UV/H2O2 coupled with adsorption in the decolorization and phytotoxicity effects of dye mixtures

UV/H2O2 is an effective process for the decolorization of dyes in water; However, after treatment if complete mineralization is not achieved the toxicity of the wastewater usually increases due to the generation of intermediated more toxic than the dye. Thus, a subsequent process to reduce toxicity of the treated effluent is desirable to reduce treatment costs and to allow discharge in water corps or for water reuse. Few UV/H2O2 studies reported UV/H2O2 efficiency in mixtures of dyes and other few considered couple processes with adsorption to decrease phytotoxicity. The present study reported the decolorization by UV/H2O2 of three textile dyes in water and their binary and ternary mixtures at different initial concentrations. Also, the effect of the initial concentration of H2O2 was studied in time. After UV/H2O2 treatment the effluents were treated by adsorption using a commercial aluminosilicate and a silica gel (waste from industry). The decolorization and phytotoxicity effects (using a Raphanus sativus bioassay) were evaluated before and after UV/H2O2 and adsorption processes.