Recovery of palladium from palladium phthalocyanine complex adsorbed on silica

This study presents the feasibility of recovering palladium from the spent silica waste wherein palladium is adsorbed on silica as palladium phthalocyanine complexes. The spent silica having palladium phthalocyanine complexes adsorbed on it is thermally calcined in air to partially burn the organic moiety of the complex followed by palladium dissolution as H2PdCl4 in hydrochloric acid. The palladium is recovered as PdCl2 by judiciously adjusting the pH of filtrate obtained. Recovered silica retains its structure and can be re-used.