Promising Approach for Recycling of Spent CIGS Targets by Combining Electrochemical Techniques with Dehydration and Distillation

This study proposes an innovative approach to separate and recover copper, indium, gallium, and selenium (CIGS) from spent CIGS targets, which combines electrochemical techniques with dehydration and distillation. The leaching solution of the CIGS first underwent a two-step electrodeposition process to recover selenium and copper. Then, the remaining solution was distilled to recycle HCl and crystallize indium and gallium chlorides. Next, the as-obtained hydrates were dehydrated by refluxing thionyl chloride (SOCl2). Afterward, anhydrous InCl3 was recovered and separated from GaCl3 by a simple filtration, and the latter was separated from SOCl2 by distillation. The recovery of indium was ca. 99.99% with a purity of ca. 99.99%, while ca. 99.98% of gallium was recovered with a purity of ca. 99.99%. Both the recovery and purity are the highest to the best of our knowledge. The separation process was rationally designed to take full advantage of the potential difference of all the elements and the property of the dehydrating agent. This is an environmentally benign, economical, and practical method to recycle spent CIGS efficiently.