Highly effective adsorption of antibiotics from water by hierarchically porous carbon: Effect of nanoporous geometry

Pharmaceutical antibiotics have recently become emerging environmental contaminants. To enhance the removal efficiency of antibiotics in water, hierarchically porous carbons (HPCs) with designed porous patterns are used in both batch and column mode adsorption processes in this study, and the role of their nanoporous geometry in the adsorption dynamics are explored. THPC (HPC with trimodal pores) and DHPC (HPC with bimodal pores) exhibit remarkably superior adsorption performances to the selected antibiotics than those of commercial activated carbon (AC) with similar surface area, especially in column mode adsorption. The effective treatment volumes of the HPC-columns remain up to 8–10 times those of the AC-columns for the removal of tetracycline and 4–6 times for the removal of tylosin. The mass transfer rates of the carbon-based columns present the order of THPC > DHPC > AC. As comparison, the columns based on monomodal mesoporous carbon (MEC) and microporous carbon (MAC) exhibit low effective treatment volumes although their high mass transfer speed. The interconnected meso/macropores in HPCs benefit the intraparticle mass transfer of guest molecules and the accessibility of adsorption sites. The micropores linking to the meso/macropores not only provide adsorption sites but also facilitate adsorption affinity.