Adsorption and breakdown of penicillin antibiotic in the presence of titanium oxide nanoparticles in water

► Interactions were studied between an antibiotic and TiO2 nanoparticles in water. ► Ampicillin adsorbs to TiO2nanos and also is rapidly degraded by TiO2 nanos. ► TiO2-enhanced degradation products include penilloic and penicilloic acids. ► TiO2 removes 100–10,000 times more antibiotic from water than Al2O3 nanoparticles. The fate and transport of antibiotics in natural water systems is controlled in part by interactions with nanometer (10−9m) metal oxide particles. Experiments were performed by mixing solutions of ampicillin (AMP), a common, penicillin-class human and veterinary antibiotic, with 25nm-TiO2 (anatase) nanoparticles at different pH conditions. Both sorption and degradation of AMP were observed in the AMP-nanoparticle solutions. For AMP concentrations from ∼3μM to 2.9mM the overall AMP removal from solution can be described by linear isotherms with removal coefficients (Kr) of 3028 (±267)Lkg−1 at pH 2, 11,533 (±823)Lkg−1 at pH 4, 12,712 (±672)Lkg−1 at pH 6, and 1941 (±342)Lkg−1 at pH 8. Mass spectral analysis of AMP solutions after removal of the solid nanoparticles yielded ions that indicate the presence of peniclloic acid, penilloic acid and related de-ammoniated by-products as possible compounds resulting from the degradation of AMP at the TiO2 surface.