A kinetics study of diffusion-adsorption of antibiotics chloramphenicol, tinidazole, and ofloxacine, and anti-inflammatory agent piroxicam at MnO2/ErGO and AgNPs/MnO2/ErGO-modified glassy-carbon electrode

Abstract

A glassy carbon (GC) electrode was modified with MnO₂/GO and AgNPs/MnO₂/GO composite materials. After electrochemical reduction, the reduced MnO₂/ErGO and AgNPs/MnO₂/ErGO materials exhibited large electrochemical active surface areas of 0.079 cm² and 0.087 cm², respectively; the charge transfer resistance (R_ct) was relatively small, at 0.188 kΩ and 0.077 kΩ, respectively. In this study, two antibiotics, namely chloramphenicol (CAP) and tinidazole (TNZ) were adsorbed onto the surface of MnO₂/ErGO-GCE, and the antibiotic ofloxacine (OFX) was adsorbed onto the surface of AgNPs/MnO₂/ErGO-GCE. The results show that the adsorption process took place within 3 minutes and followed a pseudo-second-order kinetic model with saturation adsorption capacities of 1,310.16, 1,873.41, and 1,140.93 mg.g^-1, respectively. For the anti-inflammatory drug piroxicam (PRX), the diffusion process across the solution – AgNPs/MnO₂/ErGO-GCE electrode interface was more dominant than the adsorption process, with the diffusion process occurring rapidly within less than 30 s. This study provides further insights into the mechanism of the diffusion-adsorption processes of antibiotics and anti-inflammatory agents on electrode-modified surfaces.