Photocatalytic Oxidation Process Research Articles

Enhanced Photodegradation of Congo Red Using RSM‐Optimized TiO₂ on Borassus flabellifer Male Inflorescence Biochar

AbstractThis study explores the use of biochar, derived from Borassus flabellifer male inflorescence biomass as an alternative support for titanium dioxide (TiO2) to enhance its photocatalytic activity in degrading Congo red (CR) dye pollutant. The biochar was synthesized through controlled pyrolysis and subsequently combined with TiO2 to form a nanocomposite via hydrothermal method. The primary goal of creating this nanocomposite is to breakdown azo dyes, such as CR, using UV irradiation. Comprehensive characterization techniques, including XRD, FTIR, SEM coupled with EDAX, XPS, and UV‐DRS confirmed the successful integration of biochar with TiO2. The enhanced photocatalyst performance is attributed to the increased surface area, improved light absorption, and efficient charge separation facilitated by the biochar support. Furthermore, the experimental parameters were optimized using the response surface methodology (RSM). These studies demonstrated that the CR concentration, contact duration, pH, and photocatalyst quantity are critical factors in the photocatalytic oxidation process. The strong correlation coefficient for the first order model indicated that the data described by the RSM, agreed with the obtained results. This study highlights the potential of agricultural waste‐derived biochar as a cost‐effective and sustainable support for TiO₂, offering a viable solution for the remediation of dye‐contaminated water.

Decolorization of Acid Red 337 dye with hydroxyl and sulfate radical based advanced oxidation processes using different iron Catalyst: An experimental and statistical Investigation

The removal efficiencies of Acid Red 337 dye were investigated by combining advanced oxidation processes based on OH and SO4− radicals. The photocatalytic oxidation processes were carried out at the natural pH (5.4) and acidic pH (3.0) values of the dye solution. In the experiments, iron (II) sulfate (Fe2+) and potassium ferrioxalate (FeOx) were used as catalysts, hydrogen peroxide (H2O2) and peroxymonosulfate (PMS) were used as oxidants to compare dye removal efficiency and to determine the optimum doses. This comparison provided the opportunity to identify suitable catalysts and oxidants for dye removal. Furthermore, time-based comparisons were conducted from 2 to 10 min using the optimum catalyst doses. It was obtained that PMS was more effective as an oxidant in the presence of both iron catalysts for colour removal. The colour removal efficiency of 98.2 % was achieved in the PMS/Fe2+/UV process with doses of 1 mM PMS and 0.1 mM Fe2+ at pH 5.4 and an irradiation time of 10 min. In experiments using light-sensitive ferrioxalate (FeOx), colour removal was achieved in the PMS/FeOx/UV process with an efficiency of 97.8 %. Additionally, an artificial neural networks (ANNs) model effectively optimized the oxidation parameters, with predicted values closely matching the experimental data. The ANNs model yielded excellent statistical performance, with a root mean square error (RMSE) of 0.0317, 0.0223 and coefficient of determination (R2) of 0.9690 and 0.9854 for UV/Fe2+/H2O2-UV/FeOx/H2O2 and UV/Fe2+/PMS-UV/FeOx/PMS oxidation systems respectively.

Degradation of Nile Blue by Photocatalytic, Ultrasonic, Fenton, and Fenton-like Oxidation Processes

The aim of this study is to investigate new catalytic systems for the degradation of a dye that has been classified as first-degree toxic pollutant. Advanced oxidation process such as photocatalytic oxidation, ultrasonic oxidation, Fenton, and Fenton-like constitute a promising technology for the treatment of wastewater containing organic compounds. Waste effluents from textile industries are a major source of water pollution. These wastewaters contain dyes, which have high toxicity and low biodegradability. In this study, degradation of Nile Blue (NB), an azo dye, was studied using the photocatalytic oxidation (TiO2 and silver-loaded TiO2 (Ag-TiO2) as catalyst), ultrasonic oxidation, Fenton (Fe(II)/H2O2), and Fenton-like (Cu(II)/H2O2, V(IV)/H2O2) processes. It was found that the photocatalytic degradation of NB increased with decreasing pH, and the degradation rate also increased in the presence of TiO2/UV compared to UV irradiation alone. In addition, Ag loading on TiO2 dramatically reduced the degradation time. The ultrasonic degradation of NB was also studied using different initial dye concentrations at different pH values and amplitudes. Concentrations of Fe(II), Cu(II), V(IV) and H2O2 on degradation ratio were investigated. It is found that Fe(II) ion is more effective than Cu(II) and V(IV) ions in the degradation of NB.

