Sustainability assessment of low-cost adsorbent production from pyrolyzed post-consumer mixed plastic waste

Abstract

The increasing production of plastic materials and rising environmental concerns regarding their disposal underscore the necessity for enhanced solutions to address plastic waste management, particularly for that which is difficult to recycle, such as post-consumer mixed plastic waste. Pyrolysis emerges as a promising alternative, as it not only eliminates the plastic waste, but also allows the production of gases, a liquid oil, and a solid char, all of which can have industrial application. Particularly, the char can be processed and utilised as an adsorbent to capture noxious gases and clean wastewater. This work examines a cost-effective method for producing adsorbents from the char obtained during the pyrolysis of post-consumer mixed plastic waste. The environmental impact of this production process is quantified using the Life-Cycle Assessment methodology. Results show that the primary contributors to the environmental impact are the phase of activation, followed by washing and filtering, largely due to the utilisation of substantial electricity, potassium carbonate, and hydrochloric acid. These factors make the environmental impact of this production method higher than that of other similar adsorbents obtained from hard coal and coconut shells, but lower than that of olive-waste cake for several impact categories. The analysis provided in this article includes a list of actions to optimise the production process by reducing its environmental impact. In this way, the production of adsorbents from post-consumer mixed plastic waste will not only be technically feasible and economically viable, but also environmentally beneficial.