Evaluation of animal hairs-based activated carbon for sorption of norfloxacin and acetaminophen by comparing with cattail fiber-based activated carbon

Millions of tons of keratin wastes, including wool, hairs, horns, hooves and feather, are produced annually. They are almost pure keratin protein and hard degraded in environment. The use of keratin wastes as carbonaceous precursors for preparation of activated carbon could be a suitable method to solve the pollution. The paper presents the possibility of preparing activated carbon from keratin wastes (animal hairs, AH) and compares its physicochemical characteristics and sorption properties with the activated carbon derived from lignocellulose (cattail fibers, CF). Prior to activation at 500 °C for 1 h, AH and CF were dipped in phosphoric acid solution under two impregnation conditions: room temperature and pressure for 12 h (labeled as R) and high temperature and pressure for 20 min (labeled as H), producing R-AHAC, H-AHAC, R-CFAC and H-CFAC. R-AHAC and H-AHAC are mainly microporous, while R-CFAC and H-CFAC consist of a mix of micropores and mesopores. R-AHAC exhibits uneven carbonization and a much lower surface area than H-AHAC, while R-CFAC displays similar physicochemical properties to H-CFAC. H-AHAC shows higher (N+O+H) content, total acidic and basic functional groups and pH of point of zero charge than R-CFAC and H-CFAC. For H-AHAC and R-CFAC, sorption kinetics and isotherms of norfloxacin (NOR) and acetaminophen (ACP) agreed well with the pseudo-second-order model and Freundlich model. Additionally, with normalization of adsorbent surface area, sorption of NOR and ACP on H-AHAC was prominently higher than that on R-CFAC, which was attributed to their differences in physical and chemical characteristics.

► Activated carbons were produced from keratin and lignocellulose materials.
► High temperature and pressure impregnating methods (100 °C and 0.1 MPa) were used.
► H-AHAC had lower surface area, but higher acidic and basic groups than R-CFAC.
► H-AHAC had lower NOR sorption, but higher ACP sorption than R-CFAC per unit gram.
► H-AHAC showed much higher NOR and ACP sorption than R-CFAC per unit surface area.