Highly dispersed sepiolite-based organic modified nanofibers for enhanced adsorption of Congo red

Abstract

Abstract Acid-activated sepiolite fibers (ASEP) were grafted with amino groups using (3-aminopropyl) triethoxysilane to prepare an emerging organic-inorganic hybrid nanofibers (NH2-ASEP). Owing to the high surface area and pore volume, and the highly dispersed nanofibers with functional amino-groups, the prepared NH2-ASEP exhibited good adsorption performance towards Congo red (CR) anionic dye. It displayed a large sorption capacity (522 mg/g at pH = 8.0, 25 °C), low sorption equilibrium time (within 10 min), and renewability. Equilibrium adsorption data of NH2-ASEP towards CR dye were evaluated using Freundlich, Langmuir and Sips isotherm models, and the Langmuir isotherm exhibited a better fit with a maximum adsorption capacity of 539.71 mg/g, which is very close to the experimental data and higher than those of the reported fiber adsorbents. The adsorption process of CR dye onto NH2-ASEP surface followed a pseudo-second order rate expression. Highly dispersed sepiolite-based organic modified nanofibers have great potential applications in the fields of water treatment, membrane separation, catalysis, pH responsive delivery and other environmental remediation.