ADA螯合纤维素的合成与吸附性能研究

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第一章绪论

ADA 螯合纤维素的合成与吸附性能研

究

摘要

本文主要以去除水体中的重金属污染物为主要研究目的，将 ADA（N-(氨

基甲酰甲基)亚氨基二乙酸）接枝于纤维素分子链上，合成了一种新型环境功能

材料，用于治理水体中重金属污染，对其吸附过程的热力学、动力学及吸附稳定

常数等诸多特征进行研究，探讨其相应的吸附机理。

本文通过将 ADA（N-(氨基甲酰甲基)亚氨基二乙酸）基团接枝到纤维素上，

制备了具有氨基、羧基等配位体的 DA 螯合纤维素。考察了反应温度、反应时间、

质量比、碱浓度等因素对接枝情况的影响，采用四因素三水平正交表及单因素影

响实验来进行研究，得到其最优的合成条件：反应温度 343 K，ADA 与纤维素

的质量比 1:1，使用的碱浓度为 12%，反应时间 4.0 h。此时 ADA 螯合纤维素含

氮量为 1.29 w%，平均 1g ADA 螯合纤维中中含有 0.46 mmol ADA 基团。

用溴化钾压片法对 ADA 螯合纤维素进行红外光谱分析：在ADA 螯合纤维素

中，由于-N-H 及的伸缩振动，使得 3200-3500 cm- 1 处的吸收峰明显

增宽吸收增强，在 1650-1545cm-1 和1420-1300cm-1 出现了羧酸盐的吸收带。对

ADA 螯合纤维素进行电镜扫描分析，实验结果表明改性前纤维素呈筒状，表面

较光滑饱满；改性后的 ADA 螯合纤维素则总体上形状更加卷曲，更多褶皱，纤

维也更加蓬松，出现较多裂痕。在螯合纤维素制备过程中，纤维素晶体结构被破

坏，比表面积得到了显著增大，有利于吸附的进行。

研究了 ADA 螯合纤维素吸附 Cu2+、Cd2+、Ni2+的吸附过程，溶液酸度对其吸附

容量影响较大，在 pH 4-5 弱酸性溶液中 ADA 螯合纤维素对重金属吸附效果较

好。对吸附过程的动力学进行研究，结果表明：二级吸附动力学方程可以较好地

拟合 ADA 螯合纤维素对上述污染物的吸附；其平衡吸附量和吸附速率均随着温

度的升高而增大； ADA 螯合纤维素对 Cu2+、Cd2+、Ni2+的平衡吸附容量在 318 K

时，分别为 44.61mg/g， 28.45 mg/g 和31.12 mg/g；对上述三种污染物的吸附表

观活化能分别为 12.6 kJ/mol，21.7 kJ/mol 和15.1 kJ/mol。ADA 螯合纤维素的等

温吸附模型用 Langmuir 模型能够更好的拟合。研究对上述三种污染物的吸附热

ADA 螯合纤维素的合成与吸附性能研究

力学结果表明：当温度在 288 K-318 K 范围内变化时， 298K 下20 kJ/mol

<△H<418 kJ/mol，吸附是一个吸热过程，升高温度对吸附有利；△S>0 表明吸

附是个熵增过程，体系的混乱度增加，吸附过成 ΔG<0，说明吸附是自发进行

的。ADA 螯合纤维素对重金属离子的吸附是一个化学吸附的过程，且吸附反应

较易进行，升高温度对吸附有利。

ADA 螯合纤维素对多种重金属离子都有较好的吸附效果。将阳离子交换树

脂和活性炭与ADA 螯合纤维素作静态吸附实验，发现 ADA 螯合纤维素的吸附

容量接近市售的强酸性阳离子交换树脂，高于木质颗粒活性炭，但是ADA 螯合

纤维素对重金属离子的吸附过程主要是以配位键为主要作用力的为化学吸附过

程，且其吸附过程快速稳定。

在298 K 温度，对 ADA 螯合纤维素进行脱附循环再生，使用的洗脱液为 1

mol/L 的盐酸。经过六次循环再生后，其对 Cu2+、Cd2+、Ni2+的吸附仍保持了原吸

附容量的 90%以上。良好的再生与循环利用性能是 ADA 螯合纤维素的一个重要

特性。

关键字：ADA 螯合纤维素 Cd 吸附机理动力学热力学循环利用

ABSTRACT

In this paper, in order to remove heavy metal contaminants from waste water, a

chelating cellulose was synthesized through grafting ADA on the molecular structure

of cellulose, its adsorption performance and adsorption mechanism was detaily

studied.

ADA chelating cellulose has amnion and carboxyl groups on its molecular

第一章绪论

structure. To determine the optimum conditions of synthesizing, orthogonal

experiment and single reaction conditions influence experiment were conducted, in

which heavy metal adoption performance reflected its grafting results. The best

synthesized condition was determined: synthesis temperature 343 K, the mass ration

of ADA to cellulose 1:1, added alkali concentration 12%, reaction time 4 h. In

optimized preparing conditions, the nitrogen content of the cellulose was 1.29w%,

meaning that there is 0.46 mmol ADA group in each gram of ADA chelating

cellulose.

To analyze the infrared spectrometer of ADA chelating cellulose, KBr squash

method was applied. After the reaction of epoxy fibers with ADA, 3200-3500 cm-1

absorption peak was significantly widened because of -N-H and . The

carboxylate absorption band also appeared at 1650-1545cm-1and 1420-1300cm-1.