Fluoropyridine modulated local charge distribution of carbon nitride to facilitate photocatalytic oxidative γ-valerolactone production

Synthesis of γ-valerolactone (GVL) from renewable biomass resources under mild reaction condition with metal-free catalysis is attractive but challenging. Herein, a novel porous fluoropyridine-incorporated carbon nitride (FPCN) was constructed and applied for photocatalytic oxidation of biomass-based 5-methyltetrahydrofurfural alcohol (5-MTHFA) to GVL. The catalyst exhibits excellent photocatalytic activity (93% 5-MTHFA conversion), with an 81% GVL yield, which is significantly higher than that of pyridine-incorporated carbon nitride and pure g-C3N4. Catalyst characterization and density functional theory (DFT) calculations showed that the porous structure of FPCN provides more exposed active sites for catalytic reaction, and the incorporated fluoropyridine rings effectively modulate the localization of electron cloud density, resulting in an enhanced photogenarated carrier separation efficiency and adsorption capacity for 5-MTHFA. Mechanistic studies reveal that photocatalytic oxidation process of 5-MTHFA mainly involves hydroxyl group oxidation and decarboxylation. This work provides new insight into designing carbon nitride-based photocatalysts for the efficient selective oxidation of renewable biomass to produce fine chemicals.

Enhancing degradation of novel brominated flame retardants by sulfate modified C3N4: Synergistic effect of photocatalytic oxidation and reduction processes

Novel brominated flame retardants (NBFRs) pose serious risks to aquatic organisms and human health due to their persistence and toxicity. Herein, sulfate ions (SO42-) decorated C3N4 (SO42-@CN) photocatalyst material was synthesized for the rapid degradation of NBFRs by a synergistic effect of photocatalytic oxidation and reduction reactions. Compared with bare C3N4, the SO42-@CN exhibited efficient photocatalytic NBFRs removal performance. The degradation rates constant of hexabromobenzene and pentabromotoluene by SO42-@CN were 0.177 and 0.0906 min-1, respectively, which were 2.9 and 6.7 times higher than that by C3N4. It was confirmed that SO42-@CN could generate more active substances (such as sulfate radicals, and hydroxyl radicals) and promote the oxidation of NBFRs. Meanwhile, SO42- accelerated the separation of photogenerated electron-holes by promoting the formation of hydrogenated structures, allowing more photogenerated electrons to participate in the debromination reduction process. This work provides a new insight for the practical application of visible light driven photocatalytic technology in NBFRs residues degradation.

Rational modulation of covalent organic frameworks heterogeneous catalyst: Structural cationization effect on accelerating photocatalytic oxidation process

Photocatalytic technology has been playing a key role in energy conversion and environmental remediation. It is critical and challenging that understanding and modulating the local structure effect on accelerating each rate-dependent step during the photocatalytic process. Herein, we utilize the highly ordered and structurally tunable COFs as a favorable platform for integrating multiple modulations of photochemical properties, including light capture, exciton dissociation, charge separation, and mass transfer by structural cationization strategy. Moreover, it is found that the cationized COF has a strong enrichment ability on the sulfide substrates, exhibiting an extremely fast selective oxidation rate of sulfides even in air. The calculation results indicate that the structural cationization successfully aggregates reaction substrates and increases the molecular collision probability, generating a reaction environment to promote the photocatalytic performances. This study will be expected to facilitate the new insights for the exploration of highly active COFs heterogeneous photocatalysts.

