Biosorption of Cr(III) and Cr(VI) from Synthetic Solutions on NaOH-Modified Peel of Artocarpus nobilis Fruit – Adsorption Equilibrium Studies

The value addition of the peel of the edible fruit of Artocarpus nobilis , a plant endemic to Sri Lanka, performed through treatment with 0.010 M NaOH solution leads to the high removal of Cr(VI) and Cr(III) demonstrating its superior nature as a biosorbent. Owing to the fact that this waste material of a locally available edible fruit employed in the biosorption process makes it low-cost, environmentally friendly and energy efficient, which are of great advantages when compared to chemical treatment procedures practiced at present. The static experiments conducted using synthetic solutions of Cr(VI) and Cr(III) ions with NaOH-modified peel of Artocarpus nobilis fruit (NWBF) lead to the optimum parameters of 0.200 biosorbent dosage, 120 min shaking time and 30 min settling time. Regression analysis of linear and nonlinear fitting of adsorption data gathered through solution analysis after the suspension of NWBF and Cr species reaches equilibrium, followed by various error function determinations indicate that the Cr(III)/NWBF system follows Langmuir, Freundlich or Temkin isotherms, while the Cr(VI)/NWBF follows Freundlich and Sips isotherms. The monolayer adsorption capacities ( q _max ) determined through nonlinear curve fitting are 52.90 mg g ^− 1 and 14.39 mg g ^− 1 for Cr(VI) and Cr(III), respectively. Adsorption characteristics of NWFB are complicated due to non-homogeneous characteristics which lead to less precise results compared to those of homogeneous surfaces.