Synthesis of nanocrystalline titanium dioxide for photodegradation treatment of remazol brown dye

Visible light responsive heterophase Titania monoliths for the fast and efficient photocatalytic decontamination of organic pollutants

The article reports the synthesis of an ordered mesoporous network of heterophase TiO2 monoliths as a visible light-responsive photocatalyst using tri-block copolymers of Pluronic F108, P123 and F127 as structure-directing agents (SDAs) and temperature-controlled calcination (450-650 °C) has been carried out by direct templating-assisted hydrothermal approach. The structural/surface morphology and topographical properties of the photocatalyst are characterized using FE-SEM-EDAX, HR-TEM-SAED, p-XRD, VB-XPS, PLS, TG/DTA, UV-Vis-DRS, BET/BJH and zeta potential analysis. The undoped heterophase mesoporous TiO2 monoliths with in-built lattice/surface defects exhibit visible light photocatalytic properties, successfully dissipating Reactive Brown 10 (RB-10) dye. The influence of physicochemical parameters, such as SDAs, temperature, pH, dye concentration, catalyst dosage, photosensitizers and light intensities, are optimized for maximum photocatalytic performance at a shorter timespan. The F127-assisted mesoporous TiO2 monolith (550 °C) exhibits superior degradation kinetics (15 min) for RB-10 dye solution (20 ppm) at pH 2.0-3.0 using a photocatalyst dosage of 50 mg and 2 mM of KBrO3, irradiated with 150 W/cm2 tungsten lamp. The photocatalysts are fabricated without complicated chemical modifications and display topmost efficiency in quickly decontaminating persistent pollutants. The photoproducts from RB-10 photocatalytic degradation are investigated using HR-MS analysis. The photocatalyst can be reused efficiently for six cycles, even under extreme conditions.

Synthesized Cr/TiO2 immobilized on pumice powder for photochemical degradation of acid orange-7 dye under UV/visible light: influential operating factors, optimization, and modeling

The current study aimed to investigate the removal efficiency of acid orange-7 (AO7) using synthesized Cr/TiO₂ immobilized on pumice powder under visible light and UV irradiation. The characterization of synthesized nanocatalyst examined by scanning electron microscope, X-ray diffraction, and Fourier transforms infrared. The optimum of experimental parameters including catalyst dosage, dye concentration, time and pH, D-optimal Design (DOD) along with response surface methodology obtained by R software. The initial and outlet concentration was measured using a spectrophotometer. Besides, Analysis of variance results for the quadratic model showed simple linear regression with high significance and provided as a predicting model. The differences less than 0.2 between multiple and adjusted R² in two models indicate that two examined models fitted suitably. The highest removal efficiency of AO7 was 95 and 74% under visible and UV irradiation, respectively. Therefore, the higher removal efficiency in visible light reduces the costs and energy, moreover, offers an environmentally friendly method. The results showed that the removal efficiency of AO7 increased considerably with rising catalyst dosage and time, as well as minimizing dye concentration, and pH.

Mechanochemical synthesis of nanophotocatalysts SiO2/TiO2/Fe2O3: their structural, thermal and photocatalytic properties

In the study the mechanochemical synthesis was used to prepare photocatalytic materials based on TiO2, SiO2, and Fe2O3. During the preparation the impact of composition, milling speed, and calcination process on the properties of the composites was investigated. The structural and thermal properties of photocatalysts were determined using the N2 adsorption/desorption, XRD, and FT-IR/PAS methods. The thermal stability of the obtained materials was also examined (TG/DTG). Moreover, their photocatalytic activity was tested in relation to Methylene Blue at UV and Vis radiation. The results indicate that the mechanochemical synthesis in the high-energy planetary mill is an effective method for obtaining materials with photocatalytic properties at the UV and Vis radiation. It was shown that the removal process of MB may be described by the pseudo-first-order kinetics.