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本文提出了测定水中剩余臭氧的碘化钾-淀粉分光光度法。该方法是根据臭氧和碘化钾在微酸性条件下的定量反应: O_3+2I~-+2H~+=O_2+I_2+H_2O 生成的碘用淀粉显色,用磷酸二氢钾-磷酸氧二钠缓冲溶液调节溶液的pH=5.9,于560nm处测定。该显色反应的摩尔吸光系数ε=2.59×104、桑德尔灵敏度S=1.85×10~(-3)/臭氧浓度在0—1ppm符合比耳定律。六聚偏磷酸钠能有效地消除 2μg/mlFe~(3+)、5μg/ml Cu~(2+)的干扰。应用本法对实际水样进行了测定,并和碘量法作了比较,结果令人满意。本法的优点是灵敏度较高、所用仪器设备简单、操作方便。
This paper presents a potassium iodide-starch spectrophotometry for the determination of residual ozone in water. The method is based on the quantitative reaction of ozone and potassium iodide under slightly acidic conditions: the iodine produced by O3 + 2I ~ + 2H ~ + = O_2 + I_2 + H_2O is colored with starch, and is buffered with potassium dihydrogen phosphate-disodium phosphate The pH of the solution was adjusted to 5.9, measured at 560 nm. The molar absorptivity of this color reaction ε = 2.59 × 104, Sangdel sensitivity S = 1.85 × 10 -3 / O concentration 0-1ppm in line with Beer’s law. Sodium hexametaphosphate can effectively eliminate 2μg / ml Fe ~ (3 +), 5μg / ml Cu ~ (2+) interference. The actual water sample was measured by this method and compared with iodometric method, the result was satisfactory. The advantage of this method is the high sensitivity, the equipment used is simple and easy to operate.