Wastewater Treatment Techniques Research Articles

Construction of piezoelectric fenton-like system over BaTiO3/α-FeOOH for highly efficient degradation of demethylchlortetracycline

Heterogeneous Fenton-like system is a promising technique for wastewater treatment, while Fe2+ regeneration limits its degradation efficiency. Piezoelectric materials can produce free electrons under mechanical stress. Based on this, a piezoelectric Fenton-like system coupling piezoelectric effect and Fenton-like reaction was proposed. Composite material BaTiO3/α-FeOOH was synthesized by sol–gel and hydrothermal method. Under ultrasonic vibration BaTiO3 continuously generated free electrons, which reduced Fe3+ to Fe2+ and realized Fe3+/Fe2+ cycle. The piezoelectric Fenton-like system based on BaTiO3/α-FeOOH was used to remove demethylchlortetracycline (DMCT) from water. The degradation ratio of DMCT can reach 100 % within 5 min, and the coupled system exhibited excellent adaptability and stability. Free radical capture and quantitative detection determined that •OH and •O2− were the main active oxygen species. A comprehensive catalytic mechanism was proposed and supported by energy band structure analysis, finite element method simulation, and Density Functional Theory (DFT) simulation calculations. The piezoelectric electrons generated by BaTiO3 were transfered to α-FeOOH to improve the Fe3+/Fe2+ cycle. In addition, the possible degradation mechanism of DMCT was proposed through Ultra Pressure Liquid Chromatography-Mass Spectrometry (UPLC-MS) measurement and DFT calculation, and the overall pollution toxicity of DMCT was assessed according to toxicity prediction. Overall, this work provided a new insight on coupling effect between piezoelectric effect and Fenton-like reaction.

Sustainable Wastewater Treatment: Recent Progress in the use of Bio-Waste-Derived Adsorbents for Organic Dye Removal

There are serious health and environmental hazards associated with the growing amount of organic dyes in wastewater from sectors like food processing, leather, and textiles. These pollutants are frequently ineffectively removed by traditional wastewater treatment techniques. Adsorbents made from bio-waste have become a viable substitute because of their high removal efficiency, affordability, and sustainability. The adsorption of organic dyes is facilitated by the distinct surface chemistries of these adsorbents, which are made from a variety of biomass sources. Through synthesis and modification approaches, recent research has concentrated on enhancing these materials' adsorption capacity, selectivity, and overall performance. Adsorbents made from bio-waste have potential uses in pollutant degradation, nutrient recovery, and value addition in addition to dye removal. But issues like leaching and long-term stability need to be carefully thought out. This review highlights the recent advancements in the application of bio-waste-derived adsorbents for organic dye removal from wastewater, emphasizing their potential contributions to sustainable wastewater treatment and resource recovery.

Enhanced solar interfacial evaporation through lignin-polyaniline composite coatings on Balsa wood substrates

Solar interfacial evaporation employing wood-derived substrates is increasingly acknowledged as a viable desalination and wastewater treatment technique. This study presents an optimized method that enhances the efficiency of solar interfacial evaporation by applying a coating of lignin-polyaniline composites (EHL-PANI) onto balsa wood substrates. Initial assessments involved comparing evaporators made from various kinds of wood, identifying balsa wood-based photothermal evaporators as the most effective, with an evaporation rate of 1.63 kg·m−2·h−1 and an efficiency of 72.7 %. Photothermal properties were further improved through the chemical oxidation of enzymatic hydrolysis lignin (EHL) with polyaniline, producing a composite with notably high dispersion stability and uniform particle distribution. This modification resulted in reduced particle size and enhanced stability of the polyaniline, which is crucial for boosting photothermal activity. Additionally, the EHL-PANI composites demonstrated exceptional light absorption, exceeding 95 %, and significant photothermal conversion efficiency across a broad wavelength range, attributable to polyaniline's broadband light absorption characteristics. A prototype evaporator, featuring the EHL-PANI coated on a balsa wood substrate, was constructed to assess performance, achieving a water evaporation rate of 2.10 kg·m−2·h−1 and an efficiency of 80.7 % under solar illumination of 1 kW·m−2.

