Valorization of waste pistachio shells to bimetallic magnetic hydrochar for sustainable dual-action wastewater remediation: A comprehensive study with mechanistic insights and life cycle assessment

Abstract

This research outlines an integrated experimental and theoretical strategy for converting Pistachio-shells by hydrothermal carbonization into a bimetallic magnetic hydrochar (BMHC), for effective adsorptive-degradation of organic pollutants. Environmental sustainability of BMHC is supported by life cycle assessment(LCA). Adsorption experiments showed rapid and efficient dye (MB, CV) and antibiotic (TC) removal within 50 min, with >97% efficiency. The catalytic properties of BMHC, facilitated Peroxymonosulfate (PMS)-driven complete degradation of targeted contaminants, through ROS generation. DFT calculations demonstrated the regioselectivity for targeted moieties. The degradation intermediates were identified by LCMS and possible degradation pathways were derived. In-silico toxicity assessment of these intermediates confirmed the process safety. Employing 'Hook and Destroy' approach, BMHC demonstrated magnetic separation and reusability over five cycles. This extensive research demonstrates waste-to-resource conversion of Pistachio-shells to BMHC, with dual functionality in adsorption and degradation, as well as magnetic recoverability, which advocates its potency for water treatment solutions.