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Proof of Concept for Light Conducting Membrane Substrate for UV-Activated Photocatalysis as an Alternative to Chemical Cleaning
摘要： Adopting an effective strategy to control fouling is a necessary requirement for all membrane processes used in the water/wastewater treatment industry to operate sustainably. The use of ultraviolet (UV) activated photocatalysis has been shown to be effective in mitigating ceramic membrane fouling by natural organic matter. The widely used configuration in which light is directed through the polluted water to the membrane’s active layer suffers from inefficiencies brought about by light absorption by the pollutants and light shielding by the cake layer. To address these limitations, directing light through the substrate, instead of through polluted water, was studied. A UV conducting membrane was prepared by dip coating TiO2 onto a sintered glass substrate. The substrate could successfully conduct UV from a lamp source, unlike a typical alumina substrate. The prepared membrane was applied in the filtration of a humic acid solution as a model compound to study natural organic matter membrane fouling. Directing UV through the substrate showed only a 1 percentage point decline in the effectiveness of the cleaning method over two cleaning events from 72% to 71%, while directing UV over the photocatalytic layer had a 9 percentage point decline from 84% to 75%. Adapting the UV-through-substrate configuration could be more useful in maintaining membrane functionality during humic acid filtration than the current method being used.
关键词： photocatalytic membrane,membrane fouling,Titanium dioxide,water treatment
更新于2025-09-19 17:15:36
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TiO2 coated on PVDF membrane for dye wastewater treatment by a photocatalytic membrane
摘要： This work investigated the membrane modi?cation to increase hydrophilicity aiming for application in a photocatalytic membrane. The modi?ed poly(vinylidene ?uoride) (PVDF) ?at sheet membrane was coated with titanium dioxide (TiO2). The chemical and physical changes of membranes were characterized by contact angle, SEM and porosity. The results found that TiO2 successfully modi?ed the PVDF membrane by decreasing the contact angle from 127.1° to 114.3° on increasing the TiO2 concentration from 0.1 to 1.0 g/L. The contact angles were decreased with the increase of coating time. The water permeation after PVDF membrane modi?cation decreased compared with the original membrane, whereas water ?uxes increased with the increase of TiO2 concentration. TiO2 particles were observed on the membrane surface while the porosity of the membrane coated with TiO2 decreased. The optimum condition of membrane coating was obtained at 1.0 g/L of TiO2 and 60 min of coating time. The decolorization of RB 19 by photolysis and photolysis followed by ?ltration was less than 10%; in contrast, the decolorization of RB 19 by photocatalytic oxidation was as well as a photocatalytic membrane for 60 min. The TiO2 photocatalytic membrane is a feasible technology for RB 19 decolorization in wastewater.
关键词： dye,wastewater treatment,PVDF,membrane modi?cation,photocatalytic membrane
更新于2025-09-19 17:15:36
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Hydrogen and Oxygen Evolution in a Membrane Photoreactor Using Suspended Nanosized Au/TiO2 and Au/CeO2
摘要： Photocatalysis combined with membrane technology could offer an enormous potential for power generation in a renewable and sustainable way. Herein, we describe the one-step hydrogen and oxygen evolution through a photocatalytic membrane reactor. Experimental tests were carried out by means of a two-compartment cell in which a modified Nafion membrane separated the oxygen and hydrogen evolution semi-cells, while iron ions permeating through the membrane acted as a redox mediator. Nanosized Au/TiO2 and Au/CeO2 were employed as suspended photocatalysts for hydrogen and oxygen generation, respectively. The influence of initial Fe3+ ion concentration, ranging from 5 to 20 mM, was investigated, and the best results in terms of hydrogen and oxygen evolution were registered by working with 5 mM Fe3+. The positive effect of gold on the overall water splitting was confirmed by comparing the photocatalytic results obtained with the modified/unmodified titania and ceria. Au-loading played a key role for controlling the photocatalytic activity, and the optimal percentage for hydrogen and oxygen generation was 0.25 wt%. Under irradiation with visible light, hydrogen and oxygen were produced in stoichiometric amounts. The crucial role of the couple Fe3+/Fe2+ and of the membrane on the performance of the overall photocatalytic system was found.
