LAUSR

Abstract Magnetic MCM-41composite particles were prepared and modified with (3-aminopropyl) triethoxysilane (APTES), then grafted with poly(glycidyl methacrylate) p(GMA) by surface-initiated atom transfer radical polymerization (SI-ATRP). The p(GMA) grafted magnetic MCM-41 particles were functionalized with tris(2-aminoethyl)amine (TAEA), and used as a cationic adsorbent for the adsorptive removal of Direct Blue 6 (DB-6) and Direct Black-38 (DB-38) from aqueous medium. The mMCM-41 and mMCM-41-p(GMA)-TAEA particles were characterized by BET, X-ray diffraction (XRD), thermogravimetric (TGA), Fourier transform infrared spectroscopy (ATR-FT-IR), Zeta potential, nitrogen adsorption–desorption isotherms (BET method), scanning electron microscope (SEM) and analytical methods. VSM data shows that the mMCM-41-p(GMA)-TAEA display a paramagnetic behavior with saturation magnetization of about 19.6 emu/g. Adsorption potential of two different textile dyes (i.e., DB-6 and DB-38) was evaluated by varying experimental conditions (i.e., pH, temperature, ionic strength and initial dye concentration). Both dyes were removed from aqueous medium with high efficiency in a wide pH range of 4.0–7.0. The equilibrium adsorption data were analysed by Langmuir, and Freundlich models. The experimental equilibrium data was found to fit the Langmuir model well for adsorption of DB-6 and DB-38 dyes on the mMCM-41-g-p(GMA)-TAEA particles. The adsorption kinetic data were also analysed using pseudo-first order, and pseudo-second-order kinetic equations. It was found that the pseudo second-order model can describe the adsorption data well. The presented adsorbent can be regenerated using 0.1 M HNO3 solution and desorption efficiency was more than 96%. Hence, mMCM-41composite particles were very stable, and easily regenerated.