Co-carbonization of biomass and oily sludge to prepare sulfamethoxazole super-adsorbent materials.

Different biomass materials (walnut shell, coconut shell or cottonwood sawdust) were co-pyrolyzed with carbon-enriched oily sludge to produce aqueous phase sulfamethoxazole (SMZ) adsorption materials. The co-pyrolysis char was activated with K2CO3 to modify its micro-structure and functional groups. Results show that ACs prepared from the mixture contained more mesopores than biomass-based ACs, more porous and higher yield than oily sludge-based ACs. One-step activation method was more attractive than two-step activation in larger specific surface area (up to almost 4 times), wider pore size distribution (2-3 nm), stronger SMZ adsorption ability (higher than 2 times). The maximum BET surface area was 1342 m2/g for the ACs prepared from the mixture of walnut shell and oily sludge by one-step activation and it had the maximum SMZ adsorption capacity up to 361.9 mg/g, which is higher than previous reported values. The capacity of SMZ adsorption of ACs was mainly attributed to pore size distribution, specific surface area and functional groups. Among them, the appropriate content of CO and CO functional groups, larger specific area and more pores range from 2 to 3 nm lead to higher adsorption capacity.