Nanofiltration membranes for drinking-water treatment ideally reconcile three intrinsically conflicting objectives: high water permeance, effective rejection of organic micropollutants, and selective permeation of beneficial mineral ions. Herein, a cost-effective dual-salt synergistic strategy is proposed, where sodium chloride (NaCl) and sodium bicarbonate (NaHCO3) are introduced into the piperazine (PIP) aqueous phase to fabricate high-performance NF membranes via subsequent interfacial polymerization (IP) with trimesoyl chloride (TMC). Molecular dynamics (MD) simulations revealed that NaCl and NaHCO3 reduced PIP diffusion through complementary kinetic pathways-NaCl via salting-out-induced elevation of aqueous-organic interfacial tension, and NaHCO3 via N-H⋯O[double bond, length as m-dash]C hydrogen bonding between the secondary amine groups of PIP and the carbonyl oxygen of HCO3 --collectively minimizing monomer supply at the reaction front and maximizing the fractional free volume (FFV) of the PA network. Consistently, experimental characterization confirmed that the fabricated membranes exhibited a progressively reduced crosslinking degree (minimum 38.10%) and an enhanced negative surface charge, accompanied by increased surface roughness and reduced PA layer thickness-structural and physicochemical features that synergistically govern both water transport and solute selectivity. Compared with the control membrane, the optimized membrane achieved a 147.7% higher pure-water permeance (23.09 L m-2 h-1 bar-1) while maintaining a comparable Na2SO4 rejection of 98.27%. It also exhibited a markedly higher CaCl2/Na2SO4 selectivity (S = 51.66) that enabled selective Ca2+/Mg2+ permeation for mineral retention and antiscaling capability, together with effective rejection of charged antibiotic micropollutants and robust operational stability. This work establishes a rational and scalable design strategy for high-performance NF membranes that reconcile micropollutant removal, mineral retention, and energy-efficient operation in drinking-water treatment.

Herein, plasma etching was applied to prepare the CeO2 of abundant oxygen vacancies (OVs) for excellent catalytic ozonation of oxalic acid (OA). After plasma etching with atmosphere of O2 for 15 min, the modified CeO2 (O-CeO2-15) significantly enhanced the elimination of OA to 47.15 % within 60 min at the pH of 7.15. The COD was reduced by 20 mg/L, 1.7 times that of pristine CeO2 catalytic ozonation. The adsorption of O3 by OCeO2-15 was twice that of the pristine CeO2. Raman, XPS, H2-TPR and CV characterization results magnified that O-CeO2-15 had abundant oxygen vacancies (OVs) and great reducibility. The theoretical calculation results demonstrated that the O3 adsorbed on the OVs was converted to center dot O3 by electron transfer, which leaded to chain reaction to generate Reactive oxygen species (ROS), and part of O3 was decomposed into *O as the main ROS to degrade OA. This study provided a convenient and eco-friendly enhanced OVs method and gained a different insight into the mechanism of CeO2 degradation of pollutants.

Polyamide (PA) thin-film composite (TFC) nanofiltration (NF) membranes, which are extensively utilized in seawater desalination and water purification, are limited by the upper bounds of permeability-selectivity. Recently, constructing an interlayer between the porous substrate and the PA layer has been considered a promising approach, as it may resolve the trade-off between permeability and selectivity, which is ubiquitous in NF membranes. The progress in interlayer technology has enabled the precise control of the interfacial polymerization (IP) process, which regulates the structure and performance of TFC NF membranes, resulting in a thin, dense, and defect-free PA selective layer. This review presents a summary of the latest developments in TFC NF membranes based on various interlayer materials. By drawing from existing literature, the structure and performance of new TFC NF membranes using different interlayer materials, such as organic interlayers (polyphenols, ion polymers, polymer organic acids, and other organic materials) and nanomaterial interlayers (nanoparticles, one-dimensional nanomaterials, and two-dimensional nanomaterials), are systematically reviewed and compared. Additionally, this paper proposes the perspectives of interlayer-based TFC NF membranes and the efforts required in the future. This review provides a comprehensive understanding and valuable guidance for the rational design of advanced NF membranes mediated by interlayers for seawater desalination and water purification.

