Preparation of highly elastic and environmentally friendly porous nanofibrous aerogel for organic dyes adsorption

Abstract

This study delineates the synthesis and property evaluation of highly elastic polyethersulphone (PES) nano-fibrous aerogels (NAs) reinforced with environmentally benign materials, namely sodium alginate, gelatin and cornstarch (CS) via freeze drying and post cross-linking treatment. Compression test results demonstrate that modified NAs possess good compression resistance and high elasticity, attributed to the inter-connected and cross-linked network structure. Brunauer-Emmett-Teller analysis demonstrates that the specific surface area and average pore diameter of these NAs decrease with increasing CS content, leading to a more compact network structure and increased substance density. In dye adsorption experiments, various pH values, temperatures, contact times and initial concentrations are comprehensively investigated to explore the adsorption mechanism. Adsorption results are well fitted using the pseudo-second-order kinetics, Langmuir isotherm and Elovich models because of the adsorption mechanism being of chemisorption type. NAs exhibit the highest adsorption capacities for methylene blue (298.62 mg/g) and methyl orange (243.70 mg/g) at pHs 7 and 1, respectively, at 333 K. Fourier-transform infrared spectroscopy and X-ray photo-electron spectroscopy results demonstrate that the adsorption mechanism mainly involves electrostatic attraction, hydrogen bonding, π–π stacking, van der Waals forces and pore diffusion and filling, with the primary mode being chemical adsorption, complemented by physical adsorption. Finally, the excellent re-generation and recycling efficiencies after five cycles confirm the great potential of the eco-friendly adsorbent in wastewater treatment.