Environmentally friendly recovery of Ag from end-of-life c-Si solar cell using organic acid and its electrochemical purification

Abstract

Environmentally friendly and reusable methanesulfonic acid (MSA) was used with the addition of an oxidizing agent to extract Ag from solar cells. Recovery using varying MSA:H2O2 mixing ratios of 100:0, 90:10, 75:25, 50:50, and 0:100 revealed that Ag can be effectively extracted in a MSA-rich solution. The concentration of Ag ions dissolved in each mixture was analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), which established that the optimal extraction condition is a MSA:H2O2 ratio of 90:10. The addition of HCl to the leaching solution used for Ag recovery prompted the precipitation of AgCl, which was then reacted in turn with NaOH and H2O2 to recover Ag metal powder. This Ag metal powder was analyzed by glow discharge mass spectrometry (GDMS) and found to have a low purity of around 99% (2N), but this was found to be improved through subsequent electrorefining to a purity of 99.995% (4N5).