A new perspective of membrane fouling control by ultraviolet synergic ferrous iron catalytic persulfate (UV/Fe(II)/PS) as pretreatment prior to ultrafiltration

Comparison of UV/PS and VUV/PS as ultrafiltration pretreatment: Performance, mechanisms, DBPs formation and toxicity assessment

Ultrafiltration (UF) is widely used in drinking water plants, nevertheless, it still encounters challenges stemming from inevitable membrane fouling caused by natural organic matter (NOM). Herein, this work applied VUV/PS as UF membrane pretreatment and used UV/PS for comparison. VUV/PS system exhibited superior ability in removing NOM compared to UV/PS system. HO and SO4- played crucial roles in the degradation. [SO4-]ss was notably higher than [HO]ss in the systems, yet HO was of greater significance. [HO]ss and [SO4-]ss in the VUV/PS process were remarkably higher than those in the UV/PS process, due to the function of 185 nm photons. VUV/PS pretreatment basically recovered flux and effectively reduced fouling resistance, with better performance than UV/PS. Fouling mechanism was dominated by multiple mechanisms after UV/PS pretreatment, whereas it was transformed into pore blockage after VUV/PS pretreatment. Moreover, the UF effluent quality after VUV/PS pretreatment outperformed that of UV/PS but fell short of that without pretreatment, possibly due to the generation of abundant low MW substances under the action of HO and SO4-. After chlorine disinfection, UV/PS and VUV/PS pretreatments increased the DBPs production and cytotoxicity. Specifically, oxidant PS affected the membrane surface morphology and fouling behaviors, and had no obvious effect on interception performance and mechanical properties. In actual water treatment, VUV/PS and UV/PS pretreatments exhibited excellent performance in alleviating membrane fouling, improving water quality, and reducing DBPs formation and acute toxicity.

VUV coupled with low-dose H2O2 as pretreatment prior to UF: Performance, mechanisms, DBPs formation and toxicity evaluation

Ultrafiltration (UF) is widely used in drinking water plants; however, membrane fouling is unavoidable. Natural organic matter (NOM) is commonly considered as an important pollutant that causes membrane fouling. Herein, we proposed VUV/H2O2 as a UF pretreatment and used UV/H2O2 for comparison. Compared to UV/H2O2, the VUV/H2O2 system presented superior NOM removal. In the VUV/H2O2 system, the steady-state concentration of HO• was approximately twice that in the UV/H2O2 system, which was ascribed to the promoting effect of the 185 nm photons. Specifically, 185 nm photons promoted HO• generation by decomposing mainly H2O at a low H2O2 dose or by decomposing mainly H2O2 at a high H2O2 dose. The VUV/H2O2 pretreatment also demonstrated better membrane fouling mitigation performance than did UV/H2O2. An increase in the H2O2 dose promoted HO• generation, thereby enhancing the performance of NOM degradation and membrane fouling alleviation and shifting the major membrane fouling mechanism from cake filtration to standard blocking. The VUV/H2O2 (0.60 mM) pretreatment effectively reduced disinfection byproducts (DBPs) formation during chlorine disinfection. Additionally, the oxidant H2O2 affected the membrane surface morphology and performance but had no evident effect on the mechanical properties. In actual water treatment, the VUV/H2O2 pretreatment exhibited better performance than the UV/H2O2 pretreatment in easing membrane fouling, ameliorating water quality, and reducing DBPs formation and acute toxicity.

Reduction of fouling of gravity-driven membrane by combined treatment of persulphate/nanoscale zero-valent iron/ultraviolet and dynamic dual coagulant flocs layer

