Yihe Qin,Run Yuan,Shaojun Luo,Haiming Huang,Xuwen He
Catalysts with high catalytic performance are crucial for the catalytic ozonation of organic wastewater. This study synthesized an efficient, stable, and practical Fe-Mn/Al 2 O 3 ozone catalyst for wastewater treatment using an impregnation calcination method, and applied it in the catalytic ozonation of wastewater. When the concentration of manganese nitrate was 0.15 mol/L, the Mn/Fe ratio was 3:1, the immersion time was 24 hours, the calcination temperature was 500 ℃, and the calcination time was 4 hours, the prepared Fe-Mn/Al 2 O 3 had the best catalytic effect on simulated wastewater, with a chemical oxygen demand (COD) removal efficiency of 73.6%. At the same time, the physicochemical properties of the catalyst were investigated, and the catalytic effect of the catalyst on actual coking wastewater was investigated on a laboratory scale. When the ozone concentration was 20 mg/L, the gas flow rate was 0.5 L/min, the catalyst concentration was 400 g/L, and the pH was 7.02, the actual COD removal efficiency of coking wastewater was 71.6%. The pilot test results showed that the COD of the treated coking wastewater could stably meet the standard (COD<80 mg/L), with an average COD removal rate of about 58.3%, indicating that the Fe-Mn/Al 2 O 3 had high catalytic activity and good stability. Kinetic analysis showed that the degradation process of organic pollutants followed the pseudo-second-order kinetic equation. The results of water quality analysis such as conventional water quality indicators, fluorescence spectroscopy, and molecular weight classification indicated that the large molecular organic pollutants were efficiently degraded. Mechanism analysis indicated that the active components of the catalyst reacted with ozone through electron transfer to enhance the ozone utilization efficiency and efficiently remove organic pollutants. This study can provide theoretical support and technical reference for the standardized discharge of coking wastewater in the future.
Antimony(III) or Sb(III) contamination in surface waters poses a serious threat to the ecological system and human health, and green and cost-effective technologies are urgently needed to mitigate its toxic effects. We green synthesized a novel oxidative sorbent, referred to as Al2O3-supported Fe–Mn binary oxide nanoparticles (Fe–Mn@Al2O3), and investigated its removal effectiveness and dynamic quantitative removal mechanisms of Sb(III) at environmentally relevant levels from simulated surface water. Fe–Mn binary oxides (Fe–Mn) were successfully attached on the surface of Al2O3via intermolecular hydrogen bonding, resulting in the formation of Fe–Mn@Al2O3 with a larger specific surface area, greater oxidizing reactivity, and more sorption sites compared to Fe–Mn. The resulting composite is mainly composed of FeOOH, Fe2O3, MnO2, and Al2O3. Life cycle assessment (LCA) indicated that the Fe–Mn@Al2O3 synthesis met green chemistry principles. Fe–Mn@Al2O3 at a Fe : Al2O3 molar ratio of 1 : 2 displayed an enhanced Sb(III) sorption capacity of 272.2 mg g−1 at pH 6.4 within 48 h. Sorption kinetic data were adequately simulated with the pseudo second-order kinetic model and the intraparticle diffusion model, suggesting that the sorption kinetics were a combination of chemisorption and intraparticle diffusion. The Freundlich isotherm model outperformed the Langmuir model in simulating the sorption isotherm data, which aligns with the heterogeneous surface sorption sites of Fe–Mn@Al2O3. MnO2 in Fe–Mn@Al2O3 oxidized Sb(III) to Sb(V), whereas FeOOH and Al2O3 acted as adsorption sites towards Sb(III) and Sb(V). Most importantly, Fe–Mn@Al2O3 still maintained high sorption efficiencies towards Sb(III) after five consecutive regeneration cycles. The dynamic quantitative removal mechanisms were proposed thereafter. Upon equilibrium, 92.8% of Sb(III) was sorbed by Fe–Mn@Al2O3, and 94.9% of sorbed Sb(III) was oxidized to produce Sb(V) and Mn(II). 59.1% of the formed Sb(V) was adsorbed onto Fe-Mn@Al2O3 and 40.9% of Sb(V) was released into the solution. The new quantitative and mechanistic insights contribute to an improved understanding of the uptake of Sb(III) by Fe–Mn@Al2O3 in natural and engineered systems, and the results may guide further preparation and application of reactive adsorbents for removal of redox-active contaminants from water.
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