二氧化硫及其衍生物的紫外吸收光谱特征

UV-visible absorption spectral properties of sulfur dioxide and its derivatives

运用紫外可见光光谱分析方法对SO2溶于水和有机溶剂时的吸收光谱特征进行研究,同时也对SO2衍生物亚硫酸钠(Na2SO3)、亚硫酸氢钠(NaHSO3)、焦亚硫酸钠(Na2S2O5)水溶液的吸收光谱特征进行研究,并探讨盐酸(HCl)对其光谱性质的影响.结果表明:①SO2在水、乙醇、甘油、正丁醇中分别在276、277、276、278 nm有一特征吸收峰,在有机溶剂中的吸光强度远大于在水中的吸光强度;②Na2S2O5和NaHSO3水溶液在257 nm处有一特征吸收峰,Na2SO3未见特征吸收峰,加入HCl后,3种化合物溶液均在276 nm出现特征吸收峰;③HCl能增强SO2及其衍生物水溶液的吸光强度,且呈浓度依赖关系;而CaCl2和NaCl对SO2及其衍生物水溶液的吸光强度有降低作用.因此可得出结论:①SO2在水中的吸光强度远小于在有机溶剂中的吸光强度;②HCl对SO2溶于水中的吸光强度的增强作用是H+的作用而不是Cl-的作用;③SO2衍生物溶液不存在或很少存在SO2分子,但加入适量HCl可使该衍生物用作"SO2供体",亚硫酸氢钠酸性溶液和焦亚硫酸钠酸性溶液可作为"SO2供体"用于SO2毒理学和生理学的研究和实践.

The absorption spectra of SO2 dissolved in water or organic solvents and the spectra of SO2 derivatives— sodium sulfite（Na2SO3）,sodium bisulfite（NaHSO3） and sodium metabisulfite（Na2S2O5） dissolved in water were studied by ultraviolet-visible spectrophotometry.The effect of HCl on the spectral properties of SO2 and its derivatives was also investigated.The results show that：（1） SO2 in water,ethanol,glycerol and n-butyl-alcohol had a characteristic absorption peak at 276,277,276,278 nm,respectively.The absorption intensity of SO2 in organic solvents was much stronger than that of SO2 in water.（2） Na2S2O5 and NaHSO3 exhibited an absorption peak at 257 nm,and no absorption peak of Na2SO3 was found.However,NaHSO3,Na2SO3 and Na2S2O5 all exhibited absorption peaks at 276 nm with the addition of HCl.（3） The absorption intensity of SO2 and its derivatives at 276 nm was strongly enhanced in the presence of HCl in a concentration-dependent manner,but CaCl2 and NaCl decreased their absorption intensity.These results led to the following conclusions：（1） the absorption intensity of SO2 in water was much less than that of SO2 in organic solvents.（2） Enhancing effect of HCl on the absorption intensity of SO2 in water at 276 nm was due to H＋,not Cl-.（3） There was no or few SO2 molecule in Na2S2O5,NaHSO3 or Na2SO3 solution.But these solutions with proper HCl addition can be used as ＂SO2 donor＂.The acidic NaHSO3 or Na2S2O5 solution can be used as ＂SO2 donor＂ in the studies of the toxicology and physiology of SO2.