(509ap) Recovery of Cobalt from Spent Catalyst Using Edta as a Chelating Agent

Metals like Ni, Mo, Co, Pb etc. are widely used as catalyst. After periodical use catalyst becomes inactive. In such cases, fresh catalysts have to be replaced and the spent catalyst will be discarded as waste material. This spent catalyst causes pollution wherever it is disposed off. Therefore, a suitable and economically viable method is required for recovery of metal from these polluted locations or directly from the spent catalyst.

Metal extraction and recovery experiments were conducted primarily for cobalt with varying experimental conditions to study their effect on the recovery of chelating agent and the metal ions. Effects of parameter such as EDTA concentration, Solid to Liquid ratio and pH related to extraction and recovery efficiencies of the chelator as well as workable recovery conditions was observed.

The results showed that EDTA was capable of extracting Co from the catalyst and could be recovered by the use of HNO3. Thus, EDTA proved to be strong and reusable chelating agent for Cobalt metal from the catalyst, which makes it valid remediation agent for metal extraction from other polluted sources like contaminated soil, sewage sludge and saline water etc. Optimum recovery (90%) of Co was obtained at 0.8 M concentration of EDTA and solid /liquid ratio was kept 1:20. The reactor used was a stirred batch reactor and the rotating speed of the stirrer was kept at 950 rpm and the temperature was kept as 100o C at the optimum recovery point.