Constructed Wetland as a Low-Energy Technique for Wastewater Treatment – Seasonal Impact, Performance and Phytomanagement

Constructed Wetland as a Low-Energy Technique for Wastewater Treatment – Seasonal Impact, Performance and Phytomanagement

Cost-Effective Synthesis of MXene Cadmium Sulfide (CdS) for Heavy Metal Removal.

Background Environmental contamination resulting from the release of untreated industrial wastewater has emerged as a critical worldwide issue. These effluents frequently have high levels of heavy metals and antibiotics, which are bad for aquatic ecosystems and human health. Oftentimes, conventional wastewater treatment techniques fall short of effectively eliminating these pollutants. Innovative materials that may efficiently absorb or break down contaminants from contaminated water sources are, therefore, desperately needed. Hydrothermally produced MXene cadmium sulfide (CdS) composites have shown great promise as an adsorbent material because of their special qualities, which include high surface area, chemical stability, and customizable surface functions that improve their adsorption capacity for heavy metals and antibiotics alike. Aim The aim of this study is to produce MXene-CdS nanoparticles in a cost-effective method for the simultaneous removal of heavy metals from aqueous contaminants for water pollution control. Methods and materials MXenes were synthesized by selectively etching Ti3AlC2 MAX-phase ceramics using aqueous HF. CdS nanoparticles were synthesized separately and integrated with MXenes via a hydrothermal process. The resulting MXene CdS nanocomposites were characterized using scanning electron microscopy (SEM) for morphology, energy dispersion spectrum (EDS) for elemental composition, X-ray diffraction(XRD) study for phase identification, and removal of heavy metals viaMXene CdS. Results Consistent distribution of CdS nanoparticles on the MXene surface and the creation of MXene CdS nanomembranes with a well-defined shape were observed by SEM analysis. Ti, C, Cd, and S elements, indiciaries of a successful composite formation, were confirmed to be present by EDS. The crystalline structure of both the MXene and CdS phases was confirmed by the distinctive peaks seen in the XRD patterns. MXene-CdS composites facilitate the effective removal of chromium ions from contaminated water. The excellent hydrophilicity of the produced nanomembrane allowed for effective interaction with watery contaminants. Conclusion This study showcases the successful synthesis and characterization of MXene-CdS nanocomposites for environmental remediation, particularly in removing toxic metals like chromium from industrial effluents. SEM analysis confirmed the uniform distribution of CdS nanoparticles on the MXene surface, while elemental composition validated their integration. XRD analysis confirmed the crystalline structures of both components. The nanocomposite exhibited excellent hydrophilicity, enhancing the efficient adsorption of heavy metals. Its large surface area and chemical stability contribute to high adsorption efficiency, making it ideal for wastewater treatment. The scalable synthesis process supports practical applications. This research highlights MXene-CdS nanocomposites as a cost-effective, sustainable solution for water pollution control.

Comparing energy and exergy of multiple effect freeze desalination to MEE MSF RO

Freeze desalination is a promising technique for wastewater treatment and zero/minimum liquid discharge systems, often requiring multiple stages to produce potable water. This research focuses on developing a Multiple Effect Freeze Desalination (MEFD) system based on experimental data for Single-Stage Desalination Efficiency (SSDE) and Single-Stage Recovery Rate (SSRR). The study analyzes various MEFD setups, calculating cooling energy consumption and correlating it with electrical usage through the coefficient of performance (COP). Comparisons with Reverse Osmosis (RO), Multi Effect Evaporation (MEE), and Multi-Stage Flashing (MSF) suggest that MEFDs may face challenges in matching RO efficiency but can compete with MEE and MSF within specific operational ranges. Exergy assessments indicate difficulties against even 10-stage MSF systems. Achieving SSDE and SSRR levels above 65% enables MEFDs to rival 10-stage MSF plants in terms of energy efficiency, surpassing MEE and MSF at over 85% efficiency. Despite these challenges, MEFDs offer benefits for treating high salt concentrations and resisting corrosion.

