Cosorption of organic chemicals with different properties: Their shared and different sorption sites

Complementary sorption of different chemicals was expected and investigating the relationship between the sorption inhibition of primary sorbate (ΔQpri) and sorption of secondary sorbate (Qsec) could provide a new angle to understand coadsorption of different chemicals. This study used bisphenol A (BPA) as the primary adsorbate, sulfamethoxazole (SMX) as the competitor, and carbon nanotubes as model adsorbents to study their complementary and competitive adsorption. At low BPA concentrations, the sorption of SMX (Qsec) exceeded BPA sorption inhibition (ΔQpri), indicating that these two chemicals complementarily adsorbed on their respectively preferred sorption sites. At high BPA concentrations, higher ΔQpri was observed in comparison to Qsec, which may be resulted from different packing efficiencies of the adsorbed SMX and BPA. This study emphasized that both competitive and complementary sorption should be discussed in binary sorption system.

► Sorption site overlapping increases with adsorbate concentration.
► Sorption site energy distribution shows evidence for sorption site overlapping.
► Sulfamethoxazole disrupts the high packing efficiency of the adsorbed bisphenol A.
► Both complementary and competitive sorption occur in binary sorption system.