Facile synthesis of sustainable magnetic core-shell silicate nano copolymers for toxic metals extraction in fixed bed column

Abstract

Heavy metals enter our environment through diverse resources, causing harmful effects owing to their inherent toxicity and facile migration into aqueous medium, becoming an environmental challenge. Among technologies able to remove these contaminants, the adsorption process emerges as a promising application for water treatment. Herein, functionalized silica magnetic nanoparticles using inorganic and organic have been employed as adsorbents to remove environmental hazards from wastewater effectively. Magnetic silicate core-shell amino-functionalized (Fe3O4 @SiO2-AP) nanocomposites were synthesised using acrylic acid (AA) and para-aminobenzoic acid (PABA) as dual copolymer for Cd (II) removal. The characterization analysis confirmed the formed crystal nanostructure and the copolymers were chemically introduced in the magnetic silicate core-shell nanoparticle. The Cd (II) adsorption results on (Fe3O4 @SiO2-AP) nanocomposites achieved an impressive qmax of 32.50 mg/g at pH 8, adsorbent dosage of 3 g/L, and Cd (II) concentration of 100 ppm. The laboratory-scale fixed-bed column showed the breakthrough curves are flow rate independent, achieving metal removal of 99% for 405 min, at pH 8, influent ion concentration of 100 ppm, flow rate of 5 mL/min, and 1 cm bed height. The Freundlich model was the most suitable for fitting equilibrium data (R2adj = 0.981) indicating a multi-layer adsorption phenomenon in the heterogeneous surface sites of the (Fe3O4 @SiO2-AP) nanocomposites. The pseudo-second-order model (R2adj =0.999) confirms that the adsorption rate depends on nanocomposites active sites and occurs by chemical sorption mechanism. The reusability adsorption-desorption experiments slightly decreased from 97.5 to 86.7% in the sixth cycle stability, demonstrating the material stability.