Application of efficient photocatalytic process using a novel BiVO/TiO2-NaY zeolite composite for removal of acid orange 10 dye in aqueous solutions: Modeling by response surface methodology (RSM)

Synthesis and characterization of MoS2-COOH/gly/Mn nanocomposite as an efficient adsorbent for Ultra-trace determination of trifluralin herbicide

The world is confronting a severe water crisis. To clean up water from heavy metals, microorganisms, chemicals, and other types of pollutants, nanocomposites have been receiving great attention specifically due to the high surface area affording to work effectually even at low concentrations. In this research, we synthesized a new amino acid-modified MoS2 nanocomposite by chemically immobilizing Mn (II). The synthesized absorbent MoS2-COOH/gly/Mn was identified by thermogravimetric analysis (TGA), nitrogen adsorption measurement, X-ray diffraction (XRD), analysis of energy dispersive X-ray mapping (EDAX and MAP), field emission scanning electron microscopy (FE-SEM), and Fourier Transform Infrared spectrometry (FT-IR). The nanocomposite was employed as an adsorbent through the solid phase microextraction (SPME) method while trifluralin herbicide was chosen as a model compound. For the monitoring of trifluralin molecules, we employed an ion mobility spectrometry apparatus featuring a corona discharge ionization source. The SPME method's effectiveness was examined by investigating the stirring rate and extraction time as two crucial parameters, aiming to achieve trace analysis of trifluralin. Under the optimized condition of the trifluralin extraction, the coefficient (R2) and linear dynamic range (LDR) correlation were obtained at 0.9961 and 0.5-10 μg L-1, respectively. Relative recovery values the described approach were obtained in the span of 96-97% for agricultural wastewater samples. The quantification (LOQ) and limit of detection (LOD) were calculated at 0.5 and 0.15 μg L-1, respectively. The proposed nanocomposite absorbent has the capability to be applied as an efficient material for the extraction of trifluralin herbicide from different solutions.

Mesoporous bimetallic S-doped nanoparticles prepared via hydrothermal method for enhanced photodegradation of 4-chlorophenol

Magnesium oxides (MgO) have gained shown significant promise for a variety of applications, which can be modified by ions doping. In this study, bimetallic Ag-doped S-MgO nanoparticles were prepared by hydrothermal method and used for photocatalytic degradation of 4-chlorophenl (4-CP). EDX suggested the presence of no impurities, which mainly contained Mg, Ag, and S elements, suggesting that S and Ag were incorporated into the lattice of MgO as a result of successful doping. Estimated bandgap of Ag-doped S-MgO nanoparticles was 3.7 eV, lower than MgO (7.8 eV), but useful to improve optical characteristics and photocatalytic efficiency to degrade 4-CP up to a maximum of 99.60 ± 0.50%. The synergetic parameter during photocatalysis of 4-CP was 6.91, confirming the degradation of 4-CP. Quenching experiments proved the presence of hydroxyl radicals (•OH) and singlet dioxygen (1O2) that were critical in 4-CP degradation. The kinetics rate constant was increased by 24.8% from 0.086 ± 0.004 to 0.108 ± 0.005 min-1 by the addition of sulfate in the reaction medium. The work proposes a new synthetic method for preparing catalysts that are capable of producing in-situ •OH radicals and 1O2 to decompose the organic contaminants.

Metal Oxides Nanoparticles: General Structural Description, Chemical, Physical, and Biological Synthesis Methods, Role in Pesticides and Heavy Metal Removal through Wastewater Treatment