As a by-product of wastewater treatment, waste activated sludge (WAS) has complex composition, strong hydrophilic extracellular polymeric substance (EPS), which make it difficult to dewater. In this study, an electro-peroxone oxidation-Fe(III) coagulation (E-peroxone-Fe(III)) sequential conditioning approach was developed to improve WAS dewaterability. At E-peroxone oxidation stage, hydrogen peroxide was generated through 2-electron path on a carbon polytetrafluoroethylene cathode, and reacted with the sparged O3 to produce hydroxyl radicals. At the subsequent coagulation stage, Fe(III) was dosed to coagulate the small WAS fragments and release water from WAS. Along E-peroxone-Fe(III) subsequent conditioning process, the physicochemical properties of WAS, main components, functional groups and evolution of protein secondary structure, and typical amino acids in EPS, as well as the type and semi-quantitative of elements in WAS, were investigated. The results indicated that under the optimal conditions, the reductions of specific resistance to filterability (SRF) and capillary suction time (CST) for WAS equalled 78.18% and 71.06%, respectively, and its bound water content decreased from 8.87 g/g TSS to 7.67 g/g TSS. After E-peroxone oxidation, part of protein and polysaccharide migrated outside from TB-EPS to slime, the ratio of α-helix/(β-sheet + random coil) declined, even some of organic-N disintegrated to inorganic-N. At Fe(III) coagulation stage, re-coagulation of the dispersed WAS fragments and easy extraction from inner EPS for protein and polysaccharide occurred. Furthermore, the protein secondary structure of β-sheet increased by 13.48%, the contents of hydrophobic and hydrophilic amino acids also increased. In addition, a strong negative correlation between the hydrophobic amino acid content of Met in slime and CST or SRF (R2CST = -0.999, p < 0.05 or R2SRF = -0.948, p < 0.05) occurred, while a strong positive correlation between the hydrophilic amino acid content of Cys in TB-EPS and CST or SRF (R2CST = 0.992, p < 0.05 or R2SRF = 0.921, p < 0.05) occurred, which could be related to the WAS dewaterability.

Graphene oxide lamellar 2D membranes are widely researched for ion separation and molecular sieving in aqueous solution. Extension of the research of GO-based membranes for organic solvent nanofiltration has drawn much attention but is still in its infancy. The relatively low solvent permeability remains a difficult problem to overcome. Inspired by the shell of the Namib Desert beetle, a heterostructured lamellar membrane was prepared by incorporating MoS2 quantum dots (MQDs) into the graphene oxide membrane. A dual-functional zone was formed, where hydrophilic areas exhibited excellent absorption performance for polar solvents and hydrophobic regions were propitious to the discharge of polar solvents when incorporating a moderate amount (10%) MQDs, denoted as GM-10 (nonpolar solvents presented the opposite performance). The synergistic effects of the dual-functional zone successfully improved the transport efficiency for various solvents, and the flux of various solvents for GM-10 was over three times higher than that of the pure GO membrane. Simultaneously, the composite biomimetic membrane showed excellent stability. This paper provides a novel strategy for constructing a heterostructured dual-functional zone for 2D lamellar membrane modification without the sacrifice of rejection, revealing the potential for further optimization of separation performance and membrane stability.

