Electrospun amine-functionalized silica nanoparticles-cellulose acetate nanofiber membranes for effective removal of hardness and heavy metals (As(v), Cd(ii),Pb(ii)) in drinking water sources

Due to growing urbanisation and the rising population, the world is approaching a point where there will be insufficient clean water for human consumption. Still, a significant proportion of the population lacks access to clean, safe water. Water hardness and heavy metal contamination are major factors affecting water quality. In this study, an efficient and convenient method of water purification was developed by incorporating amine-functionalized silica nanoparticles (AMS NPs) into cellulose acetate (CA) electrospun nanofiber membranes. The AMS NPs and electrospun membranes were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) elemental mapping, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Photoelectron Spectroscopy (XPS) and Dynamic Light Scattering (DLS). The hardness removal properties of membranes were optimized by changing the loading amount of AMS NPs, the amine content of the synthesized AMS NPs, and the membrane dosage. The removal of hardness (Ca(ii) and Mg(ii)) from water samples was studied using Atomic Absorption Spectroscopy (AAS), whilst heavy metal removal was studied using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Under both static and dynamic conditions, the optimized electrospun nanofiber membrane removed approximately 50% of the total hardness from synthetic water (500 ppm) in 8 hours. The adsorption of Ca(ii) and Mg(ii) followed pseudo-second-order kinetics. The isothermal data fitted well with the Freundlich model for Ca(ii) and Mg(ii). Under both dynamic and static conditions, the optimized membrane removed more than 90% of As(v), Cd(ii), and Pb(ii). The results show that the biodegradable AMS/CA nanocomposite membranes have significant potential for water softening and heavy metal removal.