Mineralization of sulfamethoxazole by ozone-based and Fenton/Fenton-like-based processes

Ozone-based and Fenton/Fenton-like-based processes were used to mineralize sulfamethoxazole (SMX). The oxidants were ozone (O-3), hydrogen peroxide (H2O2) and persulfate (PS); Fe(II), Cu(II) and Fe(III) were used as metal activators of the oxidants. The effects of Fe(II) concentration in UV/oxidant/Fe(II) systems on SMX mineralization were evaluated. The mineralization rate of SMX was consistent with pseudo-first order kinetics. The results in this study suggested that hydroxyl radicals were responsible for the mineralization of SMX in UV/O-3-based and UV/H2O2-based systems; moreover, sulfate radicals were the main reactive species in UV/PS-based systems. Fe(II) was a better activator than Cu(II) and Fe(III) in UV/oxidant/Mn+ systems. With the addition of 0.5 mM Fe(II), the SMX mineralization rate constants in UV/O-3/Fe(II), UV/H2O2/Fe(II) and UV/PS/Fe(II) were 0.04089 +/- 0.00754, 0.19486 +/- 0.06356 and 0.05715 +/- 0.03212 min(-1). UV/H2O2/Fe(II) exhibited the highest mineralization rate and it was also the most energy-efficient system for SMX mineralization.