Double-function synergistic treatment system: Mask-biochar package for methylene blue adsorption and high-quality bioproducts recovery via pyrolysis in wastewater treatment and fuel production

Abstract

Waste disposable masks cause serious environmental pollution due to their slow degradation. This study investigated a simple and efficient method to recycle masks for high-value additional utilization. Polypropylene-based waste masks were dismantled and combined with Enteromorpha clathrate biochar (AC) to produce mask-biochar packages (M-AC), which were applied to wastewater (containing methylene blue) treatment. The results showed that compared with AC alone, the removal rate of MB solution by mask-biochar packages (M-AC) increased by 18.50 %. Then, the used mask-biochar packages (M-AC) were pyrolyzed at 550 °C to obtain hydrocarbon-rich bio-oil and composite biochar (MAC). Compared to MAC alone, the mask-biochar package (M-MAC) increased the removal rate of MB by 10.16 %. The composite biochar has achieved a high adsorption capacity of 820.925 mg·g−1 without any activator and acid washing process. The hydrocarbon content is 55.31 % which makes it a hydrocarbon-rich bio-oil. This study provided effective experimental support for the combined use of biomass and mask for waste treatment and for the production of biochar.