Enhanced removal of sulfonamide antibiotics by KOH-activated anthracite coal: Batch and fixed-bed studies

• Published in: Environmental pollution (1987) 2016-04, Vol.211, p.425-434
• Main Authors: Zuo, Linzi, Ai, Jing, Fu, Heyun, Chen, Wei, Zheng, Shourong, Xu, Zhaoyi, Zhu, Dongqiang
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Anthracite; Antibiotics; Batch adsorption; Carbon - chemistry; Charcoal - chemistry; Coal; Dinitrobenzenes; Fixed-bed adsorption; Isotherms; KOH activation; Microporosity; Models, Chemical; Molecular size; Nitrophenols; Porosity; Sulfamethoxazole; Sulfonamides; Sulfonamides - analysis; Sulfonamides - chemistry; Surface chemistry; Water Purification - methods
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2015.12.064

The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m2/g), high pore volume (1.23 cm3/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution. •A high efficiency adsorbent for sulfonamide removal is prepared from anthracite.•Effects of adsorbent porosity are studied in both batch mode and fixed-bed mode.•KOH-activated anthracite shows high adsorption for sulfonamides in both modes.•The micropores of activated carbon impede fixed-bed adsorption of sulfonamides. The large specific surface area, high pore volume and enlarged micropores make KOH-activated anthracite coal a superior adsorbent for sulfonamides.