Leaching recovery of silver from used radiographic films

Abstract

A preliminary leaching recovery of silver metal from waste radiographic films with potassium hydroxide (KOH) in a water bath was investigated. The rinsed and cleansed films were sized into squares before being dried in an oven at 20 °C for 30 min. Silver oxide was precipitated with potassium hydroxide at varying concentrations at 90 °C in a water bath by agitated leaching. The leach solutions were filtered and the filtrates obtained analyzed for silver with Atomic Absorption Spectrophotometer. The results obtained showed that the leach liquors assayed 648.27, 984.86 and 1017.82 mg/L for KOH solutions of molar concentrations 0.02, 0.5 and 1.0 M, respectively. The silver oxide precipitate obtained after filtration was also thermally decomposed at 450 °C. Future research will include analysis for the silver content of the residue resulting from thermal decomposition. The study showed that silver metal in waste radiographic films can be leached with potassium hydroxide in a water bath at 90 °C and thus further confirm waste radiographic films as a secondary resource for silver recovery.