Recovery of indium tin oxide (ITO) and glass plate from discarded TFT-LCD panels using an electrochemical method and acid treatment

Abstract

The recovery of ITO and the glass substrate from discarded TFT-LCDs, without crushing the glass substrate, was done by using an electrochemical method and acid treatments. Anodic conditions did not show any redox reaction of the ITO except oxygen evolution. The oxygen evolution lifted the ITO layer off the glass substrate with the remaining colour filer and black matrix. Recovery of the ITO was 75%, but it showed an In–Sn ratio of 15.9 : 1. The recovered ITO was not suitable for reuse directly. It may be that it needed the addition of extra Sn. However, this work presented a new process for the resource circulation of the indium from discarded LCD panels. The free glass substrate was then recovered after removing the colour filter and black matrix by using an acid solution. The optical transmittance of the recovered glass substrate was about 90% in the visible region, and the average roughness was 0.96 nm.