Polyvinylpyrrolidone (PVP) was added during solvothermal synthesis to regulate the morphology and structure of HKUST-1 crystals, which were then in situ incorporated into a polyimide (PI) matrix to fabricate mixed matrix membranes (MMMs). The morphology and structure of the HKUST-1 crystals were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption test. On the basis of CO2 adsorption experiments of HKUST-1, gas permeation measurements of the MMMs, and grand canonical Monte Carlo (GCMC) simulations, the effect of HKUST-1 crystal size on the CO2 permeation performance of the MMMs was inves- tigated, and the mechanism by which PVP regulates the CO2 separation performance of MMMs was elucidated. The results showed that, owing to the steric hindrance effect of PVP, the HKUST-1 crystals synthesized with PVP exhib- ited an average particle size of 1-3 mu m and a specific surface area of 731-1 007 m(2)& centerdot;g(-1). Compared with HKUST-1 crystals synthesized without PVP, their average particle size was significantly reduced with a narrower size distribu- tion and a larger specific surface area, while more Cu2+ metal sites and aromatic ring structures were exposed. This enhances the interfacial compatibility between HKUST-1 and PI, as well as the pi -pi interactions and Lewis acid interactions between HKUST-1 and CO2. The MMM prepared by in situ incorporation of HKUST-1 (K30), whose synthesis was regulated by K30-type PVP with a dopping amount (mass fraction) of 3%, exhibited a CO2 permeabili- ty of 142.81 Barrer [1 Barrer=7.5 & times;10(-14) cm(3)(STP)& centerdot;cm & centerdot;cm(-2)& centerdot;s(-1)& centerdot;Pa-1] and a CO2/N-2 selectivity of 25.05, which are 76 times and 18 times those of the pristine PI membrane, respectively. These results demonstrate that tailoring the mor- phology of HKUST -1 crystals via PVP is an effective approach to enhancing the CO2 separation performance of MMMs.

The substantial emission of nitrous oxide (N2O), which has strong greenhouse effect and thus huge environmental impact, from wastewater treatment has attracted widespread attention. Accurate assessment of environmental impacts and effective mitigation of N2O emission are urgently needed. Reliable prediction and effective control of N2O emission depend heavily on mathematical modeling, which in turn requires accurate determination of N2O yield and emission factors. Although numerous studies have investigated mechanism and pathways of N2O generation in different biological processes, reported N2O yields vary significantly due to differences in the regions and operational conditions. Elucidating the pathways and influencing factors of N2O generation are the key to developing reliable models and implementing effective mitigation strategies. This study reviewed current advances on N2O generation and emission from typical biological processes. The pathways of N2O generation were summarized comprehensively, and the factors affecting N2O production were discussed quantitatively. Key factors including water quality and operation conditions were identified for representative processes (e.g., AAO and SBR), and the mechanism are discussed. Based on quantitative analysis of the roles of those key factors, strategies for N2O abatement in practical wastewater treatment processes are proposed. This study advances the understandings on the mechanism of N2O generation in biological wastewater treatment and also support the accurate assessment and effective control of N2O emissions.

To develop an environmentally friendly Ti-based mesoporous catalyst for efficient persulfate activation toward organic pollutant degradation, Co- and Zr-doped mesoporous TiO2 catalysts (Co-TiO2 and Zr-TiO2) were pre- pared. The mechanisms governing active species generation and tetracycline (TC) degradation performance during sodium persulfate (PDS) activation were investigated. Structural characterization results revealed that both Co and Zr doping significantly enhanced the specific surface area and oxygen vacancy concentration of the catalysts. Specif- ically, Zr4+ doping induced lattice distortion due to its larger ionic radius compared to Ti4+, while Co doping facilitat- ed electron migration owing to the electronegativity difference between Co and Ti. TC degradation experiments dem- onstrated that the Co-TiO2/PDS and Zr-TiO2/PDS systems achieved TC degradation rates of 93.1% and 89.6% within 6 h, respectively, significantly outperforming the undoped TiO2/PDS system. Their reaction rate constants were 2.8 times and 2.4 times higher than that of the undoped system. Quenching experiments and electron spin resonance (ESR) analysis confirmed that hydroxyl radicals (& centerdot;OH) was the primary active species in the Co-TiO2/PDS system, whereas singlet oxygen (O-1(2)) served as the primary active species in the Zr-TiO2/PDS system. Phosphate (PO43-) addition experiments demonstrated that modulating hydroxyl groups on the catalyst surface could optimize the reactant utilization efficiency (eta(RU)) of the Co-TiO2/PDS system. This study elucidates the discrepancies in the PDS activation process by metal-doped mesoporous TiO2 catalysts and the regulatory mechanisms governing reactive species and contaminant degradation performance.