A way to macroporous and alveolar geopolymer foams elaboration: Influence of operating parameters on porosity characteristics

Alveolar cellular foams are widely used in a wide range of applications, from aeronautics and filtration systems to chemical and transformation processes. Their porous characteristics make them a prime candidate for reactions, radiative transfer and flow. Geopolymeric foams, which have their origins in civil engineering, are materials with promising potential in terms of mechanical, thermal and acoustic resistance. As they are mainly used in civil engineering, the structures currently being developed are mainly closed-pore matrices. However, if they are to invert the field of photocatalytic oxidation processes, solar collectors or concentrated solar power plants, the supports need to develop a high exchange surface area. Metal alveolar foams have been identified as ideal but very costly supports. Geopolymeric foams could meet these requirements, but their surface areas are currently too limited for photoreactors. In this study, it is proposed to develop and optimize the operating conditions for geopolymer foam synthesis in order to impart macroporous properties and an interconnected alveolar structure. Based on two well-established synthesis methods (direct foaming and replication), operating conditions such as foaming agent and surfactant content, and drying and calcination conditions, are studied. Geopolymer foams are produced with different macroporous characteristics. We aim to define the synthesis conditions required to produce interconnected macroporous alveolar foams with milimetric pores. In civil engineering, these materials have the advantage of being easy to design, use and shape according to the application.

Hollow TiO2/Bi2MoO6 Janus-nanofibers for photo-reforming of antibiotics into carbon monoxide

Photo-reforming is an environmentally friendly technology for converting organic wastewater into carbon monoxide (CO), a potential energy source and an important industrial material. Achieving efficient photo-reforming of CO production remains a challenge due to the limitation on fast photogenerated carrier recombination. Here, the TiO2/Bi2MoO6 hetero-nanofibers are well-designed to possess unique Janus interface and ingenious hollow structure. The photo-deposition experiments demonstrated that the Janus binary interface can realize the directional migration of interfacial charges and the spatial separation of redox sites. Moreover, the hollow framework allows full exposure of the bicomponent to reactants and provides excellent optical absorption through multiple light scattering inside the tube, as evidenced by theoretical simulations via COMSOL Multiphysics. The photo-reforming yield of CO from 6000 ppm tetracycline hydrochloride (TCH) solution reaches 2.69 μmol∙g−1∙h−1 (corresponding degradation rate of 44.55 % after 5 h), about 1.44-fold superior to that of the TiO2/Bi2MoO6 core-shell hetero-nanofibers. 13C isotope tracing experiments showed that the efficiency of CO production in the photocatalytic TCH oxidation process is superior to that in carbon dioxide reduction process. Furthermore, when oxygen was introduced into the photocatalytic system, the photo-reforming CO yield from the TCH solution was significantly increased to 60.45 μmol∙g−1∙h−1, which was 22.47 and 5.12 times higher than in carbon dioxide and air atmosphere, respectively. This work provides a promising interfacial engineering to design efficient photo-reforming catalysts for energy production and environmental remediation.

Efficient photocatalytic water decontamination over a wide pH range by C and O co-doped carbon nitride with tunable band structure

The metal-free, non-toxic, and highly tunable structure of carbon nitride confers unique advantages in photocatalytic advanced oxidation processes. Regulating the generation of radical and non-radical species during photocatalysis to maintain high degradation efficiency across different water matrices is of great practical significance for the application of carbon nitride. In this study, a C and O co-doped modified carbon nitride (UCN) with a high specific surface area was developed for efficient photodegradation of p-chlorophenol (p-Cl) without exogenous oxidants. Characterizations demonstrated that UCN in higher specific surface area exposed more active sites. Additionally, with rising doping levels, UCN exhibited enhanced light absorption capability and a narrower bandgap, which favored the separation of photogenerated electron-hole pairs. The primary active species were identified as holes, accompanied by the generation of superoxide radicals (·O2–) and singlet oxygen (1O2) depending on the pH value. Under acidic conditions, 1O2 was predominantly generated, whereas ·O2– dominated under alkaline conditions. As a result, the removal efficiency of p-Cl was enhanced under both strongly acidic and alkaline conditions. The pseudo-first-order rate constants for p-Cl removal at pH 3, 7, and 11 were 0.0558, 0.0354, and 0.0443 min−1, respectively. Moreover, combining DFT calculations and LC-MS data, analysis on the intermediate products of p-Cl degradation revealed unique characteristics at different pH values, further proving the flexible tunability and providing insights into the practical application of modified carbon nitride.