In this study, persulphate and nanoscale zero-valent iron were activated by ultraviolet irradiation (PS/nZVI/UV), followed by formation of dynamic flocs with AlCl3-TiCl4 coagulant directly injected into a gravity-driven membrane (GDM) tank. Membrane fouling caused by typical organic matter fractions including humic acid (HA), HA together with bovine serum albumin (HA-BSA), HA combined with polysaccharide (HA-SA) and the HA-BSA-SA mixture at pH of 6.0, 7.5 and 9.0 were evaluated by specific flux and fouling resistance distribution. The results showed that GDM pre-layered with AlCl3-TiCl4 flocs exhibited the maximum specific flux, followed by AlCl3 and TiCl4. Pre-oxidation with 0.5 mM PS and 0.1 g nZVI under UV radiation for 20 min was beneficial to degrade HA and SA fraction with molecular weight >100 kDa and <30 kDa, and BSA fraction with <30 kDa. The presence of BSA attributed mostly to irreversible fouling, SA together with BAS could exacerbate irreversible fouling, while HA caused the least fouling. The irreversible resistance of a PS/nZVI/UV-GDM system was 62.79%, 27.27%, 58.03% and 49.68% lower than that of control GDM in the treatment of HA, HA-BSA, HA-SA and HA-BSA-SA, respectively. The PS/nZVI/UV-GDM system could achieve the highest foulants removal efficiency at pH of 6.0. Morphological observations confirmed the differences in biofouling layers in different water types. Over 30-day operation, the bacterial genera on the biofouling layer could affect the organic removals, while the type of organic matter that was present influenced the relative abundance of bacterial genera.

Chemical-free vacuum ultraviolet irradiation as ultrafiltration membrane pretreatment technique: Performance, mechanisms and DBPs formation

Membrane fouling induced by natural organic matter (NOM) has seriously affected the further extensive application of ultrafiltration (UF). Herein, a simple, green and robust vacuum ultraviolet (VUV) technology was adopted as pretreatment before UF and ultraviolet (UV) technology was used for comparison. The results showed that control effect of VUV pretreatment on membrane fouling was better than that of UV pretreatment, as evidenced by the increase of normalized flux from 0.27 to 0.38 and 0.73 after 30 min UV or VUV pretreatment, respectively. This is related to the fact that VUV pretreatment exhibited stronger NOM degradation ability than UV pretreatment owing to the formation of HO•. The steady-state concentration of HO• was calculated as 3.04 × 10-13 M and the cumulative exposure of HO• reached 5.52 × 10-10 M s after 30 min of VUV irradiation. And the second-order rate constant between NOM and HO• was determined as 1.36 × 104 L mg-1 s-1. Furthermore, fluorescence EEM could be applied to predict membrane fouling induced by humic-enriched water. Standard blocking and cake filtration were major fouling mechanisms. Moreover, extension of UV pretreatment time increased the disinfection by-products (DBPs) formation, the DBPs concentration was enhanced from 322.36 to 1187.80 μg/L after 210 min pretreatment. However, VUV pretreatment for 150 min reduced DBPs content to 282.57 μg/L, and DBPs content continued to decrease with the extension of pretreatment time, revealing that VUV pretreatment achieved effective control of DBPs. The variation trend of cytotoxicity and health risk of DBPs was similar to that of DBPs concentration. In summary, VUV pretreatment exhibited excellent effect on membrane fouling alleviation, NOM degradation and DBPs control under a certain pretreatment time.

Sulfadiazine removal efficiency with persulfate driven by electron-rich Cu-beta zeolites

Surface electron transport and transfer of catalysts have important consequences for persulfate (PS) activation in PS system. In this paper, an electron-rich Cu-beta zeolites catalyst was synthesized utilizing a straightforward solid-state ion exchange technique to efficiently degrade sulfadiazine. The X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) results revealed that Cu element substitutes Al element and enters the beta molecular sieve framework smoothly. Furthermore, the X-ray photoelectron spectroscopy (XPS) measurements demonstrated that the Cu-beta catalyst is primarily Cu0. Cu-beta zeolites catalyst can exhibit excellent catalytic activity to degrade sulfadiazine with the oxidant of PS. The optimal sulfadiazine removal performance was explored by adjusting reaction parameters, including sulfadiazine concentration, catalyst dosage, oxidant dosage, and solution pH. The sulfadiazine removal efficiency in the Cu-beta zeolites/PS system could reach 90.5% at the optimal reaction condition ([PS]0 = 0.5 g/L, [Cu-beta zeolites]0 = 1.0 g/L, pH = 7.0) with 50 mg/L of sulfadiazine. Meanwhile, The degradation efficiency was less affected by anionic interference (Cl-, SO4-, HCO3-). The surface electron transport and transfer of the Cu-beta zeolites catalyst were significant causes for the remarkable degradation performance. According to electron paramagnetic resonance (EPR) and quenching studies, the Cu-beta zeolites/PS system was mostly dominated by SO4•- in the degradation of sulfadiazine. Furthermore, two possible pathways for sulfadiazine degradation were proposed according to the analysis of intermediate products detected by the liquid chromatography-mass spectrometry (LC-MS).

