Review on solvent extraction of cadmium from various solutions

Cadmium has wide application in the manufacturing of alloys, batteries, pigments and metal plating. The solid and liquid waste is generated during the production and at the end of service life. The recovery and recycling of cadmium from these waste materials is necessary to gain the metal values and protect the environment from hazard. In hydrometallurgical processes, solvent extraction is an important process for the recovery of non-ferrous metals from different aqueous leach liquor and waste effluent/solutions. In present paper, the solvent extraction processes for the extraction and recovery of hazardous metal cadmium from aqueous solutions associated with commonly metallic and non-metallic ions, such as sulfate, chloride, nitrate and phosphate have been reviewed. Different process parameters, viz. pH, organic- to -aqueous ratio, kinetics of extraction and stripping to establish the conditions required for the extraction of cadmium and formation of a complex in the organic phase from different solutions, have been reported. The studies show the possibility of extraction and separation of cadmium from different solutions containing other metallic ions using anionic, cationic, solvating or mixed extractants. However, further attempts are also being made to develop selective organic extractants to recover cadmium efficiently on a commercial scale. The findings of these studies are also reported.