壳聚糖交联β- 环糊精吸附水中铬和镉的研究

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3.0 侯斌 2024-11-19 4 4 1.86MB 56 页 15积分

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摘要

随着现代经济的迅猛发展，一些机械加工、化学化工、矿山开采等行业排放

大量未经达标处理的重金属废水，造成了严重的水体重金属污染。环境水体中的

重金属的存在状态及变化复杂，重金属无论采用什么工艺都不能被彻底降解，只

有改变其状态从而将其从水中去除。

本文研究了壳聚糖的改性方法，制成壳聚糖交联β-环糊精高聚物(CTS-CD)，

并将其应用于水中铬和镉的吸附去除研究。详细研究了CTS-CD对水中铬和镉的

吸附性能和规律，探讨了吸附机理，研究了材料的再生和循环利用。

以戊二醛作交联剂，将β-环糊精成功交联壳聚糖大分子链上，制得CTS-CD。

研究了各合成因素对CTS-CD吸附去除铬和镉的影响，由此确定制备条件为：反

应温度T为363 K ，n(glutaraldehyde)/n(β-CD) 为3.0 ，反应时间t为90 min ，

n(chitosan)/n(β-CD)为1.2。

将制备所得到的CTS-CD用溴化钾压片法进行红外光谱法分析，结果表明，β-

环糊精已成功交联到壳聚糖分子链上。对壳聚糖和CTS-CD进行电镜扫描和X射线

衍射分析，结果表明，β-环糊精交联到壳聚糖分子链上，CTS-CD较原壳聚糖表面

褶皱增加，使得CTS-CD对铬和镉的吸附量也显著增加。

将壳聚糖交联 β-环糊精应用于不同 pH 条件下吸附去除水中铬和镉的研究，

实验结果发现：溶液的不同酸碱性对 CTS-CD 吸附铬和镉的吸附容量有一定影

响，吸附效果在弱酸性条件下其吸附容量最佳。动力学研究表明：CTS-CD 吸附

速率很快，在吸附 4.5、5 h 后基本趋于吸附平衡，且吸附速率和平衡吸附容量随

着温度的升高而增大。在 318 K、pH 值为 5的条件下，计算得壳聚糖交联 β-环

糊精吸附铬和镉的的饱和吸附容量为 103 mg/g、121 mg/g。 CTS-CD 对水中铬和

镉的等温吸附更适合用 Langmuir 等温吸附模型描述。热力学研究表明：在实验

室条件下，吸附过程中 ΔH分别为 40.6 KJ/mol、27.17 KJ/mol，即壳聚糖交联 β-

环糊精对铬和镉的吸附过程是吸热过程；四个温度下的 ΔG<0，说明吸附过程可

自发进行。

研究了壳聚糖交联β-环糊精的再生和循环利用性能。室温条件下，用0.5

mol/L的氢氧化钠溶液对CTS-CD进行脱附，蒸馏水冲洗直至冲洗水为中性，再滴

加适量0.2 mol/L的盐酸溶液进行活化再生，最后再滴加蒸馏水至流出液为中性。

实验结果表明：脱附后的CTS-CD的吸附性能基本不变，重复洗脱7 次后其对重金

属铬和镉的吸附容量仍可保持在首次吸附量的90%以上，表明CTS-CD具有良好的

再生与循环利用性能。

本文合成的壳聚糖交联β-环糊精以天然的绿色高分子材料壳聚糖为原材料，

利用分子链上的氨基和羟基作为官能团进行交联反应和吸附反应。利用戊二醛将

β-环糊交联到壳聚糖大分子链上，不但克服了壳聚糖易溶于酸性水溶液的缺点，

提高了其稳定性，还极大提高了对水溶液中铬和镉的吸附能力。随着对CTS-CD

更深入的研究，它将作为一种新型功能材料在重金属废水治理领域发挥更为重要

的作用。

关键词：壳聚糖 β-环糊精铬镉吸附热力学动力学循环利用

ABSTRACT

Recent studies found that heavy metals water accumulation in water intensifies

and heavy metal pollution is becoming more and more serious with a large number of

electroplating, metallurgy industries wastewater diacharging. Heavy metal pollution of

water bodies, was designated as the first class pollutants. How to remove heavy metal in

the water has become a major issue in the current field of environmental protection.

