Mechanistic insight into heterogeneous Fenton-like catalysis with M-Al2O3/SiO2 (M = Fe, Co and Ni) for acrylonitrile mineralization from real ABS resin wastewater: Optimization and toxicity assessment

Abstract

In this study, a novel heterogeneous catalyst M-Al2O3/SiO2 (M = Fe, Co and Ni) metal incorporate fly ash was synthesized via wet impregnation method and then evaluated the performance during treatment of acrylonitrile butadiene styrene (ABS) resin wastewater. Synthesized catalyst was characterized by several analytical techniques i.e., FTIR, XRD, BET, TEM, FE-SEM, XPS, EPR and IC-PMS techniques. Response surface methodology (RSM) based central composite design (CCD) was used to optimized the operating parameters within their ranges e.g., oxidant dose (H2O2) 5–25 mM, catalyst dose 300–1500 mg/L, pH 2.5–10.5 and reaction temperature 30–70 °C and their influences on acrylonitrile and COD removal were observed. In particular, enhanced removal of acrylonitrile (95.62%) and COD (88.95%) were obtained under the optimal conditions from RSM techniques. In order to evaluated the toxicity of resin wastewater, phytotoxicity study was carried out on various species as Vigna radiatus L., Cicer arietinum and Hordeum vulgare L. etc. Acrylonitrile and COD degradation kinetics were performed by two-step degradation and well fitted by first order kinetic model at different temperatures. The degradation pathways of acrylonitrile were elucidated by temporal evolution of intermediates and final products detected by GC-MS analysis along with reactive oxygen species (ROS) scavenger study. Over the four cycle experiments only 14.93% of acrylonitrile and 18.78% of COD removal efficiency were inhibited with and very low metal leaching. The overall operating cost of treatment process was estimated as 50.72$/m3 of ABS resin wastewater.