An efficient, green, and magnetic recycling wastewater treatment technique enabled by ZnO/NiFe2O4/BiOBr 3D nanofibers photo-fenton process

A novel magnetic recycling ZnO/NiFe2O4/BiOBr 3D nanofibers photo-Fenton system was successfully prepared by parallel electrospinning combining with solvothermal method. ZnO/NiFe2O4 composite nanofibers was prepared via parallel electrospinning, then ZnO/NiFe2O4/BiOBr 3D nanofibers was obtained by solvothermal growth of BiOBr on electrospun ZnO/NiFe2O4 composite nanofibers. The composition, morphologies, structures and photocatalytic properties of ZnO/NiFe2O4/BiOBr 3D nanofibers were systematically tested and analyzed, and some meaningful results were obtained. The prepared ZnO/NiFe2O4/BiOBr 3D nanofibers, combined with H2O2, form a photo-Fenton system that exhibits excellent photocatalytic performance. When 0.05 mL of H2O2 is added to the photo-Fenton system, the degradation rate of organic dye Rhodamine B (RhB) reaches 99.61 % under light exposure for 10 min. Capture experiments and Electron Spin Resonance (ESR) measurements have confirmed that holes (h+) and hydroxyl radicals (·OH) are the primary active species that play a dominant role in the photocatalytic degradation of Rhodamine B (RhB). Furthermore, the ZnO/NiFe2O4/BiOBr 3D nanofibers have demonstrated exceptional photocatalytic degradation efficiency towards RhB, maintaining a degradation rate of over 95 % even after undergoing three recycling experiments. Significantly, this photo-Fenton system also has good magnetic properties, which can be separated from the treatment system under the applied magnetic field, avoiding secondary pollution of the treatment system, improving reuse rate and saving costs. This study provides valuable insights for the purposeful utilization of the photocatalytic materils.

Reviewing the Phenomenon of Antimicrobial Resistance in Hospital and Municipal Wastewaters: The Crisis, the Challenges and Mitigation Methods

Antibiotic resistance is a major crisis that the modern world is confronting. This review highlights the abundance of different types of antibiotic resistance genes (ARGs) in two major reservoirs in the environment, namely hospital and municipal wastewater, which is an unforeseen threat to human lives across the globe. The review helps understand the current state of affairs and the whereabouts on the dissemination of ARGs in both these environments. The various traditional wastewater treatment methods, such as chlorination and UV treatment, and modern methods, such as electrochemical oxidation, are discussed, and the gaps in these technologies are highlighted. The need for the development of newer techniques for wastewater treatment with enhanced efficiency is urgently underscored. Nanomaterial applications for ARG removal were observed to be less explored. This has been discussed, and prospective nanomaterials and nanocomposites for these applications are proposed.

Preparation of magnetite nanoparticles and their application in the removal of methylene blue dye from wastewater

Wastewater is discharged in large amounts from different industries; thus, wastewater treatment is currently one of the main concerns, advanced oxidation is a promising technique for wastewater treatment. This research aims to synthesize magnetite nanoparticles and study their application in wastewater treatment via adsorption and advanced oxidation processes. Magnetite nanoparticles were synthesized via coprecipitation technique between ferric and ferrous sulfate at a molar ratio of 2:1. The prepared sample was characterized using FTIR, XRD, TEM, BET surface area, zeta potential, VSM, and UV‒visible spectroscopy. XRD confirmed the formation of a single face-centered cubic (FCC) spinel structure of Fe3O4. TEM revealed an average particle size of 29.2 nm and a BET surface area of 70.1 m2 g−1. UV‒visible spectroscopy revealed that the UV–visible peak of the sample was obtained at 410 nm. VSM confirmed the attraction of the sample to a magnet with a magnetization of 60 (emu/g). The removal efficiency of methylene blue was studied using adsorption and advanced oxidation methods. For adsorption, the studied parameters were dye concentration 2–10 ppm, 3–10 pH, and 50:300 mg Fe3O4/L. For advanced oxidation, peroxide was used with nanomagnetite as a catalyst, and the studied parameters were pH 2–11, magnetite dose 20–200 PPM, and peroxide dose 500–2000 PPM. The removal efficiency by adsorption reached 95.11% by adding 50 mg of Fe3O4/L and 10 ppm dye conc at 6.5 pH; on the other hand, in advanced oxidation, it reached 98.5% by adding 110 PPM magnetite and 2000 ppm H2O2 at pH 11. The magnetite nanoparticles were reused for ten cycles of advanced oxidation, for a 10% reduction in removal efficiency at the tenth cycle.

