LEACHING OF NICKEL FROM SUPPORTED NICKEL WASTE CATALYST USING AQUEOUS SULFUR-DIOXIDE SOLUTION

Waste nickel catalyst is an important secondary source for recovery of nickel. Nickel from the waste has been leached out using aqueous SO2 solution. The initial leaching kinetics is controlled by reaction at the surface involving the adsorption of SO2 and H+ resulting in the formation of product species. A kinetic model based on the above scheme has been presented. The X-ray photoelectron spectroscopy (XPS) studies indicate that easily soluble Ni(OH)2 or NiO is initially leached out, leaving behind the other nickel species which dissolves at a slower rate.