Development of a Novel MOFs-Based Nanofiber for Highly Selective Removal of Cobalt from Aqueous Solutions

The challenge of cobalt ion separation was addressed by developing a novel MOFs nanofiber, Co(II)-PIIMs. Initially, Co(II)-SIM-IIP were synthesized using zinc-based MOFs (SIM-1) as a matrix and tetraethylpentadiamine (TEPA) as a functional monomer through ion imprinting technique (IIT). Subsequently, Co(II)-PIIMs-x nanofibers were fabricated via electrospinning. Co(II)-SIM-IIP were incorporated as fillers, while PAN was used as the substrate, aiming at selectively separating cobalt ions. Optimal performance was achieved with a 10% doping level of Co(II)-SIM-IIP, resulting in adsorptive capacity peaking at 112.74 mg/g, along with membrane flux of 1095 L/m² h, and a retention rate of 43.49%. The material exhibited excellent selectivity with high selectivity factors for various ions such as Ca2+ (7.42), K+ (55.98), Mg2+ (72.30), and Ni2+ (1.28). Adsorption mechanism results indicated that cobalt adsorption by Co(II)-PIIMs is governed by the adsorption rate control step and the even distribution of cobalt on the surface, aligning with chemisorption properties. After five adsorption-desorption cycles, Co(II)-PIIMs demonstrated excellent regeneration capability, maintaining over 95% of their initial adsorption capacity. These impressive selectivity factors underscore the material's capability to selectively adsorb cobalt ions over other competing ions, making it a promising candidate for efficient separation and purification processes in environmental remediation applications.