Z-Scheme g-C3N4-Au-MoO3-x heterojunction for boosted photocatalytic H2O2 production and enhanced selective oxidation of cyclohexane

Rational design of Z-Scheme photocatalyst with outstanding charge separation and robust redox capabilities for photocatalytic H2O2 generation and cyclohexane oxidation under mild conditions still poses a significant hurdle. In response to this challenge, ternary g-C3N4-Au-MoO3-x composite catalyst was developed though combining in-situ reduced MoO3-x-Au composite and exfoliated g-C3N4 nanosheets using an ultrasonic liquid-phase approach. In addition, variations in the synthesis procedures led to the preparation of g-C3N4−MoO3-x, g-C3N4-Au, and Au-g-C3N4−MoO3-x composites, aimed at exploring their effectiveness in both H2O2 production and catalyzing cyclohexane oxidation. Notably, the g-C3N4-Au-MoO3-x composite exhibited an impressive optical rate of H2O2 generation at 723.18 µmol·L−1·h−1, achieving a 11.94-fold enhancement compared to Au-g-C3N4−MoO3-x. Meanwhile, the conversion rate of cyclohexane reached 11.59 %, with a high selectivity of 97.43 % towards KA oil (cyclohexanol and cyclohexanone), and a KA oil production rate of 1166.86 µmol·L−1·g−1. Through analyzing the photoelectrochemical properties and band energy structures, it has been established that the involvement of an Au mediator was essential and vital for the Z-Scheme electron transfer in g-C3N4-Au-MoO3-x. The incorporation of a Z-scheme heterojunction has resulted in increased light absorption, reduced charge recombination rates, and a substantial elevation in the levels of ·O2− and ·OH radicals, leading to a significant enhancement in photocatalytic efficiency for both H2O2 generation and cyclohexane oxidation. This study opens the door to on-site immediate production of hydrogen peroxide to boost the oxidation efficiency in the photocatalytic cyclohexane oxidation process.

Recent Developments in Nickel-Based Layered Double Hydroxides for Photo(-/)electrocatalytic Water Oxidation.

Layered double hydroxides (LDHs), especially those containing nickel (Ni), are increasingly recognized for their potential in photo(-/)electrocatalytic water oxidation due to the abundant availability of Ni, their corrosion resistance, and their minimal toxicity. This review provides a comprehensive examination of Ni-based LDHs in electrocatalytic (EC), photocatalytic (PC), and photoelectrocatalytic (PEC) water oxidation processes. The review delves into the operational principles, highlighting similarities and distinctions as well as the benefits and limitations associated with each method of water oxidation. It includes a detailed discussion on the synthesis of monolayer, ultrathin, and bulk Ni-based LDHs, focusing on the merits and drawbacks inherent to each synthesis approach. Regarding the EC oxygen evolution reaction (OER), strategies to improve catalytic performance and insights into the structural evolution of Ni-based LDHs during the electrocatalytic process are summarized. Furthermore, the review extensively covers the advancements in Ni-based LDHs for PEC OER, including an analysis of semiconductors paired with Ni-based LDHs to form photoanodes, with a focus on their enhanced activity, stability, and underlying mechanisms facilitated by LDHs. The review concludes by addressing the challenges and prospects in the development of innovative Ni-based LDH catalysts for practical applications. The comprehensive insights provided in this paper will not only stimulate further research but also engage the scientific community, thus driving the field of photo(-/)electrocatalytic water oxidation forward.

