Comparison of adsorption characteristics of Ni(II) on fibres of Agave americana and areca nut husk

Abstract

Heavy metal contamination is of major concern at present due to its adverse impacts on humans and the environment. Among many heavy metal remediation methods, biosorption has become attractive in the recent past due to its low-cost and environmentally sustainable nature. Nevertheless, fibrous biosorbents have not been much explored, especially for the removal of Ni(II) species. Though Ni is a micronutrient that contributes to certain cellular functions in the human body and plants, higher concentrations of it could impose adverse health effects as well as ecological damage. Hence, Ni remediation should be carried out before releasing industrial effluent to the environment. This work is thus based on a comparative study to investigate the adsorption potential of Agave americana fibre and Areca nut husk fibre for the removal of Ni(II) ions from aqueous solutions. This study aims to optimize experimental parameters varying one parameter at a time throughout a broad range keeping others constant for the two biosorbents separately. Both Agave americana fibre and Areca nut husk fibre exhibit significant adsorption capacities toward the adsorption of Ni(II) ions with average removal of 90.39% and 93.27%, respectively, in batch experiments, conducted using 10 mg L-1 Ni(II) solution under optimized conditions of 60 min shaking time, 20 min settling time, ambient pH, ambient temperature and 150 rpm agitation speed for an optimum dosage of 20.00 g L-1 of the biosorbents. Adsorption isotherm studies, conducted using Ni(II) solutions of initial concentrations in the range from 10 mg L-1 to 350 mg L-1, show that the Langmuir model is a better fit for the two types of fibre with higher regression coefficients of 0.9836 and 0.9937 than those of the Freundlich model for Agave americana and Areca nut husk fibre, with the maximum adsorption capacities of 1.03 mg g-1 and 1.68 mg g-1 respectively. These studies could be extended for the design of treatment plants for large-scale removal of Ni(II) ions from contaminated water.