Efficient adsorption of naproxen and ibuprofen by gelatin/zirconium-based metal–organic framework/sepiolite aerogels via synergistic mechanisms

Abstract

The removal of non-steroidal anti-inflammatory drugs (NSAIDs) from effluent wastewater is critical because of their adverse impacts on human health and the ecosystem. In this study, we successfully fabricated a novel biopolymer-based aerogel composite by incorporating a zirconium-based metal–organic framework, UiO-66 (MOF), and sepiolite (Sep) into gelatin (Gel) to efficiently remove naproxen (NPX) and ibuprofen (IBP). The physicochemical properties of the prepared adsorbents were comprehensively characterized, as well as batch experimental studies were carried out to probe the effect of contact time, solution pH, temperature, and coexisting ions on the adsorption process. The adsorption by the 3D mesoporous aerogel (Gel-1.0MOF-Sep) followed the pseudo-second order and the Langmuir isotherm models with maximum adsorption capacities of 8.515 and 10.23 mg/g for NPX and IBP, respectively (at 20 °C and pH 7). Furthermore, central composite design (CCD) in response surface methodology (RSM) was used to assess the simultaneous interactions of independent variables, results of which suggested that the initial concentration and pH were the dominant parameters in the adsorption process. Moreover, a thermodynamic study showed that the adsorption process was exothermic (ΔH° < 0) and thermodynamically spontaneous (ΔG° < 0). Reusability studies demonstrated that the composite aerogel exhibited superior adsorption efficiencies after five successive runs, indicating its potential use in practical applications. Furthermore, the adsorption mechanisms for the pollutants were ascribed to electrostatic interactions, π–π interactions, and hydrogen bonding. The insights show that the Gel-1.0MOF-Sep aerogels are promising alternative adsorbents for the removal of NSAIDs.