To address the efficient separation of refractory small-molecule pollutants such as p-nitrophenol (PNP) from industrial wastewater, bimetallic Co-Fe hydroxide nanoparticles were synthesized via a reverse microemulsion method and incorporated into polymer matrices. Initial studies on hybrid membranes with polyvinylidene fluoride (PVDF) matrices demonstrated enhanced hydrophilicity (contact angle reduction from 77.7 degrees to 64.9 degrees) and antifouling performance (85 % flux recovery rate), but their large pore size (similar to 70 nm) limited PNP rejection (22.5 %). To overcome this problem, polysulfone (PSF) was selected as an alternative matrix substrate. By systematically adjusting the film-forming time (15-50 min) during phase inversion, tight ultrafiltration membranes with controlled pore structures were fabricated. Prolonged film-forming time (30 min) optimized the solvent-nonsolvent exchange kinetics of the obtained PSF-3 membrane, yielding a dense selective layer with a narrow pore size distribution (3-8 nm) and molecular weight cut-off. This membrane achieved a PNP rejection rate of 71 % compared to 5 % of the PVDF membrane through synergistic "size sieving-hydroxyl adsorption" while maintaining low salt rejection (<15 %) and high flux stability (<15 % flux decline rate over 6 h). Hydrophilicity (49.6 degrees contact angle) and antifouling performance (85 % flux recovery rate after four cycles) were significantly enhanced by uniformly dispersed nanoparticles. This study highlights the critical role of film-forming time in tailoring membrane architecture and performance, providing a novel strategy for efficient small-molecule separation from saline wastewater.

Incorporating zeolitic imidazolate frameworks (ZIF) as nanofillers in polyimide (PI)-based mixed matrix membranes (MMMs) addresses the CO2 permeability-selectivity trade-off in gas separation. However, the role of ZIF crystal structures in enhancing performance remains unclear. Tailored ZIF materials were synthesized and integrated into PI membranes to study CO2 capture and diffusion. Results reveal that ZIF crystals form pi-pi conjugation with CO2, enabling strong adsorption, while weak van der Waals interactions dominate for N2. Molecular dynamics (MD) simulations confirm pi-pi interactions surpass hydrogen/amino bonding. ZIF incorporation boosts the CO2 separation performance of MMMs, achieving optimal CO2 permeability of 230.3 Barrer and CO2/N2 selectivity of 29.2 (50.3 times and 4.3 times higher than those of the neat PI membrane, respectively). The membranes are dense and based on a BPDA-ODA polyimide matrix. The enhancement mechanism differs from ZIF's intrinsic CO2 adsorption: well-dispersed ZIF improve CO2 solubility selectivity via adsorption, while pi-pi interactions facilitate diffusion. However, excessive adsorption strength (like Zn-N-60) impedes CO2 desorption, reducing diffusion efficiency. This highlights the need to balance adsorption and diffusion for optimal performance.

Smart synthesis of porous carbon with appropriate aperture distribution and high area utilization still retains an enormous challenge for efficient charge storage. Herein, a simple freeze-drying along with subsequent one-step carbonization/activation process is ingeniously devised to fabricate honeycomb-like nitrogen-doped porous carbon (NPC) framework with high-level active N/O-functional groups and hierarchical porous structure including substantial ultra-micropores (<0.7 nm). The underlying formation mechanism of such porous NPC framework is tentatively proposed. By finely regulating the dosage of NaHCO3, the optimized NPC (i.e., NPC114) is endowed with ultra-high surface area utilization of similar to 26.4 mu F/cm(2) at 1 A/g in KOH electrolyte, which is close to theoretical value of electrochemical double-layer capacitance (15 - 25 mu F/cm(2)), and even larger than the case (similar to 22.4 mu F/cm(2)) with H2SO4 electrolyte due to the inaccessible ultra-micropores by SO42- of larger size. Similarly, as for the organic system, the as-prepared NPC115 with higher meso- and macropore surface area exhibits higher energy density of 22.36 Wh/kg than other counterparts. Furthermore, NPC114, when evaluated as anode material for sodium-ion batteries, exhibited more attractive high-rate Na+-storage properties as well. The in-depth understanding into intrinsic relationship between aperture distribution and electrochemical behaviors will provide meaningful guidance for electrode material design.

