Novel insights on the adsorption ability of bentonite and its chitosan composite: Deep understanding of antibiotics removal as hazardous agents

Abstract

Due to the inappropriate wastewater discharge, antibiotic contamination in the environment has caused significant public health issues and local ecosystem disruption. Given its benefits, which include low cost and a large variety of efficient adsorbents, the adsorption process represents a favorable way to reduce antibiotic contamination. This work theoretically investigated the adsorption of amoxicillin (AMO), ampicillin (AMP), and doripenem (DOR) onto raw bentonite (B) and its composite with chitosan (BC). Simulation studies using molecular dynamics were carried out to comprehend the interactions between these antibiotics and B and BC adsorbents between 30 and 50 °C, of which the interaction energies of −59.999, −59.279, and −66.877 kcal mol−1 were obtained for AMO/B, AMP/B, and DOR/B systems, respectively. Statistical physics models, i.e., the Gaussian Monolayer Multisite Model (GMMM) and Monolayer Model Coupled to Real Gas (MMRG) were also used to fit the experimental data with good results (R2>0.999). The findings indicated that the interactions between the chosen antibiotics and the adsorbents were mostly take place by Van der Waals forces (Non-bond energies of −20.442, −20.403, and −20.884 kcal mol−1 for AMO/B, AMP/B, and DOR/B systems, respectively), with multi-molecular (1 < n < 2.5) antibiotic adsorptions occurring primarily on both bentonite and BC.