Recovery of Silver from Waste Radiographic Films by Chemical Leaching

Abstract

The major sources to recover silver are photo-processing solutions, spent rinse water, scrap film and scrap printing paper. As much as 80 % of the total silver processed for black and white positives and almost 100 % of the silver processed in colour work will end up in the fixer solution. The waste radiographic films used in the experiments were taken from Cukurova University, Balcali Hospital, Adana, Turkey and cut into small pieces. The film pieces (1-9 g) were boiled with 100 mL of various quantities of oxalic acid, nitric acid and sodium hydroxide solutions for about 2.5, 5.0, 7.5 and 10 min at boiling temperature (@ 97 ºC). The aim of the study is to recover silver from waste radiographic films by HNO3 leaching. To optimize the results of the experimental work, variance analysis was used. The statistical tests (F-tests) showed that nitric acid gave the best results compared with the other agents. Under optimum leaching conditions (radiographic films quantity, 50 g/L; nitric acid concentration, 30 g/L; stirring speed, 180 rpm; leaching time, 15 min) 89 % silver recovery was obtained.