A Review of the Dissemination of Antibiotic Resistance through Wastewater Treatment Plants: Current Situation in Sri Lanka and Future Perspectives.

The emergence of antibiotic resistance (AR) poses a significant threat to both public health and aquatic ecosystems. Wastewater treatment plants (WWTPs) have been identified as potential hotspots for disseminating AR in the environment. However, only a limited number of studies have been conducted on AR dissemination through WWTPs in Sri Lanka. To address this knowledge gap in AR dissemination through WWTP operations in Sri Lanka, we critically examined the global situation of WWTPs as hotspots for transmitting antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) by evaluating more than a hundred peer-reviewed international publications and available national publications. Our findings discuss the current state of operating WWTPs in the country and highlight the research needed in controlling AR dissemination. The results revealed that the impact of different wastewater types, such as clinical, veterinary, domestic, and industrial, on the dissemination of AR has not been extensively studied in Sri Lanka; furthermore, the effectiveness of various wastewater treatment techniques in removing ARGs requires further investigation to improve the technologies. Furthermore, existing studies have not explored deeply enough the potential public health and ecological risks posed by AR dissemination through WWTPs.

Tracking SARS-CoV-2 and its variants in wastewater in Tunisia.

Wastewater-based genomic surveillance can improve community prevalence estimates and identify emerging variants of pathogens. Wastewater influents and treated effluents from six wastewater treatment plants (WWTPs) in Tunisia were analyzed between December 2021 and July 2022. Wastewater samples were analyzed with reverse transcription solid digital PCR (RT-sdPCR) and whole-genome sequencing to determine the amount of SARS-CoV-2 RNA and assign SARS-CoV-2 lineages. The virus variants detected in wastewater samples were compared with COVID-19 prevalence data. The quantitative results in wastewater influents revealed that viral RNA concentrations at the treatment plants corroborate with locally reported clinical cases and show an increase before the increment of clinically diagnosed new COVID-19 cases between April and July 2022. Delta and Omicron variants were identified in the Tunisian wastewater. Interestingly, the presence of variant BA.5 was detected in samples prior to its inclusion as a variant of concern (VOC) by the Tunisian National Health Authorities. SARS-CoV-2 was detected in wastewater effluents, indicating that the wastewater treatment techniques used in the majority of Tunisian WWTPs are inefficient in removing the virus traces. This study reports the first identification of SARS-CoV-2 VOCs in Tunisian wastewater samples.

Co-bioaugmentation with microalgae and probiotic bacteria: Sustainable solutions for upcycling of aquaculture wastewater and agricultural residues into microbial-rice bran complexes

Aquaculture farming generates a significant amount of wastewater, which has prompted the development of creative bioprocesses to improve wastewater treatment and bioresource recovery. One promising method of achieving these aims is to directly recycle pollutants into microbe-rice bran complexes, which is an economical and efficient technique for wastewater treatment that uses synergetic interactions between algae and bacteria. This study explores novel bioaugmentation as a promising strategy for efficiently forming microbial-rice bran complexes in unsterilized aquaculture wastewater enriched with agricultural residues (molasses and rice bran). Results found that rice bran serves a dual role, acting as both an alternative nutrient source and a biomass support for microalgae and bacteria. Co-bioaugmentation, involving the addition of probiotic bacteria (Bacillus syntrophic consortia) and microalgae consortiums (Tetradesmus dimorphus and Chlorella sp.) to an existing microbial community, led to a remarkable 5-fold increase in microbial-rice bran complex yields compared to the non-bioaugmentation approach. This method provided the most compact biofloc structure (0.50 g/L) and a large particle diameter (404 μm). Co-bioaugmentation significantly boosts the synthesis of extracellular polymeric substances, comprising proteins at 6.5 g/L and polysaccharides at 0.28 g/L. Chlorophyta, comprising 80% of the total algal phylum, and Proteobacteria, comprising 51% of the total bacterial phylum, are emerging as dominant species. These microorganisms play a crucial role in waste and wastewater treatment, as well as in the formation of microbial-rice bran complexes that could serve as an alternative aquaculture feed. This approach prompted changes in both microbial community structure and nutrient cycling processes, as well as water quality. These findings provide valuable insights into the transformative effects of bioaugmentation on the development of microbial-rice bran complexes, offering potential applications in bioprocesses for waste and wastewater management.

