Fabrication of PVA Nanofibers Grafted with Octaamino-POSS and their Application in Heavy Metal Adsorption

Wastewater treatment is one of the focuses in current society, and the removal of heavy metal ions from it is crucial in wastewater treatment. Polyvinyl alcohol (PVA) nanofibers play a certain role in the adsorption of heavy metal ions, but their adsorption capacity is limited. In this work, maleic anhydride (MAH) was first grafted onto the molecular chain of PVA. Then through the condensation of the carboxyl group and the amino group, the octaamino-POSS was successfully grafted on the PVA molecular chain. Two kinds of nanofibers, PVA/octaamino-POSS nanofibers as well as PVA-g-POSS nanofibers, were fabricated by electrospinning technology for the adsorption of Pb2+ and Cu2+ in wastewater. The preparation of PVA/octaamino-POSS was used to compare which metal ion adsorption process was more stable, physical blending or chemical grafting. With the increase of contact time, the adsorption capacity of PVA/octaamino-POSS nanofibers to Cu2+ increased at first and then decreased. It was observed that the adsorption capacity of PVA-g-POSS to heavy metal ions was higher than that of PVA/octaamino-POSS. With the increase of octaamino-POSS content, the equilibrium adsorption of Pb2+ and Cu2+ on PVA-g-POSS nanofibers was significantly improved, with prominent adsorption effect for Cu2+. Based on the analysis of quasi-first-order and quasi-second-order dynamic equation, it was deduced that the chemical adsorption and physical adsorption worked together in the adsorption process of Pb2+ and Cu2+ by PVA-g-POSS, and chemical adsorption played a major role.