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Materials and Energy Recovery from E‑Waste Plastics

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journal contribution
posted on 22.02.2018, 00:00 by Sriraam R. Chandrasekaran, Sumant Avasarala, Dheeptha Murali, Nandakishore Rajagopalan, Brajendra K. Sharma
The objective of the current study was to investigate environmentally sustainable and energy efficient processes to recover value added material and energy from e-waste as a means to divert these nondegradable materials from landfills. We studied two different types of plastics (1) simple mixtures like polycarbonate/polyamide (PC/PA)) found in cell phone plastics for solvent extraction and (2) complex mixtures like PC/PA/acrylonitrile butadiene styrene (ABS)/poly methyl methacrylate (PMMA) found in many other e-waste streams for pyrolysis. Solvent extraction using N-methyl-2-pyrrolidone (NMP) was performed as an alternate to using dichloromethane (DCM) for selective dissolution and recovery of PC from simple mixtures of cell phone plastic (CPP) to avoid the use of chlorinated compounds. Using distillation a recovery of 89% and 87% pure PC was observed for NMP and DCM, respectively. Relatively close to the first run, the recycled NMP also recovered 87% of pure PC. However, in order to reduce energy consumption in the NMP solvent recovery step a nonsolvent approach using methanol precipitation was demonstrated as an alternate route. Energy consumption through methanol distillation (343.3 kJ kg–1) was significantly lower than that of NMP (413.2 kJ kg–1). For other e-waste plastic mixtures like PC/PA/ABS/PMMA, a pyrolysis approach was demonstrated for waste reduction to 57% potentially decomposable solid residue, while generating pyrolysis oil. The results obtained in this work contribute to the development of a commercial and sustainable process to recycle e-waste plastics effectively. The development of these effective recycling practices helps to reduce prevailing e-waste plastic related environmental pollution.