Photocatalysis degradation of Azo dye using nanoTiO2-coated porous cellulose gel: enhancement by adsorption and its self-clean characteristic

Three-dimensional cellulose gel was prepared by a crosslinking of the cellulose chains using epichlorohydrin in the presence of the NH4OH, and the TiO2 nanoparticles which were fixed on the surface of cellulose gel to form microcrystalline cellulose gel/nanoTiO(2) composites (MCC-TiO2). The composites were characterised by means of X-ray diffraction, thermogravimetric analysis and scanning electron microscopy, respectively. The composites showed an efficient removal of methyl orange (MO) from their aqueous solution, and a two-step mechanism is involved. At first, the MO molecules were enriched on the surface of the MCC-TiO2 by absorption, and then they were degraded there via photocatalysis, and the degradation of the adsorbed MO promoted the further adsorption of MO from the solution. After 30 min, 94% of MO was removed, and the MCC-TiO2 can be cleaned by itself and reused without additional treatments.