Concentration Dependence of TiO₂ Nanoparticles in Carbon Xerogels on Adsorption-Photodegradation Applications

A suite of composite materials comprising carbon xerogel content and TiO₂ was synthesised via a modified sol-gel method. The textural, morphological, and optical properties of the composites were extensively characterised and correlated with the observed adsorption and photodegradation performances. The homogeneity and porous structure of the composites depended on the amount of TiO₂ deposited in the carbon xerogel. During polymerisation, Ti-O-C linkages were formed, which favoured the adsorption and photocatalytic degradation of the target methylene blue dye. Adsorption was deemed favourable, and most accurately fitted by the Sips model, exhibiting a maximum uptake of 209 mg g^-1 estimated for the sample containing 50% TiO₂. However, the synergistic effect of adsorption and photocatalytic degradation for each composite depended on the amount of TiO₂ deposited in the carbon xerogel. The dye degradation process for the composites with 50%, 70%, and 90% TiO₂ improved by 37%, 11%, and 2%, respectively, after exposure to visible light after adsorption. Repeated runs demonstrated over 80% of activity was retained after four cycles. Thus, this paper provides insight into the optimal amount of TiO₂ required within such composites for maximum removal efficiency via adsorption and visible light photocatalysis.