【作者】 蔡文艳；

【导师】 俞斌；

【作者基本信息】 南京工业大学 ， 应用化学， 2006， 硕士

【摘要】 本文研究了常压微波消解分光光度法测定化学需氧量(COD)的方法,讨论了加热时间、硫酸银催化剂的用量、硫酸用量、硫酸磷酸的混酸比例以及催化剂种类对微波消解法测定COD的影响。选用邻苯二甲酸氢钾、甘氨酸和葡萄糖制成的消解水样进行测定。结果表明:(1)微波加热1min后,测得邻苯二甲酸氢钾和葡萄糖水样的COD值与采用ISO 6060-1986国际标准测得COD值基本一致,COD的回收率都达到96﹪以上;微波加热15min后,测得甘氨酸水样的COD的回收率为91﹪。所以采用常压微波消解分光光度法测定水样COD值减少消解反应时间,仍然可以获得准确的结果。(2)不加硫酸银,微波加热1min后,邻苯二甲酸氢钾和葡萄糖水样COD的回收率分别可达97﹪和96﹪,说明常压微波消解邻苯二甲酸氢钾和葡萄糖水样时,可以不使用硫酸银。但是,不加硫酸银,微波加热15min后,甘氨酸水样COD的回收率为78﹪,说明硫酸银对常压微波消解甘氨酸有催化作用。所以,采用常压微波消解分光光度法测定易氧化物质水样COD值时,可以不加硫酸银。测定难氧化物质水样COD值时,要加硫酸银。(3)在常压微波消解反应中,随着硫酸用量的减少,邻苯二甲酸氢钾水样COD的回收率逐渐降低。所以酸度是微波消解反应进行完全的重要保证。(4)采用混酸代替硫酸后,硫酸与磷酸体积比为4:1,微波加热1min后,邻苯二甲酸氢钾水样COD的回收率最高,达到了100﹪。而单独使用硫酸和磷酸,微波加热1min后,邻苯二甲酸氢钾水样COD的回收率分别为97﹪和30﹪,说明混酸对常压微波消解测定邻苯二甲酸氢钾水样的作用比单独使用硫酸和磷酸大。因此混酸可以用于常压微波消解法测定水样的COD值。(5)在常压微波消解反应中,采用硫酸铜、硫酸银和硫酸镍作为催化剂微波加热1min后,邻苯二甲酸氢钾水样COD的回收率达到101﹪,而加入硫酸银和硫酸镍,水样COD的回收率分别为97﹪和93﹪,说明在常压微波消解反应中,硫酸铜的催化作用比硫酸银大。而硫酸镍没有明显的催化作用。所以可以选择硫酸铜作催化剂参与常压微波消解反应。更多还原

【Abstract】 A method for the spectrometric determination of COD by microwave atmospheric digestion was studied. The digestion time, the dosage of Ag₂SO₄ catalyst, the dosage of sulfuric acid, the mixed acid （H₂SO₄-H₃PO₄） ratio and different catalysts have an effect on the method for the determination of COD by microwave atmospheric digestion. Water samples of potassium hydrogen phthalate, glycine and glucose were chosen to be used with the determination of COD. The results are found that:（1） COD which potassium hydrogen phthalate and glucose samples were heated in 1 minute by microwave digestion coincided with that in 2 hours by heater according to international standard ISO 6060-1986. The recovery ratios were both 96%. The recovery ratio of glycine is 91% in 15 minutes by microwave digestion. Thus when the digestion time was decreased in the spectrometric determination of COD by microwave atmospheric digestion, the result could be gained accurately.（2） Without Ag₂SO₄ by microwave digestion in 1 minute, the recovery ratio of potassium hydrogen phthalate and glucose were 97% and 96%, respectively. The result manifested that it was feasible without Ag₂SO₄ in the spectrometric determination of COD by microwave atmospheric digestion. But without Ag₂SO₄ by microwave digestion in 15 minutes, the recovery ratio of glycine was 78%. The result illustrated that Ag₂SO₄ catalyst had an influence on the oxidation of samples. Therefore the spectrometric determination of COD by microwave atmospheric digestion of easy oxidation samples could react without Ag₂SO₄. To determination about that of difficult oxidation, Ag₂SO₄ had to be added.（3） With the dosage of H2SO₄ was decreased in the reaction by microwave atmospheric digestion, the recovery ratio of potassium hydrogen phthalate was declined increasingly. So the reaction by microwave digestion is guaranteed to complete oxidation by acidity importantly.（4） The ratio of mixed acid （H₂S;-H₃P;） which was 4:1 had a good result in the determination of COD by microwave atmospheric digestion as to potassium hydrogen phthalate. That was 100% in 1 minute. However when H₂SO₄ and H₃PO₄ were used respectively, the recovery ratios were 97% and 30% in 1 minute by microwave digestion. The result indicated that mixed acid was更多还原