Development of stable PVA-PAA-SiO2 water responsive self-healing membrane

Lim, Grace Qian Von (2024) Development of stable PVA-PAA-SiO2 water responsive self-healing membrane. Final Year Project, UTAR.

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Abstract

Water pollution has emerged as a significant environmental issue due to the rising levels of untreated or partially treated wastewater being directly discharged into the river or oceans. Self-healing material that has the ability to localised response to damage in a meantime has come under the spotlight as the alternative means to cope with the issue of declined performance of membrane due to mechanical abrasion. However, the performance and stability of the self�healing membrane still remains a significant challenge. In this present work, PVA-PAA is used as the self-healing material coated on a PES membrane. Silica nanoparticles (SiO2 NPs) are added to improve the performance of the membrane in terms of water permeation flux, self-healing efficiency, stability in water and mechanical properties. The SiO2 NPs were synthesized from tetraethyl orthosilicate (TEOS) using the Stӧber method and they were characterized using FTIR and XRD. Subsequently, the membranes were prepared by employing six distinct loadings of SiO2 NPs (0 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt% and 0.5 wt%) in the PVA-PAA composite membranes. Among these modified membranes, the addition of 0.3 wt% SiO2 NPs showed the most promising results in the PVA-PAA membrane. The PVA-PAA membrane with 0.3% SiO2 NPs achieved water flux of 53.84 L/m2h and self�healing efficiency of 71.43% and 90.29% after soaking in water for 24 hours and 48 hours, respectively. The dye rejection was 24.87% and 59.13% through the pristine PVA-PAA membrane and 0.3 wt% SiO2 NPs membrane, respectively. Moreover, the performance of the PVA-PAA membrane containing 0.3 wt% SiO2 NPs remained stable in terms of water flux and dye rejection even after being submerged in water for 2 weeks. Also, the tensile strength and elongation of the PVA-PAA membrane with 0.3 wt% SiO2 NPs were measured at 11.41 MPa and 138.73%, respectively, surpassing those of the pristine PVA-PAA membrane. From these findings, it could be concluded that the addition of SiO2 NPs into the PVA-PAA composite membrane fabrication had greatly contributed to the development of self-healing membrane with enhanced permeability, rejection and stability.

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