Photocatalytic Degradation of Organophosphates Using Nanocrystalline ZnO Synthesized by Modified Sonochemical Method

Organophosphates, especially their ester, are not only toxic to humans but equally toxic to aquatic and other animal life on Earth when exposed to them. Here, we designed an efficient and easy way to degrade hexamethyl phosphoramide and omethoate organophosphate catalytically in a natural way into non-toxic products. Both hexamethyl phosphoramide and omethoate are possible carcinogens and cause serious health issues in humans and other animals when exposed to them. In this work, a modified sonochemical method was used for the synthesis of ZnO nanoparticles using zinc acetate dihydrate, ethylenediamine dihydrochloride, and polyvinylpyrrolidone. Sodium hydroxide was used as the precipitating agent, and distilled water was used as the solvent. An Elmasonic ultra-sonicator with 240-watt power was used for the preparation of ZnO nanoparticles. The synthesized ZnO nanoparticles with a high surface area (250 m2/g), average particle size of 23 ± 1 nm, and a mesoporous structure with 1.858 nm average pore size were then used for the degradation of organophosphate, i.e., hexamethyl phosphoramide and omethoate pesticide, using 10 µL of concentration to check their catalytic efficiency for the first time. The degradation products were identified using gas chromatography–electron impact mass spectrometry (GC/EIMS). The results showed that omethoate was completely degraded, while hexamethyl phosphoramide showed partial degradation, both producing fewer toxic intermediates.