Atenolol removal from aqueous solutions using Bi2O3/TiO2 under UV-C and visible light irradiations

Hydrothermally improved natural manganese-containing catalytic materials to degrade 4-chlorophenol

Natural manganese-containing mineral (NMM) was used as a catalyst in heterogeneous catalytic ozonation for 4-chlorophenol (4-CP) degradation. The surface and structural properties of NMM were modified by the hydrothermal aging process and called H-NMM. The catalytic activity of NMM and H-NMM were evaluated for the catalytic ozonation process (COP). The synergistic effect of NMM and H-NMM in ozonation processes for 4-CP degradation under optimal conditions (pH of 7, 1 g/L of NMM and H-NMM, 0.85 mg/min of O₃, and 15 min of reaction time) was measured by 3.04 and 4.34, respectively. During the hydrothermal process, Mn⁴⁺ and Fe²⁺ were converted to Mn²⁺ and Fe³⁺, which caused better performance of the H-NMM than the NMM. During the catalytic ozonation process, Mn²⁺ is completely oxidized, which increases the production of Hydroxyl radical (•OH). The reactive oxygen species (ROS) generated in the system were identified using radical scavenging experiments. •OH, superoxide radical (•O₂^-), and singlet oxygen (¹O₂) represented the dominant reactive species for 4-CP degradation. The O₃/H-NMM process indicated a powerful ability in the mineralization of 4-CP (66.31% of TOC degradation). H-NMM exhibited excellent stability and reusability in consecutive catalytic cycles, and the NMM exhibited desirable performance. This study offers NMM and H-NMM as effective, stable, and competitive catalysts for hastening and enhancing the ozonation process to mitigate environmentally related pollutants of high concern.

Influence of Calcination Temperature on Photocatalyst Performances of Floral Bi2O3/TiO2 Composite

Heterojunction photocatalytic materials show excellent performance in degrading toxic pollutants. This study investigates the influence of calcination temperature on the performances of floral Bi2O3/TiO2 composite photocatalyst crystal, which was prepared with glycerol, bismuth nitrate, and titanium tetrachloride as the major raw materials via the solvothermal method. XRD, SEM/TEM, BET, Uv-vis, and XPS were employed to analyze the crystal structure, morphology, specific surface area, band gap, and surface chemical structure of the calcined temperature catalysts. The calcination temperature influence on the catalytic performance of composite photocatalysis was tested with rhodamine B (RhB) as the degradation object. The results revealed the high catalytic activity and higher photocatalytic performance of the Bi2O3/TiO2 catalyst. The degradation efficiency of the Bi2O3/TiO2 catalyst to RhB was 97%, 100%, and 91% at 400 °C, 450 °C, and 500 °C calcination temperatures, respectively, in which the peak degradation activity appeared at 450 °C. The characterization results show that the appropriate calcination temperature promoted the crystallization of the Bi2O3/TiO2 catalyst, increased its specific surface area and the active sites of catalytic reaction, and improved the separation efficiency of electrons and holes.