Comparative study of UV/chlorine and VUV/chlorine as ultrafiltration membrane pretreatment techniques: Performance, mechanisms and DBPs formation

Membrane fouling, primarily resulting from natural organic matter (NOM) widely existing in water sources, has always been a chief hindrance for the prevalent application of ultrafiltration (UF). Thus, vacuum ultraviolet (VUV)/chlorine process was proposed as a strategy for UF membrane fouling control and ultraviolet (UV)/chlorine process was used for comparison. VUV/chlorine process exhibited more excellent performance on NOM removal than UV/chlorine process. [HO•]ss and [Cl•]ss were calculated as 1.26 × 10-13 and 3.06 × 10-14 M, respectively, and ClO• might not exist under the conditions of 0.08 mM chlorine and 30 min VUV irradiation. [HO•]ss, [Cl•]ss and [ClO•]ss were not available and the formation of reactive radicals was unsustainable in UV/chlorine system. Moreover, VUV/chlorine pretreatment also showed better performance on the reversible and irreversible membrane fouling control than UV/chlorine pretreatment. The dominated fouling mechanism in the final stage of filtration was cake filtration. Additionally, the amount of detected disinfection by-products (DBPs) in VUV/chlorine system was significantly lower than that in UV/chlorine system. During subsequent chlorination disinfection, the yield of DBPs with VUV/chorine pretreatment was higher than that with UV/chlorine pretreatment. VUV/chlorine pretreatment could effectively control DBPs formation when the pretreatment time was extended to 120 min. In summary, VUV/chlorine system presented a most excellent performance on membrane fouling control, NOM degradation and DBPs control.

Mutual activation between ferrate and calcium sulfite for surface water pre-treatment and ultrafiltration membrane fouling control

In this work, ferrate (Fe(VI)) and calcium sulfite (CaSO₃) were combined to treat surface water for improving ultrafiltration (UF) performance. During the pre-treatment process, the Fe(VI) and CaSO₃ activated each other and a variety of active species (Fe(V), Fe(IV), OH, SO₄^-, ¹O₂, etc.) were generated. All of the five fluorescent components were effectively eliminated to different extents. With Fe(VI)/CaSO₃ = 0.05/0.15 mM, the dissolved organic carbon and UV₂₅₄ reduced by 44.33 % and 50.56 %, respectively. After UF, these values were further decreased with the removal rate of 50.27 % and 70.79 %. In the UF stage, the terminal J/J₀ increased to 0.42 from 0.17, with the reversible and irreversible fouling decreased by 67.08 % and 79.45 % at most. The membrane pore blocking was significantly mitigated, as well as the foulants deposition on membrane surfaces was decreased to some extent. The complete blocking was altered to standard blocking and intermediate blocking, the volume when entering cake filtration was also delayed slightly. The extended Derjaguin-Landau-Verwey-Overbeek theory was employed to judge the interface fouling behavior, and the results indicated that the foulants became more hydrophilic, as well as the adhesion trend between foulants and membrane surface was weakened. Overall, these results provide a theoretical foundation for the practical application of the combined Fe(VI)/CaSO₃-UF process in surface water purification.

Reduction of Ultrafiltration Membrane Fouling by the Pretreatment Removal of Emerging Pollutants: A Review

Ultrafiltration (UF) processes exhibit high removal efficiencies for suspended solids and organic macromolecules, while UF membrane fouling is the biggest obstacle affecting the wide application of UF technology. To solve this problem, various pretreatment measures, including coagulation, adsorption, and advanced oxidation, for application prior to UF processes have been proposed and applied in actual water treatment processes. Previously, researchers mainly focused on the contribution of natural macromolecular pollutants to UF membrane fouling, while the mechanisms of the influence of emerging pollutants (EPs) in UF processes (such as antibiotics, microplastics, antibiotic resistance genes, etc.) on membrane fouling still need to be determined. This review introduces the removal efficiency and separation mechanism for EPs for pretreatments combined with UF membrane separation technology and evaluates the degree of membrane fouling based on the UF membrane's materials/pores and the structural characteristics of the cake layer. This paper shows that the current membrane separation process should be actively developed with the aim of overcoming specific problems in order to meet the technical requirements for the efficient separation of EPs.

