Sonochemical oxidation of cyanide using potassium peroxydisulfate as an oxidizing agent

In this study, the sonochemical oxidation of cyanide in the presence of peroxydisulfate (PDS) ions has been investigated. As a result of experiments, sulfate anion radicals (·SO ₄ ^-) and hydroxide radicals (·OH) produced by PDS ions in acoustic cavitation could readily oxidize and even mineralize cyanide in an aqueous environment. When the frequency of ultrasound and PDS ions were applied at 450 kHz and 60mg·L ^-1, the efficiencies of mineralization for free cyanide (CN ^-) and thiocyanate (SCN ^-) were 99.3 and 99%, respectively. The kinetics of total organic carbon (TOC) reduction for CN ^- and SCN ^- oxidation were interpreted using the modified pseudo-first-order kinetic model. In this study, carbonate and nitrate were found to be by-products of CN ^- oxidation while sulfate, carbonate and nitrate were by-products of SCN ^- oxidation.