Mechanistic evaluation in the removal of chlorpheniramine and ciprofloxacin on activated carbons.

Abstract

Chlorpheniramine (CPM) and Ciprofloxacin (CIP) adsorption onto a granular (GAC) and pelletized activated carbon (PAC) analyzing the physicochemical mechanisms involved using the carbon's characterization were studied. Adsorption isotherm studies were performed at temperatures of 25 °C at pH values of 4, 7 and 9 and at 45 °C at a pH of 7. The characterization demonstrated that GAC has a predominantly acid character due to its predominantly negative surface charge and acidic site concentration alongside the characteristic bands detected in the X-ray Photoemission Spectroscopy (XPS) study. On the other hand, PAC presented a mostly basic character due to its positive surface charge and basic site concentrations. The adsorption isotherm studies demonstrated that the Freundlich isotherm better described the equilibrium data with an average deviation percentage of 7.45 and 6.74 for GAC and PAC. The temperature and desorption studies demonstrated that the adsorption process occurs through a chemisorption mechanism, and the pH study alongside the GAC and PAC characterization demonstrated that the mechanisms involved are a combination of electrostatic interactions and pi-pi interactions between the CPM and CIP molecules and the carbon's surface. These results demonstrate that the adsorption process of these pharmaceutical compounds is done through a combination of physical and chemical interactions.