Removal of cationic dye using a magnetic nanocomposite based on poly(acrylic acid) and carboxylated cellulose nanocrystal

Abstract

Dyes are broadly used in various industries like textile, paper and pulp, dyestuffs and plastics. Miscellaneous activities at the industries discharge wastewater with extensive amount of carcinogenic dyes, which cause various environmental and health problems. Nowadays, various technologies have been invented and applied for the removal of dyes from wastewater. Among these methods, adsorption has received much attention due to its high efficiency, simplicity and economic viability. Herein, we present a novel magnetic nanocomposite based on polyacrylic acid and carboxylated cellulose nanocrystal(CCN), for effective adsorption of cationic dyes and easy magnetic separation of the adsorbent nanocomposite from the wastewater after the adsorption process. The functionalization of Fe3O4 was performed by carrying out an in situ polymerization of acrylic acid, CCN and acrylic modified Fe3O4, which will act as a crosslinker. The fabricated nanocomposites were characterized employing FTIR, XPS, FESEM, TGA, Zeta Potential and Magnetization. The magnetization (magnetization vs magnetic field) hysteresis of the nanocomposite confirmed the magnetic nature of the as-synthesized materials. The synthesized nanocomposite exhibited excellent adsorption for methylene blue and the kinetics data were fitted to pseudo-first-order and pseudo-second-order models to figure out the adsorption mechanism where, the resultant data support mostly to pseudo second order kinetic model. We also studied adsorption using Langmuir and Freundlich isotherm model where adsorption followed the Langmuir isotherm model. The effects of pH on the adsorption of dye were also investigated by monitoring the kinetics at variable pH. The pH dependent zeta potential was employed to describe the observed pH effects on the adsorption capacity.