Amino-Functionalized Mesoporous Silicas MCM-48 as Zn(II) Sorbents in Water Samples

Amino-functionalized MCM-48 (NH2-MCM-48) modified with 3-[2-(2-aminoethylamino)ethylamino]-propyl-trimethoxysilane (DTES) was synthesized by a co-condensation method and was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrum, and thermogravimetric analysis techniques. Batch adsorption studies of Zn(II) on NH2-MCM-48 were investigated. The effect of experimental parameters including pH, adsorbent dose, Zn(II) concentration, and adsorption time was studied, and the research results indicated NH2-MCM-48 has a higher adsorption capacity for Zn(II) than other adsorbents. The experimental data were fitted to Langmuir and Freundlich isotherm models, and the Langmuir equation showed better correlation with the experimental data 0 than the Freundlich. According to the parameters of the Langmuir equation, the maximum adsorption capacities of Zn(II) onto NH2-MCM-48 were (83.33, 90.91, and 100.00) mg.g(-1) at (303, 313, and 323) K, respectively. The adsorption kinetics data were found to follow the pseudosecond-order kinetic model. The thermodynamic parameters (Delta G(0), Delta H-0, and Delta S-0) were measured, and the negative value of Gibbs energy indicated the adsorption process was spontaneous in nature. Moreover, the adsorbent was applied in environmental samples, and the removal rate and recovery of Zn(II) from water were high. These results indicate that NH2-MCM-48 is an efficient adsorbent to remove Zn(II) from polluted water.