甲苯-2,4-二氨基甲酸甲酯的光降解考察金红石TiO2颜料紫外屏蔽特性

以甲苯-2,4-二氨基甲酸甲酯(2,4-TDC)为分子探针模型,构建了一种新的评价金红石二氧化钛颜料紫外屏蔽性能的反应体系,系统地考察了反应条件对分子探针光降解的影响,并对一系列二氧化钛颜料紫外屏蔽性能进行了对比研究。结果表明,金红石二氧化钛作用下,2,4-TDC光降解过程符合一级反应动力学;随着二氧化钛颜料用量的增加,2,4-TDC光降解速率常数呈现指数次下降趋势;紫外光照下表面包覆的金红石二氧化钛颜料不能完全抑制·OH和h⁺活性物种的产生。根据2,4-TDC的光降解速率常数,能体现一系列工业金红石二氧化钛颜料紫外屏蔽性能差异。该方法具有条件温和、操作简便、实验周期短、结果重现性好等优点,将在二氧化钛颜料的紫外屏蔽性能测试中具有潜在的应用价值。

Investigation of UV-Shielding Properties of Rutile Titanium Dioxide Pigments via Photodegradation of Dimethyl Toluene-2,4-dicarbamate

Dimethyl toluene-2,4-dicarbamate(2,4-TDC) was selected as a model molecule to investigate the UV-shielding properties of TiO₂ pigments. The results show that the degradation of 2,4-TDC follows the first-order kinetics at different volume ratios of tetrahydrofuran to n-hexane. The decrease of the degradation kinetics constant of 2,4-TDC shows an exponential power tendency with the increase of the amount of TiO₂. Moreover, it is found that the reactive species such as ·OH and holes still play a minor role on the photodegradation of 2,4-TDC in presence of TiO₂ pigments. Based on the degradation kinetics constant of 2,4-TDC, the UV-shielding properties of different TiO₂ pigments can be directly evaluated within four hours. This study might have potential applications in industrial production and practical use for evaluating the UV-shielding properties of TiO₂ particles as it has advantages like mild reaction conditions, simple operation and excellent reproducibility.