A new heterogeneous catalytic system for decolorization and mineralization of Orange G acid dye based on hydrogen peroxide and a macroporous chelating polymer

The decolorization and the mineralization of the Orange G dye in aqueous solutions with hydrogen peroxide in a heterogeneous system, involving a new catalyst, obtained by the adsorption of Cu(II) ions onto a macroporous chelating polymer functionalized with diethylenetriamine, was investigated. Special attention has been paid to the effect of solution pH, H2O2 and dye concentration, reaction time, temperature and amount of catalyst on the decolorization efficiency of Orange G containing water. The decolorization kinetics of Orange G by this catalytic system was also elucidated, based on experimental data. The oxidation reaction was found to follow pseudo-first-order kinetics with respect to dye concentration. The rate constants for temperatures ranging from 24 to 50 °C and the activation parameters were calculated. Activation energy, as well as activation enthalpy and entropy were calculated using the Arrhenius and Eyring equations, respectively. The new tested catalyst displayed good stability and was efficient for the decolorization and mineralization of Orange G dye under mild reaction conditions. Complete color removal was achieved in 30 min at 24 °C and in 15 min at 50 °C (pH = 7, [H2O2] = 130 mmol L−1, in the presence of 0.06 g of the catalyst) at an initial dye concentration of 50 mg L−1. The tested heterogeneous catalyst is a new cost effective alternative for the treatment of wastewaters containing Orange G dye. ► The degradation of Orange G with H2O2, in a heterogeneous system, was studied. ► A new catalyst, with Cu(II) adsorbed on a macroporous chelating resin, was tested. ► Optimal conditions: 50–177 mg/L OG, pH 7, 130 mmol/L H2O2, 0.6 g Cu(II)-A, 60 min. ► Maximum 94% total organic carbon removal at 50 °C for dye solution of 50 mg L−1. ► High catalytic effect (Ea = 20 kJ/mol) due to activation complex on catalyst surface.