The removal of trace amounts of antibiotics from water environments while simultaneously avoiding potential environmental hazards during the treatment is still a challenge. In this work, green, harmless, and novel asymmetric mesoporous TiO2 (A-mTiO2) was combined with peroxodisulfate (PDS) as active components in a controlled-release material (CRM) system for the degradation of tetracycline (TC) in the dark. The formation of reactive oxygen species (ROS) and the degradation pathways of TC during catalytic PDS activation by A-mTiO2 powder catalysts and the CRMs were thoroughly studied. Due to its asymmetric mesoporous structure, there were abundant Ti3+/Ti4+ couples and oxygen vacancies in A-mTiO2, resulting in excellent activity in the activation of PDS for TC degradation, with a mineralization rate of 78.6%. In CRMs, ROS could first form during PDS activation by A-mTiO2 and subsequently dissolve from the CRMs to degrade TC in groundwater. Due to the excellent performance and good stability of A-mTiO2, the resulting constructed CRMs could effectively degrade TC in simulated groundwater over a long period (more than 20 days). From electron paramagnetic resonance analysis and TC degradation experiments, it was interesting to find that the ROS formed during PDS activation by A-mTiO2 powder catalysts and CRMs were different, but the degradation pathways for TC were indeed similar in the two systems. In PDS activation by A-mTiO2, besides the free hydroxyl radical (·OH), singlet oxygen (1O2) worked as a major ROS participating in TC degradation. For CRMs, the immobilization of A-mTiO2 inside CRMs made it difficult to capture superoxide radicals (·O2−), and continuously generate 1O2. In addition, the formation of sulfate radicals (·SO4−), and ·OH during the release process of CRMs was consistent with PDS activation by the A-mTiO2 powder catalyst. The eco-friendly CRMs had a promising potential for practical application in the remediation of organic pollutants from groundwater.

In an effort to explore the potential application prospects of membrane separation technology in treating nuclearcontaminated wastewater, a TFN nanofiltration membrane incorporating the ZIF-8@Ti3C2Tx nanocomposite was successfully synthesized using the interfacial polymerization method. This involved doping the microemulsion of ZIF-8@Ti3C2Tx into the aqueous (organic) phase. The morphology and structure of ZIF-8@MXene nanocomposites and TFN nanofiltration membranes were characterized. The selective removal of ReO4- from simulated radioactive wastewater using the TFN nanofiltration membrane was evaluated. The results indicated that the ZIF-8@Ti3C2Tx composite, uniformly dispersed in the polymer, effectively enhanced the pore structure and polarity of the nanofiltration membrane, thereby improving its permeability. The electronegativity of ZIF8@Ti3C2Tx also enhanced the negative charge on the surface of the polymer membrane, significantly improving the membrane's performance in rejecting ReO4- while maintaining a low retention rate for Na+. This design facilitates the efficient selection of ReO4- from high-salinity wastewater. In addition, the layer spacing of Ti3C2Tx further improved the screening of ReO4- and Na+. However, when 0.75 g & sdot;L- 1 of microemulsion was added, it became challenging to disperse the microemulsion completely in the organic phase. This led to the agglomeration of composites in the nanofiltration membrane, weakening both flux and selectivity. Optimal performance was achieved with a microemulsion doping amount of 0.5 g & sdot;L- 1, resulting in the nanofiltration membrane M-O-1 exhibiting the best performance (Jp = 41.92 L & sdot;m2 & sdot;h- 1 and R(ReO4- ) = 65.81%). Even at a high salt concentration (20 g & sdot;L- 1), the M-O-1 membrane retained approximately 55% of pollutants after continuous operation for 5 h, indicating that the TFN nanofiltration membrane containing ZIF-8@Ti3C2Tx holds significant promise for selectively extracting 99Tc from wastewater with a high salt content.

