Recovery of metallic lead from End-Of-Life silicon solar modules using salt bridge electrowinning

Abstract

Toxic lead (Pb) in end-of-life silicon solar modules must be recovered to keep it out of the environment. Present literature on Pb recovery from solar waste is sparse and uses chemicals like nitric or hydrochloric acid. Previously, the authors reported Pb recovery from silicon modules by leaching and electrowinning in acetic acid. However, the Pb recovered from acetic solution contained a small amount of metallic Pb with the rest being lead oxides/acetates. These Pb compounds require further processing to obtain metallic Pb for reuse in solar panel solder, leading to additional cost and chemical waste. This paper reports recovery of metallic Pb using an electrochemical system with two half cells connected through a salt bridge. The salt bridge enables optimized recovery rates of Pb as high as 99.99 % for synthetic leachates. The first experiment to recover Pb from real silicon module waste shows 80 % recovery without optimization. The new method offers a low-cost, closed-loop, direct pathway to metallic Pb recovery from end-of-life silicon solar modules for reuse in new modules.