Because of the unique advantages, ultrasound (US) has become a popular technology for water organic treat-ment. In order to compensate for the disadvantages of expensive equipment and large energy input caused by US, researchers combine US with iron-based sono-catalyst to realize the rapid and efficient degradation of pollutants. Aiming at the ultrasonic hot spot and sonoluminescence effect, in this work, Z-type heterojunction sono-catalyst FeII-MIL-88B/GO/P25 (FeII-MGP) was synthesized for TC-HCl removal. The physicochemical properties of the material were characterized by SEM, XRD, XPS and BET. The addition of GO contributed to the formation of the Z-Scheme heterojunction. At the optimal reaction conditions determined by influential factor experiments (ul-trasonic power of 100 W, sono-catalyst dose of 0.3 g/L, H2O2 dose of 20 mM and pH 5), in only 7 min, 83.3 % of TC-HCl was removed, and the TOC degradation efficiency reached 52.2 %. The contrast experiment demon-strated that the US/FeII-MGP/H2O2 system had the best pollutant removal performance. After three repeated experiments, the removal efficiency decreased by only 6 %. & BULL;OH was identified as the major radical from the quenching experiments and technical EPR. UV-vis and Mott-Schottky measurements suggested that the possible carrier transfer paths followed the Z-Scheme heterojunction model.

Industrialization and urbanization have resulted in large volumes of municipal wastewater containing abundant refractory humic acid (HA), which is difficult to biodegrade with carcinogenic byproducts and has posed a great threat to human health. Photocatalysis is a promising advanced oxidation process (AOP) for the efficient degradation of HA. In this work, a novel three-step electrochemical method was employed to fabricate electrochemically converted N-doped TiO2 nanotubes/graphene (ENTG) composite film. Compared with traditional hydrothermally synthesized N-doped TiO2/graphene (NTG) nanoparticles, the ENTG photocatalyst exhibited enhanced degradation performance, recyclability and stability. It was found that ETNG can extend the range of light absorption to over 400 nm and narrow the band gap to 2.7 eV. The degradation rate for HA was up to 92.3% under the optimum condition. The preparation mechanism for ENTG is based on an electrochemical reduction–deposition hypothesis, while the degradation mechanism is dependent on adsorption and free radical oxidation. According to a free radical quenching test, both •OH and •O2− radicals were produced, and •OH played the dominant role in HA degradation. In general, ENTG is a promising photocatalyst for further application in municipal wastewater treatment.

Chemical conditioning is a common but chemicals consuming procedure for improving sludge dewatering performance. However, real-time monitoring of dewaterability for accurate regulation of conditioner dosage is still tricky. One of the pending questions causing this challenge is that the key mechanisms affecting water release are not fully revealed. This study traced the entire process of water release in sludge flocs to investigate and clarify the possible release resistances, including the viscous resistance derived from binding effect of contact interface, and the interfacial resistance originating from morphology of pore wall, as well as the resistance arising from structure of flocs. Key resistances in an individual nanopore were determined using the state-of-art principles in confined water flow. Then the investigation was expanded to the multi-porous flocs scale. Based on the water release behavior and inspired by the similitude of water and electricity, an online quantifier derived from electrical impedance spectroscopy (EIS) analysis was developed to achieve real-time determination of dewaterability in a probe-like type. Our results showed that both viscous resistance of pores and structural resistance of flocs affected the water release, the contribution of flocs structural resistance cannot be neglected. Moreover, strong linear correlations (r & GE; 0.943, p < 0.01) were obtained between the online quantifier, named normalized spectral dimension, and the sludge dewaterability in two typical sludge conditioning processes. The optimal dosages were successfully revealed by normalized spectral dimension in an established semi-automatic conditioning and online dewaterability monitoring system. These observations may promote the development of smart sludge treatment technologies.

