Passivation process and the mechanism of packing particles in the Fe0/GAC system during the treatment of ABS resin wastewater

Abstract

This study provides mechanistic insights into the passivation of the packing particles during the treatment of acrylonitrile–butadiene–styrene (ABS) resin wastewater by the Fe0/GAC system. The granular-activated carbon (GAC) and iron chippings (Fe0) were mixed together with a volumetric ratio of 1:1. GAC has a mean particle size of approximately 3–5 mm, a specific surface of 748 m2 g−1, a total pore volume of 0.48 mL g−1 and a bulk density of 0.49 g cm−3. The iron chippings have a compact and non-porous surface morphology. The results show that the packing particles in the Fe0/GAC system would lose their activity because the removal of TOC and for ABS resin wastewater could not carried out by the Fe0/GAC system after 40 days continuous running. Meanwhile, the availability of O2 and intrinsic reactivity of Fe0 play a key role on the form of passive film with different iron oxidation states. The passive film on the surface of iron chippings was formed by two phases: (a) local corrosion phase (0–20 d) and (b) co-precipitation phase (20–40 d), while that of GAC was mainly formed by the co-precipitation of corrosion products with and because and would not easily reach the Fe0 surface. Therefore, in order to avoid the occurrence of filler passivation, high concentrations of and in wastewater should be removed before the treatment process of the Fe/GAC system.