可见光辐射下活性炭-铁酸镍杂化催化剂光催化氧化氨氮

铁酸镍（NiFe₂O₄）中的镍原子抑制其光芬顿催化活性. 然而，活性炭（AC）能激活其光芬顿催化活性，结果导致复合催化剂AC-NiFe₂O₄在过氧化氢存在时可见光辐射下也可催化氧化氨氮. 用X射线衍射（XRD），透射电镜（TEM），傅里叶变换红外（FTIR）光谱，紫外-可见漫反射光谱（UV-Vis DRS），比表面积和振动样品磁强计对催化剂进行了表征. 光催化降解氨氮的实验表明，该复合催化剂在10 h内氨氮的降解率可达到91.0%，而同样条件下没有催化剂时氨氮的去除率只有24.0%. 对照实验表明，裸铁酸镍在可见光辐射下，氨氮的降解率只有30.0%. 这表明活性炭加速了氨氮的氧化速率. 动力学研究表明，氨氮的氧化遵循一级反应动力学规律，其表观反应动力学常数为3.538×10^-3 min^-1. 机理研究表明，氨氮的氧化是通过生成HONH₂ 中间体，然后转化为NO₂^- .8次循环实验表明该复合催化剂容易分离、可循环使用、且催化活性十分稳定. 因此，该催化剂具有潜在的应用价值.

Photocatalytic Oxidation of Ammonia via an Activated Carbon-Nickel Ferrite Hybrid Catalyst under Visible Light Irradiation

The nickel atoms in a metal ferrite lattice inhibit photocatalytic activity with hydrogen peroxide. However, activated carbon bonded on nickel ferrite (AC-NiFe₂O₄) induces photocatalytic activity of nickel ferrite with hydrogen peroxide, enabling photo-Fenton catalytic oxidation of ammonia under visible-light irradiation in the presence of hydrogen peroxide. The AC-NiFe₂O₄ catalyst was characterized using X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, and a vibrating sample magnetometer at room temperature. The photocatalytic tests showed that the ammonia degradation efficiency approached 91.0% in the presence of the AC-NiFe₂O₄ catalyst, whereas the efficiency was only 24.0% without the catalyst under similar conditions over 10 h. Another test showed that the single NiFe₂O₄ catalyst achieved a degradation efficiency of only 30.0% under similar conditions, indicating that activated carbon can accelerate the rate of ammonia oxidation. Exploration of the oxidation mechanism showed that the oxidation pathway involves an HONH₂ intermediate, forming nitrite ions. Kinetic studies showed that the oxidation of ammonia follows a pseudo-first order kinetic law, with a rate constant of 3.538×10^-3 min^-1. The catalyst was used in eight runs, and shown to be stable, recoverable, separable, and reusable, suggesting that it has potential applications in the disposal of ammonia.