Sustainable cobalt (II) removal from wastewater using an electrospun Ag-MOF/polycaprolactone-chitosan nanofiber membrane: Optimization and regeneration performance.

A novel nanofiber membrane integrating a silver metal-organic framework (Ag-MOF), polycaprolactone (PCL), and chitosan (CS) was developed through electrospinning techniques to create the Ag-MOF/PCL-CS nanofiber membrane aimed at the real removal of cobalt (II) ions from aqueous solutions. The successful synthesis of this hybrid membrane was rigorously characterized using FT-IR, XRD, XPS, SEM-EDX, and nitrogen adsorption/desorption isotherms. Additionally, batch adsorption studies were conducted to assess various parameters, counting pH, initial Co(II) concentration, contact duration, temperature, and the dosage of the adsorbent. The optimal settings for adsorption were determined to be a pH of 6.0, an adsorbent dosage of 0.02 g, and a communication duration of 100 min, which collectively enabled the membrane to reach a maximum adsorption capability of 499.2 mg/g. The adsorption behavior was created to align with the Langmuir isotherm model, indicative of monolayer adsorption, and the process adhered to pseudo-second-order kinetics, which points to a mechanism of chemisorption. A thermodynamic assessment exposed that the adsorption procedure is endothermic, through an enthalpy change (ΔH°) of 71.32 kJ/mol, and a positive entropy change (ΔS°) of 253.07 J/mol.K, suggesting an increase in randomness during the adsorption process. Notably, the membrane demonstrated exceptional reusability, sustaining a high level of performance across five cycles of adsorption as well as desorption. The underlying adsorption mechanism was thoroughly examined, and process optimization was systematically conducted via the Box-Behnken design methodology. These results highlight the promising application of Ag-MOF/PCL-CS nanofiber membrane as effective and regenerable biosorbents, demonstrating significant potential for cobalt ion remediation in water treatment processes.