关键词： water splitting,photocatalytic membrane reactor,photocatalysis,Z-scheme
更新于2025-09-19 17:15:36
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Potential use of green TiO2 and recycled membrane in a photocatalytic membrane reactor for oil refinery wastewater polishing
摘要： Membrane bioreactors (MBRs) have been successfully used in oil refinery wastewater treatments. However, a polishing treatment of the MBR permeate is required to remove the recalcitrant organic compounds. In this study, the coupling of a photocatalytic membrane reactor (PMR) and MBR was investigated for the treatment of oil refinery wastewater. Titanium dioxide (TiO2) nanoparticles, synthesised by a cleaner route assisted by microwave radiation, and recycled membrane, an end-of-life reverse osmosis membrane converted to an ultrafiltration membrane by oxidation, were prepared for use as a PMR. The recycled membrane could completely retain the catalyst particles. The PMR exhibited higher efficiency and stability in the removal of organic matter than those of the individual photocatalysis and membrane processes. Adsorption of organic compounds was observed on the catalyst surface. These compounds were degraded releasing active sites for reaction/adsorption. A chemical oxygen demand analysis revealed that up to 60% of the organic matter in the MBR permeate was decomposed in the PMR, which also contributed to membrane fouling mitigation. The membrane fouling resistance in the PMR was 7.3 times lower than that in the system operated without the catalyst. In addition, membrane degradation was not observed upon the use of the catalyst. The results indicate that the PMR with the green TiO2 and recycled membrane is a highly active, stable, and promising system for the polishing of oil refinery wastewater previously treated by the MBR.
关键词： oil refinery wastewater,titanium dioxide nanoparticle,recycled membrane,photocatalytic membrane reactor,recalcitrant compound
更新于2025-09-19 17:13:59
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Monolayer porphyrin assembled SPSf/PES membrane reactor for degradation of dyes under visible light irradiation coupling with continuous filtrationa?°
摘要： Porphyrin-based catalytic oxidation of hydrocarbon bonds is considered to be the most representative biomimetic catalysis. To mimic the biomimetic catalytic oxidation of nature under illumination of visible light, a monolayer of meso-tetrakis (1-methylpyridinium-4-yl) porphyrin immobilized sulfonated polysulfone/ polyethersulfone blend membrane (TMPyP@SPSf/PES) was prepared via a facile electrostatic assembly method. The visible light response region of TMPyP was expanded after it was immobilized on the SPSf/PES membrane surface, which resulted in the increase of the photocatalytic performance, and the Rhodamine B (RhB) degradation was increased from 30.0% to 93.4%. A photocatalytic membrane reactor (PMR) equipped with TMPyP@SPSf/PES membrane was employed for RhB treatment under continuous flow filtration coupling with photocatalysis, and the optimized degradation was up to 98.3%. Moreover, the TMPyP@SPSf/PES membrane can be reused for photocatalytic degradation of RhB after regeneration in TMPyP solution. More importantly, the TMPyP@SPSf/PES membrane can also efficiently degrade other cationic and anionic dyes (such as degradation of methylene blue 99.1%, acid fuchsin 96.8%). Finally, the oxidation mechanism and degradation pathway of RhB were further investigated by electron spin resonance (ESR), ultra-performance liquid chromatography and high-definition mass spectrometry (UPLC–HDMS) and gas chromatography-Mass spectrometry (GC–MS). It was revealed that the photogenerated hole (h+), superoxide radical (?O2?), and singlet oxygen (1O2) controlled the oxidation process. The degradation of RhB includes N-de-ethylate, wrecked of chromophore structures and opening-ring of benzene.
关键词： Photocatalytic membrane reactor,Biomimetic catalysis,Dye wastewater,TMPyP@SPSf/PES membrane,Electrostatic assembly
更新于2025-09-19 17:13:59
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Improved disinfection performance towards human adenoviruses using an efficient metal-free heterojunction in a vis-LED photocatalytic membrane reactor: Operation analysis and optimization
摘要： Waterborne human viruses, with ubiquitous prevalence in aquatic environments, extremely low infectious doses, and high resistance to common disinfection processes, pose a substantial threat to human health. Herein, for the first time, a photocatalytic membrane reactor (PMR) driven by visible light emitting diodes (Vis-LEDs) was applied for effective water disinfection of human adenoviruses. The photocatalyst used in the PMR was selected to be a metal-free heterojunction (named as CNO) with the advantages of visible-light-response, efficient virucidal effects, green properties and easy recovery via microfiltration. The disinfection performance of the Vis-LED PMR towards human adenoviruses was improved by adjusting operation with response surface methodology (RSM). Based on twenty sets of operating data, a semi-empirical model was established with a high accuracy of R2 = 0.9622 for predicting the final adenovirus inactivation after 300-min operation. The optimal operating solution was found to be 5.00-log MPN/mL, 320.30 mg/L and 502.65 min for initial virus concentration (IVC), photocatalyst loading (PL) and hydraulic retention time (HRT), respectively. Under the optimized operation, all human adenoviruses were completely inactivated without regrowth, accompanied by severe damage to capsids, within 600 min in the Vis-LED PMR. In addition, the CNO photocatalyst could be retained inside the reactor via low-energy microfiltration with excellent recovery (99.9 wt%) but without obvious chemical or structural changes. Our work can offer a simple, effective, economical and eco-friendly water disinfection device against resistant pathogenic microbes, with controllable efficiency by facilely varying operating solutions.
