Abstract

Adsorption of silver from synthetic photographic and spent fix solutions on granulated activated carbon in a batch process has been investigated. The synthetic solutions prepared had similar properties to medical X-ray and photographic process effluents. Sodium and ammonium thiosulfates are the major lixiviants used in the dissolution of silver halides present in photographic and medical X-ray films. The resultant solutions contain substantial amounts of recoverable silver complexes in the form of thiosulfates. The as received carbons were alkaline in nature when contacted with deionised water. These carbons showed very low silver recoveries. However, when these carbons were pre-treated with 0.5 mol/dm 3 sulphuric and nitric acids at 25 °C, it had resulted in significant silver recoveries of 98.5% and 95% from sodium and ammonium thiosulfate solutions, respectively. These results were achieved in a narrow range of pH between 3 and 4. Batch atmospheric stripping of adsorbed silver by 2.0 mol/dm 3 HNO 3 at 85 °C was also investigated.

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