Ultrasonic destruction of surfactants

This study investigates the effectiveness of ultrasonic (US) treatment in removing and mineralizing surfactants in wastewater. It examines the complex mechanisms and variables (acoustic conditions, solution temperature, initial dose, etc.) that affect sonolytic processes. The effect of water matrix components (such as salts and the presence of secondary pollutants) on process performance is thoroughly investigated. Various treatments are analyzed through a detailed comparison of synergistic hybridization processes. The study also provides a comprehensive review of current environmental applications and explores potential directions for surfactant degradation using ultrasound. Insightful information is presented to advance sustainable wastewater treatment techniques. The literature review clearly reveals the promising future of sonotreatment for degrading various surfactants under different conditions. The use of multifrequency mechanisms and the integration of other advanced oxidation processes (AOPs) with the US process have significantly enhanced the energy efficiency of the sonochemical system. Additionally, the results highlight the need to focus on developing new sonoreactor designs, identifying degradation intermediates, and hybridizing the sonochemical system under innovative operating conditions.

Effective removal of toxic mixed azo dyes and Cr (VI) ions from wastewater using an integrated approach

The textile industry generates a significant amount of wastewater, including hazardous dyes, pigments, and heavy metals. The integrated approach of isolated bacterial strain and the bacterially synthesized ZnO nanoparticles was used in the removal of mixed azo dyes and Cr(VI) in a lab-scale bioreactor. It resulted in 77.19 % bromocresol purple (4th day), 50.11 % on bromocresol blue (3rd day), and 50.59 % bromocresol green (4th day) removal. Mixed azo dyes and Cr(VI) were removed using bacterial strain, which showed the maximum removal of Cr(VI) was 73.6 % at 25 ppm (3rd day) and mixed azo dyes removal was a maximum of 49.01 % at 75 ppm. A lab-scale reactor study using bacterial strain resulted in 45.89 % (5th day) of mixed azo dye and Cr(VI) removal. However, when the reactor was employed with synthetic wastewater and bacterially synthesized ZnO nanoparticles, achieved a maximum removal of 53.84 % at 120 min. Also, a phytotoxicity study on the Cicer arietinum plant with different concentrations of mixed azo dyes and chromium concentrations showed a maximum length of 5.5 cm at 100 ppm (3rd day). The bacterial strain and synthesized ZnO nanoparticles integrated technique providing an economically viable and scale-up solution for wastewater treatment techniques.

The anti-fouling and mechanism of Fe3O4@PVDF catalytic membrane in-situ coupling Fenton oxidation for organic pollutants removal

Polyvinylidene fluoride (PVDF) membrane is a promising technique for deep treatment of organic wastewater. However, the unavoidable membrane contamination greatly restrictions its field of application. Herein, we successfully prepared Fe3O4@PVDF membrane with excellent anti-fouling and catalytic ability by non-solvent induced phase inversion method. Meanwhile, Fe3O4@PVDF membrane was characterized by SEM, XRD, FTIR, Water contact Angle and membrane aperture analyzer. The properties of separation and anti-fouling were also evaluated by cross flow filtration of humic acid (HA). Compare with pristine membrane, the pure water flux, rejection rate and FRR respectively increase from 556.81 L m-2 h−1, 65.42 %, 68.26 % to 656.96 L m-2 h−1, 99.64 %, 90.17 % under in-situ Fenton reaction condition. In addition, further mechanistic insights by XDLVO theory, 3D-EEM and EPR verified that high anti-fouling mainly attribute to excellent hydrophilicity of Fe3O4@PVDF and in-situ degradation of HA by OH and 1O2· This work provides insights for improving the separation properties and anti-fouling properties of PVDF membrane in the field of treatment organic wastewater.

