Highly efficient persulfate oxidation process activated with Fe0 aggregate for decolorization of reactive azo dye Remazol Golden Yellow

Abstract

The commercially available Fe0 aggregate has advantages of low-cost, fast-effective decontamination, reusability, and ease of operation. However, little study has been done on the performance of Fe0 aggregate as a catalyst in degradation of azo dyes, particularly used in persulfate (PS) oxidation process. This study investigated decolorization of a reactive azo dye, Remazol Golden Yellow (RGY, Reactive Orange 107), by persulfate oxidation activated with Fe0 aggregate. RGY decolorization was not effective in ultrasound-activated, heat-activated, and base-activated persulfate oxidation; however, a significant decolorization improvement was achieved by applying Fe0 aggregate to activated persulfate (PS/Fe0). Decolorization was strongly influenced by pH, Fe0, persulfate dosages and temperature. The suitable conditions for RGY decolorization were pH 6.0, PS 5×10–3M, and Fe0 0.5g/L. This condition yields 98% color removal of 100mg/L RGY solution within 20min treatment; the azo bonds of RGY were completely broken down. RGY decolorization followed the first-order kinetics. Activation energy of the PS/Fe0 system was 0.479kJ/mol, suggesting the temperature dependence of RGY decolorization is small. The presence of inorganic salt in RGY solution had an adverse effect on decolorization. The inhibitory effect of various inorganic salts on decolorization followed the sequence of Na2HPO4≫NaHCO3≫NaClO4>NaCl>NaNO3>NaClO4>no salt. The Fe0 aggregate was reusable and a satisfactory decolorization efficiency was achieved with the repeated use of Fe0 for five times. The PS/Fe0 process provides an efficiency and effective technology for RGY decolorization.