分光光度法测定水的化学需氧量

PINGDINGSHAN UNIVERSITY

毕业论文

题 目: 分光光度法测定水的化学需氧量

院(系专业年级: 化学2005级化学

姓 名: 朱晓娜

学 号: 051050122

指导教师: 吴华涛 讲师

2009年4月30日

摘 要

化学需氧量（COD）是水质监测的一个重要参数。本文利用重铬酸钾在消解过程中被水样中的还原性组分还原而得到Cr(Ⅲ)或Cr(Ⅵ)，溶液中的Cr(Ⅲ)或Cr(Ⅵ)的浓度与其吸光度值成正比，因此可以通过光度法测定水样中COD值。实验中分别采用加热回流和超声波两种方法进行消解并对各自测定的COD含量进行了比较。两种方法的测定结果呈良好线性相关，但是与声化学消解法相比，回流消解法测定标准水样COD结果稍微偏高。声化学消解法又快速、节能、环保等优点，值得在环境监测工作中推广应用。 关键词：加热回流，超声波 ，COD，分光光度法

Abstract

The chemical oxygen demand(COD) is an very important parameter of water quality monitor. Potassium dichromate can be reduced to Cr(Ⅲ) or Cr(Ⅵ) by reductive substances in water on digestion. The content of Cr(Ⅲ) or Cr(Ⅵ) in solution is proportional to their’s absorbance value, so the COD in water can be determined by spectrophotometry. Heating reflux and ultrasonic wave are introduced into digestion, meanwhile the results of COD by two methods of digestion are compared. The results of two methods are good linear. Comparing with ultrasonic wave digestion, the COD results by heating reflux digestion are slight higher. The ultrasonic wave digestion is more fast, energy saving, environmental than heating reflux, so more widely applied in the environmental monitoring work.

Key word: Heating reflux digestion, Ultrasonic wave digestion, COD, Spectrophotometry

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目录

1 前 言 ······················································································ 1 2 实验部分 ················································································ 3

2.1 实验原理············································································· 3

2.2 试剂及仪器 ········································································· 4

2.2.1 仪器 ············································································ 4

2.2.2 药品 ············································································ 4

2.3 溶液的配制 ········································································· 4

2.3.1 氧化剂的配制 ······························································· 4

2.3.2 标准COD水样的配制 ················································· 4

2.3.3 催化剂的配制 ·················&#