Optimization,equilibrium, and kinetic studies of adsorptive removal of cobalt(II) from aqueous solutions using Cocos nucifera L.

Water discharged by several industries contains toxins, and it needs to be treated before disposal or reuse. In the present study, feasibility of adsorptive removal of Cobalt(II) ion in waste water, using Cocos nucifera leaf powder, is exhaustively studied and reported. Effects of contributing parameters like Cobalt(II) ion concentration, initial solution pH, adsorbent dosage, and temperature are studied and the levels of parameters optimized, following a two level?four full-factorial experimental design with 6 center points and 24 non-center points. 15?g/L of Cocos nucifera leaf powder could reduce the Cobalt(II) ion concentration by 84.82% in 70?min at a pH of 5.0 and a temperature of 303?K. Freundlich model is marginally superior to Langmuir, Halsey, and Temkin models in representing the equilibrium, at the optimized conditions. Pseudo-second-order kinetics model describes the adsorption process with a rate constant of 0.1238?g/mg-min. From thermodynamic analysis, it is noted that the adsorption is endothermic and facilitated.