Performance and interactions of diclofenac adsorption using Alginate/Carbon-based Films: Experimental investigation and statistical physics modelling

The occurrence of pharmaceutical wastes, especially the non-steroidal anti-inflammatory drugs like diclofenac, in water resources is a relevant issue in the context of environment protection and depollution. Therefore, this paper reports the preparation and application of alginate/carbon films (AC-films) as a new adsorbent for the removal of diclofenac (DCF) in water treatment. This novel adsorbent was obtained from alginate sodium and activated carbon with a film-based shape. The impact of operating parameters and thermodynamics of DCF adsorption on AC-films were studied to identify the best removal conditions. DCF adsorption mechanism was analyzed via physicochemical characterization including SEM-EDX, BET and FTIR, and statistical physics calculations. Results showed that a maximum DCF adsorption of 29.9 mg/g was obtained at pH 3 and 303 K. DCF adsorption performance of AC-films was highly depended on temperature and solution pH where the adsorption capacities decreased with increments of these operating variables. Statistical physics calculations allowed to sketch the DFC orientation on tested adsorbent. Pseudo-first-order kinetic and Temkin isotherm were the best models to fit the DCF adsorption data. Thermodynamic calculations confirmed an exothermic (i.e., enthalpy of −45.43 kJ/mol), favourable and spontaneous adsorption of this pollutant. The adsorption geometry of DCF on AC-films was discussed and interpreted at different temperatures via statistical physics calculations. In short, AC-films can be considered as a promising adsorbent to remove DCF from water and has a significant potential to be applied in wastewater treatment at industrial level