摘要重金属废水毒性强，难以被微生物降解，进入环境后会通过食物链最终进入人体并积累，毒性持续的时间长。六价铬属于“五毒”之一，人体接触后轻则出现不适，重则致癌、致命。为了避免含Cr(VI)废水引发的生态环境问题和生物毒害性，废水必须进行处理后再排放。81526

吸附法在废水处理技术中应用广泛，使用价廉易得的吸附剂同时又能高效地吸附水中污染物，是学者们研究的共同目的。天然沸石在我国分布广泛，属于简单易得的原材料，表现出良好的离子交换性、吸附性、催化性能。本实验利用天然沸石作为吸附剂，探索了天然沸石对Cr(VI)的吸附特性。

实验结果表明，Cr(VI)溶液初始浓度越高，天然沸石对Cr(VI)的去除率越低。天然沸石对Cr(VI)的吸附效果在酸性条件下更显著。随着振荡反应时间的延长，去除率逐步增高。用动力学和热力学方程拟合实验数据，发现Legergren准二级动力学方程比准一级动力学方程更能描述天然沸石对水中六价铬的吸附，Langmuir吸附等温模型的拟合程度更好。

毕业论文关键词：天然沸石；吸附；六价铬

Abstract The toxicity of heavy metal waste water is strong, and can difficultly to degraded by microorganism。 It can finally enter the human body through food chain, and accumulate in the body, having long-term toxicity effects。 Cr(VI) is one of the five most dangerous maters, it can make people uncomfortable, or worse, can cause cancer and dead。 In order to avoid the wastewater containing Cr(VI) causing ecological environment problems and biological toxicity, waste water must be treated before discharge。

Adsorption method has been widely applied in wastewater treatment technology。

It is a common goal of scholars to use cheap adsorbent to adsorb the pollutants in the water efficiently。 Natural zeolite is widely distributed in our country, and it’s easy to get。 It has good adsorption, ion exchange and catalytic activity。 This experiment uses natural zeolite as adsorbent to explore the adsorption characteristics of Cr(VI)。

The experimental results show that the higher concentration of Cr(VI) initial solution, the lower removal rate of Cr(VI) is。 Acidic conditions are better for the adsorption。 The removal rate gets higher as the reaction time prolongs。 Fitting the experimental data in the kinetic and thermodynamic equations, we found that Legergren pseudo-second order model can explain this adsorption procedure of Cr(VI) on natrual zeolite better。 Langmuir isotherm shows better calculation results。

Key words: Natural zeolite; Adsorption; Chromium (VI)

目录

第一章  绪论 1

1。1 重金属废水的来源及其危害 1

1。2 六价铬的来源及危害 2

1。3 六价铬废水的处理方法 3

1。3。1 沉淀化学法 3

1。3。2 电解法 4

1。3。3 离子交换法 5

1。3。4 混凝法 5

1。3。5 萃取法 5

1。3。6 膜分离 6

1。3。7 光催化法 6

1。3。8 生物法 7

1。3。9 吸附法 8

1。4 天然沸石的特点 8

1。5 天然沸石在环境治理中的应用 8

1。5。1 水处理