettability, the petroleum pollutions in wastewater (using n-hexadecane as model compound) can be selectively absorbed inside the OPC-M and then could be biodegraded by the loaded microbials. Compared with that of free microbials and porous carbon loading with microbials (PC-M) which has a degradation rate of 64.10%, and 89.3%, respectively, the OPC-M possesses a higher degradation performance of 96.75%. Also, their degradation half-lives are measured to be 72.96 h, 29.53 h and 15.34 h, respectively. The degradation kinetics of both PC-M and OPC-M fit well with the first-order kinetic equation. The degradation mechanism for n-hexadecane were explored by GC–MS and the results show that n-hexadecane can be degraded by enzymes in microbials into n-hexadecyl alcohol, n-hexadecaldehyde, n-hexadecanoic acid, and finally converted into water and carbon dioxide. This combination of selective absorption and biodegradable OPC-M may open up an effective green way for the purification of oily wastewater.
Nasir A.M.Adam M.R.Mohamad Kamal S.N.E.A.Jaafar J....
18页
查看更多>>摘要：? 2022Consumption of pathogenic contaminated water has claimed the lives of many people. Hence, this scenario has emphasized the urgent need for research methods to avoid, treat and eliminate harmful pathogens in wastewater. Therefore, effective water treatment has become a matter of utmost importance. Membrane technology offers purer, cleaner, and pathogen-free water through the water separation method via a permeable membrane. Advanced membrane technology such as nanocomposite membrane, membrane distillation, membrane bioreactor, and photocatalytic membrane reactor can offer synergistic effects in removing pathogen through the integration of additional functionality and filtration in a single chamber. This paper also comprehensively discussed the application, challenges, and future perspective of the advanced membrane technology as a promising alternative in battling pathogenic microbial contaminants, which will also be beneficial and valuable in managing pandemics in the future as well as protecting human health and the environment. In addition, the potential of membrane technology in battling the ongoing global pandemic of coronavirus disease 2019 (COVID-19) was also discussed briefly.
查看更多>>摘要：? 2022 Elsevier B.V.Microbial fuel cell (MFC) is a modern technique for treating industrial wastewater and converting the organic content to bioenergy. However, improvements and modifications of MFCs are necessary to overcome the internal resistance and improve the transfer process of electrons. Nanomaterials such as multi walled carbon nanotubes (MWCNTs) could be a promising material to be contributed in the MFCs modifications. In this study, two identically designed vertical flow packed bed dual chamber 3D-MFCs were constructed and operated in a continuous mode. Both MFCs were fueled with actual automobile wash wastewater (AWW) and inoculated with anaerobic aged sludge. One microbial fuel cell named as MFC1 was packed with graphite granules coated by pristine MWCNTs. The second MFC named as MFC2 was packed with graphite granules coated by acids-activated MWCNTs using a mixture of HCl, H2SO4, and HNO3 as a new approach for of MWCNTs activation. Removal efficiency of organic content and bioenergy generation were considered to evaluate the performance of the 3D-MFCs. The results revealed that the removal efficiency of the organic matters was relatively comparable in both 3D-MFCs. Maximum removal efficiency of COD was 87%±2.0 and 90%±1.1in MFC1 and MFC2, respectively. On the contrary, the power output in MFC2 was higher than its value in the MFC1. Maximum achieved power density was 332 mW/m3 and 462 mW/m3 in MFC and MFC2, respectively indicating the effect of acid activation on promoting the electrode conductivity. Sodium dodecyl sulfate (SDS) in addition to oil and grease (O&G) were found in considerable concentrations in the actual AWW. The removal of SDS and O&G was 87.3%±1.1 and 83% ±2.0 in MFC1, whereby, in MFC2 it was 99.99%±0.1 and 88%±1.7, respectively. The promising results potentially encourage the application of the suggested technique for automobile wash wastewater.
查看更多>>摘要：? 2022 Elsevier B.V.Reverse osmosis (RO) membranes are widely used in the advanced treatment of coal chemical wastewater. Nevertheless, membrane fouling is an intractable concern which decreases permeate flux, impairs water quality and increases energy consumption. Mapping the spatial distribution of membrane fouling and identifying the key factor for flux decline are of great significance for membrane fouling control. In this study, each membrane sample from first-stage and second-stage RO membrane elements was divided into 12 regions for autopsy. The results showed that membrane fouling at both stages was exacerbated from the feed end to the concentrate end owing to the concentrating effect and concentration polarization. Organic and inorganic foulants mainly deposited at the concentrate end and near the permeate tube, whereas biofouling did not show a regular distribution pattern. Biofouling was the paramount contributor to flux decline, whether at the first stage (40%) or the second stage (27%). However, the effect of inorganic fouling became prominent at the second stage due to the higher concentration of inorganic ions and stronger interactions with other foulants. Suggestions for membrane fouling control strategies include reinforced anti-biofouling countermeasures at the lead element, anti-scaling schemes after the first stage, and customized feed spacer and membrane designs for specific fouling at different locations.
NSTL
Elsevier