USST_Arts_117121358改性玉米芯吸附水中重金属离子的实验研究

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摘要

自然水体中的重金属污染随着现代工业的发展日趋严重，而重金属离子不可

生物降解而且能通过食物链进行生物富集，对环境和人体健康造成了很大的威胁。

生物吸附法因其原料来源广泛、价格低廉、无二次污染等优点，已经成为处理重

金属污染的一个研究热点。

本论文采用废弃的玉米芯作为原料，利用酒石酸进行改性，并对其优化，确

定了最佳改性方案，将改性玉米芯作为吸附剂吸附水中的 Cu2+和Pb2+，采用扫描

电镜、红外光谱、X射线和 TG 热分析仪对改性前后的玉米芯进行了表面结构表征。

探讨了改性玉米芯在吸附过程中的影响因素：吸附时间、pH、溶液初始浓度、投

加量和温度，分析了在不同温度下改性玉米芯对 Cu2+和Pb2+的吸附动力学和吸附

热力学，研究了不同阳离子对吸附效果的影响，考察了 Cu2+和Pb2+在改性玉米芯

上的竞争吸附，以及改性玉米芯的再生性能，并对改性玉米芯对 Cu2+和Pb2+的吸

附机理进行了初步的探讨。实验结果如下：

（1）最佳优化改性条件为：酒石酸的浓度为 1.5 mg/L，水浴的搅拌温度为 50℃，

搅拌的时间为 2 h，加热的温度为 120℃，加热时间为 3 h。

（2）通过表征，发现改性后的玉米芯表面疏松多孔，激发了更多的有效官能

团，这些使得改性玉米芯对重金属离子的吸附性能提高。

（3）在298K下，模拟重金属废水Cu2+和Pb2+的初始浓度为50 mg/L，溶液的pH

值为5，改性玉米芯的投加量为5 g/L，吸附平衡时间为120 min，在此条件下，改

性玉米芯对Cu2+和Pb2+的吸附去除率分别为68%和92%，并且增加吸附的温度，有

利于吸附的进行，当温度上升到318K时，改性玉米芯对Cu2+和Pb2+的吸附去除率达

到了86%和98%。

（4）利用准一级动力学模型和准二级动力学模型对改性玉米芯吸附 Cu2+和

Pb2+的动力学曲线进行拟合，结果可知，准二级动力学方程拟合的显著性最好，且

随温度的升高，吸附越容易进行，说明此吸附属于吸热反应，存在着化学吸附；

通过实验，计算出改性玉米芯对 Cu2+、Pb2+的吸附过程表观活化能较小，分别为

26.25 kJ/mol 和23.95 kJ/mol，说明该过程具有物理吸附的属性，且吸附反应较容

易进行。

（5）利用 Langmuir 吸附等温模型和 Freundlich 吸附等温模型对改性玉米芯吸

附Cu2+和Pb2+的吸附等温线进行拟合，Freundlich 吸附等温模型线性拟合更好。在

不同温度下的吸附热力学参数结果可知，ΔG＜0，ΔH＞0，ΔS＞0，可知改性玉

米芯对 Cu2+、Pb2+的吸附过程是自发、吸热熵增的过程，温度的升高有利于吸附反

应的进行，且在吸附过程中固液界面的混乱性增加。

（6）利用0.1 mol/L的盐酸溶液对吸附饱和的改性玉米芯进行再生，从再生6

次后的结果可知，对Pb2+的去除率仍为80%以上，对Cu2+的去除率为50%以上，相

对吸附效果减少较小，说明玉米芯再生性能较好，是良好的吸附材料。

（7）通过对溶液中其他阳离子对改性玉米芯吸附Cu2+和Pb2+的影响可知，同

种阳离子浓度的增大，会降低改性玉米芯对Cu2+和Pb2+的吸附效果，在相同浓度下，

三价的Al3+对Cu2+和Pb2+吸附的影响要比二价的Ca2+和Mg2+对其吸附影响要大，而

二价的又比一价的K+和Na+的影响要大，说明阳离子所带的电荷数越高，对Cu2+和

Pb2+吸附的影响越大。

（8）对改性玉米芯吸附Cu2+和Pb2+的竞争吸附研究中可知，改性玉米芯对Cu2+

和Pb2+吸附效果均会受到竞争吸附的影响从而使得吸附量降低，其中改性玉米芯对

Pb2+的吸附具有优先选择性，所以改性玉米芯对Pb2+的吸附效果比Cu2+好。

（9）对比玉米芯改性前后对Cu2+和Pb2+的吸附效果可知，改性玉米芯对Cu2+

和Pb2+的吸附效果要远远大于普通玉米芯。

关键词：玉米芯改性铜离子铅离子吸附动力学吸附热力学

竞争吸附吸附机理

ABSTRACT

With the development of modern industry, heavy metal pollution of natural water is

getting worse and worse. Heavy metal ions have caused great threat to the environment

and human health beacause of its non-biodegradable and bioaccumulation through the

food chain. Biological adsorption method has become a research focus in the treatment

of heavy metal pollution because of the advantages of its huge material sources, low

cost, no secondary pollution and etc.

This paper took waste corncob for raw material and chosen tartaric acid modified

cobcorn as adsorbent. Several modification methods were chosen and the condition of

optimization of the adsorbent was to apply to adsorption Cu2+ and Pb2+ in the solution.

At the same time, using scanning electron microscopy, infrared spectroscopy, X-ray