Nanotechnology (NT) is now firmly established in both the private home and commercial markets. Due to its unique properties, NT has been fully applied within multiple sectors like pharmacy and medicine, as well as industries like chemical, electrical, food manufacturing, and military, besides other economic sectors. With the growing demand for environmental resources from an ever-growing world population, NT application is a very advanced new area in the environmental sector and offers several advantages. A novel template synthesis approach is being used for the promising metal oxide nanostructures preparation. Synthesis of template-assisted nanomaterials promotes a greener and more promising protocol compared to traditional synthesis methods such as sol-gel and hydrothermal synthesis, and endows products with desirable properties and applications. It provides a comprehensive general view of current developments in the areas of drinking water treatment, wastewater treatment, agriculture, and remediation. In the field of wastewater treatment, we focus on the adsorption of heavy metals and persistent substances and the improved photocatalytic decomposition of the most common wastewater pollutants. The drinking water treatment section covers enhanced pathogen disinfection and heavy metal removal, point-of-use treatment, and organic removal applications, including the latest advances in pesticide removal.

Phenol red dye removal from wastewater using TiO2-FSM-16 and Ni-FSM-16 photocatalysts

In this study, the performance of Ni-FSM-16 and TiO₂-FSM-16 photocatalysts in phenol red removal was explored. The XRD, FE-SEM, and BET tests were used to characterize the catalysts. All experiments were performed at ambient temperature and under UV (20 W). The parameters including dye concentration (20-80 mg/L), photocatalyst concentration (0-8 g/L), UV exposure duration, and contact time (0-160 min) were optimized using RSM software. BET values of Ni-FSM-16 and TiO₂-FSM-16 were 718.63 m²/g and 844.93 m²/g, respectively. TiO₂-FSM-16 showed better performance in dye removal than Ni-FSM-16. At pH 3, the maximum dye removal by TiO₂-FSM-16/UV and Ni-FSM-16/UV was obtained 87% and 64%, respectively. The positive hole species had the main role in photocatalytic phenol red removal. The reusability study was done for up to 7 cycles, but the catalysts can be reused effectively for up to 3 cycles. The synergistic factor for the TiO₂-FSM-16 and TiO₂-FSM-16/UV processes were calculated to be 1.55 and 2.12, respectively. The dye removal efficiency by TiO₂-carbon and Ni-carbon was slightly lower than those obtained by the FSM-16 ones. The TiO₂-FSM-16 and Ni-FSM-16 catalysts had a suitable surface and acceptable efficiency in phenol red removal.

Adsorption and Photocatalytic Degradation of Pesticides into Nanocomposites: A Review

The extensive use of pesticides in agriculture has significantly impacted the environment and human health, as these pollutants are inadequately disposed of into water bodies. In addition, pesticides can cause adverse effects on humans and aquatic animals due to their incomplete removal from the aqueous medium by conventional wastewater treatments. Therefore, processes such as heterogeneous photocatalysis and adsorption by nanocomposites have received special attention in the scientific community due to their unique properties and ability to degrade and remove several organic pollutants, including pesticides. This report reviews the use of nanocomposites in pesticide adsorption and photocatalytic degradation from aqueous solutions. A bibliographic search was performed using the ScienceDirect, American Chemical Society (ACS), and Royal Society of Chemistry (RSC) indexes, using Boolean logic and the following descriptors: "pesticide degradation" AND "photocatalysis" AND "nanocomposites"; "nanocomposites" AND "pesticides" AND "adsorption". The search was limited to research article documents in the last ten years (from January 2012 to June 2022). The results made it possible to verify that the most dangerous pesticides are not the most commonly degraded/removed from wastewater. At the same time, the potential of the supported nanocatalysts and nanoadsorbents in the decontamination of wastewater-containing pesticides is confirmed once they present reduced bandgap energy, which occurs over a wide range of wavelengths. Moreover, due to the great affinity of the supported nanocatalysts with pesticides, better charge separation, high removal, and degradation values are reported for these organic compounds. Thus, the class of the nanocomposites investigated in this work, magnetic or not, can be characterized as suitable nanomaterials with potential and unique properties useful in heterogeneous photocatalysts and the adsorption of pesticides.

