Removal of imidacloprid pesticide using nanoporous activated carbons produced via pyrolysis of peach stone agricultural wastes

Abstract

This study describes the preparation of nanoporous activated carbons from the agricultural waste of peach stones. These materials were utilized as adsorbents for removing imidacloprid pesticide from aqueous media. Two types of activated carbons (PSAC 300 and PSAC 500) were synthesized via chemical activation with orthophosphoric acid followed by pyrolysis at 300 and 500 °C, respectively. Brunauer, Emmet, and Teller (BET) analysis revealed a mesoporous structure for PSAC 500 with lower surface area and pore volume than that of the microporous PSAC 300. Both PSAC 300 and PSAC 500 successfully removed imidacloprid with removal efficiencies of about 80% and 99%, respectively, at 10 mg/L of imidacloprid and pH 5.2, while PSAC 500 exhibited a maximum adsorption capacity of 39.37 mg/g. Fourier transform infrared (FTIR) spectroscopy measurements along with thermodynamic calculations inferred that physisorption occurred via hydrogen bonding and pi–pi stacking. The two activated carbons were successfully regenerated and reused for three consecutive cycles. This work has implications for waste valorization and production of value-added products from waste.