Adsorption and desorption studies of Ni2+ ions on to coconut shell char

Heavy metal discharge with wastewater (WW) is a major environmental concern, widely discussed today. Heavy metals in WW can be removed by several methods including adsorption. Activated carbon (AC) derived from coconut shells is widely used, but expensive adsorbent. In this study coconut shell char (CSC) was tested as an effective low-cost adsorbent for heavy metal removal from aqueous solutions. Batch adsorption experiments were conducted using CSC as the adsorbent to remove Ni2+ from water. CSC has 12% removal efficiency for a solution of 25 mg Ni2+/L with a dose of 2 g adsorbent/200 mL solution. The isotherm results have shown that, equilibrium data best obey to Langmuir monolayer model. The adsorption kinetics studies revealed, that adsorption behave according to the pseudo-second order model. It was identified that adsorption process has two steps as external diffusion and intraparticle diffusion. Furthermore, desorption abilities of H2SO4, NaOH, NaCl and Distilled water as desorbing agents were analysed and found H2SO4 to be the most effective desorbing agent.