Loofah activated carbon with hierarchical structures for high-efficiency adsorption of multi-level antibiotic pollutants

For antibiotic contaminants, biochar adsorbents have been regarded as one of the most suitable materials due to their safety for human health and good adsorption performance. In this study, loofah activated carbon (LAC) was prepared by a simple high temperature carbonization process, while mixing LAC with agarose solution under stirring at 90 degrees C, after which LAC-loaded agarose aerogel (LAC-AA) adsorbents could be obtained by freeze-dried under a vacuum condition. The LAC is consisted of hierarchical laminae-trestle-laminae (L-T-L) microstructure with highly ordered, whose surfaces are fully covered by nanoscale protrusions. The unique hierarchical structures possessing high specific surface areas (similar to 736.86 m(2) g-1) and abundant active surface sites, which contribute significantly to the adsorption of antibiotics (to name a few, tetracycline (TC), ofloxacin (OFO) and norfloxacin (NFO)). The results indicate that the capacity of adsorption towards TC, NFO and OFO (1-40 ppm) by the LAC-loaded agarose aerogel (LAC-AA) adsorbents is 537.6, 434.8 and 581.4 mg g(-1), respectively, which is significantly greater than that of currently-available adsorbents. In parallel, the atomic adsorption model's simulation further confirms that the OFO is prone to be adsorbed on the LAC with the lowest adsorption energy that resulted in the largest adsorption capacity.

Automated summary

Biochar adsorbents, particularly the LAC-loaded agarose aerogel adsorbents, are effective in adsorbing antibiotic contaminants due to their high specific surface areas and abundant active surface sites. The unique hierarchical structures of LAC contribute significantly to the adsorption capacity of antibiotics.