Functionalized Nanoporous Silica by Mono and Dendrimeramine in Methylene Blue Removal from Wastewater

Many organic dyes such as Methylene Blue are toxic, carcinogenic, and non-biodegradable due to their aromatic complex structure and high solubility in water. It is, therefore, essential to remove them from effluents discharged into the environment. In this study, SBA-15 mesoporous silica was synthesized by the hydrothermal method and later functionalized with mono- amine (NH2-SBA-15) and dendrimer amine (MDA-SBA-15). Then, the effect of surface modification on adsorption efficiency of Methylene Blue was examined in a batch system. The prepared materials were characterized by XRD, FT-IR, SEM, and BET analyses. The results showed that, under identical conditions, removal efficiency with MDA-SBA-15 was 2.6 and 3.3 times higher than those achieved with NH2-SBA-15 and SBA-15, respectively. Equilibrium isotherms were analyzed by Langmuir, Freundlich, Tempkin, and Dubnin–Radushkevich isotherms. Equilibrium data was best described by the Langmuir isotherm models, indicating a monolayer adsorption process. Tempkin isotherm parameters indicated that the adsorption process by MDA-SBA-15 was exothermic. The removal efficiency of Methylene Blue from aqueous solutions by MDA-SBA-15 was more than 90%, which was higher than the efficiency achieved by other nano-sorbents. This showed that MDA-SBA-15 could be used as an effective adsorbent in wastewater treatment.