粉煤灰改性研究

摘 要

粉煤灰是热电厂燃烧煤炭的过程中产生的固体残渣。我国是世界上最大煤炭生产国和消费国，也是世界上几个以煤为主要能源以煤主的国家之一。煤炭在我国经济社会发展中占有极其重要的地位。随着能源需求的进一步增加，燃煤数量的进一步增大，粉煤灰给环境带来的一系列环境问题日益严重。研究如何最大限度的减小粉煤灰的危害，多渠道的利用和改性粉煤灰，已迫在眉睫。
本课题利用粉煤灰的多孔性和吸附性，以西安市灞桥热电厂的粉煤灰为主要原料，用两种方法对粉煤灰进行改性实验研究。改性灰Ⅰ的制备实验参数为：煅烧温度为850 ℃，锻烧时间为2h ；粉煤灰与助溶剂的重量比为10∶15 ；氢氧化钠的浓度为3mol/L，固液比为1∶10 ； 老化时间为2h，温度为55 ℃；晶化时间为5h，温度为100 ℃；活化温度为500 ℃，时间为1h。改性灰Ⅱ的制备实验参数为：30mg铁粉，150mg粉煤灰：0.3mL浓度为0.96mol/L的盐酸，在100℃的沸水浴中活化20min的样品吸附效果最佳。
通过正交实验，确定了改性灰的最佳吸附条件。通过单因素实验以及对含铬废水中铬离子去除率的研究，讨论了实验条件对废水中铬离子去除率的影响。并进行了原状粉煤灰和改性灰Ⅰ、改性灰Ⅰ和改性灰Ⅱ的吸附性能的对比研究。研究表明，改性灰Ⅰ在pH值4～10，六价铬离子浓度10mg/L～100mg/L，吸附温度20℃～35℃，按化学计量比硫酸亚铁余量50％的操作条件下，铬离子有较高且稳定的去除率，达到99％以上。改性灰Ⅱ在pH值3～3.5之间，六价铬浓度10 mg/L，吸附温度30℃，六价铬可完全被还原和吸附去除，而只在pH值为3.2，三价铬的吸附去除率能达到80%的最好处理效果。

关键词：粉煤灰，改性，吸附，铬离子，对比

ABSTRACT

The fly ash is the solid residue emerges in the course that the heat and power plant burns the coal.Our countries is the biggest country of produce and consume to coal in the world.For our country economy social development, coal occupies the most important position.With the increasing of the energy requirement, the quantity of coal burned is increasing, and a series of environmental problems caused by fly ash is serious day by day.How to maximum decrease the danger of fly ash and the multi-channel use of fly ash, already is extremely urgent.
This subject researched two methods modification experiment to fly ash produced by the Ba bridge heat and power plant of Xi'an utilizing the capability of porous and absorb of fly ash.The parameters of synthesizing the quality modified fly ash Ⅰ were : calcining temperature was 850℃; calcining time was 2h; ratio of fly ash height to dissolve-assisting solvent weight was 10:15; concentration of NaOH was 3mol/L; solid to liquid ratio:1 was 10; aging time was 2 h at 55℃; crystallization time was 5h at 100℃; activation time was 1h at 500℃.The parameters of synthesizing the quality modified fly ash were: iron ash was 30mg, fly ash was 150mg; hydrochloric acid with a concentration of 0.96mol/L was 0.3mL.The sample activated in boiled water at 100℃ for 20min has the best adsorption capacity.
With orthotropic experiments，the best absorption condition were determined .With monofactorial experiments, chromium ion ' s wipe off from possess chromium wastewater was researched.The influence on the rate of the chrome ion ' s wipe off was discussed with the changes of experimental conditions.Besides, experiments on performance of absorb contrast between original state fly ash and the first method modification fly and two methods modification fly ash were carried out. In conclusion, the sample which produced by the first modification method of treatment was in pH value of 4-10, chromium ion（Ⅵ） density of 10mg/L-100mg/L, absorb temperature of 20 degree Centigrade - 35 degree Centigrade, the surplus of green vitriol is 50% ‘s operation conditions according to chemistry measure, and the chromium ion has high and steady ‘s rate of wipe off, all can be more than 99%. the sample which produced by the second modification method of treatment was in pH value of 3-3.5, chromium ion（Ⅵ） density of 10mg/L, absorb temperature of 30 degree Centigrade, chromium ion（Ⅵ）can be restored and completely. But in pH value of 3.2, chromium ion（Ⅲ）can be adsorbed 80% and attained the best result.

KEY WORDS：fly ash, modification, absorb, chromium ion, contrast

目 录

第1章 前 言 1
1.1 粉煤灰处置不当产生的环境问题 2
1.1.1 对大气的污染 2
1.1.2 对地表水及地下水的污染 2
1.1.3 粉煤灰在被利用过程中对环境的后期影响 3
1.1.4 其他影响 3
1.2 国内外粉煤灰利用的现状及展望 3
1.2.1 国内外粉煤灰利用的现状 3
1.2.2 粉煤灰资源综合利用的展望 8
1.3、本课题的目的、意义及内容 9
第2章 粉煤灰的产生、性质、应用及改性研究现状 11
2.1 粉煤灰的产生 11
2.2.1 粉煤灰颗粒的外观 12
2.2.2 粉煤灰的密度 13
2.2.3 粉煤灰的细度 13
2.2.4 其他物理性质 14
2.3 粉煤灰的化学组成与性质 14
2.3.1粉煤灰的化学组成 14
2.3.2 粉煤灰的化学性质 15
2.4 粉煤灰的活性 16
2.5 粉煤灰在环境工程中的应用 18
2.5.1 利用粉煤灰处理废水 18
2.5.2 利用粉煤灰处理废气 22
2.6 粉煤灰改性研究及应用现状 23
2.6.1 粉煤灰改性的物质基础 23
2.6.2 改性的目的和方法 23
2.6.3 净化机理分析 25
2.6.4 粉煤灰改性吸附材料的应用 25
第3章 研究思路与方法 27
3.1 研究思路 27
3.2 研究方法 28
3.2.1粉煤灰改性方法 28
3.2.2 吸附和过滤 28
3.2.3 铬离子浓度的测定 28
3.2.4 相同实验条件下的对比实验 29
第4章 改性灰制备及吸附性能研究 30
4.1 材料及仪器 30
4.1.1 实验试剂及药品 30
4.1.2 实验主要原料 31
4.1.3 实验仪器 31
4.2 改性灰制备方法及步骤 32
4.2.1 实验原料的预处理 32
4.2.2方法及步骤 32
4.2.3 原状粉煤灰和改性灰的吸附性能研究方法 33
4.3 原状粉煤灰和改性灰的吸附性能的结果与分析 36
4.3.1 标准曲线绘制 36
4.3.2 原状粉煤灰与改性灰的吸附性能研究 37
第5章 实验条件对铬离子去除率的影响 43
5.1 正交实验 43
5.2 原状粉煤灰与改性灰Ⅰ的单因素实验及对比研究 46
5.2.1灰铬比对三价铬去除率的影响 46
5.2.2 实验水样pH值对三价铬去除率的影响 48
5.2.3 吸附温度对三价铬去除率的影响 50
5.2.4 实验水样铬浓度对三价铬去除率的影响 51
5.3 改性灰Ⅱ的单因素实验研究 52
5.2.1水样pH值对六价铬、总铬去除率的影响 53
5.2.2 吸附温度对六价铬、总铬去除率的影响 54
5.4 两种改性方法比较 55
第6章  结论 57
参考文献 58
致谢 63
毕业设计小结 64
附录  英文翻译 65

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