Novel Nano-Fe₂O₃-Co₃O₄ Modified Dolomite and Its Use as Highly Efficient Catalyst in the Ozonation of Ammonium Solution

Abstract

Catalytic ozonation is a new method used for removal of NH4OH solution. Therefore, high catalytic performance (activity and selectivity) should be achieved. In this work, we report the synthesis and catalytic performance of Fe2O3-Co3O4 modified dolomite in the catalytic ozonation of NH4OH solution. Dolomite was successfully activated and modified with Fe2O3 and Co3O4. Firstly, dolomite was activated by heating at 800°C for 3 h and followed by KOH treatment. Activated dolomite was modified with Fe2O3 by the atomic implantation method using FeCl3 as Fe source. Fe2O3 modified dolomite was further modified with Co3O4 by precipitation method. The obtained catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), N2 adsorption–desorption (BET), and temperature-programmed reduction (H2-TPR). From SEM image, it was revealed that nano-Fe2O3 and Co3O4 particles with the size of 80–120 nm. Catalytic performance of activated dolomite, Fe2O3 modified dolomite, and Fe2O3-Co3O4 modified dolomite in catalytic ozonation of NH4+ solution was investigated and evaluated. Among 3 tested catalysts, Fe2O3-Co3O4 modified dolomite has the highest NH4+ conversion (96%) and N2 selectivity (77.82%). Selectivity toward N2 over the catalyst was explained on the basis of bond strength M-O in oxides through the standard enthalpy ΔH°f of oxide. Catalyst with lower ΔH°f value has higher N2 selectivity and the order is the following: Co3O4 (ΔH°f of 60 kcal (mole O)) > Fe2O3 (ΔH°f of 70 kcal (mole O)) > MgO (ΔH°f of 170 kcal (mole O)). Moreover, high reduction ability of Fe2O3-Co3O4 modified dolomite could improve the N2 selectivity by the reduction of NO3- to N2 gas.

High CO Adsorption Performance of CuCl-Modified Diatomites by Using the Novel Method “Atomic Implantation”

“…Currently, clay minerals such as halloysite, dolomite, bentonite, Ilmenite, and diatomite have attracted a lot of interest because of their potential application or environmental treatment [18][19][20][21][22]. Clay-based adsorbents for adsorption of gases such as CO, CO 2 , CH 4 , H 2 S, heavy metal ions, and organic pollutants were also investigated.…”

Synthesis of high purity magnesia MgO from Algerian dolomite ore

“…superconductor materials [7], electronic and optical components and catalysts [2,12,19,20]. Magnesium oxide MgO is not available in nature.…”

Synthesis of Fe/H-ZSM-5 material by chemical vapor deposition method and its application for degradation of reactive dye

“…Các hạt oxit sắt phân bố khá đồng đều trên bề mặt chất mang ZSM-5. Trong nghiên cứu của Bouchra và cộng sự[12] đã tổng hợp vật liệu Fe/H-ZSM-5 có các hạt oxit sắt có kích thước lớn (vài µm). Như vậy, phương pháp lắng đọng hơi hóa học được ứng dụng để tổng hợp vật liệu Fe/H-ZSM-5 có ưu việt hơn so với các phương pháp tẩm, sol-gel do tạo ra các hạt oxit có kích thước hạt rất nhỏ, lắng đọng trên bề mặt chất mang H-ZSM-5.Hình 3: Ảnh SEM của H-ZSM-5 và Fe/H-ZSM5 Đường đẳng nhiệt hấp phụ-giải hấp phụ N2 của vật liệu H-ZSM-5, Fe/H-ZSM-Các thông số đặc trưng của vật liệu H-ZSM-5 và Fe/H-ZSM-Đường đẳng nhiệt hấp phụ -khử hấp phụ N2 (BET) của vật liệu H-ZSM-5, Fe/H-ZSM-5 thuộc dạng IV phân loại theo IUPAC, với vùng trễ tương ứng với sự ngưng tụ mao quản, đặc trưng cho cấu trúc vật liệu có mao quản trung bình.…”