摘要
本文所介绍的K2Cr2O7法测化学需氧量(简称CODcr)的简易快速测定法,是用K2Cr2O7作标准溶液的氧化还原滴定法。实验的原理是:在水样中加入过量的K2Cr2O7标准溶液,在强酸性和加热煮沸下,回流10分钟,使K2Cr2O7与有机化合物和还原性物质充分作用反应为Cr2O72-+14H++6e(?)2Cr3++7H2O。当样品冷却至室温时,将其稀释。待其再度冷却后,其中过量的K2Cr2O7用还原剂硫酸亚铁铵[(NH4)2Fe(SO4)2]标准溶液滴定,试亚铁灵作指示剂,反应为Cr2O72-+6Fe2++14H+=2Cr3++6Fe3++7H2O。同时做空白实验,由水样及空白所消耗的硫酸亚铁铵的量,计算出化学需氧量。
This paper introduces the simple fast determination method called Chemical Oxygen Demand by K2Cr2O7 Method (abbreviation CODcr)which is oxidation-reduction titration that use K2Cr2O7 as standard solution. The principle of the experiment is to join excessive K2Cr2O7 standard solution in water sample, the mixture of which reflux for 10 minutes while heating and boiling in strong acid, making K2Cr2O7 fully react with organic compound and reductive material,the reaction of which is K2Cr2O7-+ 14H++6e(?)2Cr3+7H2O. Dilute the sample when its temperature drops to the environment. After the temperature of the sample goes down again, titrate the excessive K2Cr2O7 with standard solution of reducing agent Ammonium ferrous sulfate [(NH4)2 Fe(SO4)J and use compound of 1.10-Phenanthroline(C12H8N2·H2O) complex and Ferrous Sulfate (FeSO4) as indicator, the finial reaction is Cr2O72-+6Fe2++14H+=2Cr3++6Fe3++7H2O. At the same dme, do blank test and calculate Chemical Oxygen Demand by the quantity of Ammonium ferrous sulfate that is consumed in sample and blank test.
出处
《广东化工》
CAS
2004年第2期34-36,共3页
Guangdong Chemical Industry
