论文总字数：22408字

摘 要

近年来，铬污染对生态环境和人体健康造成了很大的危害，如何治理含铬废水亟待解决。吸附法因高效、成本低、无二次污染等特点而在含铬废水治理方面备受关注。本课题采用一步式水热法制备了宽层间距二硫化钼W-D-N-MoS₂，并进行了材料微观结构的表征，通过调控不同变量，探究了材料对Cr(Ⅵ)的吸附性能，进行了相应的模型拟合。主要结论如下：XRD图谱表明样品为混合相态；吸附过程为吸热过程，但温度对吸附量的影响较小；初始pH值对吸附效果影响很小；吸附率随时间增加而提高，最高可达99.73%；SO₄^2-、Ca² 对吸附效果几乎无影响，表明W-D-N-MoS₂对Cr(Ⅵ)具有高选择性；在碱性条件下Cr(Ⅵ)易脱附，且脱附率随着脱附剂量的增加而提高；吸附过程更符合Langmuir吸附等温模型，材料对铬的吸附属于单分子层吸附；动力学结果表示，准二级动力学方程的拟合度更高，化学吸附起主导作用，平衡吸附量可达54.45mg/g。

关键词：含铬废水 吸附法 W-D-N-N-MoS₂ Cr(Ⅵ)

Preparation of molybdenum disulfide with widened interlayer spacing for Cr(Ⅵ) removal

Abstract

In recent years, chromium pollution has caused great harm to the ecological environment and human health. How to treat chromium-containing wastewater needs to be solved urgently. The adsorption method has great advantages of high efficiency, low cost and no secondary pollution. Therefore, it has attracted widely attention in the treatment of chromium-containing wastewater. Herein the microstructure of W-D-N-MoS₂, prepared by one-step hydrothermal method, was investigated. The adsorption performance of W-D-N-MoS₂ to Cr (Ⅵ) was verified by batch experiments under different parameters, and the corresponding model fitting was carried out. The main conclusions are as follows. The XRD pattern shows that the sample is a mixed phase of 1T-MoS₂ and 2H- MoS₂, which increases the specific surface area and active edge. The adsorption process is endothermic, but temperature’s impact on the adsorption amount is small. Initial pH value has no distinct effect on the adsorption efficiency. The adsorption rate increases with time, up to 99.73%. SO₄^2- and Ca² have almost no effect on the adsorption, indicating that W-D-N-MoS₂ has a high selectivity for Cr(Ⅵ). Cr (Ⅵ) is easy to desorb under alkaline conditions, and the desorption rate increases with the increase of the desorbing dose. The adsorption process is in accordance with the Langmuir adsorption isotherm model. The adsorption of chromium by the material belongs to monolayer adsorption. The kinetics experiment results show that the quasi-second-order kinetics equation has a higher fitting degree, and the chemical adsorption plays a leading role, and the equilibrium adsorption amount can reach 52.63mg/g.

Key words: chromium-containing wastewater; adsorption method; W-D-N-N-MoS₂; Cr(Ⅵ)

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 引言 1

1.2 水体铬污染 1

1.2.1水体铬污染现状及其危害 1

1.2.2含铬废水的来源 2

1.3 含铬废水处理的研究现状 2

1.3.1 化学还原法 2

1.3.2 膜分离法 2

1.3.3离子交换法 3

1.3.4 生物法 3

1.3.5 吸附法 3

1.4 二硫化钼的简介 4

1.4.1 二硫化钼的结构 4

1.4.2 二硫化钼的制备方法 4

1.4.3二硫化钼纳米材料在吸附处理中的研究现状 5

1.5 本课题的提出 6

1.5.1研究目的 6

1.5.2研究内容 6

第二章 实验部分 7

2.1 实验试剂及仪器 7

2.2 实验内容 8

2.2.1 W-D-N-MoS₂纳米片的制备 8

2.2.2 铬溶液的的配制 8

2.2.3 初始浓度对吸附效果的影响 8

2.2.4 初始pH值对吸附效果的影响 9

2.2.5 吸附时间对吸附效果的影响 9

2.2.6 竞争离子对吸附效果的影响 10

2.2.7 吸附-脱附实验 11

2.3 分析与测定 11

2.3.1 MoS₂纳米片的表征 11

2.3.2 吸附量的计算 12

2.3.3 吸附率的计算 12

2.3.4 脱附率的计算 12

2.3.5 吸附等温线 12

2.3.6 吸附动力学 13

第三章 结果与分析 14

3.1 材料表征 14

3.2 MoS₂纳米材料对Cr(Ⅵ)的吸附性能研究 14

3.2.1 初始浓度对吸附效果的影响 14

3.2.2 吸附等温线 15

3.2.3 初始pH对吸附效果的影响 17

3.2.4 吸附动力学 18

3.2.5 竞争离子对吸附效果的影响 20

3.2.6 吸附-脱附实验 20

第四章 结论与展望 22

4.1 结论 22

4.2 展望 23

参考文献 24

致谢 27

绪论

引言

随着工农业以及社会经济的迅速发展，大量未经处理或处理不达标的重金属废水排放到环境中，导致重金属污染问题越发严重。由于重金属污染物难降解性、生物富集性、剧毒性等^[1]特点，对生态环境及人体健康造成了极大的危害，因此，科学合理地降低水中重金属离子浓度的问题亟待解决。

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