Photo-degradation of di azo dye Bismarck Brown by advanced photo-Fenton process: Influence of inorganic anions and evaluation of recycling efficiency of iron powder

The present research work has demonstrated the usage of zero valent metallic iron (ZVMI) in the photo-Fenton process under UV light as a promising and novel technique for the complete degradation of di azo dye Bismarck Brown (BB) in aqueous medium. The influence of various reaction parameters like concentration of oxidants/dye/iron powder and pH of the solution was investigated and optimum conditions are reported. Ammonium persulfate (APS) proved to be better oxidant in comparison with hydrogen peroxide for enhancing the degradation rate and effectively inhibited the precipitation of iron hydroxides at higher dosages of iron powder which is attributed to the acidity provided by APS which is crucial for Fenton process. The rate constant for the kinetics of degradation using various oxidation processes follows the order: Fe0/APS/UV > Fe0/H2O2/UV > Fe0/APS/dark > Fe0/UV > Fe0/H2O2/dark > Fe0/dark > H2O2/UV > APS/UV. The effects of inorganic anions that are commonly found in the industrial effluents like NaCl, KNO3, Na2SO4, Na2CO3 and NaHCO3 at different concentrations on the degradation rate were studied in detail. The degradation was followed by UV-vis and GC-MS techniques.