The use of such metals as cadmium, selenium is entailed in the manufacture of thin film photovoltaic (PV) modules. The increasing awareness of environmental concerns and risks associated with the toxicity of these heavy metals has prompted the recycling of the PV modules at the end of their useful life. A hydrometallurgical processing route, namely, H_2SO_4/H_2O_2 leaching-> cation exchange separation-> electrowinning, to recycle metals from cadmium-telluride (CdTe) PV modules are proposed and investigated at the Brookhaven National Laboratory. In the leaching procedure, the stripping of both cadmium and tellurium from PV module substrates was achieved through leaching with hydrogen and dilute sulfuric acid solution using a tumbling machine. Our leach tests showed that both cadmium and tellurium were readily solubilized within 30 minutes with low strength of acid (1.0 M H_2SO_4) at ambient temperature. Leaching the CdTe PV module scraps yielded complete extraction of both cadmium and tellurium. In the separation step, cation exchange resin was used to remove and separate cadmium completely from tellurium-rich leach liquor of 0.5 M H_2SO_4. Through this operation, the cadmium was exchanged to the resin while the tellurium, on the other hand, remained in the leach liquor for the recovery. Ion exchange column studies showed that elution of the resin with high strength of H_2SO_4 solution generated concentrated cadmium solution, which was subjected to the recovery of cadmium using an electrowinning process. This paper details the leaching of CdTe PV modules with sulfuric acid solution and separation of cadmium from tellurium by cation exchange resin.
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