Synthesis and characterisation of an iron oxide mesoporous silica nano-composite and its application in removal of methylene blue dye

Abstract

Globally, effluents from textile industries and other waste streams have the potential to release vast amounts of chemical dyes and related substances into the environment. Treatment of water and waste-water to remove such pollutants is a pressing need and one promising option is the use of matrix-stabilised nanomaterials for pollutant removal via adsorption. Matrix-stabilised nanomaterials are composite substances in which the nanomaterials are embedded in a stable matrix that renders them less susceptible to the flocculation and agglomeration processes that can limit the success of water treatment via conventional nanomaterials. In this study, mesoporous silica (mSiO2) and nano-iron loaded mesoporous silica (FeO-mSiO2) were successfully synthesized and characterised alongside commercially obtained Fe nanoparticles (Fe-NP) using UV–Visible spectral analysis, FTIR, XRD, TGA/TDA and SEM analyses. The surface area of the composite material was typically 29 m2/g, with average pore volume 0.042 cm3/g, indicating scope for further refining. All test materials were evaluated for their capacity to remove methylene blue, a dye widely used in textile and chemical industries, from water and optimal conditions for removal were determined considering pH, solid: solution ratio, and contact time. Removal by FeO-mSiO2 equaled or exceeded that of the other substances under most conditions tested, with maximum removal achieved at pH 6–9, contact time 60–120 min, and a sorbent: liquid ratio 1:1000.