论文总字数：19917字

摘 要

六价铬废水毒性很强，它具有逸过生物膜的作用，对人体危害巨大可引起癌症，所以六价铬污染一直受到全球各界关注。现有研究成果大都采用还原法去除Cr(Ⅵ)^，，但还原剂的选择和使用的最佳条件仍需进一步细化。本文将以FeSO₄作为还原剂，通过实验确定处理过程各影响因子的最适范围，建立优化的还原处理工艺条件。

本文重点考察了还原阶段pH、硫酸亚铁投加比、以及沉淀阶段pH值对FeSO₄还原处理Cr(Ⅵ)废水过程三价铬和六价铬的浓度变化影响规律。实验结果表明，pH值越小，硫酸亚铁对Cr(Ⅵ)的的还原效果越好。在反应30min基本达到还原反应终点，并且pH=2-3范围内，硫酸亚铁对Cr(Ⅵ)的的还原效果相差不大，考虑到既保证还原效果又节省算投加量，选择pH=2.3时反应30-40min后即可。对于硫酸亚铁/ Cr(Ⅵ)投药比为17到18之间反应时间1h以上，便能达到很好的去除效果，Cr(Ⅵ)去除率可达99.996%以上。还原后的废水在pH=8.3的弱碱条件下沉淀效果较好，碱性过强时会导致Cr(OH)₃生成了络合物而不能被沉淀去除。

最终，本论文确定了FeSO₄还原处理Cr(Ⅵ)废水的优化工艺条件为：pH=2.0左右，FeSO₄/ Cr(Ⅵ) 投药比=18左右，还原后废水沉淀pH=8.3左右。在优化工艺条件下，对Cr(Ⅵ)浓度为362.4mg/L的实际废水进行处理，出水Cr(Ⅵ)浓度为0.00476mg/L，Cr(Ⅲ)浓度为0.2087mg/L，满足《电镀污染物排放标准》(GB21900-2008)的铬浓度排放要求。

关键词：硫酸亚铁；六价铬废水；还原法

Abstract

Hexavalent chromium wastewater is very toxic. It has the effect of escaping biofilms and can cause cancer in the human body. Therefore, hexavalent chromium pollution has been concerned by all walks of life in the world. Most of the existing research results have used reduction methods to remove Cr(VI). However, the choice of reducing agents and the best conditions for their use still need to be further refined.

In this paper, the effects of pH, Ferrous Sulfate and PH on the concentration of trivalent Chromium and hexavalent chromium in the treatment of Cr(VI) wastewater during the reduction process of FeSO4 were investigated. The experimental results show that the smaller the pH, the better the reduction effect of ferrous sulfate on Cr(VI). In the reaction 30 min basically reaches the end of the reduction reaction, and within the pH = 2-3 range, the reduction effect of ferrous sulfate on Cr(VI) is not much different, taking into account both the reduction effect and the saving of the added amount, Select pH = 2.3 to react 30-40 min. For ferric sulfate / Cr(VI) injection ratio of 17 to 18 reaction time above 1 H, can achieve a good removal effect, Cr(VI) removal rate of more than 99.996 %. The reduced wastewater has a good precipitation effect under weak alkali conditions of pH = 8.3. When the alkalinity is too strong, Cr(OH) ₃ produces a complex and can not be precipitated and removed.In the end, this paper determines that the optimum process conditions for the reduction of Cr(VI) wastewater in FeSO₄ are: pH = 2.0, FeSO₄/Cr(VI) injection ratio = 18, and the reduced wastewater precipitation pH = 8.3.

In the end, this paper determines that the optimal process conditions for the reduction of Cr(VI) wastewater treated with FeSO₄ are: pH = 2.0, FeSO₄/Cr(VI) injection ratio = 18, and the reduced wastewater precipitation pH = 8.3. Under optimal process conditions, the actual wastewater at the Cr(VI) concentration of 362.4mg/L was treated at the effluent Cr(VI) concentration was 0.00476mg/L and the Cr(III) concentration was 0.2087mg/L, Meet the Chromium concentration emission requirements of the Electroplating Pollutant Emission Standard(GB21900-2008).

Keywords: ferrous sulfate；six valent chromium wastewater；reduction method

目录

摘 要 I

Abstract II

1.1前言 2

1.2 六价铬污染的现有处理方法 2

1.2.1常见处理方法 2

1.2.2 化学还原法 2

1.2.3硫酸亚铁还原法处理优势与前景 3

1.3硫酸亚铁化学还原法原理 3

1.4 影响硫酸亚铁反应处理效果的因素 4

1.4.1 还原阶段的pH 4

1.4.2 硫酸亚铁投加比 4

1.4.3 弱碱条件沉淀Cr³ 离子pH范围 4

1.4.4 反应时间 5

1.4.5 初始六价铬废水水浓度 5

1.5六价铬和三价铬的检测方法 5

1.6本文研究意义和研究内容 5

1.6.1 研究意义 5

1.6.2 研究内容 6

第二章 实验部分 7

2.1 主要试剂、仪器 7

2.1.1试剂 7

2.1.2仪器 7

2.2 实验步骤 8

2.2.1 标准曲线绘制 8

2.2.3 三价铬沉淀实验 9

2.2.4模拟水样的测定 10

2.2.5实际废水处理 11

第三章 实验结果与分析 12

3.1 实验现象 12

3.2 具体实践结果与分析 12

3.2.1 两条标准曲线 12

3.2.2 硫酸亚铁还原效果 13

3.2.3 三价铬沉淀效果 15

3.2.4模拟水样的测定 16

3.2.5实际废水处理 18

第四章 总结与展望 21

4.1 总结 21

4.2 展望 22

参考文献 23

致谢 25

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