Title: Defluoridation of waters using low-cost HNO3 activated carbon derived from stems of Senna Occidentalis plant

Authors: Mekala Suneetha; Bethanabhatla Syama Sundar; Kunta Ravindhranath

Addresses: Department of Chemistry, Acharya Nagarjuna University, Nagarjuna Nagar, Guntur Dt., AP, India ' Department of Chemistry, Acharya Nagarjuna University, Nagarjuna Nagar, Guntur Dt., AP, India ' Department of Chemistry, KL University, Vaddeswaram, 522 502, Guntur Dt., AP, India

Abstract: A simple, accurate and reliable batch adsorption technique for the removal of fluoride has been developed using an active carbon derived from stems of Senna Occidentalis plant (NSOC). Various physicochemical parameters have been optimised. The maximum extraction of fluoride has been found to be at pH: 7 with an agitation time of 50 min at fluoride ion concentration of 5 mg/lit and at temperature of 30 ± 1°C. Adsorption isotherms have been modelled using Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherms. The correlation coefficient (R2) and dimensionless separation factor (RL) values obtained for the present adsorption system confirm that the best fit is 'the Langmuir adsorption isotherm' model. Kinetics of adsorption processes have been studied and observed to be pseudo second-order kinetics. The active carbon has been characterised using FTIR and SEM-EDX techniques. The methodologies developed are applied to real ground water samples and found to be successful.

Keywords: fluoride in water; adsorption; low cost activated carbon; plant stems; Senna Occidentalis; adsorption isotherms; adsorption kinetics; surface characterisation; case study; water defluoridation; HNO3; nitric acid; groundwater.

DOI: 10.1504/IJETM.2015.073079

International Journal of Environmental Technology and Management, 2015 Vol.18 No.5/6, pp.420 - 447

Available online: 13 Nov 2015 *

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