Degradation of a dye by 1-D nano-sized β-MnO₂ particles was investigated to understand the mechanisms involved. Batch experiments were performed in a system of β-MnO₂, hydrogen peroxide (H₂O₂), methylene blue (MB), and radical scavengers. The prepared β-MnO₂ had a 1-dimensional nano-sized structure and showed a negative zeta potential at pH higher than 3.7. In the presence of H₂O₂, MB was rapidly degraded by β-MnO₂. The rate of MB degradation was not significantly inhibited by the initial pH values from 6.05 to 10.02, but notably decreased at pH 3.04, at which point the β-MnO₂ particles dissolved. The effect mechanisms of operational parameters (i.e., H₂O₂, catalyst dose) in β-MnO₂/MB/H₂O₂ system were investigated. The removal rate of MB was remarkably reduced in the existence of p-quinone and was even more affected when sodium azide was added, indicating that the singlet oxygen radical (¹O₂) plays an important role. The obtained results point out that MB degradation by nano-sized β-MnO₂ is due to the catalytic oxidation of H₂O₂ on β-MnO₂surface reactive sites, rather than surface oxidation or adsorption. The reusability of nano-sized β-MnO₂ was also examined after five times of recycling to evaluate the applicability of β-MnO₂ for wastewater treatment.

研究了一维纳米尺寸的β - MnO ₂颗粒对染料的降解，以了解所涉及的机理。在β- MnO ₂，过氧化氢（H ₂ O ₂），亚甲基蓝（MB）和自由基清除剂的系统中进行批量实验。所制备的β- MnO ₂具有一维纳米尺寸结构，并且在高于3.7的pH下显示出负的ζ电势。在H ₂ O ₂的存在下，MB被β- MnO ₂迅速降解。。从6.05到10.02的初始pH值并未显着抑制MB降解速率，但在pH 3.04时显着降低了MB降解速率，此时β- MnO ₂颗粒溶解了。研究了β- MnO ₂ / MB / H ₂ O ₂体系中操作参数（H ₂ O ₂，催化剂用量）的影响机理。对苯二酚的存在可显着降低MB的去除率，而加入叠氮化钠则对MB的去除率影响更大，这表明单线态氧自由基（¹ O ₂）起着重要的作用。获得的结果指出，纳米级的MB降解β- MnO ₂是由于H ₂ O ₂在β- MnO ₂表面反应性位点上的催化氧化，而不是表面氧化或吸附引起的。循环使用五次后，还检查了纳米级β - MnO ₂的可重复使用性，以评估β- MnO ₂在废水处理中的适用性。