Mesoporous SiO2 nanoparticles (MSN) decorated with SnO2 quantum dots (QDs) are fabricated via simple two-step method. Morphological investigation shows that the spherical silica particles are uniformly decorated with crystalline SnO2 quantum dots. The introduction of the SnO2 quantum dots onto silica particles are also evidenced by the significant change in the specific surface area and zeta potential of the composite. Large BET surface area and uniform pore size distribution with large pore volume suggests that this composite can be exploited as an adsorbent material for organic dyes present in industrial wastewater. At room temperature, it is found to adsorb 100% of methylene blue (MB), a cationic dye within 5 min. The effects of variables such as the amount of adsorbents, contact time, pH of the initial solution, salt concentration, temperature and initial dye concentration on MB removal are studied in detail. The experimental equilibrium data is investigated using different isotherm models and it is established that Langmuir isotherm model fitted well with maximum monolayer adsorption capacity of 73.15 mg/g. The high adsorption capacity, fast removal rate and reusability of this binary nanocomposite essentially establishes that the material can be used as environment friendly and low cost adsorbent material for cationic dyes.