A designed experiment for CdS-AgBr photocatalyst toward methylene blue

A boosted photocatalytic activity was observed for the CdS-AgBr nanocomposite in the degradation of methylene blue (MB). The experimental design method based on the response surface methodology (RSM) approach used to study the simultaneous interaction effects between the influencing variables. Analysis of variance (ANOVA) of the results confirmed a significant model for processing the data because an F value of 32.34 for the suggested model was higher than that of the critical value of F_{0.05, 14, 13} = 2.55 at 95% confidence interval. This analysis also showed a non-significant lack of fit (LOF) (as a measure of the randomness of the deviations around the obtained data) because the LOF F value of 8.27 was smaller than that of the critical value of F_{0.05, 10, 3} = 8.79. R² values near to unity were achieved (the multiple correlation coefficients R² (R² = 0.9627), adjusted R² (adj-R² = 0.9226), and predicted R² (pred-R² = 0.7423)). Six center points suggested by the model included the following conditions: pH, 6.1; C_MB, 3.5 mg/L; a dose of the catalyst, 0.68 g/L; and irradiation time, 40.5 min. During the center point runs, the degradation efficiencies were obtained in the range of 38 to 43%. The optimal run included pH, 9; catalyst dosage, 1 g/L; irradiation time, 60 min; and C_MB, 2 mg/L, and the best removal efficiency of 98% was achieved during these conditions.

Post-fabrication structural changes and enhanced photodegradation activity of semiconductors@zeolite composites towards noxious contaminants

This review article provides the recent progress in semiconductor-based zeolite photoactive materials for the application of noxious contaminants removal. The rapidly expanding industrialization and globalization cause serious threats to the environment or water bodies. The semiconductor@zeolite photocatalysts were implemented for water quality management/sustainment. The exclusive properties of zeolite material have been elaborated with their role in the photocatalysis process. The photoactive material's properties like single-atom catalysts (SACs), distribution of metal in the zeolite crystal were elaborated along with their role in catalytic reactions. Differently prepared semiconductor@zeolite composites such as TiO₂@zeolite, binary and ternary composites, Fe/Ag/bismuth-modified/ZnO/ZnS/NiO/g-C₃N₄/core-shell/quantum dots modified zeolite composites, were systematically summarized. The research progress in morphologies, structural effect, degradation mechanism were recapitulated and tabulated form of % degradation with their optimal parameters such as catalyst dose, pollutant concentrations, pH, light source intensities were also provided. The significance of zeolite frameworks, the structural properties of semiconductor@zeolite photoactive materials to enhance the degradation efficiencies was explored. Analysis of the intermediate products of Norfloxacin, TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), TCDF (2,3,7,8-tetrachlorodibenzofuran), diclofenac contaminants were systematically represented and structurally identified by GC-MS/HPLC-MS techniques.

A heterogeneous peroxymonosulfate catalyst built by Fe-based metal-organic framework for the dye degradation

The regulatory control on dyes is an important issue, as their discharge into the environment can pose significant risks to human health. MIL-101(Fe) prepared by a solvothermal method was used as a catalyst to generate sulfate (SO₄^•-) and hydroxyl (HO^•) radicals from peroxymonosulfate (PMS) for the treatment of orange G (OG). The structural properties of MIL-101(Fe) were assessed by a number of characterization approaches (e.g., Fourier-transform infrared spectroscopy). The factors controlling the removal of OG were explored by a response surface methodology with central composite design (RSM-CCD) plus adaptive neuro-fuzzy inference system (ANFIS). The synthetized MIL-101(Fe) had uniform octahedral nanocrystals with rough surfaces and porous structures. The maximum catalytic removal efficiency of OG with MIL-101(Fe)/PMS process was 74% (the final concentration of Fe²⁺ as 0.19 mg/L and reaction rate of 434.2 μmol/g/h). The catalytic removal of OG could be defined by the non-linear kinetic models based on RSM. The OG removal efficiency declined noticeably with the addition of radical scavengers such as ethanol (EtOH) and tert-butanol (TBA) along with some mineral anions. Accordingly, MIL-101(Fe)/PMS is identified as an effective remediation option for the dyes based on advanced oxidation process (AOPs) based on high treatment efficiency at low dosage of low cost catalyst.

