Electrolytic desorption of silver from ion-exchange resins

Strong base ion-exchange resins Lewatit M 500 and Lewatit M 504 have steep ascending parts of isotherm curves in the range of low silver concentration in solution and can be used for silver extraction from plating rinsing effluents. Common elution methods are very inefficient for silver removal from strong base ion-exchange resins. Hence, the silver regeneration was performed by the electrolysis coupled elution process. During the process, the mass of silver deposited on the cathode and the I(t)-t curves were recorded. The electrolysis current was allowed to decrease to a value that corresponds to about 10% of the silver capacity. This was achieved from Lewatit M 500 at -1.14 V electrolysis potential using the Pt cylinder gauze working electrode and at -1.30 V using the Ni cylinder working electrode and from Lewatit M 504, at -1.10 V using the Pt cylinder gauze working electrode and at -1.19 V using the Ni cylinder electrode. During the first 3 h of the process 60-80% of the silver can be removed. The desorption process depends on the hydrodynamic conditions provided between the resin beads and solution. It is possible to reuse Lewatit M 500 for the silver adsorption and desorption processes at least three times. (C) 1998 Elsevier Science Ltd. All rights reserved.