Economics of enhanced methane oxidation relative to carbon dioxide removal

Mitigating short-term global warming is imperative, and a key strategy involves reducing atmospheric methane (CH4) due to its high radiative forcing and short lifespan. This objective can be achieved through methods such as oxidising methane at its source or implementing enhanced oxidation techniques to reduce atmospheric CH4 concentrations. In this study, we use a range of metrics to analyse both the impact and value of enhanced CH4 oxidation relative to carbon dioxide (CO2) removal on global temperature. We apply these metrics to a select group of model studies of thermal-catalytic, photocatalytic, biological and capture-based oxidation processes under different greenhouse gas (GHG) concentrations. Using a target cost of €220-1000/tCO2 for CO2 removal, our findings indicate that metrics valuing enhanced oxidation techniques based on their contribution to mitigating the long-term level of warming show these techniques are uncompetitive with CO2 removal. However, when using metrics that value enhanced oxidation of CH4 based on its impact on the immediate rate of warming, photocatalytic methods may be competitive with CO2 removal, whereas biofiltration, thermal-catalytic oxidation and capture-based units remain uncompetitive. We conclude that if the policy goal is to target the immediate rate of warming, it may be more valuable to incentivise CO2 removal and enhanced oxidation of methane under separate GHG targets.

Semiconductor Catalyst: Investigation for the Degradation of BB9 Azo Dye by Sonophotocatalytic Process

AbstractThe degradability of an azo dye, Basic Blue 9 (BB9), by heterogeneous sonocatalytic, photocatalytic, and sonophotocatalytic oxidation process was examined using simultaneous irradiation of UV‐C at 254 nm and power ultrasound at 20 kHz accompanied with a heterogeneous catalyst zinc oxide (ZnO) in the study. The effect of ZnO dose and initial dye concentration was investigated on the dye degradation in sonocatalytic, photocatalytic, and sonophotocatalytic processes at pH 5.5 (natural pH). The results obtained from the experimental studies were evaluated with the parameters of color removal, pseudo‐first‐order rate constant, and half‐life time. It was observed that the degradation of BB9 dye by the sonophotocatalytic process was higher compared to both sonocatalytic and photocatalytic degradation. as follows: 97.46, 48.64 and 56.88 %. The combination of sono and photocatalytic showed a remarkable synergistic effect in BB9 degradation. The kinetics of sonophotocatalytic oxidations, depending on the initial BB9 dye concentration, were found to follow the Langmuir‐Hinshelwood model. In addition, the effect of ZnO on the sonophotocatalytic oxidation process was higher compared to titanium dioxide and zero‐valent iron as follows: 97.47, 80.77 and 80.62 %.

Cyclodextrin-boosted photocatalytic oxidation for efficient bisphenol A removal

Wastewater contains various high-risk trace organic pollutants, such as antibiotics and endocrine disruptors, which seriously restrict wastewater reuse. Cyclodextrin-based functional materials show great potential in the removal of trace pollutants because of their adsorption catalytic synergy. Clarifying the synergistic mechanism of cyclodextrin in oxidation is the key issue in confined catalytic oxidation process design. In this work, we fabricated a BiOIO3@BiOBr/β-CD heterojunction photocatalyst to study the synergistic mechanism of cyclodextrin in the photocatalytic oxidation process. The synergistic mechanism of cyclodextrin was investigated by combining radical chemistry, electrochemistry, spectroscopy, and time-dependent density functional theory. Results showed that the excited intermediate free radicals played an important role in promoting the photocatalytic degradation process. The heterojunction photocatalyst loaded with β-cyclodextrin (β-CD) at the electronic end (C[Cat.] = 0.2 mg/mL) removed about 97% of bisphenol A (BPA) within 30 min, and the first-order kinetic constant (kCDBIB = 0.112 min−1) was about twice that of the unloaded β-CD (kBIB = 0.057 min−1). Cyclodextrin loading improved the photocatalytic performance of the heterojunction and stimulated the intermediate to increase the free radical yield and regulate the reaction path.

