There is an abundance of idle resources that have untapped potential which could help offset the dependence on non-renewable resources. Agricultural waste and plastic waste are two such idle resources that can be turned into value-added products such as activated carbon. Plastic pollution is a growing concern and finding ways to use plastic is critical to solving climate change. This study evaluates the physiochemical properties of co-pyrolysis (CoSP) process conditions on converting corn stover and plastics [PET and Polystyrene (PS)] into activated carbon (AC). The AC is achieved by a two-step chemical method of biochar and the chemical activator, KOH. A theory is developed on the biochar propensity to be chemically activated based on the composition of the lignocellulosic structure. The synergy between plastic and biomass was tested by comparing biochars and activated carbons by varying ratios of the feedstocks. Surface area and pore size of the biochars and activated carbons were measured using Brunauer-Emmett-Teller (BET). The PS CoSP biochar’s surface area ranged from 2-23 m2/g, while the PET CoSP biochar’ surface area ranged from 29-390 m2/g. Once activated, the PS CoSP AC surface area ranged from 380-594 m2/g, and the PET CoSP AC surface area ranged from 91-506 m2/g. Slow pyrolysis of corn stover yielded biochar surface area of 16 m2/g and AC surface area of 614 m2/g. Fourier Transform Infrared (FTIR) spectroscopy was used to determine the prevalent surface functional groups that influence the adsorption properties. The Scanning Electron Microscopy (SEM) images show a difference on the surface between the PET and PS CoSP biochars, with the PET biochar potentially having microplastics on the surface. Vanillin absorbent experiments were performed on the various activated carbons with up to 95% reduction shown. The best absorbent for vanillin was the AC produced from corn stover, while the ACs produced from the co-pyrolysis method adsorbed less. Overall, this study shows that changing the parameters in co-pyrolysis, such as type of plastic and ratio of biomass to plastic, will alter the physiochemical properties of biochars and activated carbons which can then be tailored to the desired application.

Evaluation of thermal and chemical conversion of agricultural and plastic waste into value-added products

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.