Recovery of metals from solar cells by bioleaching

Abstract

Solar energy is commonly seen as a clean energy source, an alternative to the fossil fuels, as there is no emission of any matter into the environment during operation, endurable operation period, minimum maintenance, robust technique and aesthetic aspects. If one considers the growing use of solar cells, the problem of recycling spent solar cells, the quantities of which will increase rapidly in the coming years, is yet to be solved. Establishing a technology for recycling and reusing the same is thus a necessity. Solar cells contain precious metals including silver, tellurium, and indium along with other heavy metals such as copper, aluminum, lead, arsenic, cadmium, selenium which are hazardous. Limited recycling will result in disposal of these recoverable metals in the waste. There remains the dearth of studies on recycling of old solar cells using microorganisms. In the current study, the recovery of metals from solar cells was investigated using Thiobacillus ferrooxidans micro-organism, and its culture supernatant was found to be effective for bioleaching of metals from solar cell powder. B, Mg, Si, Ni and Zn were removed with 100% efficiency within a reasonable time. T. ferrooxidans recovered 100% Cr, Mn, and Cu at 60 °C, however, only 41.6 and 13.4% of Al and Te were extracted respectively. These results suggest the higher temperature optimum for metal recovery from solar cells in use of the organism. The possible success in this endeavor will allow reuse of waste solar cells without affecting the environment.