Enhancing ultrafiltration of algal-rich water using ferrate activated with sodium percarbonate: Foulants variation, membrane fouling alleviation, and collaborative mechanism

Ultrafiltration (UF) is a reliable method to treat algal-rich water, whereas severe membrane fouling has impeded its actual application. To improve UF performance and alleviate membrane fouling resulted by algal foulants, a novel strategy coupling ferrate (Fe(VI)) and sodium percarbonate (SPC) was proposed. During the coupling process, Fe(VI) was activated by SPC to generate high-valent Fe intermediates (Fe(V) and Fe(IV)), which played a crucial role in high-efficiency oxidation for algal foulants, and the in-situ formed Fe(III) particles decomposed by Fe(VI) also enhanced the coagulation and adsorption capacity to the coupling system. Under the triple effects of coagulation, adsorption and oxidation, the algal foulants were efficiently eliminated. The zeta potential increased from -32.70 mV to -6.56 mV at most, the particle size was significantly enlarged, and the generated flocs possessed a great settleability. The morphology, viability, and integrity of algae cells were effectively maintained. The dissolved organic matters and fluorescent organics were efficiently removed, as well as macromolecular organics were reduced into lower molecular weight components. With the collaborative effect of Fe(VI) and SPC, the terminal specific flux was increased from 0.29 to 0.92, and the reversible and irreversible fouling resistances were reduced by 98.5% and 69.4%, individually. The surface functional groups were changed, and the dominant mechanisms were also converted to pore blocking from cake layer filtration. Overall, the experimental results would provide some new thoughts in actual production for algal-rich water treatment and UF membrane fouling alleviation.

Degradation of ciprofloxacin by persulfate activated with pyrite: mechanism, acidification and tailwater reuse

Residues of ciprofloxacin (CIP) in the environment pose a threat to human health and ecosystems. This study investigated the degradation of CIP by persulfate (PS) activated with pyrite (FeS₂). Results showed that when [CIP] = 30 μM, [FeS₂] = 2.0 g L^-1, and [PS] = 1 mM, the CIP removal rate could reach 94.4% after 60 min, and CIP mineralization rate reached 34.9%. The main free radicals that degrade CIP were SO₄˙^- and HO˙, with contributions of 34.4% and 35.7%, respectively. Additionally, compared to the control (ultrapure water), CIP in both tap water and river water was not degraded. However, acidification could eliminate the inhibition of CIP degradation in tap water and river water. Furthermore, acidic tailwater from CIP degradation could be utilized to adjust the pH of untreated CIP, which could greatly promote the degradation of CIP and further reduce disposal costs. The reaction solution was not significantly biotoxic and three degradation pathways of CIP were investigated. Based on the above results and the characterization of FeS₂, the mechanism of CIP degradation in the FeS₂/PS system was that FeS₂ activated PS to generate Fe(iii) and SO₄˙^-. The sulfide in FeS₂ reduced Fe(iii) to Fe(ii), thus achieving an Fe(iii)/Fe(ii) cycle for CIP degradation.

Effect of vacuum ultraviolet/ozone pretreatment on alleviation of ultrafiltration membrane fouling caused by algal extracellular and intracellular organic matter

Algal blooms in source water can cause algal organic matter (AOM)-related membrane fouling in drinking water treatment. Herein, the effects of vacuum ultraviolet/ozone (VUV/O₃) pretreatment on alleviating ultrafiltration membrane fouling caused by AOM, including extracellular organic matter (EOM) and intracellular organic matter (IOM), were investigated systematically. Compared to its sub-processes (UV/O₃, O₃, VUV, and UV), VUV/O₃ pretreatment showed the best performance on AOM removal and membrane fouling mitigation. After VUV/O₃ pretreatment, the DOC of EOM and IOM in feed decreased by 51.1% and 26.7%, respectively, and fluorescence components and UV₂₅₄ of EOM and IOM in feed decreased obviously. Hence, the final specific fluxes of the membranes increased significantly under the impacts of VUV/O₃, and VUV/O₃ achieved 89.5% and 97.2% mitigation of reversible fouling caused by EOM and IOM, respectively. VUV/O₃ pretreatment also reduced the foulants on membrane surface and surface roughness. Moreover, under the effects of reactive oxygen species oxidation, VUV photolysis, and direct O₃ oxidation, VUV/O₃ decreased organic load and changed the molecular weight distribution, hydrophilicity, and interaction-free energy of AOM, thus mitigating membrane fouling. Furthermore, the effects of O₃ dosage and molecular weight cut-off of ultrafiltration membrane on membrane fouling mitigation by VUV/O₃ were also investigated. All results highlighted that VUV/O₃ pretreatment had huge potential in mitigating AOM-induced membrane fouling.