Optimized strategies for (BiO)2CO3 and its application in the environment

Photocatalysis is a new type of technology, which has been developed rapidly for solving environmental problems such as wastewater or air pollutants in recent years. Also, the effective performance and non-secondary pollution of photocatalytic technology attract much attention from researchers. As a "sillén" phase oxide, the (BiO)₂CO₃ (BOC) is a great potential photocatalyst attributing to composed of alternate Bi₂O₂²⁺ and CO₃^2- layers, which is a benefit for transportation of electrons. Besides, BOC has attracted much attention from researchers because of its excellent characters of non-toxic, environmentally friendly, and low-cost. However, BOC has a defect on wide band gap, which is limited for the usage of visible light, so a great number of published papers focus on the modifications of BOC to improve its photocatalytic efficiency. This article mainly summarizes the modifications of BOC and its application in the environment, guiding for designing BOC-based materials with high photocatalytic activity driven by light. Moreover, the research trend and prospect of BOC photocatalyst were briefly summarized, which could lay the foundation for forming a green and efficient BOC-based photocatalytic reaction system. Importantly, this review might provide a theoretical basis and guidance for further research in this field.

The photocatalytic rate of ZnO supported onto natural zeolite nanoparticles in the photodegradation of an aromatic amine

Aniline and its derivate are critical environmental pollutants, and thus, the introduction of an eco-friendly catalyst for removing them is an important research future. The ZnO supported on the ball-mill prepared clinoptilolite nanoparticles (CNPs) was prepared via an ion-exchange process followed by the calcination process. The amount of loaded ZnO in the ZnO-CNP (CZ) samples varied as 0.54, 0.63, 0.72, and 0.86 meq/g as the Zn(II) concentration in the ion-exchange solution varied from 0.1 to 0.5 M. The ZnO-CNP catalyst was briefly characterized by XRD, FTIR, and DRS techniques. The pHpzc value for the various ZnO-CNPs was about 7.1 that had no change with the ZnO loading. By applying the Scherrer equation on the XRD results, a nano-dimension of about 50 nm was obtained for the catalyst. Bandgap energy of the ZnO-CNP samples was estimated by applying the Kubelka-Munk equation on the DRS reflectance spectra. The value for the CZ2 catalyst was about 3.64 eV. The supported ZnO-CNP sample was then used in the photodegradation of 2,4-dichloroaniline (DCA). Raw zeolite showed a relatively low photocatalytic activity. The degradation efficiency was followed by recording the absorbance of the DCA solution by UV-Vis spectrophotometer. The effects of the essential critical operating factors on the degradation efficiency were kinetically studied by applying the Hinshelwood equation to the results. The ZnO-CNP catalyst with 2 w% ZnO showed the best photocatalytic rate in the optimal conditions of 0.75 g/L, C_DCA: 15 ppm, and the initial pH: 5.8. Finally, HPLC analysis of the blank and the photodegraded DCA solutions at 180 and 300 min confirmed 74 and 87% of DCA molecules were degraded during these times. The results confirm that supported ZnO onto clinoptilolite caused enhanced photocatalytic activity because the zeolite internal electrical field prevents the e^-/h⁺ recombination.

The Photocatalysis-Enhanced TiO2@HPAN Membrane with High TiO2 Surface Content for Highly Effective Removal of Cationic Dyes

