Mechanism of tetracycline sorption on carbon-bentonite

Abstract

Antibiotics increased industrial production is the reason of their occurrence in wastewater, soils, groundwater, and drinking water. In this regard, treating the environment for pharmaceuticals is one of the urgent environmental challenges. Synthesis of adsorbents using different types of raw materials by the methods of mechanochemical activation makes it possible to significantly increase their sorption capacity due to the accumulation of various kinds of defects in the crystal structure of the adsorbent. We obtained the bentonite-carbon composite using roller-ring vibratory mill with coal-bentonite ratio of 30 : 70 and 50 : 50. However, the nature of the interaction between carbon and bentonite correlates with changes of surface area and porosity. The porous structure parameters of the samples show the mechanochemical activation of the mixture involves their components interactions. The authors studied the structural and chemical changes during the modification of bentonite with activated carbon by analysing the vibrational spectra of carbon, initial, and modified aluminosilicate samples. According to infrared spectroscopy of adsorbents, absorption bands characteristic of Si-O-C bond vibrations occurred. The paper investigates the sorption capacity of mechanochemically modified natural clay mineral Dash-Salakhli bentonite towards tetracycline hydrochloride. Research investigates the kinetics of the process and rapid sorption of tetracycline. The paper provides possible mechanisms of chemisorption due to donor-acceptor interaction and ion-exchange processes.