Adsorptive removal of acid yellow 17 (an anionic dye) from water by novel ionene chloride modified electrospun silica nanofibres

Sorbents for environmental remediation, based on Advanced Materials, have attracted research interest because of their better selectivity, reusability and resolution of disposal problems at end-of-life, relative to conventional activated carbon based sorbents. The adsorption behavior of non-calcinated, electrospun Silica nanofibres, with no additional co-electrospun fibre-forming polymer present, has not been much reported. This work describes the preparation and performance of a recyclable nanofibrous silica adsorbent, to effectively capture a highly water soluble anionic dye, Acid yellow 17(AY17), from water. The physical structure and chemical composition of the electrospun silica nanofibres and its modified form were elucidated by their infrared and X-ray Diffraction spectra, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and nitrogen adsorption-desorption analysis. The adsorptive removal efficiency, of the modified and as-is silica nanofibres, against AY17 was 100% and 54.6%, respectively. Improved adsorption is achieved through micropore formation, and introduction of positively charged moieties on alkali etching of the silica nanofibres, after surface protection with the prepared ionene chloride polyelectrolyte. The nature of equilibrium adsorption data was more favorably described by non-linear form of the Freundlich isotherm, and the non-linear pseudo-second-order kinetic model. The adsorption of AY17 onto the modified silica nanofibres was an exothermic process, with larger decrease in free energy compared to the endothermic process in silica nanofibre.