The elimination of dye pollutants from wastewater is a significant concern that has prompted extensive research into the development of highly efficient photocatalytic membranes. A novel method was proposed to prepare photocatalysis-enhanced poly(acrylonitrile-methyl acrylate) (PAN-based) membranes in this study. In detail, the blended membrane containing SiO₂@TiO₂ nanoparticles with a shell-core structure was first prepared via thermal-induced phase separation. The SiO₂ nanoshells were dissolved, and the released TiO₂ nanoparticles migrated to the membrane surface during a simple hydrolysis process, which prevents the TiO₂ nanoparticles from directly contacting or interacting with the polymer matrix. The hydrogen bonds bind the exposed TiO₂ with the PAN membrane surface, resulting in the formation of the TiO₂@HPAN hybrid membrane. The photocatalytic efficiency of the TiO₂@HPAN membrane doubled compared with that of nonhydrolyzed membranes. In the presence of UV light, the hybrid membrane can degrade 99.8% of methylene blue solution in less than 2 h, compared to only 86.1% for the blended membranes. Further, the TiO₂@HPAN membrane showed excellent photocatalytic activity for cationic dyes due to electrostatic attraction. Moreover, the high-flux recovery rate and recycling stability of the TiO₂@HPAN membrane lead to an excellent antifouling property. The facile preparation method proposed in this work shows extraordinary potential for the development of highly efficient selective photocatalytic materials for cationic dyes to be used in wastewater treatment applications.

Supported cuprous oxide-clinoptilolite nanoparticles: Brief identification and the catalytic kinetics in the photodegradation of dichloroaniline

The supported CuO onto the ball-mill prepared clinoptilolite nanoparticles (CNPs) was prepared via an ion exchange process in Cu(II) aqueous solution followed by the calcination process. The CuO-CNP samples with various CuO loading were briefly characterized by XRD, FTIR, and DRS. pHpzc was varied in the range of 6.3 to 6.8 depending on the amount of loaded CuO in the samples. The band gap energy was estimated by applying the Kubelka-Munk equation on the DRS results that varied from 2.41 to 2.50 eV depending on the CuO loading. Based on the Scherrer equation nano-sized CuO-CNP at about 50 nm was estimated. The CuO-CNP contained 3.9% CuO showed the highest photocatalytic activity toward dichloroaniline (DCA). The effects of the experimental variables on DCA photodegradation were studied by using the Hinshelwood model. The optimal conditions for obtaining a higher rate for DCA photodegradation were the catalyst dose of 0.5 g/L, C_DCA: 5 ppm, and the initial pH: 3. HPLC analysis of the photodegraded DCA solutions for 180 and 300 min gave the degradation extents 71% and 90%, respectively.

Metal- and metal/oxide-based engineered nanoparticles and nanostructures: a review on the applications, nanotoxicological effects, and risk control strategies

The production and demand of nanoparticles in the manufacturing sector and personal care products, release a large number of engineered nanoparticles (ENPs) into the atmosphere, aquatic ecosystems, and terrestrial environments. The intentional or involuntary incorporation of ENPs into the environment is carried out through different processes. The ENPs are combined with other compounds and release into the atmosphere, settling on the ground due to the water cycle or other atmospheric phenomena. In the case of aquatic ecosystems, the ENPs undergo hetero-aggregation and sedimentation, reaching different living organisms and flora, as well as groundwater. Accordingly, the high mobility of ENPs in diverse ecosystems is strongly related to physical, chemical, and biological processes. Recent studies have been focused on the toxicological effects of a wide variety of ENPs using different validated biological models. This literature review emphasizes the study of toxicological effects related to using the most common ENPs, specifically metal and metal/oxides-based nanoparticles, addressing different synthesis methodologies, applications, and toxicological evaluations. The results suggest negative impacts on biological models, such as oxidative stress, metabolic and locomotive toxicity, DNA replication dysfunction, and bioaccumulation. Finally, it was consulted the protocols for the control of risks, following the assessment and management process, as well as the classification system for technological alternatives and risk management measures of ENPs, which are useful for the transfer of technology and nanoparticles commercialization.

