Theoretical and experimental studies of cephalexin adsorption on aluminium as a new alternative of removal from wastewater.

Abstract

Cephalexin (CPX) is an antibiotic widely used to treat many infections. CPX has become an emerging pollutant present in wastewater. On the other hand, it is well known that organic compounds can be adsorbed over metal surfaces when the metal is in active state such as when it is rusting. This work proposes an alternative for the elimination of CPX from wastewater, applying electrochemical principles using a conventional and cheap substrate, aluminium. The first part consisted of obtaining the active states of aluminium electrodes carrying out voltametric curves at different pH (4, 7 and 9) to find the particular condition of interaction between CPX and metal surface. The potential was used in the potentiostatic tests to set the activation potential of metal at different times. After the treatment, electrolyte solutions were analysed using UV-vis spectra, and the aluminium surfaces were studied by optical micrographs and X-ray diffraction. In addition, aluminium-CPX interactions were corroborated by quantum-chemical calculations and adsorption isotherms. All results indicate that it was possible for the CPX removal at basic pH conditions, where the molecule adsorption on the aluminium substrate occurs due to a strong electrostatic interaction.