Potential use of Foundry Sand as Heterogeneous Catalyst in Solar Photo-Fenton Degradation of Herbicide Isoproturon

This study deals with employing foundry sand (FS) as new low cost iron source in heterogeneous photo-Fenton process for the degradation of herbicide isoproturon (IPU) in aqueous solution. The characterization of the FS by EDS confirmed presence of iron (23%) required for photo-Fenton and simultaneously confirmed absence of any heavy metals which may be susceptible to leaching. The photo- Fenton effects of different reaction parameters like H2O2 concentration [H2O2]0, operating pH, initial concentration of IPU [C0], FS dose, recycling of FS, effect of area/volume ratio were investigated. Results showed that the maximal removal efficiency were achieved when reaction parameters were [H2O2]0= 2.2 mM, pH 3, FS dose=0.5 g/L, [C0] =25 mg/L. Under optimum condition, 97% degradation efficiency of IPU was achieved within 150 min of reaction. The catalyst recycling test was performed and FS was effectively recycled for 4 times with 20% reduction in degradation efficiency. SEM-EDS analysis of recycled FS confirmed morphology of FS unchanged. Solar baffled batch reactor (SBBR) with recirculation confirmed 70% degradation of IPU after 6 h. IPU mineralization was confirmed with TOC reduction, NH4+ generation along with formation of intermediates as confirmed through LC-MS.