Oxytetracycline Sorption onto Synthetized Materials from Hydroxyapatite and Aluminosilicates

Oxytetracycline (OTC) is listed as an emerging contaminant due to the adverse effects that it has on human health and the environment. Being a broad spectrum antibiotic, OTC is widely used and is found in large concentrations in wastewater. Advanced wastewater treatment is an effective method for the removal of this pollutant; however, these tertiary treatments are expensive and generally not applied in nondeveloped countries. In this work, the removal of OTC by adsorption using sustainable materials synthesized from hydroxyapatite (HA) and aluminosilicates by chemical precipitation method was performed. Four different adsorbent materials were obtained: mixing hydroxyapatite and kaolin (HA-K), hydroxyapatite with natural clay (HA-NC), hydroxyapatite with synthetic zeolite (HA-SZ), and hydroxyapatite with natural aluminosilicates (HA-NA). The adsorbent materials were characterized by FT-IR, pHpzc, cation exchange capacity (CEC), SEM/EDX, TEM (particle size), and XRD. Kinetic tests and adsorption isotherms of OTC were carried out by varying conditions of the aqueous media as pH value, temperature, and the presence of ionic strength. Different kinetic and isothermal models were applied to the obtained data. All the synthesized materials showed an acceptable sorption capacity for OTC removal. The elimination of this antibiotic was greater than 50% in the four synthesized materials. Experimental data showed a better fit to the Elovich kinetic model, indicative of a heterogeneous chemical sorption process. Kinetic and thermodynamic parameters showed that the synthetized materials from HA and aluminosilicates are potential and alternative adsorbent materials for OTC removal from water.