ABSTRACT

Potassium birnessites were prepared using two methods, sol–gel or oxidation. The solids were characterised by element chemical analysis, powder X-ray diffraction, FT-IR spectroscopy, thermal analyses, and nitrogen adsorption. The evolution of the properties as a function of the preparation method was discussed. The photocatalytic performance of these solids was preliminarily tested for the degradation of 4-nitrophenol. The degradation pathway and the nature of the by-products were investigated by mass spectrometry. The solids showed good catalytic behaviour, although their preparation must be improved, mainly concerning the calcination step involved in sol–gel synthesis, which led to the formation of Mn₂O₃ that worsened the catalytic behaviour.

摘要

钾水钠锰矿采用两种方法制备，溶胶-凝胶法或氧化法。通过元素化学分析、粉末 X 射线衍射、FT-IR 光谱、热分析和氮吸附来表征固体。讨论了作为制备方法函数的性质演变。初步测试了这些固体的光催化降解4-硝基苯酚的性能。通过质谱法研究了降解途径和副产物的性质。固体表现出良好的催化行为，尽管它们的制备必须改进，主要涉及溶胶-凝胶合成中涉及的煅烧步骤，这导致形成 Mn ₂ O ₃，从而使催化行为恶化。