A visible-light-responsive chiral mesoporous TiO2 photocatalyst was employed for the photodegradation of tetracycline in seawater to avoid the potential biotoxicity of nanophotocatalysts. Compared with achiral mesoporous TiO2, the key structural parameters, including Ti3+ and oxygen vacancies, affecting the visible-light response and activity of the chiral mesoporous TiO2 photocatalyst were clarified. The influence of salt ions in seawater on photocatalytic degradation was systematically explored to reveal the photodegradation mechanisms in complex seawater. Based on the results of radical-trapping experiments and electron spin resonance spectroscopy, the active species generated by photocatalysts excited by visible light were the same in freshwater and seawater. However, the results of density functional theory calculations and the analysis of intermediate products showed that free radicals ((OH)-O-center dot and O-center dot(2)-) could not efficiently compete with Mg2+ and Ca2+ in seawater and therefore could not overcome the interference of salt ions to attack the nitrogen atom in tetracycline (TC). The main interference of the photocatalytic process in seawater was the enrichment around the atoms of high electronegativity in TC molecules with Mg2+ and Ca2+, which hindered the attack of holes and completely blocked the attack of (OH)-O-center dot or O-center dot(2)- radicals on TC molecules. Depositing Ag as acceptors for photogenerated electrons in chiral M-TiO2 could effectively enhance the production of holes, thereby significantly improving the catalytic degradation of seawater pollutants. Due to its high performance, the Ag-deposited chiral M-TiO2 catalyst was used for loading on polyurethane sponge cubes, which were placed in hollow porous plastic balls to prepare photocatalytic floating spheres for removing TC in seawater. The rate of removal for TC in simulated seawater by the floating spheres exceeded 85% after 10 h. This work not only identified the mechanism of photodegradation of antibiotic pollutants in different water environments but also has promising potential for the treatment of trace pollutants in seawater using heterogeneous photocatalysis.

Aiming at the effective remediation of antibiotic contaminants in groundwater, in-situ chemical oxidation (ISCO), using controlled release materials (CRMs) as an oxidant deliverer, has emerged as a promising technique due to their long-term effective pollutant removal performance. This study used different microstructures of mesoporous manganese oxide (MnOx) and sodium persulfate as active components to fabricate CRMs. Following that, a comparative study of tetracycline (TC) degradation and the formation of reactive oxygen species (ROS) by mesoporous MnOx powder and CRMs were conducted. The ROS formed during peroxodisulfate (PDS) activation by powder catalysts and CRMs differed, but MnOx powder catalysts and CRMs both had good reaction stoichiometric efficiency (RSE) for PDS, thus completely mineralizing TC. In PDS activation by mesoporous MnOx powder, oxygen vacancies (OVs) caused by defects in the catalysts contributed to the generation of singlet oxygen (1O2). The 1O2 and free radicals (·SO4- and ·OH) both worked as major ROS participating in TC degradation. Concerning the release of CRMs in static groundwater, the immobilization of catalysts inside CRMs made it difficult to release 1O2 in the solution, thus slowing the degradation of TC by CRMs containing MnOx(1) in static groundwater. In the TC remediation in dynamic groundwater, the water flowing slowly passed through the CRM layer, and TC molecules were trapped. Therefore, 1O2 degraded the trapped TC in the CRM layer in dynamic groundwater. Compared to TC, the toxicity of most intermediates during the TC degradation by CRMs has decreased in static and dynamic groundwater.

