Abstract
Some aspects of adsorption, catalytic and photocatalytic interactions of organic dyes with TiO2-based binary nanocomposites. / O. Lavrynenko, M. Zahornyi, O. Pavlenko. Nano Studies. – 2023–2024. – # 23/24. – pp. 77-98. – eng.
Nanocomposites based on titanium dioxide with an anatase structure, modified with noble metals (Ag, Pd, Au) and nanocerium were synthesized using the chemical deposition method. It is shown that nanocomposites form loose aggregates with the size of individual particles in the range of 8–16 nm, which are capable of forming colloid-stable dispersions upon contact with dye solutions. The influence of the nature of the doping admixture on the sorption, catalytic, and photocatalytic properties of nanocomposites during their interaction with solutions of cationic and anionic dyes has been determined. We have investigated that the ZPC (Zero Point of Charge) of most composites was close to neutral and ranged from 6.9 to 9.2. In solutions of dyes, the sign of the particle charge changed due to the possible hydrolysis and deviation of pH values. Maximum adsorption capacity of MB (Methylene Blue) dye is found to be 12.96 mg/g. The effect of increasing the color intensity of the solution upon contact with nanocomposites was revealed, which is due to the sensitization of photocatalysts by the dye molecules. It is shown that the photocatalytic destruction of dye molecules is characterized by a gradual decrease in the intensity of all characteristic bands and is accompanied by a hypsochromic shift of the chromophore band in UV–Vis (UltraViolet–Visible) spectra. At the same time, during the catalytic destruction of dye molecules, the destruction of the chromophoric part of the molecules is faster compared to photocatalysis, but the temperature of the system does not affect the aromatic part of the dye. It was stated that for the effective destruction of organic dyes in an aqueous environment, it is advisable to combine the catalytic process at 50–60°С and the UV or visible light irradiation in 60 min. Fig. 9, Tab. 3, Ref. 49.