Oxidation, adsorption and other appropriate processing method can treat that waster

water which contains a large quantity of heavy metal complex ions and chelate content.

Chitosan-β-cyclodextrinpolymer(CTS-CD), a kind of natural polymer, was

synthesized by immobilizing-β-cyclodextrin(β-CD) onto the molecular structure of

chiosan by the cross-linking function of glutar-aldehyde. The adsorption on properties

of heavy metal complex ions on CTS-CD in water were invertigated. The adsorption

mechanism and adsorbent regenerative and recycling were discussed.

The infrared spectroscopy analysis( by the potassium bromide tablet method)

results of prepared CTS-CD showed that, β- cyclodextrin has been successfully cross-

linked to the chitosan chains. SEM and X-ray diffraction analysis of chitosan and

prepared CTS-CD showed that, β- cyclodextrin has crosslinked to the chitosan molecule

chains, increasing the surface area greatly. Thus, the adsorption capacity of CTS-CD

significantly increased.

The adsorption properties of chromate and cadmium on CTS-CD in water were

investigared. The experiments showed that the solution pH significantly influenced the

adsorption capacity, and the adsorption capacity got the maximum when pH value of 5.

At 318 K, pH of 5, the equilibrium capacity of chromate and cadmium on CTS-CD

were 104 mg/g、121 mg/g after 5 h. The adsorption rate and adsorption capacity

increased with temperature, and raising temperature was beneficial for this adsorption

reaction. The adsorption process could be modeled by pseudo second-order kinetics

very well. The apparent activation energy of chromate and cadmium adsorption by

CTS-CD were 32.291 kJ/mol、1.206 kJ/mol. The adsorption pattern fitted Langmuir

isotherms well. The experiments indicated that ΔH of chromate and cadmium were all

above zero, and ΔS of them were above zero too. At 288K～318K, ΔG of the

adsorption processes were below zero. The adsorption rate constant increased with

temperature, and the adsorption pattern fitted Langmuir isotherms, which was

monomolecular layer absorption.

The regeneration and recycle of CTS-CD was studied to increase the utilization

ratio. At room temperature, 0.5 mol/L sodium hydroxide was used for CTS-CD’s

desorption, and 0.2 mol/L hydrochloric acid solution was uesd for activating treatment,

then the regenerated CTS-CD was reused to adsorb chloro-acetic acids. The adsorption

capacity of CTS-CD can still reach more than 90% of maxima. Owing to favorable

regenerated and recycling ability, CTS-CD has a broad prospect of application.

In this paper, the only nature of the cationic chitosan and widely used in industrial

production of β-cyclodextrin were used as raw materials for synthesis of CTS-CD,

overcoming the weakness of chitosan recycling, introducing of the β-cyclodextrin

envelope in order to increase the adsorption capacity of pollutants, and CTS-CD

regeneration and recycling performance is good. As a further study of CTS-CD, it will

play more important role in the field of water pollution control.

Keywords:Chitosan, β-cyclodextrin, Chromium, Cadmium, Thermodynamics,

Dynamics, Recycling

中文摘要

ABSTRACT

第一章绪论 ...................................................................................................................... 1

§1.1 重金属废水简介 .................................................................................................. 1

§1.1.1 重金属的来源与形态 ............................................................................... 1

§1.1.2 重金属废水的危害 ................................................................................... 1

§1.1.3 重金属废水的处理方法 ........................................................................... 1

§1.2 吸附法简介 ........................................................................................................... 5

§1.2.1 吸附类型与吸附机理 ............................................................................... 5

§1.2.2 吸附剂的类型 ........................................................................................... 6

§1.2.3 影响吸附的因素 ....................................................................................... 7

§1.2.4 吸附工艺在水处理中的研究进展 ........................................................... 7

§1.3 壳聚糖简介 ......................................................................................................... 8

§1.3.1 壳聚糖的分子结构 ................................................................................... 8

§1.3.2 壳聚糖的性质 ........................................................................................... 8