Aiming at enhancing the degradation efficiency of antibiotics in slightly polluted water bodies, the photocatalytic synergistic sodium peroxysulfate (PDS)-activated catalytic oxidation using chiral mesoporous TiO2 under irradiation of visible light (PDS/vis-TiO2) was employed to degrade tetracycline (TC). The differences in active species and degradation pathways of PDS activation (PDS/TiO2), visible light photocatalysis (vis-TiO2), and PDS/vis-TiO2 systems using mesoporous TiO2 as catalysts for TC degradation were comparatively studied. The results showed that the asymmetric helical stacking structure introduced abundant Ti3+ into chiral mesoporous TiO2, not only improving its visible light response but also activating PDS by Ti3+/Ti4+ couples to form free radicals. Both the photo- generated holes h(+) and the free radicals (like center dot OH) in the PDS/vis-TiO2 system could simultaneously participate in TC degradation. Within 5 h, the removal rate of TC (the concentration of TC in the solution was 5 mg center dot L-1) using the PDS/vis-TiO2 system could reach over 95%, far exceeding that of the PDS/TiO2 system (with a TC removal rate of 48.9%) and the vis-TiO2 system (with a TC removal rate of 71.1%). PDS/vis-TiO2 system had a high removal rate of TC in solutions with different concentrations, and the degradation all followed a first-order kinetic reaction process. Even when the initial concentration of TC reached 15 mg center dot L-1, the 5 h removal rate of TC by PDS/vis-TiO2 system could still reach 67.2%, which further indicated that the PDS synergistic photocatalysis had an effective ability to degrade TC. However, the removal rate of TC at low concentrations by PDS/vis-TiO2 was faster than using the same amount of TiO2 catalyst and PDS. Added PDS in the photocatalytic system would be activated by the photo-generated electrons to generate free radicals, which then consume photo-generated electrons to improve the separation rate of photo-generated holes and electrons, thus achieving synergistic enhancement on the pollutant degradation. Additionally, the free radicals after PDS activation would also enhance TC degradation. The density functional theory calculation and intermediate product analysis results indicate that the degradation pathway of TC in the PDS/vis-TiO2 system includes the degradation pathway of attacking TC by h(+), as well as the degradation pathway of TC after the free radicals attack.

A novel visible-light-responsive chiral mesoporous TiO2 photocatalyst was employed for photo-degrading tetracycline in seawater to void the potential biotoxicity of nano-photocatalysts. Compared with achiral mesoporous TiO2, the key structural parameters affecting the visible light response and activity of chiral mesoporous TiO2 photocatalyst were clarified. Then, the influence of salt ions in seawater on photocatalytic degradation was systematically explored, aiming to reveal the photodegradation mechanisms in complex seawater. Considering the results from radical trapping experiments and electron spin resonance (ESR) spectroscopy, the active species generated by photocatalysts excited by visible light was the same whether in freshwater or seawater. However, the results from Density Functional Theory (DFT) calculation and intermediate product analysis showed that free radicals (∙OH and ∙O2−) were difficult to form an efficient competition with Mg2+ and Ca2+ in seawater, so they could not overcome the interference of salt ions to attack the N2 atom in the molecules of tetracycline (TC). The main interference of the photocatalytic process in seawater was the enrichment around the atoms with high electronegativity in TC molecules by many Mg2+ and Ca2+. This enrichment hindered the h+ attack for TC molecules and completely blocked up the attack of free ∙OH or O2− radicals on TC.

为了获得具有高效分离CO2性能的膜材料,选用1-乙烯基咪唑(VIM)为油相,1-丁基-3-甲基咪唑三氟甲磺酸盐(BmimOTF)为表面活性构筑反胶束微乳液合成ZIF-8纳米粒子,再通过微乳液聚合制备ZIF-8/PVIM乳胶液,将其与聚酰亚胺(PI)共混制备混合基质膜.同时,结合气体吸附和渗透实验系统研究了微乳液组成对混合基质膜CO2分离性能的影响规律.结果表明:由于微乳液中纳米反胶束的保护,合成的ZIF-8粒子平均粒径小于30 nm;随微乳液中表面活性剂及水相中配体浓度的增加,合成的ZIF-8粒子数增多且粒径也有所增大.所制备的混合基质膜中分子传质通道增多,膜的CO2渗透性显著提高,CO2分离选择性呈先增大后减小的趋势,但变化的幅度较小;微乳液中油相增多,合成的Z1F-8粒子粒径有所减小,所制备的混合基质膜中分子扩散传质通道减少,膜的CO2渗透性减小,CO2分离选择性也有所下降.在优化的微乳液组成及乳胶液掺杂量下,所制备的ZIF-8/PVIM-PI混合基质膜的CO2渗透系数PCO2可达1862.6×10-16mol·m-1·s-1·Pa-1,CO2分离选择性αP(CO2/N2)和αP(CO2/CH4)均大于 40.

