Insights on size-exclusion effect of ordered mesoporous carbon for selective antibiotics adsorption under the interference of natural organic matter

Size-exclusion effect played a significant role in conquering the interference of natural organic matter (NOM) on antibiotics adsorption. However, due to a complex micro-/meso-porous structure in reported carbon materials, the quantitative relationship between pore/NOM size and size-selective adsorption was still unclear. Here, pore size of ordered mesoporous carbons (OMCs) was precisely adjusted to-4.8 nm,-6.2 nm and-8.1 nm. The smallest pore-size OMC-0 (-4.8 nm) exhibited the strongest size-exclusion of macromolecular humic acid (HA) with the largest capacity retention rate of 70.3% -84.4% for sulfamethoxazole (SMX) adsorption, much higher than 54.4% -69.1% of OMC-1 (-6.2 nm) and 50.0% -58.9% of OMC-2 (-8.1 nm). Moreover, with the increase of HA molecular weight from <30 kDa to >100 kDa, the size-exclusion effect of three OMCs was also effectively strengthened, thus achieving a rising retention rate from 54.8% -68.3% to 78.7 % -100.0%. Meanwhile, OMC-0 completely eliminated the interference of >30 kDa HA, leading to an ultrahigh capacity retention rate of 96.4% -100.0%. Therefore, this study provided a viable direction of designing highly selective adsorbents/catalysts for effective antibiotics removal.