为探究FeCl3混凝调理过程中活性污泥脱水性能与电化学阻抗谱参数的关联关系,选取北京3座污水处理厂的剩余活性污泥,研究不同调理投药量下活性污泥的毛细吸水时间(CST)、比阻(SRF)、抽滤含水率、Zeta电位、电导率以及电化学阻抗等指标的变化,通过Pearson相关性分析讨论污泥脱水性能与阻抗谱参数(ds/fc)的相关性,并探讨ds/fc 预测污泥脱水性能的可行性.实验结果表明,FeCl3调理活性污泥的较适投加量为100 mg·g-1;超过100mg·g-1时,活性污泥CST、SRF、抽滤含水率基本不再下降,Zeta电位却缓慢升高;电化学阻抗Z则随着投加量的增加而持续下降,且Nyquist图中高频区半圆面积减小,这表明电子更易转移、污泥更易导电.相关性分析表明,活性污泥的脱水性能均与ds/fc 呈显著正相关(r＞0.639,p＜0.01);3种活性污泥CST、SRF、抽滤含水率分别与ds/fc的线性回归结果显示它们之间呈线性关系,且线性方程斜率为正值(R2＞0.921,p＜0.01).上述研究结果表明,活性污泥的ds/fc参数可以作为指示脱水性能的潜在指标.本研究结果可为污泥减量化技术提供参考.

In this work, as a new strategy, ultrasound/H2O2/MOF system was firstly applied by environmental-benign FeMOFs (MIL-53, MIL-88B and MIL-101) for tetracycline hydrochloride removal. The synthetic Fe-MOFs were characterized by XRD, FTIR, SEM, XPS, N-2 sorption-desorption isotherms and CO-FTIR. MIL-88B demonstrated the best catalytic performance because of its highest amount of Lewis acid sites. Influencing factors, contrast experiment, and corresponding dynamics were carried out to obtain the best experimental conditions and reaction system. Under optimal conditions ([Tetracycline hydrochloride] = 10 mg/L, [MIL-88B] = 0.3 g/L, [H2O2] = 44 mM, [ultrasound power] = 60 W, and pH = 5.0), the-first-order kinetic rate constant k was calculated to be 0.226 min(-1), higher than the simple combination of the ultrasound system (0.004) and MIL-88B/H2O2 system (0.163), indicating the importance of synergistic effect between ultrasound and Fenton reaction. EPR test and quenching experiment proved that (OH)-O-center dot is mainly responsible for tetracycline hydrochloride removal. The major reaction path is the adsorption and decomposition of H2O2 by coordinative unsaturated iron sites on Fe-MOF, but it is not the only path. The direct decomposition of H2O2 and the cavitation effect caused by ultrasound also contribute to the generation of (OH)-O-center dot.

针对水热法制备的氮掺杂TiO2/还原氧化石墨烯纳米颗粒(NTG)分离回收性及稳定性差的问题,采用电化学法制备了氮掺杂TiO2纳米管/还原氧化石墨烯复合膜(ENTG),并通过场发射扫描电镜(FESEM)等表征其特性.结果 表明,ENTG中纳米管阵列的管径约为167 nm、管长约为6 μm,TiO2晶型为锐钛矿相,氮以间隙掺杂形式进入TiO2晶格.不同光催化剂(TiO2纳米管TNT、氮掺杂TiO2纳米管N/TNT、NTG、ENTG)对腐殖酸(HA)的去除效果表明,当HA浓度较低时,4种光催化剂去除HA的过程均符合准一级动力学模型;无论在紫外光区还是可见光区,ENTG的光催化性能均优于其他3种催化剂,且在可见光区去除HA的效果更好.另外,光催化重复试验结果表明,ENTG分离回收方便且催化稳定性较好,在饮用水处理领域具有较大的应用潜能.