Accelerate sulfamethoxazole degradation and detoxification by persulfate mediated with Fe2+&dithionite: Experiments and DFT calculation

Advanced oxidation process (AOPs) is one of the most effective technologies for organic pollutants removal. In this study, diverse reactive species generation and enhanced sulfamethoxazole (SMX) degradation were investigated based on persulfate (PDS) activated by Fe²⁺&dithionite (DTN). When involving Fe²⁺&dithionite in PDS, SMX degradation efficiency reached 84 % within 30 min following a pseudo-first-order kinetic, which was higher than those in Fe²⁺/PDS (50.4 %) and Fe²⁺/O₂/DTN (41.3 %). SO₄^•- and ^•OH were identified as dominant reactive species with a crucial role of FeSO₃⁺ based on quenching experiment and electron spin resonance (ESR). The contributions of SO₄^·-, ^·OH, and other species to SMX degradation were 60.1 %, 33.9 %, and 6 %, respectively. In Fe²⁺/DTN/PDS system, SMX was effectively degraded under nearly neutral pH (5.0-9.0), with activation energy of 96.04 kJ·mol^-1. The experiments and density functional theory (DFT) calculation demonstrated that three functional groups (benzenesulfonamido, benzene ring, and oxazole ring) were attacked for SMX degradation. Moreover, acute toxicity to Vibrio fischeri has enhanced in the earlier degradation process due to the intermediates and weaken with the continuous reaction. This work not only provides a high-activity SO₄^·--AOP for refractory pollutant treatment with possible dual radical generation resources, but elucidated diverse reactive species formation with Fe²⁺&dithionite.

New insights into the transformation of effluent organic matter during Fe(II)-assisted advanced oxidation processes: Parallel factor analysis coupled with self-organizing maps

The negative effects of effluent organic matter (EfOM) on receiving aquatic environments and advanced treatment facilities pose significant concerns. However, the effective removal of EfOM is challenging due to its chemically complex nature and its refractory characteristics. In this study, two Fe(II)-assisted oxidation processes including UV/Fe(II)/H₂O₂ and UV/Fe(II)/persulfate (UV/Fe(II)/PS) were investigated to promote EfOM reduction. Fe(II) was essential for promoting EfOM degradation. The mineralization rate of EfOM increased from 7 to 29% with 2 mM Fe(II) addition in the UV/H₂O₂ process and to 23% with 0.8 mM Fe(II) addition in the UV/PS process. A preliminary experiment was conducted to obtain the optimal molar ratio of oxidant to Fe(II) for practical applications based on different indicators. The form of Fe(III) prevalent at different pH values strongly affected Fe(II)/Fe(III) cycling, thus determining the progress of EfOM degradation. A machine learning approach consisting of parallel factor analysis coupled with self-organizing maps (PARAFAC-SOM) was employed with fluorescence spectra to visualize the degradation behavior of EfOM in the different reaction systems. Four components (i.e., two humic-like substances, one fulvic acid, and one tryptophan-like substance) were eventually identified, and their reductions reached more than 62% during the Fe(II)-assisted oxidation processes. The degradation orders for each component in the different oxidation processes were initially evaluated by SOM analysis with F_max percentage data. The degradation behavior of EfOM in the UV/Fe(II)/H₂O₂ and UV/Fe(II)/PS systems exhibited different trends based on the best matching unit map and component planes. The humic-like component was more refractory than the other three components in both oxidation processes. The microbial humic-like and high-molecular-weight fulvic acid substances showed higher reactivity with SO·₄^- than with ·OH, while the tryptophan-like substance was more reactive in the UV/Fe(II)/H₂O₂ system than in the UV/Fe(II)/PS system. The outcomes of this study provide new insights into the degradation behavior of EfOM, promoting the development of advanced wastewater treatments.

