Use of Zinc Oxide Nano-photocatalyst as a Recyclable Catalyst for Removal of Arsenic and Lead Ions from Polluted Water

Abstract

Background & objectives: Considering the effects of pollutants of industrial origin, such as heavy toxic metals-containing wastewater, on rivers and surface waters and the importance of their removal, in this study, the preparation, characterization and evaluation of zinc oxide nanophotocatalyst based on magnetic organic-metallic frameworks ( 2 @Cr-MIL-101 ), abbreviated as ZISM nanophotocatalysts, was evaluated in removing of lead (Pb 2+ ) and arsenic (As 3+ ) metals from aqueous samples. Methods: This experimental study was performed using a ZnO-based nano-photocatalyst and a reactor consisting of an ultraviolet (UV) source and a reaction chamber for water samples contaminated with lead (Pb 2+ ) and arsenic (As 3+ ). To determine the removal efficiency of contaminants by ZISM nano-photocatalyst, the effect of various parameters including contaminant concentration, amount of nano-photocatalyst, pH and reaction time were investigated. Results: The results showed that with increasing the amount of ZISM nano-photocatalyst and pH, the removal of lead and arsenic increased. The maximum removal of Pb 2+ and As 3+ was obtained 99.8 and 98.3, in initial concentration of 5 mg/L, nano-photocatalyst dose of 250 mg/L, pH =8 mg/L and reaction time of 60 min. Conclusions: According to the results, the ZISM nano-photocatalyst emerged as an efficient and recyclable nano-photocatalyst, which was a potential and environmentally friendly process for the removal of toxic heavy metals as hazardous water pollutants. This photocatalyst showed good recyclability in 5 consecutive periods.