Selective Adsorption Performance of a High-Capacity Mesoporous Silica Aerogel for Fluoroquinolones

Fluoroquinolone antibiotics (FQs) are widely applied in veterinary practice and animal husbandry and frequently persist in organic waste liquids (OWLs), creating substantial environmental and health risks when untreated. A high-capacity mesoporous silica aerogel (SA-60) was produced via a cost-effective sol–gel route from water glass, followed by ambient pressure drying at 60 °C for 6 h. SA-60 exhibited pronounced selectivity, providing a maximum adsorption capacity of 630.18 mg·g−1 for enrofloxacin (ENR) in acetonitrile. Adsorption efficiency was weakly dependent on pH. Mechanistic analysis indicated combined physical and chemical interactions, with intra-particle diffusion governing the overall rate. Thermodynamic evaluation showed a spontaneous and endothermic process for ENR adsorption. Organic solvent type and water content were major determinants of adsorption efficiency. Durable performance was observed, with capacity retention above 80% after five adsorption-desorption cycles. The mesoporous architecture (surface area 249.21 m2·g−1; average pore diameter 10.81 nm) supported the high uptake. These results identify SA-60 as a sustainable adsorbent for removing hazardous FQs from OWLs, offering a simple, energy-efficient approach for the source-level control of antibiotic pollution and improved environmental management.