关键词： operation analysis,photocatalytic membrane reactor,Vis-LED,metal-free heterojunction,human adenoviruses,optimization
更新于2025-09-11 14:15:04
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Fouling process and anti-fouling mechanisms of dynamic membrane assisted by photocatalytic oxidation under sub-critical fluxes
摘要： Membrane fouling is often considered as a hindrance for the application of microfiltration /ultrafiltration (MF/UF) for drinking water production. A novel process of photocatalytic membrane reactor/dynamic membrane (PMR/DM), operating in a continuous mode under sub-critical flux, was proposed for the mitigation of membrane fouling caused by humic acids (HAs) in water. The mechanism of membrane fouling alleviation with synergistic photocatalytic oxidation and dynamic layer isolating effect was comprehensively investigated from the characterization of foulants evolution responsible for the reversible and irreversible fouling. The results showed that the PMR/DM utilized photocatalytic oxidation to enhance the porosity and hydrophilicity of the fouling layer by converting the high molecular weight (MW) and hydrophobic HA molecules with carboxylic functional groups and aromatic structures into low-MW hydrophilic or transphilic fractions, including tryptophan-like or fulvic-like substances. The fouling layer formed in the PMR/DM by combination of photocatalytic oxidation and DM running at sub-critical flux of 100 L?h-1?m-2, was more hydrophilic and more porous, resulting in the lowest trans-membrane pressure (TMP) growth rates, as compared to the processes of ceramic membrane (CM), DM and PMR/CM. Meanwhile, the dynamic layer prevented the foulants, particularly the high-MW hydrophobic fractions, from contacting the primary membrane, which enabled the membrane permeability to be restored easily.
关键词： Photocatalytic Membrane Reactor,Sub-critical Flux,Dynamic Membrane,Humic Acids,Membrane Fouling
更新于2025-09-10 09:29:36
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Comprehensive Membrane Science and Engineering || 3.5 Photocatalytic Processes in Membrane Reactors
摘要： Photocatalytic membrane reactors (PMRs) represent an interesting alternative technology useful both in the field of water and air purification and in organic syntheses. The necessity to develop chemical products and industrial processes that reduce or eliminate the use and the generation of toxic substances along with the risk for human health and for environment constitutes the aim of the research efforts based on the principles of green chemistry.
关键词： air purification,green chemistry,Photocatalytic membrane reactors,water purification,organic syntheses
更新于2025-09-04 15:30:14
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Polydopamine‐coated poly(vinylidene fluoride) membranes with high ultraviolet resistance and antifouling properties for a photocatalytic membrane reactor
摘要： We modi?ed poly(vinylidene ?uoride) (PVDF) membranes with a polydopamine (PDA) coating for photocatalytic membrane reactor application with appropriate UV resistance and studied the effects of the PDA coating conditions (i.e., coating time and dopamine concentration) and UV irradiation time on the modi?ed PVDF membrane properties. The PVDF membrane that was surface-coated with the appropriate dopamine solution concentration and coating time played a key role in controlling the membrane properties and in protecting the modi?ed membrane against UV radiation. The optimization of the coating condition not only completely protected the modi?ed membrane from free-radical attack initiated through UV irradiation but also improved the membrane hydrophilicity, antifouling properties, ?ltration performance, and mechanical strength of the membrane. UV irradiation of the membrane that was surface-coated with a high-concentration dopamine solution for a long coating time resulted in a higher mechanical strength than that of the membrane without the application of UV irradiation.
关键词： free radical scavenger,photocatalytic membrane reactor,polydopamine,UV-resistance
更新于2025-09-04 15:30:14