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Color removal from wastewater by photocatalytic process using titanium dioxide-coated glass, ceramic tile, and stainless steel sheets
摘要： Dye pollutants from textile industries are a major wastewater problem because they have complex chemical structures. Photocatalysis is a promising wastewater treatment method, which is used to remove dyes under light irradiation in the presence of a photocatalyst. In this article, titanium dioxide (TiO2) photocatalyst was synthesized through sol-gel technique and coated on different substrates (i.e. transparent glass, glazed ceramic tile, and stainless steel) by doctor blade technique. The coated substrates were used in an innovative reactor to remove colors in dye wastewater. The photocatalytic activities of the designed reactor were determined using a synthetic dye wastewater (methylene blue) under UV irradiations (36W-UVA or 30W-UVC lamps). The results showed that the optimum substrate yielded the highest color removal efficiency (93.03 ± 0.66%) was TiO2-coated glass under UVC irradiation. The recycling ability of TiO2-coated glass sheet was also evaluated. It was found that TiO2-coated glass sheet provided the same efficiencies for 20 cycles. In addition, the actual wastewater from textile industry was tested in this study with different pH values (i.e. pH = 3e11). The maximum color removal obtained was 87.86 ± 0.23% at pH value 11 on TiO2-coated glass under UVC irradiation. The color removal was found to decrease with decreasing pH.
关键词： Photocatalysis,Color removal,Wastewater treatment,Titanium dioxide,Dye wastewater
更新于2025-09-23 15:23:52
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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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Pulsed light for a cleaner dyeing industry: Azo dye degradation by an advanced oxidation process driven by pulsed light
摘要： Water pollution by wastewater containing dyes is an environmental issue that can be mitigated by the use of advanced oxidation processes (AOP). Pulsed light (PL) is an emerging food processing technology that uses eco-friendly lamps and can potentially be adapted as light source of an UV-based AOP. In the present work, a PL/H2O2 process was tested for the decolourization of two azo dyes, and a pulsed light/H2O2/ferrioxalate process was tested for the decolourization of one azo dye. The efficiency of the PL/H2O2 process in a batch reactor under different parametric values: dye concentration, pH, H2O2 and salt doses was followed by spectrophotometry and fitted to first-order kinetics; and several degradation products were detected. In the PL/H2O2 process, decolourization rates increased at low dye concentrations and high H2O2 doses, were pH-dependent and were inhibited by the addition of NaCl, Na2SO3 or Na2CO3. More than 50 % decolouration was achieved with the PL/H2O2 process for both dyes after applying 54 J/cm2 (25 light pulses). The PL/H2O2/ferrioxalate process achieved > 95 % decolouration for Methyl orange when applying 21 J/cm2 (10 pulses); that level of energy can be supplied by PL commercial systems in nine and four seconds respectively. No known toxic degradation products were detected. Results show that a PL/H2O2 process has potential to be used for the efficient degradation of dyes from wastewater. Furthermore, the efficacy of this process can be improved by the use of ferrioxalate. PL technology could become an alternative light source to contribute to decrease the environmental impact of wastewater produced by the dyeing industry.
关键词： pulsed light,ferrioxalate,advanced oxidation process,azo dye,wastewater remediation
更新于2025-09-19 17:15:36
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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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Applying facilely synthesized CuO/CeO <sub/>2</sub> photocatalyst to accelerate methylene blue degradation in hypersaline wastewater
摘要： Textile and dye effluents have strong color, unstable pH and COD, a lot of inorganic salt, and high biotoxicity. It is difficult and inefficient to remove dyes from high‐saline wastewater by traditional methods. In this study, a simple synthetic CuO/CeO2 photocatalyst is used to achieve high efficiency photodegradation of methylene blue in high salt wastewater. The p‐type CuO/n‐type CeO2 heterojunction photocatalyst is synthesized by a modified hydrothermal‐calcination method. The XRD and XPS reveal the successful synthesis of CuO/CeO2 composite. The SEM and TEM images show that the sample consists of large amounts of well‐dispersed CuO nanosphere loading on the CeO2 layers. DRS exhibits the absorption band (about 510 nm) and the band gap energy (2.43 eV) of the CuO/CeO2 composite. Compared with pure CuO, CeO2, and TiO2 (P25), the prepared CuO/CeO2 can increase the mineralization rate of MB by 18.19%~33.74%. More than 80% of MB can be effectively removed in the wastewater containing 5~80 g/L NaCl with a wide pH value range of 2.11~9.02, and the degradation processes follow the pseudofirst‐order reaction kinetics. Active species trapping experiments confirm that the degradation of methylene blue is mainly attributed to hydroxyl radical; besides, O2?? and hole (h+) also play important roles. Chlorine ions have dual effects in photocatalytic reactions. This work could provide a new approach to construct new heterojunction photocatalysts and a deeper insight for the treatment of hypersaline dye wastewater.
关键词： methylene blue,dye wastewater,hypersaline,UV/H2O2,CuO/CeO2,photocatalysis
更新于2025-09-10 09:29:36