Rapid production of hydroxysodalite from a clay-based waste through microwave-assisted technique for treatment of wastewater contaminated with zinc cation

In the current work, the cabbage-like hydroxysodalite powder was produced from a clay-based waste deposited in the landfill of raw vegetable oil refinery through the microwave-assisted technique to treat the wastewater discharged from a zinc extraction industry. The selected waste was a Ca-bentonite, mainly containing montmorillonite, illite, and kaolinite which contaminated with the vegetable oil components. The effects of microwave irradiation power, and time on crystalline structure of products as well as uptake of heavy metal ions like zinc, cadmium, nickel, and aluminum were studied in details. The experimental results showed that the partial recrystallization of hydroxysodalite under the irradiation power of 200 W within 10–15 min contributes to the enhancement of adsorption efficiency. The maximal uptake of heavy metal ions was obtained in the relative crystallinity range of 22.5–43.0%. The prepared adsorbent possessed the higher efficiency, 94.0%, for the immobilization of Zn2+ from the concentrated wastewater, 413 mg L−1. The competitive adsorption of Cd2+, Ni2+, and Al3+ ions over the hydroxysodalite was extremely dependent on the ion concentration. Furthermore, the adsorption kinetics of Zn2+ over the hydroxysodalite particles follows the pseudo-second-order (PSO) model, indicating the chemical nature of treatment process. The equilibrium data were fitted by the Langmuir isotherm, confirming the homogenous, and monolayer adsorption. The presented route for the production of hydroxysodalite is facile, and rapid in comparison to hydrothermal method.

Highly efficient adsorption assisted photocatalytic decontamination of metronidazole by Co3O4 doped graphitic carbon nitrides

Since traditional wastewater treatment techniques only partially remove antibiotics like metronidazole (MTZ), the rising use of these drugs causes their entry into wastewater and receiving surface waterways. A flexible method that may effectively degrade such organic pollutants is adsorption assisted photocatalytic degradation. Herein, an easy mixing-and-heating procedure was used to synthesize visible light-induced g-C3N4/Co3O4 heterojunction photocatalysts. The structural properties and morphology of as-prepared materials were measured using characterization techniques such as FTIR, FSEM, and XRD analysis. The as-prepared catalyst has demonstrated a remarkable adoption and photocatalytic performance in degrading MTZ. It was found that 0.2 weight percent of Co3O4 was the optimum amount for achieving the best photocatalytic efficiency. A key factor in boosting photo-generated carrier separation is the synergistic interaction between g-C3N4 and Co3O4. The kinetics study of MTZ adsorption and degradation as well as factors effecting such as pH (2-10) and catalyst dosage process were investigated. The functional treatment method attained 78% degradation of MTZ under the following general conditions: pH = 6, g-C3N4/Co3O4 = 0.04 g/L, and reaction time = 200 min and MTZ concentration = 20 mg/L. A possible mechanism for the photocatalytic degradation was introduced, wherein O 2 • − was found to be the leading radical, whereas h + and H O • radicals contribute moderately to the degradation process. The research presents an appealing and environmentally friendly technique for the practical remediation of waste water carrying antibiotics.

Emerging pollutants in waste water: Challenges and advancements in treatment technology