Development of Fe/HNT and Fe/HNT-Al2O3 composite catalysts and application in successive treatment processes for pharmaceutical industry wastewater

The pharmaceutical industry wastewater (PIW) was treated by successive use of electro Fenton (EF) and photocatalytic oxidation (PcO) processes. Nano-particular powdered Fe/HNT (Iron/Halloysite nanotube) heterogeneous semiconductor catalyst was initially produced with Fe(OH)3 sludge modification precipitated after EF process. Thus, photocatalyst material was produced from the waste sludge and used in the PcO process. Photocatalyst Fe/HNT powder was immobilized on a three-dimensional (3D) reticulated Al2O3 ceramic support to enable rapid recovery of the catalyst from the PcO reactor system. Particle morphology and chemical configuration of the heterogeneous catalysts were analyzed with SEM (Scanning Electron Microscopy)-EDS (Energy-Dispersive X-ray spectrometry), UV-DRS (Ultraviolet Diffuse Reflectance Spectra) and XRD (X-ray diffraction). The Fe/HNT layer was calcined at three different temperatures (350, 450 and 600 °C). The optimum temperature was determined as 350 °C for better photocatalytic performance and practical reasons such as energy consumption. The successive use of EF + PcO processes for degradation of three different PIW samples was investigated by using two catalyst forms (nanoparticle and reticulated) and light sources (visible and sun light). The max TOC removal efficiency by EF + sun light-PcO (with Fe/HNT) successive treatment process was obtained as 78.4 %. Besides, the energy consumption value was calculated for optimum process state and calculated as 48.8 kWh/kg TOC at the EF + sun light-PcO (with Fe/HNT) successive treatment process.

Engineering bifunctional sites in covalent polymers for boosting photocatalytic H2S oxidation

The development of catalyst for photocatalytic hydrogen sulfide (H2S) oxidation with excellent efficiency and regeneration properties is a significant challenge. Herein, the pyridine units as bifunctional sites are incorporated in covalent polymers (CPs) by CN coupling reaction, which exhibit photocatalytic H2S selective oxidation to sulfur conversion (95 %) under visible light in a continuous flow system, more than twice that of the pristine sample (40 %). Meanwhile, the photocatalytic H2S conversion rate had a linear function relationship with pyridinic N content, demonstrating the substantial role of pyridine in photocatalytic H2S oxidation process. According to experimental results, the pyridine unit not only acted as the structural base site to improve the H2S chemisorption, but also served as electron withdrawing unit to construct electron donor-acceptor (D-A) structure with benzene, which optimized the light absorption, charge separation and migration. In addition, series in-situ measurements and electron density difference simulations revealed the significant role of electron D-A structure in H2S adsorption and activation process. By exploring the effect of pyridine unit in CPs on H2S conversion process, this work provides a new idea for the subsequent study of photocatalytic H2S oxidation.

Solvothermal synthesis of Bi12TiO20/Bi4Ti3O12 heterostructure with highly efficient photodegradation of MO under UV irradiation

The sillenite-structured bismuth titanate (Bi12TiO20) is thought to be a viable photocatalyst for environmental remediation. However, the performance of Bi12TiO20 as a photocatalyst is severely constrained by its limited range of light sensitivity and the rapid photoinduced electron-hole pair recombination. A practical and effective way to overcome these limitations is to combine Bi12TiO20 with adequate photocatalysts to create heterojunctions. Here, a one-step solvothermal technique is used to synthesize Bi12TiO20/Bi4Ti3O12 heterojunction (BTO). The electric field that exists between B12TiO20, Bi4Ti3O12 and the closed interfacial contacts had a synergistic effect on the constructed composites, which resulted in high charge transfer abilities. Therefore, the BTO heterojunction demonstrated increased photocatalytic efficacy in the presence of ultraviolet irradiation. The MO removal efficiency of optimal BTO was 97.15%, significantly higher than that of pure Bi2O3 (46.9%). Furthermore, the cycling experiment demonstrated that the BTO heterojunction is stable and reusable. The probable mechanism of photocatalytic MO oxidation over BTO heterojunction was studied by various scavengers. The •OH radicals and holes played essential roles in BTO system of photocatalytic oxidation process.

