Agricultural waste valorisation via activated carbon synthesis: A comprehensive study of material properties and environmental applications

Abstract

This study presents a comprehensive characterization of activated carbons derived from five agricultural waste materials: corn cob, coconut shell, rice husk, sugarcane waste, and groundnut shell. A systematic investigation was conducted to evaluate their physical, chemical, and adsorptive properties for potential application in water treatment. The activated carbons were characterized using multiple analytical techniques, including proximate analysis, bulk density measurement, scanning electron microscopy (SEM), iodine number determination, and methylene blue adsorption studies. Results revealed that coconut shell-derived activated carbon exhibited superior characteristics with the highest BET surface area (1000.15 m²/g), optimal fixed carbon content (88.92 %), and maximum methylene blue removal efficiency (96%). SEM analysis confirmed well-developed porous structures across all samples, with distinct morphological variations based on precursor materials. Bulk density varied significantly among samples, ranging from 0.121 g/cc (rice husk) to 1.562 g/cc (groundnut shell). Notably, sugarcane waste-derived activated carbon showed the highest iodine number (1593 mg/g), indicating excellent microporosity. The methylene blue adsorption capacity followed the order: coconut shell (80 mg/g-Lt) > groundnut shell (76.5 mg/g-Lt) > sugarcane waste (69.17 mg/g-Lt) > corn cob (64.7 mg/g-Lt) > rice husk (51.67 mg/g-Lt). This study demonstrates that agricultural waste materials can be effectively converted into high-performance activated carbons for water treatment applications, with coconut shell emerging as the most promising precursor among the studied materials.