Production of activated carbon derived from rice hulls using sugar cane bagasse as activating agent

Abstract

Widespread contamination of natural water resources by pollutants poses a significant environmental challenge. This thesis explores the potential of activated carbon derived from rice husk as a viable adsorbent for eliminating contaminants from aqueous solutions, specifically focusing on methylene blue as a model solution. The study provides a comprehensive analysis of adsorption kinetics, isotherms, and their implications for environmental remediation. It involves the gasification of rice husk using sugarcane bagasse, another economical agricultural byproduct, as a source of carbon dioxide (CO2) in an oxygen-rich environment to activate the carbon. This process utilizes the two crucible method minimizing oxygen use and using CO2 as an oxidizing agent. This approach enhances activated carbon development by increasing its porosity and providing a substantial surface area, making it suitable for various treatment applications. The present work demonstrated that the adsorption efficiency of methylene blue and iodine was maximum when rice husk underwent chemical and physical treatment with HNO3 and NaOH 1N for 2 hours at 710◦C for 30 minutes, with a heating rate of 10◦C·min-1, and sugarcane bagasse as the activating agent. The activated carbon derived from rice husk exhibited an iodine number of 836 mg·g-1, methylene blue removal rate at 94.1% and its adsorption capacity was reported as 285 mg·g-1 at a temperature of 25◦C. Adsorption kinetics were explored by examining the contact time and initial concentration of the pollutant. Experimental data were fitted to various kinetic models, including pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The results of methylene blue adsorption were in agreement with the pseudo-second-order kinetic model (R² > 0.99), indicating that chemisorption is the rate-controlling step. Additionally, the study evaluated adsorption isotherms by varying the initial concentrations of the pollutant. Langmuir, Freundlich, BET, and Temkin isotherm models were applied to the dataset. The Langmuir isotherm model showed the best fit (R² > 0.99), suggesting monolayer adsorption with a finite number of adsorption sites. This research has practical implications for designingwater treatment systems based on adsorption to eliminate water contaminants. Activated carbon from rice husk, enhanced by using sugarcane bagasse as an activating agent, emerges as a promising adsorbent with minimal technical constraints. Future research may focus on optimizing activated carbon production strategies and designing larger-scale adsorption systems."

Date	23 Feb 2024
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Frédéric Monette (Supervisor)