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.

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.