Removal of Amoxicillin Antibiotic from Aqueous Solution Using an Anionic Surfactant

Abstract

A novel separation technique based on an aqueous surfactant extraction to remove organic contaminants from aqueous solutions was investigated. A model was developed regarding the kinetic partitioning of amoxicillin and regarding the mechanism governing the forward transfer of amoxicillin in a reverse micelle system. Results were interpreted in terms of a two-film theory for flat interface. To confirm the relevance of the developed separation technique, it was applied to the elimination of amoxicillin by adsorption on an anionic surfactant, sodium dodecyl sulfate. The effects of various parameters such as contact time, pH, temperature, and initial concentration of sodium dodecyl sulfate were investigated at an agitation speed of 350 rpm. The percentage of maximum adsorption capacity of amoxicillin was found to be 87.7 % for the following optimal conditions: amoxicillin concentration of 4 mg/L, 40 min contact time, pH 4, 50 °C, and 0.01 g/L initial sodium dodecyl sulfate concentration. The results showed that the pseudo-first-order model provides most adequate correlation of experimental data compared to the pseudo-second-order model. Three statistical functions were used to estimate the error deviations between experimental and theoretically predicted kinetic adsorption values, including the average relative error deviation (ARED), the sum of the squares of the errors (SSE), and the standard deviation of residuals (S res). The results showed that, both Freundlich equation and pseudo-first-order equation provide the best fit to experimental data. Adsorption isotherm data appeared to be accurately described by a Freundlich model. The thermodynamic parameters (∆G, ∆H, and ∆S) showed that the process was feasible, spontaneous, and exothermic.