Ag Compound Recovery from Used X-ray Film Using Supercritical Water

Abstract

Irrespective of the complex composition of industrial wastes, technical difficulties of material recycling must be resolved. For organic-inorganic composite wastes, supercritical water oxidation enables recovery of inorganic materials by decomposing organics into CO₂. We studied the recovery of Ag/AgBr from used X-ray films using supercritical water oxidation. Supercritical water oxidation treatment was conducted in a batch-type reactor at 673K and 25MPa with hydrogen peroxide as the oxidizing agent.
Results show that Ag/AgBr powder was recovered in 7min with no solid organic remaining. Organics can be decomposed into CO₂ within 30min. The AgBr was attacked and dissolved in water, while organics were decomposed catalytically by the effects of AgBr.
These results show that positive and negative effects of inorganics on the decomposition of organics and recovering inorganic materials can occur during supercritical water oxidation of organic-inorganic composite wastes.