Carbon and TiO₂ synergistic effect on methylene blue adsorption

Due to its high efficiency, low cost and a simple operation, the adsorption process is an important and widely used technique for industrial wastewater treatment. Recent studies on the removal of artificial dyes by adsorption include a large number of adsorbents, such as: activated carbon, silicates, carbon nanotube, graphene, fibers, titanates and doped titanates. The carbon insertion in the TiO₂ structure promotes a synergistic effect on the adsorbent composite, improving the adsorption and the charge-transfer efficiency rates. However, there are few studies regarding the adsorption capacity of TiO₂/Carbon composites with the carbon concentration. This study evaluates the effect of carbon (resorcinol/formaldehyde) insertion on TiO₂ structure through the adsorption process. Adsorbents were prepared by varying the carbon weight percentages using the sol-gel method. The physicochemical properties of the catalysts prepared, such as crystallinity, particle size, surface morphology, specific surface area and pore volume were investigated. The kinetic study, adsorption isotherm, pH effect and thermodynamic study were examined in batch experiments using methylene blue as organic molecule. In addition, the effect of carbon phase on the adsorption capacity of TiO₂-carbon composite was deeply investigated. SEM micrographs showed that TiO₂ phase grows along the carbon phase and FT-IR results showed the presence of Ti−O−C chemical bonding. The experiments indicate that the carbon phase acted as a nucleation agent for the growth of TiO₂ during the sol-gel step, with a TiO₂ structure suitable for blue methylene adsorption, resulting in a material with large surface area and slit-like or wedge-shaped pores. Further experiments will show the best carbon concentration for methylene blue adsorption using a TiO₂ based material. - Highlights: • This article deals with the adsorption of methylene blue onto TiO₂-Carbon composite. • The sol-gel synthesis was efficient to insert TiO₂ particles on carbon structure. • The TiO₂ nanoparticles presented mesopore area around the carbon structure. • The wedge shapes pores which were the main responsible for methylene blue removal. • A new TiO₂-Carbon materials can be used for removal of large pollutants molecules.