Adsorption of antibiotics and iopromide onto single-walled and multi-walled carbon nanotubes

• Lincomycine, sulfamethoxazole, and iopromide adsorbed onto CNT.
• Freundlich isotherm model well fit adsorption of all target compounds.
• Adsorption of target compounds more onto single walled CNT than multi-walled CNT.
• Higher specific surface area of single walled CNT causing it to adsorb more organics.

Engineered carbon nanotubes (CNTs) have shown a great promise for many remediation applications. The adsorption of two antibiotics (lincomycine and sulfamethoxazole) and one contrast medium (iopromide) on single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) was investigated using batch adsorption experiments. These selected pollutants have high detection frequencies in aquatic environments. The adsorption results were compared with those of conventional powdered activated carbon (PAC). Adsorption isotherms for all pollutants on CNTs and PAC were nonlinear and could be described reasonably well with the Freundlich isotherm model. The adsorption generally followed the order SWCNT > PAC > MWCNT. The relatively low adsorption on MWCNT was probably due to its lower specific surface area than other carbon materials. However, correlation of adsorption to the surface area of carbon materials suggests other factors such as properties of adsorbate and type of interaction between pharmaceuticals and CNTs may also contribute to the adsorption processes. Implications of the adsorption results for the removal of pharmaceuticals from aqueous solution using CNTs are briefly discussed.