Photocatalytic gold recovery from spent cyanide plating bath solutions

A new procedure is presented for the photocatalytic treatment of the highly stable gold-cyanide complexes remaining in spent plating bath solutions. The process allows the recovery of gold by photocatalytic reduction, increasing simultaneously the availability of cyanide for removal treatment. Gold recovery requires a non-oxidant atmosphere and the presence of hydroxyl radical scavengers. The use of mixed TiO2/SiO2 photocatalysts leads to an improvement in the gold recovery rate.