Functionalization of sodium magnesium silicate hydroxide/sodium magnesium silicate hydrate nanostructures by chitosan as a novel nanocomposite for efficient removal of methylene blue and crystal violet dyes from aqueous media

Abstract

Herein, sodium magnesium silicate hydroxide/sodium magnesium silicate hydrate nanostructures were facilely synthesized using the hydrothermal method. After that, the synthesized nanostructures were modified by chitosan as a novel nanocomposite for the efficient removal of the methylene blue and crystal violet dyes from aqueous media. The synthesized nanostructures and their chitosan composite were characterized using several tools such as XRD, FT-IR, EDX, CHN, and SEM. The functionalization of nanostructures with chitosan led to the appearance of chitosan XRD peaks at 2Θ = 8.9° and 21° whereas the intensities of the other XRD peaks were affected. The SEM analysis showed that the nanostructures consist of spheres and irregular shapes. Also, the nanocomposite consists of cotton and large irregular shapes due to the functionalization of the synthesized nanostructures with chitosan. Also, the EDX analysis confirmed that the nanocomposite consists of Si, Mg, Na, O, C, and N with weight percentages equal to 7.24%, 5.73%, 10.59%, 30.99%, 43.25%, and 2.20%, respectively. The CHN elemental analysis confirmed that the nanocomposite contained C, H, and N with weight percentages equal to 53.28%, 4.32%, and 1.92%, respectively. Hence, pH = 8, time = 50 min, and temperature = 298 K are the ideal values that achieves the maximum removal of the examined dyes. The maximum adsorption capacity of the nanostructures and nanocomposite toward the methylene blue dye is 19.07 and 20.25 mg/g, respectively. Also, the maximum adsorption capacity of the nanostructures and nanocomposite toward the crystal violet dye is 18.62 and 23.51 mg/g, respectively. The adsorption processes are chemical and exothermic. Besides, the adsorption processes followed the pseudo-second-order kinetic model and the Langmuir isotherm.