Deterioration of cross linked polymers of thermoset plastics of e-waste as a side part of bioleaching process

Abstract

Bioleaching is a process of metal extraction which requires very low energy and less emission of toxic gases. The polymers that are left out after bioleaching were very hard to degrade as they are thermoset or cross linked polymers. But studies revealed that the polymers could be deteriorated with the help of various environmental factors like sunlight, UV etc. This characteristic feature was an important parameter for the construction of an electronic device. An attempt has been done to find out the ability of microbes to deteriorate plastics after metal recovery from WPCB. A. niger was used to leach out copper in this experiment as it holds nearly 75% of the metallic fraction present on the surface of WPCB and also according to the resource recovery efficiency copper was known to have larger profit than that of the rest of the metals present in it. A period of 21 days was given for bioleaching after which the bioleachate was drained. The set up was set aside for 45 days to know the strength of the microorganisms to degrade the cross linked polymers with the help of the enzymes they produce. Thus it was found that the microbes used for bioleaching turned to be potent to deteriorate plastics. It was confirmed with the help of SEM analysis. The degradation ability was tested before and after bioleaching with the help of Thermo-Gravimetric-Differential Thermal Analyser (TG-DTA) and the change in molecular group was studied with the help of Fourier Transform Infrared Spectrometer (FTIR).