Low concentration of peroxymonosulfate coupled with visible light triggers oxygen reactive species generation over constructed Bi25FeO40/BiOCl Z-scheme heterojunction for various tetracycline antibiotics removal

Photocatalytic peroxymonosulfate (PMS) oxidation systems demonstrate significant potential and promising prospects through the interconnection of photocatalytic and PMS oxidation for simultaneously achieving efficient pollutant removal and reduction of PMS dosage, which prevents resource wastage and secondary pollution. In this study, a Z-scheme Bi25FeO40/BiOCl (BOFC) heterojunction was constructed to carry out the photocatalytic PMS oxidation process for tetracyclines (TCs) pollutants at low PMS concentrations (0.08 mM). The photocatalytic PMS oxidation rate of Bi25FeO40/BiOCl composites for tetracycline hydrochloride (TCH), chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DXC) reaches 86.6%, 83.6%, 86.7%, and 88.0% within 120 min. Simultaneously, the BOFC/PMS system under visible light (Vis) equally displayed the practical application prospects for the solo and mixed simulated TCs antibiotics wastewater. Based on the electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) valence band spectrum, a Z-scheme electron migration pathway was proposed to elucidate the mechanism underlying the performance enhancement of BOFC composites. Bi25FeO40 in BOFC composites can serve as active site for activating PMS by the formation of Fe3+/Fe2+ cycle. Toxicity estimation software tool (T.E.S.T.) and mung beans planting experiment demonstrates that BOFC/PMS/Vis system can reduce toxicity of TCs wastewater. Therefore, BOFC/PMS/Vis system achieves efficient examination in different water environments and efficient utilization of PMS, which displays a scientific reference for achieving environmentally-friendly and resource-saving handling processes.

Photocatalytic Oxidation Process for Petroleum Wastewater Treatment and The Possibility of Using Tapered Bubble Column (TBC): A Review

<p>The photocatalytic oxidation of organic and petroleum wastewater treatment is an advanced oxidation process (AOP) with several benefits. It operates at normal temperatures and pressure, is inexpensive, does not produce secondary waste, and us easily accessible. Many studies have employed bubble columns, slurry bubble columns, and three-phase fluidized reactors in the photocatalytic process for wastewater treatment. Pure TiO2 and Fe-doped TiO2 are considered the most promising catalysts. The aim of this work was to review the literature on the photocatalytic process for organic pollutants and petroleum wastewater (produced water) treatment, with a special focus on pure TiO2 and Fe-doped TiO2 as well as to study the possibility of using a tapered bubble column reactor for this treatment. A circulating upflow tapered bubble column reactor with a light lamp at the center facilitates the separation of the gas-liquid-solid phases with no dead zone in the photocatalytic process.</p>

Cu2O/WO3 S-scheme heterojunctions for photocatalytic degradation of levofloxacin based on coordination activation

Heterogeneous photocatalytic degradation of antibiotic involves the activation of antibiotic molecules and the photocatalytic oxidation process. However, the simultaneous improvement of these processes is still a challenge. Herein, S-scheme heterojunctions consisted of Cu2O nanocluster with defective WO3 nanosheets were constructed for efficient photocatalytic degradation of levofloxacin (LVX). The typical CNS-5 composite (5 wt% Cu2O/WO3) achieves an optimal LVX degradation efficiency of 97.9% within 80 min. The spatial charge separation and enhancement of redox capacity were realized by the formation of S-scheme heterojunction between Cu2O and WO3. Moreover, their interfacial interaction would lead to the loss of lattice oxygen and the generation of W5+ sites. It is witnessed that the C–N of piperazine ring and CO of carboxylic acid in LVX are coordinated with W5+ sites to build the electronic bridge to activate LVX, greatly promoting the further degradation. This work highlights the important role of selective coordination activation cooperated with S-type heterojunctions for the photocatalytic degradation and offers a new view to understand the degradation of antibiotics at molecular level.