Sorption of the emerging pollutant oxytetracycline on eggshell. Experimental and theoretical approaches

Abstract

The constant use of drugs for health treatments increases the presence of antibiotics, analgesics, antipyretics and hormones in wastewater and water bodies, negatively affecting the biosphere. Among the emerging pollutant sources, the main are wastewater, hospital effluents, agriculture, animal breeding and improper management of industrial effluents. Therefore, it is essential to develop or adapt methods to remove these pollutants from environmental matrices. This work studies experimental and theoretically the removal of the widely used antibiotic oxytetracycline (OTC) from water through its sorption by a globally abundant solid waste: eggshell (ES). Experimentally, the OTC sorption by ES powders has been performed at different OTC concentrations. The obtained isotherm has been fitted by the Langmuir, Freundlich and Sips models. Theoretically, first principles calculations to model the OTC molecule on different CaCO3 surfaces were done. Experimentally the maximum sorption capacity was 15 ± 3 mg/g at RT, disclosed by the best model representing the data, the Langmuir one at a single site. Theoretically OTC sorption involves the interaction between Ca2 + of ES and O atoms of OTC. Therefore, ES waste is a promising material for low-cost remediation technologies based on the sorption process for the treatment of waters containing OTC.