Self-supported trimetallic NiZnLa nanosheets on hierarchical porous graphene oxide-polymer composite fibers for enhanced phosphate removal from water

Phosphate-induced water eutrophication has attracted global attention. Fabricating adsorbents with both high phosphate adsorption affinity and accessible separation property is challenging. Herein, PG@NZL, a hierarchical nanocomposite fibrous membrane, was fabricated via in-situ growth of La-doped NiZn-LDH (NiZnLa 0.1 ) over electrospun graphene oxide-polymer composite fibers (PG). The porous surface of the PG fibers provided abundant anchor sites for the vertical self-supported growth of NiZnLa 0.1 nanosheets , contributing to a high surface area. The La-doped NiZnLa 0.1 trimetallic LDH achieved a much higher adsorption capacity than NiZn-LDH. The negative adsorption energy (-1.45 eV), calculated with DFT , confirmed its spontaneous adsorption potential for phosphate. Interestingly, the PG fibers contributed to oxygen vacancies and the metal center electronic structure evolution of NiZnLa 0.1 , thus strengthening the coordination with phosphate. Mechanistic analysis revealed that the high adsorption capacity of PG@NZL is attributed to its superior anion exchange property, oxygen vacancies, and inner-sphere complexation. Therefore, the flexible and easily separated PG@NZL nanocomposite fibrous membrane is a promising adsorbent for effectively treating phosphate-bearing wastewater.