Adsorption of pharmaceutical antibiotics on template-synthesized ordered micro- and mesoporous carbons

The presence of pharmaceutical antibiotics in aquatic environments poses potential human health and ecological risks. We synthesized ordered micro- and mesoporous carbons, and further conducted batch experiments to systematically examine their adsorption properties toward three antibiotics, sulfamethoxazole, tetracycline, and tylosin, in aqueous solution. In comparison, nonporous graphite, single-walled carbon nanotubes, and two commercial microporous activated carbons were included as additional adsorbents. Adsorption of low-sized sulfamethoxazole was stronger on the activated carbons than on other carbonaceous adsorbents resulting from the pore-filling effect; in contrast, due to the size-exclusion effect adsorption of bulky tetracycline and tylosin was much lower on the activated carbons, especially for the more microporous one, than on the synthesized carbons. After normalizing for adsorbent surface area, adsorption of tetracycline and tylosin on the synthesized carbons was similar to that on nonporous graphite, reflecting complete accessibility of the adsorbent surface area in adsorption. Additionally, compared with other porous adsorbents the synthesized carbons showed faster adsorption kinetics of tetracycline and tylosin, which was attributed to their regular-shaped, open and interconnected three-dimensional pore structure. The findings indicate that template-synthesized micro- and mesoporous carbons are promising adsorbents for the removal of antibiotics, particularly, the bulky and flexible-structured compounds, from aqueous solution.