Efficient catalyst prepared from water treatment residuals and industrial glucose using hydrothermal treatment: Preparation, characterization and its catalytic performance for activating peroxymonosulfate to degrade imidacloprid

Abstract

Water treatment residuals (WTRs), as by-products of drinking water treatment plant, were used as catalyst for persulfate activation to degrade organic pollutants. In this study, G-HWTRs were successfully prepared by hydrothermal treatment, which combined WTRs and a hydrothermal reducing agent (industrial glucose) in different ratios. These materials manifested upgraded performance compared with raw WTRs and HWTRs (prepared only with WTRs under hydrothermal condition) in imidacloprid (IMD) degradation. The elemental composition, structure, morphological and magnetic properties of the G-HWTRs were investigated. And the influences of peroxymonosulfate (PMS) concentration, G-HWTRs dosage, initial pH, water matrix on IMD degradation were determined. The results demonstrated that G-HWTRs-3 had the best catalytic performance, 10 μM IMD was almost completely degraded in the system of G-HWTRs (0.2 g L−1) and PMS (0.1 mM) within 2 h without pH adjustment. Based on the results of the electron spin-resonance spectroscopy (ESR) tests and radicals scavenging experiments, all of SO4−, OH, 1O2 and O2− were the reactive oxygen species driving the IMD degradation, and OH was regarded as the main role of IMD degradation. The possible degradation pathways of IMD were further proposed based on the degradation intermediates that identified by LC-MS. Besides, further experiments indicated G-HWTRs has degradation potential for various pollutants, the degradation rate of atrazine (ATZ), acetochlor (ACE) and simazine (SMX) within 2 h achieved 92.54%, 83.88% and 90.25%, respectively. These results confirmed G-HWTRs has good catalytic performance and activation potential on PMS, providing an effective method for remediating organic polluted wastewater.