Recycling of Spent Nickel Catalyst Used in Hydrodechlorin of Hazardous Chlorinated Aromatic Compounds

Abstract

In the present study, a simple hydrometallurgical process for the recovery of spent Raney nickel catalyst was described. Deactivated Raney nickel catalyst is produced by treatment of waste water contaminated with chlorinated aromatic contaminants using Raney Al-Ni alloy in alkaline conditions. In this hydrometallurgical process, deactivated nickel slurry is dissolved in excess of aqueous sulfuric acid by co-action of peroxosulfate, unreacted H2SO4 is separated from aqueous aluminium and nickel sulphate solution by dialysis and Ni(OH)2 was precipitated under strongly alkaline conditions with aim to separate aluminium in the form of water soluble KAl(OH)4. Isolated Ni(OH)2 is converted by neutralization to the nickel sulphate which is directly applicable as the source of in-situ produced nickel slurry as effective dechlorination catalyst in co-action of NaBH4.