Presence of sulfides in waste water causes water pollution and sometimes also it causes air pollution with the formation of hydrogen sulfide. Generally sulfide comes to the water body from the effluents of some chemical, petrochemical and tannery industries. As separation of soluble sulfides is difficult by conventional processes, chemical treatment of sulfide is generally followed to convert it into less hazardous and more separable form. A common treatment method in this regard is wet-air oxidation of sulfide to sulfate.
In the present work oxidation of sulfide by hydrogen peroxide in the presence of nano- size hydrated ferric oxide catalyst was investigated. The nano-size catalyst was prepared by treating ferric chloride solution with ammonia solution and citric acid. Characterization of the catalyst was done by FTIR, XRD, TGA SEM and EDX. The catalyst was found to be very effective in oxidizing the sulfide by hydrogen peroxide. The reaction proceeds through the intermediate formation of thiosulfate, sulfite and eventually sulfate. Sulfide was analyzed by methylene blue method. Analysis of sulfate was done by spectrophotometer after the addition of Bacl2. The effects of sulfide concentration, catalyst loading, H2O2 dosing and temperature on the oxidation of sulfide were investigated. Kinetic rate equations and activation energies for the catalytic sulfide oxidation reaction were calculated from the experimental data.