Enhanced removal of Thiamethoxam from wastewater using waste-derived nanoparticles: adsorption performance and mechanisms

Abstract

Thiamethoxam (TMX) is a highly toxic systemic neonicotinoid pesticide and its entry into water bodies can greatly endanger human health and aquatic ecosystems. Hence, developing low-cost, ecofriendly and efficient adsorbents is urgently needed for removal of TMX from contaminated water. In this study, the nanostructured alum water treatment residuals (nWTR) were produced, characterized and evaluated, for the first time, for TMX removal from wastewater through sorption and mechanism studies. The impact of pH, sorbent/TMX solution ratio, exposure time, initial TMX concentration, and temperature on the TMX removal process were examined. The maximum adsorption capacity of TMX by nWTR was enhanced 2.6 times higher than that of bulk WTR due to enlarged specific surface area and pore volume. The adsorption equilibrium and kinetics data best followed Langmuir and first order models respectively. The thermodynamic study showed that the adsorption reaction of TMX onto nWTR was a spontaneous and endothermic process. The suggested mechanisms of TMX sorption by nWTR are hydrogen bonding, Al and Fe complexes formation and electrostatic interlinkage. Furthermore, the reusability study showed that nWTR sorbent can be effectively applied for up to 3 consecutive cycles for the remediation of TMX contaminated wastewater. The study demonstrates the potential use of nWTRs as cost effective, stable, reusable and promising adsorbent for TMX removal from wastewater.