Functionalization of Sodium Magnesium Silicate Hydroxide/Sodium Magnesium Silicate Hydrate Nanostructures Using 2,3-Dihydroxybenzaldehyde as a Novel Nanocomposite for the Efficient Removal of Cd(II) and Cu(II) Ions from Aqueous Media

Abstract

Cd(II) and Cu(II) ions cause many diseases in humans. Therefore, they should be removed from water sources using simple and cost-effective adsorbents. Consequently, sodium magnesium silicate hydroxide/sodium magnesium silicate hydrate nanostructures were synthesized and functionalized using 2,3-dihydroxybenzaldehyde as a novel nanocomposite. Several instruments were used to characterize the synthetic products, such as an X-ray diffractometer (XRD), a Fourier-transform infrared spectrophotometer (FT-IR), an N2 adsorption/desorption analyzer, a CHN elemental analyzer, an energy-dispersive X-ray spectrophotometer (EDS), and a field emission scanning electron microscope (FE-SEM). The functionalization of the nanostructures with 2,3-dihydroxybenzaldehyde led to the disappearance of the XRD peaks of the nanostructures and the presence of a broad XRD peak at 2θ = 32°. In addition, the FE-SEM images revealed that the nanostructures consisted of spheres, cubes, and irregular shapes with an average grain size of 115 nm, and the nanocomposite consisted of spherical conglomerates consisting of needle-like shapes. The anticipated morphology following the functionalization of the nanostructures with 2,3-dihydroxybenzaldehyde resulted from the presence of 2,3-dihydroxybenzaldehyde on the backbones of the nanostructures. The EDS results showed that the nanostructures were composed of O, Na, Mg, and Si with weight percentages equal to 38.59%, 5.95%, 16.60%, and 38.86%, respectively. Additionally, the nanocomposite was composed of C, N, O, Na, Mg, and Si with weight percentages equal to 55.31%, 2.23%, 30.09%, 6.56%, 2.98%, and 12.83%, respectively. The synthesized nanostructures and nanocomposite samples were utilized for the efficient removal of cadmium and copper ions from aqueous media using the ion exchange and chelation adsorption procedures, respectively. Optimum conditions for removing the cadmium and copper ions were achieved at a pH, time, and temperature equal to 7.5, 80 min, and 298 K, respectively. The maximum uptake capacities of the synthesized nanostructures and nanocomposite samples toward cadmium ions were 89.44 mg/g and 155.04 mg/g, respectively, and the maximum uptake capacities of the synthesized nanostructures and nanocomposite samples toward copper ions were 103.73 mg/g and 177.94 mg/g, respectively. Moreover, the adsorption processes were exothermic, chemical, and followed the pseudo-second-order model and Langmuir equilibrium isotherm model.