Publication

Abstract : The study focuses on exploring the binding mechanisms of Ni(II) ions and determining the maximum uptake capacity of the biosorbent. The fresh biosorbent was subjected to sulfuric acid treatment to enhance the porosity and to introduce the specific sulfonic groups onto the surfaces of the biosorbent. Characterization techniques like scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and elemental analysis were utilized to understand the biosorption mechanisms. The results exhibit the likelihood of both physical and chemical interactions of the biosorbent with the Ni(II) ions. Out of the isotherm models investigated, Langmuir model presented a better fit to the experimental data favoring monolayer adsorption. In addition, intra-particle diffusion model revealed the possibility of both pore and film diffusion. Compared with pseudo–first-order model, pseudo-second-order kinetic model obtained a better fit. The outcome of the thermodynamic studies showed the exothermic nature of the biosorption process with a negative enthalpy value (ΔH°). Additionally, it is also significant to note that the adsorption of Ni(II) ions was favored only at lower temperatures. A maximum removal efficiency of 97% was observed for 25 mg/L Ni(II) solution. Moreover, the results of the desorption studies using 0.3 N HCl were also encouraging, with a removal efficiency of almost 91%. © 2017 Desalination Publications. All rights reserved.