Mechanistic insights of diclofenac adsorption on functionalized Clay-Based adsorptive Film: Bridging experimental and molecular dynamics findings

This study aims to formulate and characterize a functionalized clay-based adsorbent film (ENDFIL) for the effective removal of diclofenac (DCF) at trace concentrations. ENDFIL was prepared using kaolin, cetylpyridium chloride, and sodium alginate. DCF adsorption on ENDFIL was tested under different operating conditions, including changes in the adsorbate concentration, contact time, solution pH, and temperature. ENDFIL exhibited 95 % DCF removal and 286.2 µg/g adsorption capacity, and its best performance was obtained at pH 5.82. Equilibrium and kinetic studies indicated that the Redlich-Peterson isotherm and pseudo-second-order kinetic models were the most suitable for correlating DCF adsorption on ENDFIL. Thermodynamic studies indicated that the removal of DCF using this adsorption film was exothermic where electrostatic interactions and hydrogen bonding played a relevant role. Molecular dynamics simulations revealed stable energy fluctuations in DCF/ENDFIL complex, indicating a competitive adsorption capacity of this new material for DCF removal from water. The reusability study of ENDFIL using acetic acid for regeneration was analyzed indicating that the adsorbent showed a competitive performance up to 6 adsorption–desorption cycles. This research aligns with the goals of SDG 6 and SDG 14, which are associated with “clean water and sanitation” and “life below water”, respectively.