§1.3.3 壳聚糖的衍生化反应 ............................................................................... 9

§1.4 β-环糊精简介 ................................................................................................... 10

§1.4.1 β-环糊精的分子结构 ............................................................................. 10

§1.4.2 β-环糊精的衍生化反应 ......................................................................... 11

§1.5 壳聚糖交联 β-环糊精的研究进展 .................................................................. 12

§1.6 本课题的研究内容和意义 .............................................................................. 12

第二章实验部分 ........................................................................................................... 14

§2.1 实验仪器与材料 .............................................................................................. 14

§2.1.1 实验仪器 ................................................................................................. 14

§2.1.2 实验试剂和材料 ..................................................................................... 14

§2.1.3 试剂的配制 ............................................................................................. 15

§2.2 实验方法 .......................................................................................................... 16

§2.2.1 CTS-CD 的制备方法 .............................................................................. 16

§2.2.2 β-CD 固载量的测定 ............................................................................... 17

§2.2.3 红外光谱分析 ......................................................................................... 18

§2.2.4 扫描电镜分析 ......................................................................................... 18

§2.2.5 X-射线衍射分析 ..................................................................................... 18

§2.2.6 四氯合镉酸溶液的配制 ......................................................................... 18

§2.2.7 重金属的测定方法 ................................................................................. 19

§2.2.8 吸附容量的测定方法 ............................................................................. 20

第三章实验结果与讨论 ................................................................................................ 22

§3.1 CTS-CD 的合成及其参数的影响 ................................................................... 22

§3.1.1 反应温度的影响 ..................................................................................... 22

§3.1.2 反应时间的影响 ..................................................................................... 22

§3.1.3 交联剂与 β-CD 的摩尔比 ...................................................................... 23

§3.1.4 壳聚糖与 β-CD 的摩尔比 ...................................................................... 24

§3.2 CTS-CD 的结构表征 ....................................................................................... 24

§3.2.1 光谱分析 ................................................................................................. 24

§3.2.2 X-射线衍射分析 ..................................................................................... 26

§3.2.3 电镜扫描图 ............................................................................................. 27

§3.3 CTS-CD 对重金属吸附效果研究 ................................................................... 28

§3.3.1 pH 对吸附效果的影响 ........................................................................... 28

§3.3.2 初始浓度对吸附效果的影响 ................................................................. 29

§3.3.3 吸附动力学曲线 ..................................................................................... 30

§3.3.4 吸附动力学方程 ..................................................................................... 32

§3.3.5 表观吸附活化能 ..................................................................................... 35

§3.3.6 等温吸附模型 ......................................................................................... 36

§3.3.7 吸附过程热力学 ..................................................................................... 38

§3.3.8 吸附容量对比 ......................................................................................... 40

§3.3.9 小结 ......................................................................................................... 40

§3.4 吸附机理探讨 ................................................................................................... 41

§3.5 CTS-CD 的再生与循环利用 ........................................................................... 42

§3.6 共存离子对 CTS-CD 的吸附干扰试验 ........................................................... 42

第四章结论 .................................................................................................................... 43

参考文献 ......................................................................................................................... 45

在读期间公开发表的论文和承担科研项目及取得成果 ............................................. 51

致谢 ............................................................................................................................... 53

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摘要：

摘要随着现代经济的迅猛发展，一些机械加工、化学化工、矿山开采等行业排放大量未经达标处理的重金属废水，造成了严重的水体重金属污染。环境水体中的重金属的存在状态及变化复杂，重金属无论采用什么工艺都不能被彻底降解，只有改变其状态从而将其从水中去除。本文研究了壳聚糖的改性方法，制成壳聚糖交联β-环糊精高聚物(CTS-CD)，并将其应用于水中铬和镉的吸附去除研究。详细研究了CTS-CD对水中铬和镉的吸附性能和规律，探讨了吸附机理，研究了材料的再生和循环利用。以戊二醛作交联剂，将β-环糊精成功交联壳聚糖大分子链上，制得CTS-CD。研究了各合成因素对CTS-CD吸附去除铬和镉的影响，由此确定制备条件为：反...

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