diffraction and TG thermal analyzer to characterize the surface morphology of corncob

before and after modified. The influence factors in adsorption process of the modified

corncob adsorbing Cu2+ and Pb2+ were discussed, such as adsorption time, pH value of

the solution, initial concentration of the solution, modified corncob quantity and the

react temperature. The adsorption kinetics and adsorption thermodynamics of the

modified corncob adsorbing Cu2+ and Pb2+ under different temperature were analyzed.

The adsorption effects of the modified corncob adsorbing Cu2+ and Pb2+ through adding

different cations into the initial solution, the competitive adsorption of Cu2+ and Pb2+ on

the modified corncob and the regeneration performance of the modified corncob were

also studied. The adsorption mechanism of the modified corncob adsorbing Cu2+ and

Pb2+ was discussed preliminarily. The experimental results were as follows:

(1) The optimization of modification as follows: 1.5 mg/L of the concentration of

tartaric acid, 50℃ of water bath mixing temperature for 2 h stirring time, 120℃ of

heating temperature for 3 h heating time.

(2) Through the characterization, found that the surface of the modified corncob

was much losser and more porous, and more and more effective functional groups were

motivated which made an enhancement of heavy metal adsorption ability for the

modified corncob.

(3) The results indicated that the condition of adsorbing Cu2+ and Pb2+ from

aqueous solution was, under the room temperature, 120 min adsorption time 120 min,

0.5 g/L modified corncob quantity, about 5 of the pH of the solution, for 50 mg/L, water

sample. Under this situation, the ratio of elimination of the modified corncob was 68%

and 92%. Increasing the adsorption temperature was helpful to the process of adsorption.

When the temperature rose to 318K, the removal rate of Cu2+ and Pb2+ by the modified

corncob reached 86% and 98%, respectively.

(4) The adsorption kinetics of adsorprion process of the modified corncob was

analyzed. The result showed that the adsorption of Cu2+ and Pb2+ could be well

described by the pseudo-second-order reaction equation. And higher the temperature

was, easier the adsorption of Cu2+ and Pb2+ was. This phenomenon indicated that the

adsorprion process of the modified corncob was endothermic reaction and exist a

chemical adsorption. The values of apparent activation energy of the modified corncob

adsorbing Cu2+ and Pb2+ were 26.25 kJ/mol and 23.95 kJ/mol, respectively. The low

values indicated that the process of adsorption has the property of physical adsorption

and the adsorption reaction was easier to go.

