Modeling Tetracycline Antibiotic Sorption to Clays

Abstract

Sorption interactions of three high-use tetracycline antibiotics (oxytetracycline, chlortetracycline, tetracycline) with montmorillonite and kaolinite clays were investigated undervaried pH and ionic strength conditions. Sorption edges were best described with a model that included cation exchange plus surface complexation of zwitterion forms of these compounds. Zwitterion sorption was accompanied by proton uptake, was more favorable on acidic clay, and was relatively insensitive to ionic strength effects. Calcium salts promoted oxytetracycline sorption at alkaline pHs likely by a surface-bridging mechanism. Substituent effects among the compounds in the tetracycline class had only minor effects on sorption edges and isotherms under the same solution pH and ionic strength conditions. At low ionic strength, greater sorption to montmorillonite than kaolinite was observed at all pHs tested, even after normalizing for cation exchange capacity. These results indicate that soil and sediment sorption models for tetracyclines, and other pharmaceuticals with similar chemistry, must account for solution speciation and the presence of other competitor ions in soil or sediment pore waters.

Sorption of aromatic hydrocarbons onto montmorillonite as affected by norfloxacin

“…S3). To examine the contributions of individual Nor species to overall sorption, we calculated species-specific equilibrium sorption contribution [28]. The overall sorbed amount at a given pH value can be represented as the sum of the contributions of individual species:…”

Preparation of amino-Fe(III) functionalized mesoporous silica for synergistic adsorption of tetracycline and copper

“…Among these methods, adsorption remains attractive because of its advantages of easy operation, energy savings and high removal capacity. Many adsorbents have been used to adsorb antibiotics or heavy metals from water separately, but fewer were used to remove them together (Figueroa et al, 2004;Ge et al, 2012;Ji et al, 2009;Oh et al, 2007;Sassman and Lee, 2005;Vu et al, 2010;Yang and Jiang, 2014;Hasan et al, 2013). In recent years, the cosorption of antibiotics and heavy metals from water by some adsorbents has been attracting increasing concern due to the realistic demands (Kang et al, 2010;Ling et al, 2013;Wang et al, 2008).…”

The veterinary antibiotic oxytetracycline and Cu influence functional diversity of the soil microbial community

“…Therefore, residual concentrations of pharmaceutical antibiotics can be found in soils, surface and ground water (Hamscher et al, 2002;Kolpin et al, 2002;Simon, 2005). The fate of antibiotics including sorption and fixation, mobility and transport is well documented (Tolls, 2001;Figueroa et al, 2004;Kulshrestha et al, 2004), whereas the knowledge about their ecotoxicity and the effect of antibiotics on soil microbial functioning is scarce (Thiele-Bruhn, 2003;Boxall et al, 2003).…”