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Solar Heterogeneous Photocatalytic Oxidation for Water and Wastewater Treatment: Problems and Challenges
摘要： Solar operation of heterogeneous photocatalytic oxidation reactors is looked at as a sustainable process for water and wastewater treatment, because it does not consume electric power and chemicals. However, there are still problems for technical-scale application. The problems addressed in this article are large area demand, water evaporation from open reactors and lack of simple photocatalyst recovery. An optimum solar reactor type is the parabolic compound collector reactor with borosilicate glass tubes. Challenges for further research are improvement in mass transfer as well as identification of novel photocatalysts which make use also of visible light, are efficient and stable, and are easy to be produced in an economically feasible way. Also the combination of photocatalysts with adsorbents is promising. Although membrane filtration processes have been successfully combined with solar photocatalytic oxidation and represent a safe barrier against spreading photocatalyst nanoparticles into the aquatic environment, more simple and less energy-consuming methods for photocatalyst recovery would be desirable.
关键词： Photocatalyst recovery,Novel photocatalysts,Solar photocatalytic oxidation,Photocatalysis adsorption hybrid process,Mass transfer
更新于2025-09-23 15:23:52
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Wastewater treatment using a hybrid system combining adsorption, photocatalytic degradation and membrane filtration processes
摘要： In the present study, Chooka’s Wastewater treatment was investigated using di?erent combinations of adsorption, photocatalytic degradation, and membrane ?ltration process. Polymeric membranes were fabricated using wet phase inversion method employing polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and dimethylformamide (DMF) as a polymer matrix, hydrophilic additive, and solvent, respectively. Activated carbon and TiO2 nanoparticles were selected as an adsorbent and photocatalyst, respectively. TiO2 nanoparticles were synthesized using the sol-gel method and activated carbon was purchased from Merck Company. Liquid-liquid displacement (LLDP), scanning electron microscope (SEM) and contact angle tests were implemented to characterize the fabricated membranes. FT-IR and XRD analysis were also used for TiO2 nanoparticles characterization. The wastewater of Iran pulp and paper factory (Chooka) was used as the feed in separation processes. In hybrid separation systems, 6 di?erent con?gurations were considered and wastewater compositions were measured to determine the e?ectiveness of the utilized processes before and after treatment. Accordingly, the mean pore size of the fabricated PAN/PVP (16%/3%) membrane obtained from LLDP analysis was 9.72 nm. SEM results also indicated thicker active layer for the PAN/PVP membrane than that of the neat PAN membrane. According to the results of the contact angle tests, with the increasing of PVP content in the polymer matrix, the hydrophilicity of membranes improved. It was also found that membrane ?ltration had the best performance among single stage processes and the best separation performance was achieved when photocatalytic degradation, adsorption, and membrane ?ltration were used in series, respectively.
关键词： Photocatalytic degradation,Membrane ?ltration,Adsorption,Hybrid process,Wastewater treatment
更新于2025-09-23 15:22:29
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Optimizing electrospinning-hydrothermal hybrid process based on Taguchi method for modulation of point defects in ZnO micro/nano arrays towards photoelectronic application
摘要： Unlike previous work generally adopting high temperature annealing (≥500 ℃) to suppress defects in hydrothermal grown ZnO, this work suppressed ZnO defects by optimizing overall process parameters of low temperature electrospinning-hydrothermal hybrid process (≤300 ℃) with Taguchi method and Analysis of Variance (ANOVA). Sum ratio of defect peaks to eigen peaks (SRDE) in room-temperature photoluminescence (PL) spectrum was proposed to evaluate defect conditions in 27 experiments (L27 (38)). With the optimal process, good crystal quality (SRDE=0.31) was achieved at low temperature (200 ℃), of which the SRDE decreased by 68.04% compared with the initial counterpart. Then confirmation experiment was conducted to validate the selected levels, and results of signal-to-noise ratio (SNR) showed good agreement with the predicted ones. Besides, the response time and recovery time of the ZnO photodetectors with optimal process were decreased by 72.5% and 79.3%, respectively, compared with the initial ones. This method can also be used to fabricate ZnO materials with other wanted defect features.
关键词： Point defect,photodetector,ZnO micro/nano array,electrospinning-hydrothermal hybrid process,Taguchi method
更新于2025-09-09 09:28:46