Carbon Ratio Controlled in-situ Synthesis of Ordered Mesoporous Hybrid Silica/Carbon Materials via Soft Template Method

Abstract

A strategy for the synthesis of hybrid ordered mesoporous silica-carbon (Si/C) materials with moderate pore volume and surface area has been developed from the pre-calcinated MCM and the carbon precursor of Tectonagrandis (TG) dry leaves powder by the direct carbon loading method. The carbon precursor of pre-activated carbon (PAC) from the dry leaves powder of TG was prepared with the assistance of sulphuric acid by the partial chemical activation method. The controlled studies of the carbon loading method indicate that the PAC is a better precursor for the preparation of hybrid Si/C material than activated carbon from TG leaves. By this direct carbon loading strategy, the carbon content in the silica matrix is fixed up to 50 weight percentages with respect to silica and renders a novel and highly ordered mesoporous Si/C (OMSC) material. The synthesized hybrid Si/C materials are completely characterized by physico-chemical analyses. The observed 2θ values (2θ = 1.15o , 1.5ο , 1.8ο ) of SAX’s analysis, XRD patterns and thermogravimetric analysis of hybrid Si/C materials indicate that the synthesized materials are considerably different from carbon coated Si/C materials. The OMSC hybrid material containing high surface area has been chosen for dye adsorption that exhibits excellent dye adsorption behavior with Methylene Blue (MB) dye up to 97% in a short span of time. The effects of material dosage, contact time and initial concentration of MB dye adsorption were discussed. Adsorption kinetics of the pseudo first order (PFO) and pseudo second order (PSO) model along with adsorption isotherms of Langmuir and Freundlich were verified for the adsorption of MB on OMSC2. The experimental result was best fitted to the pseudo second order kinetic models and Freundlich adsorption isotherm. The calculated maximum adsorption capacity (qm) (279 mg g-1) is in good agreement with the experimentally observed value, which is higher than other silica-carbon materials.