Department of Applied Chemistry and Biotechnology, National Institute of Technology (KOSEN), Niihama College, Japan.
Department of Applied Chemistry and Biotechnology, National Institute of Technology (KOSEN), Niihama College, Japan.
Chemosphere. 2021 Jan;263:128141. doi: 10.1016/j.chemosphere.2020.128141. Epub 2020 Aug 29.
Methylene blue (MB) has recently been proposed as a new chemical probe to colorimetrically verify the presence of hydroxyl radicals and was applied to the microbubble technique in this report. The degradation of MB in water was observed by air microbubbles under acidic condition or adding HO. The discoloration of MB induced by air microbubbles supports that hydroxyl radicals are generated by the collapse of microbubbles in water. The decomposition rate of MB increases with increasing the concentration of acids (HCl, HNO, HSO) and HO up to ab. 2 mM, and becomes almost constant above ab. 2 mM. Note that the decomposition rate of MB mainly depends on pH, not the kind of acid and that adding salt slightly enhanced the decomposition of MB. The fact that the blue-shift of the absorbance band of MB was observed for not HO but acids proposed that the methyl groups of MB are preferentially dissociated under acidic conditions due to the protonation of dimethylamino group.
亚甲蓝 (MB) 最近被提议作为一种新的化学探针，用于比色验证羟基自由基的存在，并在本报告中应用于微泡技术。在酸性条件下或添加 HO 时，观察到空气中的微气泡使水中的 MB 降解。空气微气泡引起的 MB 褪色表明，羟基自由基是由水中微气泡的破裂产生的。MB 的分解速率随着酸（HCl、HNO、HSO）和 HO 浓度的增加而增加，直至约 2 mM，超过 ab 后几乎保持不变。2 mM。请注意，MB 的分解速率主要取决于 pH 值，而不是酸的种类，并且添加盐略微增强了 MB 的分解。观察到 MB 的吸收带蓝移不是 HO 而是酸，这表明在酸性条件下，由于二甲氨基的质子化，MB 的甲基优先解离。
