Co-transport of antibiotics and graphene oxide in porous aquifer media

s The environmental transport of antibiotics is influenced by their chemical properties and environmental conditions, with graphene oxide (GO) acting as a pollutant carrier that alters their behavior. This study investigated the transport mechanisms of sulfamethoxazole (SMX) and tetracycline (TC) across pH 5.0–9.0, humic acid (HA) concentrations of 0–10 mg L −1 , and a range of GO concentrations, using quartz sand columns, batch experiments, and modeling. TC exhibited strong adsorption in fine sand (max 44.5 mg kg −1 ) via carboxyl complexation and electrostatic attraction, while SMX showed high mobility due to hydrophilicity and weak polarity. Elevated pH enhanced TC migration by weakening adsorption through electrostatic repulsion but had little effect on SMX. HA promoted TC migration via complexation but had minimal impact on SMX. GO significantly enhanced TC migration (up to 42.9 % at 30 mg L −1 GO) by providing adsorption sites, while both antibiotics facilitated GO dispersion by altering its surface charge. Alkaline conditions accelerated TC-GO migration via electrostatic repulsion, whereas acidic conditions strengthened SMX-GO interactions. Fine sand inhibited TC-GO transport via pore clogging, while HA further promoted co-transport. These findings elucidate how antibiotic properties and GO-related environmental factors jointly regulate pollutant transport, aiding groundwater-soil contamination control.