A novel ternary heterogeneous TiO2/BiVO4/NaY-Zeolite nanocomposite for photocatalytic degradation of microcystin-leucine arginine (MC-LR) under visible light

Microcystin-leucine arginine (MC-LR) is a carcinogenic toxin, produced by cyanobacteria. The release of this toxin into drinking water sources can threaten public health and environmental safety. Therefore, effective MC-LR removal from water resources is necessary. In the present study, the hydrothermal method was used to synthesize a novel ternary BiVO₄/TiO₂/NaY-Zeolite (B/T/N-Z) nanocomposite for MC-LR degradation under visible light. FESEM, FTIR, XRD, and DRS were performed for characterizing the nanocomposite structure. Also, the Response Surface Methodology (RSM) was applied to determine the impact of catalyst dosage, pH, and contact time on the MC-LR removal. High-performance liquid chromatography was performed to measure the MC-LR concentration. Based on the results, independent parameters, including contact time, catalyst dosage, and pH, significantly affected the MC-LR removal (P < 0.05). In other words, increasing the contact time, catalyst dosage, and acidic pH had positive effects on MC-LR removal. Among these variables, the catalyst dosage, with the mean square and F-value of 1041.37 and 162.84, respectively, had the greatest effect on the MC-LR removal efficiency. Apart from the interaction between the catalyst dosage and contact time, the interaction effects of other parameters were not significant. Also, the maximum MC-LR removal efficiency was 99.88% under optimal conditions (contact time = 120 min, catalyst dosage = 1 g/L, and pH = 5). According to the results, the B/T/N-Z nanocomposite, as a novel and effective photocatalyst could be used to degrade MC-LR from polluted water.

Experimental data on the removal of acid orange 10 dye from aqueous solutions using TiO2/Na-Y zeolite and BiVO4/Na-Y zeolite nanostructures: A comparison study

The increase of textile factories, along with the continuous development of industrialization has led to excessive discharge of high toxicity wastewater along with a diverse range of contaminants in wastewater. In this regard, to reduce their operating costs and treatment time, in this work, two synthesized nanostructures, TiO₂/Na-Y zeolite and BiVO₄/Na-Y zeolite was compared to remove acid orange 10 (AO10) from the aqueous solutions. The obtained optimum operating conditions including initial dye concentration, initial pH, contact time, catalyst dosage and AO10 removal efficiency were 20 mg/L, 3, 7 min, 0.2 g/100 mL, and 99.77% for TiO₂/Na-Y zeolite and 20 mg/L, 3, 200 min, 0.2 g/100 mL and 46.13% for BiVO₄/Na-Y zeolite composite, respectively. The structural characteristics of the synthetized materials were also determined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and fourier-transform infrared spectroscopy (FTIR).

S-scheme bismuth vanadate and carbon nitride integrating with dual-functional bismuth nanoparticles toward co-efficiently removal formaldehyde under full spectrum light

It is crucial to develop more effective photocatalysts in the field of clean environment. In response, the S-scheme BiVO₄/g-C₃N₄ heterojunction modified by in situ reduced non-noble metal Bi nanoparticles was used to synergistically degrade formaldehyde under full spectral irradiation. The results, that investigated by careful characterizations and density functional theory (DFT) calculations, proved that BiVO₄/g-C₃N₄ form an S-scheme heterojunction, which can effectively improve the separation efficiency of photogenic carriers and maintain the original strong redox capability of semiconductor materials. The SPR effect of Bi elemental substance enhanced the optical response and provided more oxidative species. Thus, the photocatalytic activity of BiVO₄/Bi/g-C₃N₄ was significantly improved through their joint efforts, that the degradation efficiency of HCHO (800 ppm) for 6 h is 96.39% under 300 W Xenon lamp without filter with the pseudo-second-order rate constant of 4.16 ppm^-1·h^-1 and CO₂ selectivity of 98.41%. Surprisingly, the degradation efficiency also reached to 49.35% and 32.23% under visible and near-infrared light irradiation, respectively. Moreover, we also tested its photocatalytic decomposition effect on formaldehyde in coatings, indicating that it has a broad prospect in future coatings applications. This study may provide an expected photocatalyst, an efficient non-noble metal modified S-scheme heterojunction, to degrade volatile organic gases under a broad spectrum light.

