Highly efficient water desalination via electrospun ethyl cellulose/polystyrene composites integrated with metal-organic frameworks

This investigation focused on the design of an advanced polymeric scaffold that integrates Ethylcellulose (EC) and Polystyrene (PS) to fabricate four novel Metal-Organic Framework/Ethylcellulose-Polystyrene (MOF/ECPS) adsorptive membranes for the aim of water desalination. These membranes were created using in situ synthesis of ZIF-8, UiO-66-NH₂-EDTA, and UiO-66- NH₂ in the presence of electrospun ECPS nanofibers, along with ex-situ synthesis of MIL-125-NH₂/ECPS electrospun nanofibers. The NaCl removal performance of these nanocomposite adsorptive membranes was evaluated under ideal conditions. These conditions included starting NaCl content, intercalated MOF percentage, pH, temperature, dosage, and adsorbent contact time. The synthesized nanocomposites were successfully recycled 25 times without experiencing a significant reduction in adsorption capacity, except for MIL-125-NH₂, which showed a decrease after 18 recycles. In this investigation, four different kinetic models were utilized: Elovich, intraparticle diffusion, pseudo-first-order, and pseudo-second-order. Adsorption characteristics were found to be in line with pseudo-second-order kinetics. Analysis of the adsorption isotherm parameters using the Langmuir and Freundlich models revealed that the surfaces of UiO-66-NH₂/ECPS, UiO-66-NH₂-EDTA/ECPS, and ZIF-8/ECPS nanocomposites are heterogeneous and exhibit multilayer Na⁺ adsorption. In contrast, the adsorption of Na⁺ on the MIL-125-NH₂/ECPS nanocomposite follows a monolayer adsorption mechanism. Studies in thermodynamics demonstrate that adsorption occurs as an exothermic and spontaneous process that adheres to pseudo-second-order kinetics and isotherm models.