Photocatalysis degradation of Azo dye using nano TiO2 -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/nanoTiO₂ 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.