Abstract

In anthropocene context of water pollutions by industrial chemicals and microplastics, sustainable development of water purification membrane technologies that are inexpensive, energy-saving and biodegradable is the urgent need for environmental remediation. Biodegradable cellulose filter papers are popular, low-cost and eco-friendly membrane materials, yet their large porous structure requires functional enhancement for effective microfiltration. In this paper, we synthesized nanosilica hydrogel (SG) via our chemical procedure of rice husk ash recycling. Silica nanoparticles derived from SG hydrogel exhibited nanoscale particle sizes, suggesting that hard agglomeration of stacked nanosilica powder is prevented by hydration layers in hydrogel structure. Particularly, hydration layers in SG hydrogel make silica nanoparticles water-lubricated for brush coating on cellulose filter substrates. Obtained nanosilica/cellulose membranes (SG/Cell) were analyzed with top-view/cross-section scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and attenuated-total-reflectance Fourier-transform infrared spectroscopy (ATR FTIR). The nanosilica coating significantly upgraded the porous network of cellulose substrates for aqueous microfiltration. Direct-flow filtration experiments demonstrated that SG/Cell membranes achieved fast water permeance (178.09 – 242.79 L m^-2 h^-1) and high organic removal efficiency (88.4 – 99.7 %) under hydraulic pressure (0.01 bar), markedly outperforming regular cellulose membranes. In general, the advantages of SG/Cell membranes include simplicity, low-pressure operation, cost effectiveness, scalability and environmentally friendly biodegradation. The approach of brush coating of water-lubricated nanomaterials hydrogel on cellulose filter papers is promising to prepare practical water purification membranes.