Magnetised nanocomposite mesoporous silica and its application for effective removal of methylene blue from aqueous solution

Via a new synthetic route, magnetized nanocomposite mesoporous material (MNCM) was prepared using silica (SiO₂) and nano-magnetite (Fe₃O₄). The formation mechanism of MNCM was determined using various spectroscopic analyses. Among the synthesized materials, MNCM-1, prepared with a molecular weight ratio of Fe₃O₄ to SiO₂ of 0.14:1, had a homogeneous mesopore structure with a mean pore size of 4.68 nm, specific surface area of 576 m² g^-1, and a pore volume of 0.65 cm³ g^-1. MNCM-1 had magnetic properties (2.9 emu) and structural strength, as well as higher and faster adsorptive MB removal than other mesoporous materials. The removal of MB by MNCM-1 was found to be a physisorption process with an electrostatic interaction between negatively charged silanol (Si-O^-) and positively charged MB, and was thermodynamically favorable at higher temperatures. The economic assessment revealed that treatment costs for MB-containing water using MNCM-1 were 16-80 times lower than those with other mesoporous materials, due to the use of the cheap Si precursor and the higher sorption capacity. Furthermore, MNCM-1 can be reused and regenerated without any defects after easy separation using a magnet. Because MNCM-1 can be produced economically on a large scale, it may have significant effects for adsorption-based treatment systems with regard to the removal of MB from waste water.