Materials, Methods & Technologies, Volume 15, 2021

Abstract: Addressing the problem of microbial resistance to antibiotics is one of the main priorities of the World Health Organization (WHO). One way to fight this is to reduce and control the use of antibiotics in the world. However, the COVID 19 pandemic has led to sudden and uncontrolled consumption of antibiotics because they are used as standard medical prophylaxis despite the fact that they do not act on the Corona virus. Another way to fight microbial resistance is to reduce the contact of antibiotics with bacteria. Traces of antibiotics in wastewater cause resistance of bacteria that are in them and have a detrimental effect on humans and the environment due to the limited removal of antibiotics by traditional wastewater treatment. In this study, we investigated the possibility of using as an adsorbent to remove the antibiotic hydroxyapatite obtained from shells of river shells (NHAP/U) from the family Unionidae, a material that accumulates in large quantities on the banks of large rivers as waste. The resulting adsorbent NHAP/U was characterized and tested for removal from wastewater of the most commonly used antibiotic during the COVID-19 pandemic amoxicillin (AMOX). In order to predict the optimal adsorption conditions using the Response Surface Method (RSM), the influence of variable factors (adsorption conditions), pH values, adsorbent dose, contact time and temperature on the adsorbent capacity was investigated. Maximum removal of 97.8% of AMOX was achieved under defined conditions. The best adsorption of AMOX was achieved for pH between 5.0 and 7.0. Adsorption data for amoxicillin at 25, 35 and 45 °C were compared with isothermal models Langmuir, Freundlich, Dubinin-Radushkevich and Temkin, as well as for modelling adsorption kinetics using pseudo-first order, pseudo-second order and Elovich kinetic model. The results showed that the adsorption of AMOX on NHAP/U followed a pseudo-second kinetic model and a Freundlich isothermal model. Thermodynamic parameters indicate the endothermic, feasible and spontaneous nature of the adsorption process.