The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support. In this study, citric acid (CA) was used as a modifier to prepare Al 2 O 3 supported Mn-Ce oxides (Mn-Ce/CA-Al 2 O 3 ) by the impregnation-calcination method. The characterization results showed that adding citric acid enhanced the dispersion of Mn-Ce oxides on the support, rendering Mn-Ce/CA-Al 2 O 3 with a larger specific surface area and abundant surface hydroxyl groups, thereby providing more reaction sites for catalytic ozonation. The Mn-Ce/CA-Al 2 O 3 exhibited excellent catalytic ozonation performance in degrading Reactive Black 5 (RB5) dye. It achieved nearly complete decolorization of RB5 within 60 min, with a COD removal efficiency of 60%, which was superior to the sole ozonation (30%). Furthermore, the Mn-Ce/CA-Al 2 O 3 system demonstrated significant degradation of RB5 over a wide pH range of 3–11. Based on the XPS and EPR analysis results, a preliminary mechanism of catalytic ozonation over the Mn-Ce/CA-Al 2 O 3 was proposed. The redox cycle of Mn 3+ /Mn 4+ and Ce 3+ /Ce 4+ effectively accelerated the electron transfer process, thus promoting the generation of reactive oxygen species (ROS) and improving the degradation of RB5. Meanwhile, the Mn-Ce/CA-Al 2 O 3 exhibited superior catalytic stability and effective treatment capabilities for real dye wastewater.
Qian Zhang,Ruo Yu Yin,Zhi Huang,Yan-ying Liu,Jun-ming Hong
The development of high-efficiency catalysts for peroxymonosulfate (PMS) activation is critical for pollutant treatment in environmental applications. In this research, a Co organic framework (CoHHTP) combined with graphene oxide (GO) (CoHHTP/GO) with a 2D structure was prepared for PMS activation to treat the azo dye Reactive Black 5 (RBK5). The combination of CoHHTP and GO via oxygen groups resulted in the high activity of CoHHTP/GO, and almost 100 % performance was achieved within 30 min under various pH, temperature, PMS loading, and catalyst loading conditions. The maximum RBK5 removal efficiency was obtained with a catalyst loading of 3.0 g L −1 , PMS loading of 0.5 mM, temperature of 25 °C, and pH of 6 with a pseudo-first-order kinetics k value of 0.1903 min −1 . The activation energy of the CoHHTP/GO/PMS/RBK5 system was calculated to be 14.34 kJ mol −1 . Meanwhile, radicals and nonradicals, including SO 4 ·− , ·OH, ·O 2 − , and 1 O 2 , were proven to be generated and involved in RBK5 degradation. Moreover, RBK5 degradation pathways were identified through experimental research and density functional theory calculation.
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