Use of an anionic surfactant for the sorption of a binary mixture of antibiotics from aqueous solutions

Amoxicillin (AMX) and ampicillin (AMP) are two representative β-lactam antibiotics that have been used extensively in human and veterinary medicine and have gained increasing attention due to their continual introduction to the environment which would pose serious ecological risk. The present work investigates the feasibility of the removal of AMX and AMP antibiotics produced by SAIDAL, antibiotical company from aqueous solutions. To this end, a novel separation technique based on an aqueous surfactant extraction has been developed for the treatment of a complex medium consisting of a mixture of antibiotics amoxicillin and ampicillin using an anionic surfactant namely Sodium Dodecyl Sulphate (SDS). The efficiency of the applied treatment was evaluated by HPLC analysis. The main parameters influencing the process have been investigated such as: contact time, agitation speed, temperature, pH, initial effluents concentration and surfactant concentration. The results obtained confirm the proposed technique. Thus, a removal rate of 59.76% of ampicillin and 72.73% of amoxicillin was achieved under optimum conditions (contact time of 40 min, agitation speed of 350 rpm, temperature of 40°C, pH 4, initial antibiotics concentration of 20 and 10 mg/L of SDS). The thermodynamic parameters obtained (ΔG_AMX = 2.6 kcal/mol, ΔG_AMP = -2.37 kcal/mol, ΔH_AMX = 4.51 kcal/mol, ΔH_AMP = 5.47 kcal/mol K, ΔS_AMX = 24.28 kcal/mol K and ΔS_AMP= 26.75 kcal/mol K) showed that the process is feasible, spontaneous and endothermic.