BATCH AND FIXED-BED STUDIES OF AMMONIA TREATED COCONUT SHELL ACTIVATED CARBON FOR ADSORPTION OF BENZENE AND TOLUENE

Abstract

There have been numerous reports linking volatile organic compounds (VOCs) to both acute and chronic health issues as well as environmental damage including global warming. In this study, ammonia was used to enhance the hydrophobicity and affinity of a low-cost, renewable and sustainable activated carbon made from coconut shells (PHAC-AM). Batch and fixed-bed investigations were utilized in determination of removal rates and adsorption capacities for benzene and toluene using activated carbon modified with ammonia (PHAC-AM). The adsorption process was tested using the Tempkin, Freundlich, and Langmuir adsorption isotherms, with Langmuir model being the best and fitted the experimental results, while the Tempkin model being the least. The fitness of the models was justified for suitability and favourability using the root square mean deviation (RSMD), and equilibrium parameter (R L). According to differences obtained between predicted and experimental values, pseudo-second-order kinetic model was the most suitable in describing kinetics of the two VOCs adsorbed than the pseudo-first-order kinetics. The effects of bed height, initial VOC concentration, and influent flow rate for adsorption of benzene and toluene were investigated in fixed-bed study. For benzene and toluene, 77.30 and 69.40 mg/g were highest obtained bed capacities at initial VOC concentration of 250 mg/L, 4.5 mL/min flow rate, and 2.5 cm bed height, respectively. According to the findings, the synthesized ammonia-treated adsorbent (PHAC-AM), is a sustainable, and suitable for the remediation of VOC contaminated waters.