为获得可见光响应的高效介孔TiO2光催化剂,利用软模板法制备了螺旋堆积的手性介孔TiO2.对比分析了手性介孔TiO2和非手性介孔TiO2的差异.通过自由基捕获实验和电子自旋共振(ESR)光谱,结合福井指数(f-)的计算探索了手性介孔TiO2降解罗丹明B(RhB)的机制和路径.结果表明,手性介孔TiO2的螺旋堆积结构引入了更多缺陷,从而其Ti3+和氧空穴的含量都高于非手性介孔TiO2,因此具有更强的可见光响应和降解活性,其对RhB的去除率超过非手性介孔TiO2的4倍;手性介孔TiO2降解有机污染物分子的主要活性物种是光生空穴h+;越容易给出电子的原子位点(即f-值越高)越容易受到h+的攻击发生降解;降解过程中中间产物分析进一步得到了可见光激发手性介孔TiO2降解RhB的主要路径.

Incorporation of porous materials in a polymeric membrane is an effective strategy for improving the gas permeability of the resulting mixed matrix membranes (MMMs). However, effective improvement of selectivity of membrane toward CO2 separation is still a significant challenge due to the insufficient CO2 capture performance of porous materials. In this study, polyimide (PI)-based MMMs with enhanced CO2 capture performance were prepared for CO2 separation. First, an ionic liquid (IL) with a high affinity for CO2 was immobilized in the inner pore structures of two types of mesoporous silica (SiO2) molecules to form IL@SiO2 composites. These composites were used as nanofillers to construct the MMMs. The stable immobilization of IL inside the pores of the mesoporous SiO2 indicated that the IL@SiO2 and MMMs both exhibited higher adsorption selectivity for CO2. The gas solubility coefficient of the MMMs was positively proportional to their maximum gas adsorption capacity, which was determined by the gas adsorption capacity of the PI polymer and nanofillers. More interestingly, the diffusion coefficients of different gases in the MMMs were closely related to the confined mass transfer channels introduced by the nanofillers. The diffusion of CO2 in the confined mass transfer channels of MMMs was facilitated and N2 diffusion was slightly inhibited, which increased the diffusion selectivity of the resulting MMMs for CO2. Combined with Maxwell-Wagner-Sillar model calculations for gas permeation, it was confirmed that IL immobilization transformed the diffusion mode of CO2 in the confined mass transfer channels of the MMMs from Knudsen diffusion to facilitated diffusion. However, the immobilization of excessive ILs in the mesopores blocked the mass transfer channels of the MMMs, resulting in lower gas permeability and decreased CO2 separation selectivity.

In order to improve the separation performance and anti-fouling property of polyvinylidene fluoride (PVDF) ultrafiltration membranes, PVDF mixed matrix membranes (MMMs) were obtained by mixing PVDF with Ag@ZIF-8 using a simple one-pot microemulsion strategy. First, both Ag and ZIF-8 were generated in one micelle of the microemulsion during the formation of composites. After in-situ polymerization of microemulsion, the latex containing Ag@ZIF-8 was blended with PVDF by phase-inversion method to construct the MMMs. The small-sized Ag particles were closely distributed on the surface of ZIF-8 after the formation of ZIF-8 in micelles. The subtle interaction forces between the two facilitated the distribution of the composite in the PVDF matrix. In addition, the hydrophilic component in the latex improves the pore structure, the permeation and anti-fouling performance of the PVDF matrix compared to neat PVDF and the MMM with ZIF-8 added. Mixed-matrix ul-trafiltration membranes with 0.3 wt% of microemulsion containing Ag@ZIF-8 exhibited good permeation (Jw = 222 L m- 2 h-1) and flux recovery rate (FRR = 82%). The well-distributed Ag@ZIF-8 in PVDF polymeric matrix strengthened the dye retention of MMMs from high-salinity wastewater, due to the interaction between Ag@ZIF-8 and dye molecules. This mixed-matrix ultrafiltration membrane also showed optimum dye rejection (97.3%) and low salt rejection (0.2%). The MMMs combined with Ag@ZIF-8 in this work are promising for the removal of dye contaminants for high-salinity wastewater, so as to achieve the goal of advanced treatment for high-salinity wastewater.