生物质碳材料的重金属吸附性能及改性研究

论文总字数：28663字

摘 要

对最佳条件下的炭基吸附剂，进行微波硝酸改性，探究了不同因素对微波硝酸改性（硝酸浓度，改性温度、改性时间、改性功率）的影响。使稻壳活性炭发生微波硝酸改性的最佳条件由正交实验可获得：硝酸浓度取8 mol/L，改性温度为130 ºC，改性时间为5 min，改性功率为800 W。

采用元素分析、比表面积及孔隙分析、红外光谱(FTIR)、Boehm滴定、Zeta电位等方法对改性前后的稻壳活性炭进行分析，探究其组成炭基吸附剂的元素，吸附剂的比表面积和孔隙结构，吸附剂的表面所存在的含氧官能团，及其在不同pH下的电位、晶体结构等性质。通过静态吸附实验，研究了吸附时间、pH、铅离子浓度、温度对吸附剂除去铅离子效果的影响。实验可得，其平衡时间为120 min。其中pH显著影响着吸附，当在pH为5.5时，不论是改性前还是后稻壳活性炭对铅离子都有比较好的吸附能力。并且越是增加离子的浓度，稻壳活性炭对铅离子的吸附量也会越大，但去除率呈下降趋势。当吸附剂发生改性后，温度可使吸附过程进行的更容易。

为了研究吸附剂吸附过程的动力学和等温吸附过程，本文采取用准一级、准二级、颗粒内扩散以及 Langmuir、Freundlich等温模型分别进行了分析。通过分析可得，稻壳活性炭对铅离子的吸附符合准二级动力学，其颗粒内扩散模型呈现多段性。由吸附等温模型可知，改性后稻壳活性炭更符合Freundlich等温方程，表明通过改性作用后，吸附剂表面上的粗糙和不均匀是对离子吸附的主要原因。吸附热力学表明所有吸附过程均能自发进行，改性后吸附剂的焓值均比之前提高，说明化学吸附所占比例增加。

关键词：稻壳活性炭，吸附剂，微波硝酸改性， 静态吸附实验，吸附动力学。

Study On Heavy Metal Adsorption Properties And Modification Of Biomass Carbon Materials

03312528 Yang Haitao

Supervised by Shen Dekui

Abstact: The microwave electric heating two heating methods, with ZnCl2 as activating agent, one-step activation low-cost rice husk activated carbon were prepared. The influence of different factors (zinc chloride and precursor impregnation ratio, activation temperature, activation time, heating rate) on the adsorption effect of pore structure and heavy metal ion adsorption properties. Through the single factor experiment get the best working condition of the rice husk activated carbon for preparation of: activation temperature of 600 degrees C, activation time was 50 min, impregnation ratio (zinc chloride: rice husk) 1.5:1, heating rate of 15 degrees C / min.

The optimum conditions of carbon based adsorbent, microwave nitric acid modification, explores the different factors of microwave nitric acid modified (nitrate concentration, temperature, modification time, modification of power) the influence of. Through orthogonal experiments showed that rice husk activated carbon for optimum microwave nitric acid modification condition was: 8 mol / L nitric acid concentration, temperature of 130 ℃, change of time 5 min, power of 800 W.

The modified rice husk activated carbon before and after, the element analysis, specific surface area and pore analysis, infrared spectroscopy (FTIR), Boehm titration, Zeta potential, X ray diffraction (XRD) analysis of the composition of carbon based adsorbent element method, specific surface area and pore structure, surface oxygen functional groups, different potential pH, crystal structure and properties. Through static adsorption experiments, the effects of various factors (pH, adsorption time, concentration of heavy metal ions, temperature) effects on the adsorbent for the removal of lead ion effect. The results showed that the equilibrium time of rice husk activated carbon were 120 min. and pH has great influence on the adsorption process at pH=5.5. The modified rice husk activated carbon has good adsorption capacity for lead. With the increase of concentration, the adsorptive capacity was increased, and the removal rate is decreased. The modified adsorbent, temperature can promote the adsorption process.

Key words: rice husk activated carbon, adsorbent, microwave nitric acid modification, static adsorption experiment, adsorption kinetics

目录

摘要 1

第一章 绪论 1

1.1研究背景 1

1.2国内外研究现状 1

1.2.1重金属废水的处理方法 1

1.2.2活性炭的制备方法 1

1.2.3吸附炭材料的改性方法 2

1.3论文研究意义和研究内容 2

1.3.1课题的研究意义 2

1.3.2研究内容 2

第二章 实验材料及方法 4

2.1实验材料 4

2.2实验试剂及仪器 4

2.3实验方法 5

2.3.1稻壳活性炭的制备 5

2.3.2重金属离子吸附性能研究 5

2.3.3吸附炭材料的微波硝酸改性 5

2.3.4分析表征方法 6

第三章 微波电加热双模法制备稻壳活性炭的研究 7

3.1活化时间的影响 7

3.2升温速率的影响 7

3.3活化温度的影响 8

3.4浸渍比的影响 8

3.5小结 9

第四章 改性稻壳活性炭的重金属吸附性能的研究 11

4.1稻壳活性炭微波硝酸改性的条件优化 11

4.2改性吸附剂的吸附性能表征 13

4.2.1表面官能团和等电荷点分析 13

4.2.2元素分析 13

4.2.3Zeta电位分析 14

4.2.4拉曼光谱分析 14

4.3吸附影响因素的研究 15

4.3.1吸附时间的影响 15

4.3.2溶液pH的影响 16

4.3.3初始浓度的影响 16

4.3.4吸附温度的影响 17

4.4吸附动力学分析 17

4.4.1准一/二级动力学模型 17

4.4.2粒内扩散模型 19

4.5吸附等温线分析 20

4.6吸附热力学分析 22

参考文献 25

致 谢 26

生物质碳材料的重金属吸附性能及改性研究

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