As a precursor of disinfection byproducts, humic acid (HA) has adverse effects on aquatic environments and human health. Currently, many advanced oxidation processes (AOPs) have been proposed to remove HA from drinking water, one of which is photocatalysis. However, the long reaction time required for degradation and drawbacks of the photocatalysts limit the large-scale application of photocatalysis. Therefore, two principal objectives were achieved in this work. First regarding the technology, we combined photocatalysis with ultrasonic waves to remove HA. Second regarding the photocatalyst, quaternary Fe3O4/TiO2-N-GO (FTNG) sono-photocatalysts with different amounts of Fe3O4 were first synthesized using a simple hydrothermal method. Characterizations were performed to confirm the successful synthesis of the sono-photocatalyst and to determine some of its properties. The influence of different experimental factors such as Fe3O4 content, ultrasonic power, catalyst dosage and initial HA concentration were studied. The first-order kinetic and second-order kinetic equations were used to simulate the experimental data. The results showed that FTNG-0.2 with 0.2 g of Fe3O4, which was added upon preparation, showed the highest sono-photocatalytic ability. In our experimental setup, greater than 99% removal efficiency (UV254) and 94% mineralization rate (TOC) were achieved within 90 min at the optimum conditions (60 W ultrasound power and 1.0 g/L catalyst dosage for 30 mg/L HA). Compared with the pseudo-first-order kinetic model, pseudo-second-order model fitted better with the experimental data and it had higher R2 values of 0.92, 0.98 and 0.98 for 30, 40 and 50 mg/L of HA, respectively. According to the scavenging tests and the ESR analysis, both of the OH and O2- were produced in the reaction, however, O2- radicals were assumed to be the dominating reactive species for the HA degradation. Moreover, after five repetitive experiments, the removal efficiency of HA can still reach 88.5%, indicating high stability of FTNG-0.2 sono-photocatalyst. The mechanism of degradation of HA by FTNG-0.2 in sono-photocatalytic system was mentioned based on several factors including the ultrasonic cavitation effect, Fenton-like reactions, photocatalytic reactions, etc. In fact, this was the first study to treat HA through sono-photocatalytic process, which showed great potential in drinking water treatment.

In order to remove the humic acid (HA) from the drinking water efficiently, novel quaternary Fe3O4/TiO2-N-GO (FTNG) sonocatalysts with different amounts of Fe3O4 were simply synthesized, and a sono-photocatalytic system was used by combining photocatalysis and ultrasound processes. A series of characterizations were performed to confirm the successful synthesis of FTNG and some of its properties, and the results showed that FTNG with an appropriate amount of Fe3O4 can extend the range of light absorption to over 400nm (UV-vis spectra) and improve the separation efficiency of electrons and holes (Photocurrent responses). Raman spectra indicated the reduction of GO. Sono-photocatalytic performance was investigated under visible light irradiation and the effect of ultrasound was studied. Among all the catalysts, FTNG-0.2 with 0.2 g Fe3O4, exhibited the best HA removal abilities, about 80% for sono-adsorption and 93% for sono-photocatalysis. The removal efficiency in sono-photocatalytic system was about 42% higher than only adsorption and 26% higher than only photocatalysis. Finally, we proposed the possible reaction mechanisms. First, ultrasound pretreatment had a positive effect on HA removal, and a Fenton-like system was then established with H2O2 produced by cavitation effect. Second, the doping of Fe3O4, N and GO improved the quantum efficiency. The improvement of visible light catalytic performance is mainly attributed to the doping of N. This work is significant for the field of ultrasonic and catalytic degradation, especially for the removal of humic acid in drinking water.

Humic acid (HA), which contains abundant carboxyl groups and hydroxyl groups, is one of the major constituents of dissolved organic matter. The increase of HA in natural waters worldwide has caused great trouble in water treatment and water health. Photocatalysis is a promising technology for degrading HA. In this study, graphene oxide, TiO2 and different amounts of urea (nitrogen source) were mixed to dope nitrogen into TiO2 and RGO simultaneously and form N-TG to remove HA from aqueous solution. To confirm the effect of the N-doping and determine the best N-doping ratio for N-TG, various characterization and HA removal tests using different samples were conducted, we found the best N-doping ratio is ~1.46 at.%. The influences of the initial HA concentration, temperature and pH on HA removal performance were measured and discussed, notably, temperature range of 25–35 °C and neutral solution are more fitable for HA removal. HA removal is in the synergistic effect of adsorption and degradation. The presence of RGO almost doubles the adsorption ability of the composite, which does have a significant improvement on HA removal efficiency. Pretreated in darkness has an extra 2% improvement on HA removal efficiency.

An ultrafiltration membrane with enhanced photocatalytic performance from grafted N–TiO2/graphene oxide is prepared, characterized and tested.