Separation of WPCBs by dissolution of brominated epoxy resins using DMSO and NMP: A comparative study

Printed circuit boards (PCBs) in electrical and electronic equipment (EEE) abide of valuable and hazardous materials and due to its complex and discrete make up across manufacturers, processing of waste PCBs (WPCBs) is a massive challenge. And therefore either completely novel or improved processes are needed for recycling of WPCBs and recovery of valuable materials from it. Present comparative study, was performed for processing WPCBs using solvents N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). Various parameters, which include WPCB sizes; solid to liquid (S/L) ratio; temperature and time, were investigated to understand the WPCBs processing by dissolving bromine epoxy resin using solvents. Results showed that the rate of removal and separation of the bromine epoxy resin (BER) increases with respect to increasing various parameters. Optimum condition of complete separation of WPCBs using NMP were S/L ratio of 1:5, WPCB size/area of 4 mm/16 mm2 and 100 °C for 90 minutes, whereas for DMSO the optimum dissolution of bisphenol A were obtained in S/L ratio of 1:2, size/area of 6 mm/36 mm2 at 90 °C for 90 min. Overall, NMP proves to be better solvent for bromine epoxy resin than DMSO in terms of bisphenol A dissolution and separation of various layers of WPCB. Used solvents can be vaporised-condensed under the decompression for regeneration. This novel process can be an eco-friendly and effective option for separation and recovery of various valuable materials such as metals, glass fibres, etc. from WPCBs. Further research and testing is needed for precise evaluation between two processes using NMP or DMSO solvents, in terms of the valuable material recovery from WPCB and process techno-economics.