Photocatalytic degradation of paraquat dichloride in the presence of ZnO.WO3 composite

The study reports the synthesis of a series of ZnO.WO3 composites in different mole ratios of 40:60, 60:40, 80:20 and 20:80. They were characterized by XRD, DSC, FT-IR and TGA. The potential of these composites for catalyzing the degradation of paraquat dichloride was explored under UV light. The study revealed that the composition of all the prepared composites was the same irrespective of using different mole ratios of two components. Thus, 40:60 composite was used for further experimentation on photodegradation. The effect of various factors like pH, temperature, catalyst dose and pesticide concentration was studied for the photodegradation of paraquat dichloride. An alkaline pH was found to be more favorable for accelerating the process of photocatalytic degradation. ZnO.WO3 was found to be stable for at least three cycles of reuse. Moreover, the catalyst yielded a 88.3% degradation in the presence of ZnO.WO3 that was only 65% in the presence of ZnO and 51.3% in the presence of WO3 alone. The potential of the catalyst was also explored for real polluted wastewater obtained from runoff of agricultural fields. The kinetics of photodegradation was explored by applying different models, i.e., single first-order, indeterminate-order, first-order multicomponent and double first-order parallel models without normalization of data. It is suggested that this composite may be used not only for the remediation of waters contaminated with persistent paraquat dichloride but its potential for degrading other hazardous pollutants may also be explored.

Automated summary

The study reported the synthesis and characterization of ZnO.WO3 composites in different mole ratios for catalyzing the degradation of paraquat dichloride. The 40:60 composite showed the best photodegradation performance and was stable for multiple reuse cycles, with alkaline pH conditions being favorable. The potential of the composite for degrading other hazardous pollutants in polluted water was also explored.