Abstract

In the Anthropocene context of water pollution by industrial chemicals and microplastics, the sustainable development of inexpensive, energy-saving, and biodegradable water purification membrane technologies is the urgent need for environmental remediation. While biodegradable cellulose filter papers are popular, cost-effective, and eco-friendly membrane materials, their large porous structure requires functional enhancement for effective microfiltration. Herein, we synthesized a nanosilica hydrogel (SG) via our chemical procedure of rice husk ash recycling. Silica nanoparticles derived from the SG hydrogel exhibited nanoscale particle sizes, suggesting that the hard agglomeration of stacked nanosilica powder is prevented by the hydration layers in the hydrogel structure. Notably, these hydration layers yielded water-lubricated silica nanoparticles for brush coating on cellulose filter substrates (Cell). The generated nanosilica/cellulose membranes (SG/Cell) were analyzed via top-view/cross-section scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), attenuated-total-reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and gas adsorption analyses of the surface areas and pore structures. The largely porous Cell substrate was significantly upgraded with SG coating to produce a more mesoporous membrane with a higher surface area and pore volume for aqueous microfiltration. Direct-flow filtration experiments revealed the high organic removal efficiency (88.4–99.7%) of the SG/Cell membranes under a hydraulic pressure of 0.01 bar, markedly outperforming regular cellulose membranes. In general, the SG/Cell membranes present the advantages of simplicity, low-pressure operation, cost-effectiveness, scalability, and environmentally friendly biodegradation. Brush coating cellulose filter papers with the water-lubricated nanomaterial hydrogel represents a promising approach in the preparation of practical water purification membranes.