(5) The adsorption isotherms of adsorprion process of the modified corncob were

analyzed. The result showed that the adsorption of Cu2+ and Pb2+ could be well fitted by

Freundlich model. The parameters of thermodynsmics indicated that the adsorption

process of Cu2+ and Pb2+ were spontaneous, endothermic and an entropy increase which

was the reason why the disorder increased on the solid-liquid interface.

(6) 0.1 mol/L HCl solution was used to regenerate the saturated modified corncob.

The results showed the removal rate of Cu2+ and Pb2+ was more than 50% and 80%,

respectively after the sixth regeneration. These could explain the performance of

regeneration of modified corncob was good and the modified corncob was a good

material in adsorbing heavy metals.

(7) The adsorption effects of the modified corncob adsorbing Cu2+ and Pb2+

through adding different cations into the initial solution were analyzed. The results

showed that when increasing the concentration of the cations in the solution, the

adsorption effects of the modified corncob adsorbing Cu2+ and Pb2+ would be decreased.

Under the same concentration, the influence by the trivalent was higher than the

bivalent, and the influence by the trivalent was higher than the univalent. The study

indicated that the more charge number the cation carried the more obvious the

adsorption effects on Cu2+ and Pb2+.

(8) The result of the competitive adsorption of Cu2+ and Pb2+ on the modified

corncob showed that the competitive disturbed both the adsorption of Cu2+ and Pb2+.

The competitive adsorption made their adsorption capacity down both. The modified

corncob adsorption sequence for heavy metals was Pb2+＞Cu2+.

(9) Compared the adsorption of Cu2+ and Pb2+ of the corncob before modification

and after modification, the adsorption of Cu2+ and Pb2+ of the modified corncob was far

greater than the ordinary corncob.

Key word: Corncobs, modified, copper ion, lead ion, adsorption

kinetics, adsorption thermodynamics, competitive adsorption,

mechanism of adsorption

中文摘要

ABSTRACT

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

1.1 水环境中重金属污染的现状分析 .................................................................... 1

1.1.1 重金属废水污染现状概述 ...................................................................... 1

1.1.2 重金属废水的来源与特点 ...................................................................... 2

1.1.3 重金属废水的危害 .................................................................................. 3

1.2 水环境中重金属污染的处理方法和研究进展 ................................................ 6

1.2.1 化学法 ...................................................................................................... 6

1.2.2 物理处理法 .............................................................................................. 7

1.2.3 生物处理法 .............................................................................................. 8

1.2.4 重金属废水的处理方法的研究展望 ...................................................... 9

1.3 农林废弃物在水环境中处理方面的应用研究现状 ...................................... 10

1.3.1 农林废弃物的来源和危害 .................................................................... 10

1.3.2 农林废弃物的应用研究现状 ................................................................ 10

1.3.3 玉米芯作为吸附材料在重金属废水处理中的应用状况 .................... 14

1.4 论文的研究意义和研究内容 .......................................................................... 15

1.4.1 研究意义 ................................................................................................ 15

1.4.2 研究内容 ................................................................................................ 15

1.5 论文的创新点 .................................................................................................. 16

第二章实验部分 .......................................................................................................... 17

2.1 材料、实验仪器与化学试剂 .......................................................................... 17

2.1.1 材料 ........................................................................................................ 17

2.1.2 实验仪器 ................................................................................................ 17

2.1.3 化学试剂 ................................................................................................ 17

2.2 表征方法 .......................................................................................................... 18

2.2.1 扫描电镜（SEM） ................................................................................ 18

2.2.2 红外线光谱仪（FT-IR）....................................................................... 18

2.2.3 X 射线衍射（XRD） ............................................................................. 18

2.2.4 热重分析（TGA） ................................................................................ 19

2.3 实验方法 .......................................................................................................... 19

2.3.1 改性玉米芯吸附剂的制备方法及其优化 ............................................ 19

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