Scanning electron microscopy analysis indicated that cellulose has a cylindrical

smooth surface, while modified ADA cellulose has more curls, wrinkles and

cracks .This meant that the crystal structure of modified cellulose was destroyed and

increased its surface area, which would be beneficial for the adsorption of heavy

metals.

ADA chelating cellulose was applied in the adsorption of heavy metals, in which

pH played an important role and at pH 4-5 reached its best adsorption capacity. The

adsorption kinetic properties were also studied, turning out that Lagergren second

order equation fited well with its adsorption properties. As adsorption temperature

increase, both the adsorption capacity and adsorption rate increased. At 318 K, its the

equilibrium adsorption capacity for Cu2 +, Cd2 +, Ni2 +, was 44.61mg/g, 28.45 mg/g and

31.12 mg/g. For above adsorption process, their apparent activation energy Ea values

were 12.6 kJ /mol, 21.7 kJ/mol and 15.1 kJ/mol. Langmuir model was better fited

with ADA chelating cellulose’s isotherm adsorption process. Studies of its adsorption

thermodynamic properties showed that at 288 K-318 K, 20 kJ/mol <△H<418 kJ/mol,

the adsorption was a chemical adsorption process and easy to happen, △S> 0, the

Gibbs free energy △G <0. When the temperature increase, the absolute valued of △G

decrease, and adsorption is a spontaneous process.

ADA chelating cellulose has a better adsorption of heavy metal ions. Cationic

exchange resin and activated carbon were also included for comparison with ADA

chelating cellulose for their the adsorption of heavy metals in water, results showed

tha adsorption capacity of ADA chelating cellulose were close to ationic exchange

resin . But the ADA cellulose adsorption of heavy metal was mainly a chemical

adsorption process, and its adsorption was fast and stable.

ADA 螯合纤维素的合成与吸附性能研究

At 298 K, the regeneration of ADA chelating cellulose was conducted by

hydrochloric acid, its concentration was 1.0 mol/L. Even after six regeneration

process, the adsorption capacity of ADA cellulose for Cu2 +, Cd2 +, Ni2 + still could

reach 90% of maximal adsorption capacity. ADA chelating cellulose has good

regeneration and recycling performance.

Keywords: Chelating cellulose, Cd , Adsorption mechanism,

Dynamics, Thermodynamics, Regeneration

第一章绪论

中文摘要

ABSTRACT

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

§1.1 水污染简介................................................1

§1.1.1 水资源现状............................................1

§1.1.2 水体重金属污染........................................2

§1.1.3 水体中重金属离子处理方法..............................3

§1.1.4 吸附法在水体重金属污染处理中应用......................6

§1.2 纤维素简介................................................9

§1.2.1 纤维素结构............................................9

§1.2.2 纤维素改性方法.......................................10

§1.3 螯合纤维素吸附材料简介...................................11

§1.4 本文的研究意义和内容.....................................13

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 实验试剂及材料.......................................14

§2.1.3 试剂配制.............................................15

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

§2.2.1 ADA 螯合纤维素的合成.................................16

§2.2.2 环氧值的测定.........................................17

§2.2.3 含氮量测定...........................................17

§2.2.4 金属螯合物稳定常数测定...............................18

§2.2.5 红外光谱分析.........................................19

§2.2.6 电镜扫描.............................................19

§2.2.7 吸附容量的测定.......................................19

§2.2.8 循环再生方法.........................................20

第三章实验结果与讨论............................................21

§3.1 ADA 螯合纤维素合成工艺研究...............................21

§3.1.1 正交实验.............................................21

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

§3.1.3 反应物比例的影响.....................................23

§3.1.4 反应时间的影响.......................................23

§3.1.5 反应的碱浓度.........................................24

§3.1.6 小结.................................................25

§3.2 ADA 螯合棉纤维素的结构表征...............................25

§3.2.1 红外光谱分析.........................................25

§3.2.2 电镜扫描.............................................27

§3.3 ADA 螯合纤维素吸附性能研究...............................27

§3.3.1 pH 的影响............................................27

§3.3.2 吸附动力学曲线.......................................28

ADA 螯合纤维素的合成与吸附性能研究

§3.3.3 吸附动力学方程.......................................30

§3.3.4 表观活化能...........................................33

§3.3.5 等温吸附模型.........................................34

§3.3.6 吸附热力学...........................................37

§3.3.7 共存离子的影响.......................................38

§3.3.8 吸附材料的对比.......................................38

§3.3.9ADA 螯合纤维素的吸附机理..............................39

§3.4 ADA 螯合纤维素的再生与循环利用..........................41

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

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

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摘要：

第一章绪论ADA螯合纤维素的合成与吸附性能研究摘要本文主要以去除水体中的重金属污染物为主要研究目的，将ADA（N-(氨基甲酰甲基)亚氨基二乙酸）接枝于纤维素分子链上，合成了一种新型环境功能材料，用于治理水体中重金属污染，对其吸附过程的热力学、动力学及吸附稳定常数等诸多特征进行研究，探讨其相应的吸附机理。本文通过将ADA（N-(氨基甲酰甲基)亚氨基二乙酸）基团接枝到纤维素上，制备了具有氨基、羧基等配位体的DA螯合纤维素。考察了反应温度、反应时间、质量比、碱浓度等因素对接枝情况的影响，采用四因素三水平正交表及单因素影响实验来进行研究，得到其最优的合成条件：反应温度343K，ADA与纤维素的质量比1...

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