Removal of organochlorine pesticides using zerovalent iron supported on biochar nanocomposite from Nephelium lappaceum (Rambutan) fruit peel waste

• Main Authors: Batool, Samavia, Shah, Athar Ali, Abu Bakar, Ahmad Farid, Maah, Mohd Jamil, Abu Bakar, Nor Kartini
• Format: Article
• Published: Elsevier 2022
• Subjects: GE Environmental Sciences; QK Botany; SD Forestry
• Online Access: http://eprints.um.edu.my/33645/
• Institution: Universiti Malaya

Unique zerovalent iron (Fe-0) supported on biochar nanocomposite (Fe-0-B-RtP) was synthesized from Nephelium lappaceum (Rambutan) fruit peel waste and were applied for the simultaneous removal of 6 selected organochlorine pesticides (OCPs) from aqueous medium. During facile synthesis of Fe-0-B-RtP, Rambutan peel extract was used as the green reducing mediator to reduce Fe2+ to zerovalent iron (Fe-0), instead of toxic sodium borohydride which were used for chemical synthesis. For comparison, chemically synthesized Fe-0-B-Che nanocomposite was also prepared in this work. Characterization study confirmed the successful synthesis and dispersion of Fe-0 nanoparticles on biochar surface. Batch experiments revealed that Fe-0-B-RtP and Fe-0-B-Che nanocomposites combine the advantage of adsorption and dechlorination of OCPs in aqueous medium and up to 96-99% and 83-91% removal was obtained within 120 and 150 min, respectively at initial pH 4. Nevertheless, the reactivity of Fe-0-B-Che nanocomposite decreased 2 folds after being aged in air for one month, whilst Fe-0-B-RtP almost remained the same. Adsorption isotherm of OCPs were fitted well to Langmuir isotherm and then to Freundlich isotherm. The experimental kinetic data were fitted first to pseudo-second-order adsorption kinetic model and then to pseudo-first-order reduction kinetic model. The adsorption mechanism involves pi-pi electron-donor-acceptor interaction and adsorption is facilitated by the hydrophobic sorption and pore filling. After being reused five times, the removal efficiency of regenerated Fe-0-B-Che and Fe-0-B-RtP was 5-13% and 89-92%, respectively. The application of this Fe-0-B-RtP nanocomposite could represent a green and low-cost potential material for adsorption and subsequent reduction of OCPs in aquatic system.