High microwave responsivity Co-Bi25FeO40 in synergistic activation of peroxydisulfate for high efficiency pollutants degradation and disinfection: Mechanism of enhanced electron transfer

Cobalt doped Bi₂₅FeO₄₀ was used as a heterogeneous catalyst in microwave (MW) co-activation of peroxydisulfate (PDS) system for organic contaminant purification and disinfection simultaneously. Due to low charge-transfer resistance and fast electron migration, Co-Bi₂₅FeO₄₀ showed superior catalytic efficiencies for activation PDS to degrade over 92.0% of bisphenol A (BPA) with the initial concentrations ranging from 40 mg/L to 120 mg/L in 5.0 min. The non-radical oxidation pathway via electron transfer regime on the surface of Co-Bi₂₅FeO₄₀ was the dominant reactive species in the reaction system. Benefit from the energy transfer and cross-coupling reactions of microwave, the Co-Bi₂₅FeO₄₀/MW/PDS system can generate abundant reactive sites to facilitate the formation of more surface-bonding complexes. Microwave energy can be absorbed by Co-Bi₂₅FeO₄₀ catalysts to promote activation of PDS and production of nanobubbles. The generated nanobubbles increase the temperature of the local solution to promote the reaction. The Co-Bi₂₅FeO₄₀/MW/PDS system also exhibited excellent bactericidal capability for Escherichia coli (E.coli). The catalysts, oxidants and microwaves acted on E. coli to form physical, and oxidative pressure simultaneously, causing cell damaged and made bacterial death. This work provides prospects toward high-efficiency integration of contaminant purification and pathogenic microorganisms inactivation.

Coagulation combined with ultraviolet irradiation activated sodium percarbonate as pretreatment prior to ultrafiltration: Analysis of free radical oxidation mechanism and membrane fouling control

Novel pre-coagulation-sedimentation integrated with ultraviolet activated sodium percarbonate (SPC) (Fe(III)-UV/SPC) processes are promising methods for ultrafiltration (UF) pretreatment to ensure the safety of rural drinking water and mitigate UF membrane fouling. The process of surface water purification using the integrated coagulation-advanced oxidation processes (AOPs)-UF system relies on the idea that pre-coagulation can remove hydrophobic macromolecular organic compounds, thus facilitating the oxidation of hydrophilic molecules or medium-sized macromolecules to improve the utilization efficiency of free radicals in AOPs. Compared with the UV/SPC process, the removal rates of UV₂₅₄ and DOC in the Fe(III)-UV/SPC process (Fe(III) = 0.1 mM, SPC = 0.5 mM) were increased from 87.39 % to 41.45 %-93.56 % and 52.51 %, respectively. Furthermore, the dosage of SPC was reduced from 0.75 mM in UV/SPC process to 0.5 mM due to effects of pre-coagulation. The free radical quenching experiment showed that a significant radical sink of reactions with organic contaminants was formed by •OH and CO₃^•- in the UV/SPC process, rather than a single specific radical. The destruction of the cake layer structure, reduction in contaminant concentration, and appearance of many permeable holes on the membrane surface were the main reasons for the alleviation of UF membrane fouling. Finally, the trans-membrane pressure and reversible membrane resistance decreased from 22.33 kPa to 3.68 × 10¹¹ m^-1 to 18.28 kPa and 0.93 × 10¹¹ m^-1, respectively. These results provide new insights into the behavior of membrane fouling control and offer technical references for the long-term stable operation of the UF process.

What is the role of light in persulfate-based advanced oxidation for water treatment?

Persulfate-based advanced oxidation processes (PS-based AOPs) under UV, visible, or solar irradiation are being intensively investigated for water treatment. Tremendous advances have been made for enhancing the performance towards the destruction of target pollutants, but a deeper understanding of the role of light in different photo-activated PS-based AOPs is still needed as a basis for improving the efficiency. This paper intends to provide an in-depth review of the underlying photo-activation mechanisms and recent progress in various common photo-activated PS-based AOPs reported over the last decade. Based on a comprehensive survey of previous studies, we categorize these processes according to their reaction mechanisms, including activation by direct UV radiation, processes based on dye-photosensitization, activation through ligand-to-metal charge transfer (LMCT), and photocatalytic processes. Moreover, the improvement in performance of contaminant degradation in these processes compared with those in the absence of light are summarized. Finally, we conclude this review by proposing critical challenges and future perspectives for developing efficient photo-activated PS-based AOPs toward improvement in water treatment and remediation.

Aging retardation strategy of PVDF membranes: evaluation of free radical scavenging effect of nano-particles

ESR and spectrophotometry proved that nano-particles can effectively remove free radicals produced by NaClO, and analyzed the mechanism of delaying aging.