Abstract Microplastics, per- and polyfluoroalkyl substances (PFAS), pharmaceuticals and personal care products (PPCPs), and other emerging contaminants in wastewater have all caused serious environmental and public health issues. The effectiveness of conventional wastewater treatment techniques to remove these pollutants, such as activated sludge, membrane bioreactors, and coagulation-flocculation, is often insufficient. The difficulties and improvements in treatment technology for eliminating developing contaminants from wastewater are examined in this thorough review study. The review gives a general overview of the most important subcategories of emerging pollutants, the shortcomings of traditional wastewater treatment techniques, and the developments in treatment technologies, including advanced oxidation processes (AOPs), adsorption-based methods, and novel biological treatment approaches. The obstacles mentioned include the need for sustainable and energy-efficient solutions, regulatory and monitoring concerns, and technological and economic hurdles. A number of suggestions are made as a response to these difficulties, such as boosting oversight and regulating procedures, fostering cooperation and information sharing, encouraging industry participation, and supporting research and development. These suggestions may be put into practice in order to reduce the hazards posed by developing contaminants in wastewater and safeguard our water resources and the ecosystem over the long run. The article emphasizes the value of using a multidisciplinary and cooperative approach to solving the problems caused by new contaminants. In order to create original solutions, advance best practices, and build suitable regulatory frameworks, it underlines the necessity for ongoing research, policy development, and stakeholder collaboration. The ultimate goal of this analysis is to provide academics, decision-makers, industry stakeholders, and the general public with a useful resource in their quest to comprehend and resolve the complicated problem of developing contaminants in wastewater.

Synthesis and Characterization of Composite WO3 Fibers/g-C3N4 Photocatalysts for the Removal of the Insecticide Clothianidin in Aquatic Media.

Photocatalysis is a prominent alternative wastewater treatment technique that has the potential to completely degrade pesticides as well as other persistent organic pollutants, leading to detoxification of wastewater and thus paving the way for its efficient reuse. In addition to the more conventional photocatalysts (e.g., TiO2, ZnO, etc.) that utilize only UV light for activation, the interest of the scientific community has recently focused on the development and application of visible light-activated photocatalysts like g-C3N4. However, some disadvantages of g-C3N4, such as the high recombination rate of photogenerated charges, limit its utility. In this light, the present study focuses on the synthesis of WO3 fibers/g-C3N4 Z-scheme heterojunctions to improve the efficiency of g-C3N4 towards the photocatalytic removal of the widely used insecticide clothianidin. The effect of two different g-C3N4 precursors (urea and thiourea) and of WO3 fiber content on the properties of the synthesized composite materials was also investigated. All aforementioned materials were characterized by a number of techniques (XRD, SEM-EDS, ATR-FTIR, Raman spectroscopy, DRS, etc.). According to the results, mixing 6.5% W/W WO3 fibers with either urea or thiourea derived g-C3N4 significantly increased the photocatalytic activity of the resulting composites compared to the precursor materials. In order to further elucidate the effect of the most efficient composite photocatalyst in the degradation of clothianidin, the generated transformation products were tentatively identified through UHPLC tandem high-resolution mass spectroscopy. Finally, the detoxification effect of the most efficient process was also assessed by combining the results of an in-vitro methodology and the predictions of two in-silico tools.

Enhanced photocatalytic activity of (In–Sr–P) tridoped TiO2/Bi2O3 composite loaded on mesoporous carbon: A facile sol-hydrothermal synthesis approach

Photocatalysis attracted attention as a promising technique for wastewater treatment, especially for water contaminated with organic pollutants such as dyes. However, designing a suitable photocatalyst with a simple procedure and high catalytic performance is still a big challenge for large-scale production. Here, indium-strantiom and phosphorous tridoped Bi2O3–TiO2 composite loaded on mesoporous carbon (ISP–TiO2/Bi2O3@C) was prepared via the sol-hydrothermal method. The as-prepared ISP-TiO2/Bi2O3@C displayed a mesoporous structure with a BET surface area of 84.804 m2 g−1. The photocatalytic activity of the ISP-TiO2/Bi2O3@C composite was investigated toward the degradation of rhodamine B (RB) under exposure to UV, and sunlight. It was found that ISP-TiO2/Bi2O3@C photocatalyst exhibited superior photocatalytic activity against photodegradation of RB under UV light and sunlight irradiation with a degradation percentage of 99.12, and 95.71 %, respectively. In addition, ISP-TiO2/Bi2O3@C composite displayed a distinguished recycling ability after the fifth recovery cycle, indicating a promising candidate for photocatalytic applications under UV light and sunlight. Consequentially, the higher photocatalytic activity of ISP-TiO2/Bi2O3@C under sunlight irradiation implies that the sol-hydrothermal method is promising for the preparation of efficient and low-cost TiO2-based photocatalysts for the photodegradation of various environmental pollutants.