Study of elimination of emerging contaminants by adsorption using activated carbon of coconut (amoxicillin - penicillin - theobromine)

Emerging contaminants are recently uncovered in natural currents duo to human and industrial activities. Most of them have no legal standard and can probably cause damaging effects in aquatic life at relevant concentrations. The conventional wastewater treatment plant (WWTP) is not always effective for the removal of these huge classes of pollutants and so further water treatments are necessary. In this work, we applied the powdered activated carbon adsorption process to eliminate the selected emerging pollutants, Theobromine and two antibiotics commonly used in Spain: Amoxicillin (AMX) and Penicillin G (Peni G). Different experimental conditions such as pH and temperature, initial concentration, the amount of biomass, and contact time were studied to obtain the best removal conditions. The different contaminants were detected by ultra-performance liquid chromatography and mass spectrometry (UPLC-MS). The whole results obtained confirm the effectiveness of the process of adsorption for the purification of the liquid effluents charged with antibiotics and stimulant. The results we have obtained indicate that coconut shell activated charcoal allows better retention of this compound after 90 minutes of contact and that the elimination yields evolve with the mass of activated charcoal introduced. Furthermore, it has been shown that the initial concentration of contaminants and the variation in pH considerably influence the binding of theobromine, penicillin, and amoxicillin molecules to the sites of powdered activated charcoal. The overall results showed that the adsorption kinetics of three contaminants on activated carbon is well described by the second-order model, and the adsorption isotherms of the absorbent/absorbate systems studied are described satisfactorily by the Langmuir model.