Distributed treatment systems

This section presents a review of the scientific literature published in 2019 on topics relating to distributed treatment systems. This review is divided into the following sections: constituent removal, treatment technologies, planning and treatment management, and other topics. PRACTITIONER POINTS: Highlights changes and innovation in removal techniques and technologies in water treatment. Reviews management systems of distributed treatment systems. Discusses point-of-use treatment systems.

Present applications of titanium dioxide for the photocatalytic removal of pollutants from water: A review

The evolution of modern technology and industrial processes has been accompanied by an increase in the utilization of chemicals to derive new products. Water bodies are frequently contaminated by the presence of conventional pollutants such as dyes and heavy metals, as well as microorganisms that are responsible for various diseases. A sharp rise has also been observed in the presence of new compounds heretofore excluded from the design and evaluation of wastewater treatment processes, categorized as "emerging pollutants". While some are harmless, certain emerging pollutants possess the ability to cause debilitating effects on a wide spectrum of living organisms. Photocatalytic degradation has emerged as an increasingly popular solution to the problem of water pollution due to its effectiveness and versatility. The primary objective of this study is to thoroughly scrutinize recent applications of titanium dioxide and its modified forms as photocatalytic materials in the removal and control of several classes of water pollutants as reported in literature. Different structural modifications are used to enhance the performance of the photocatalyst such as doping and formation of composites. The principles of these modifications have been scrutinized and evaluated in this review in order to present their advantages and drawbacks. The mechanisms involved in the removal of different pollutants through photocatalysis performed by TiO2 have been highlighted. The factors affecting the mechanism of photocatalysis and those affecting the performance of different TiO2-based photocatalysts have also been thoroughly discussed, thereby presenting a comprehensive view of all aspects involved in the application of TiO₂ to remediate and control water pollution.

Enhanced photo catalytic degradation of methyl orange using p–n Co3O4-TiO2 hetero-junction as catalyst

Photo catalytic degradation of pollutants is one of the techniques used for treatment of dye contaminated wastewater. TiO2 has attracted much attention as photo catalyst for treatment of contaminated water. In this study, the photo catalytic performance of TiO2 has been enhanced by formation of p–n Co3O4-TiO2 hetero-junction. The p–n Co3O4-TiO2 hetero-junction was prepared by wet incipient impregnation method and characterized by various techniques. The photo catalytic activity of prepared composite was evaluated by photo degradation of methyl orange. The as prepared Co3O4-TiO2 composite was found as effective catalyst than Co3O4 and TiO2. The higher photo catalytic activity was attributed to p–n junction formed between Co3O4 and TiO2. The degradation data was analyzed according to Eley–Rideal mechanism in terms of 1st and 2nd order kinetics.

Efficient degradation of microcystin-LR by BiVO4/TiO2 photocatalytic nanocomposite under visible light

Microcystin-Leucine Arginine (MC-LR) is one of the most studied cyanotoxins due to its toxicity and abundant that cause health hazards for humans through of the drinking water. In this study, BiVO₄/TiO₂ nanocomposite was synthesized by hydrothermal method and employed for the removal of MC-LR. The characteristics of the catalysts were determined by FESEM, XRD and FTIR spectra. Response surface methodology (RSM) was applied to assess the effects of operating variables (pH, contact time, and catalyst dose) on the MC-LR removal. The coefficient of determination (R²) was calculated 98.7% for the response. The residual concentration of MC-LR was measured by high-performance liquid chromatography (HPLC). The results show that the highest removal efficiency of MC-LR was 98% under the optimum conditions (pH = 5, contact time = 90 min, and catalyst dose = 0.5 g/l). MC-LR decomposition efficiency by BiVO₄/TiO₂ nanocomposite was enhanced by pH reduction and increasing of contact time and catalyst dose. The prepared BiVO₄/TiO₂ nanocomposite with technological potential can be used directly in environmental preservation, specifically in the decontamination of MC-LR from aqueous solutions.