| 题名 | 强化H2O2氧化水中Cu(CN)32-的机制与方法 |
| 作者 | 陈发源 |
| 学位类别 | 博士 |
| 答辩日期 | 2014-11 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 曲久辉 ; 赵旭 |
| 关键词 | 电镀废水 铜氰络合物 电化学 H2O2氧化 电芬顿，Electroplating wastewater Copper cyanide complex Hydrogen peroxide oxidation Electrochemical Fenton |
| 其他题名 | The Mechanism and Method of Enhanced destruction of Aqueous Cu(CN)32- by H2O2 |
| 学位专业 | 环境工程 |
| 中文摘要 | 近年来，重金属污染问题日益严重，电镀废水是重金属污染的主要来源之一。电镀废水中不仅含有铜、镍、铬等多种重金属污染物，同时也含有CN-、焦磷酸盐、 EDTA等络合剂。尤其氰化镀铜工艺的漂洗水中常含有游离CN-和Cu(CN)32-。常规的混凝、沉淀等方法难以将Cu(CN)32-等络合物有效去 除。Cu催化H2O2氧化对游离CN-和Cu(CN)32-都有较好的去除，受到日益重视。但是H2O2与Cu(CN)32-反应机制， EDTA、焦磷酸等络合剂对H2O2氧化Cu(CN)32-的影响，以及铜离子的回收等诸多问题还有不清楚。因此，本论文选择Cu(CN)32-为处理对 象，详细研究了H2O2与Cu(CN)32-的反应过程以及EDTA、P2O74-对H2O2氧化Cu(CN)32-的影响及作用机制；并利用电化学系统 原位产H2O2强化氧化Cu(CN)32-和同时去除Cu离子；最后，采用H2O2-电芬顿方法对某电镀集控区综合废水进行了处理研究。本论文的主要研究 内容与结果如下： （1）首先详细研究了H2O2氧化Cu(CN)32-的效率与机制。结果发现，H2O2首先氧化Cu(CN)32-络合物中CN-，随着CN-氧化为 CNO-，Cu(CN)32-转化为Cu(CN)2-；随着Cu(CN)2-被氧化，释放出的Cu(I)与H2O2反应生成HO?。HO?对CN-有很好 的氧化作用。同时，Cu(I)/Cu(II)催化H2O2分解为O2，降低了H2O2氧化CN-的效率。 （2）EDTA、P2O74-均可强化H2O2对Cu(CN)32-的氧化作用。EDTA浓度为1.0 mM或P2O74-浓度为2.0 mM时，完全氧化Cu(CN)32-仅需4.8 mM H2O2；无EDTA、P2O74-存在的条件下，需要18.0 mM H2O2才能完全氧化Cu(CN)32-。通过紫外光谱对铜氰络合物形态转化的分析，结合顺磁共振波谱仪对Cu离子价态及自由基的分析，发现EDTA络合 Cu(II)有效抑制了H2O2分解为O2，提高了H2O2的有效利用率，进而强化H2O2对Cu(CN)32-的氧化。相比之下，P2O74-络合 Cu(II)使得Cu(I)/Cu(II)循环催化而非生成沉淀，产生更多活性物种HO?及其他氧化剂。HO?可以快速地氧化CN-。 （3）建立了处理Cu(CN)32-络合物的电化学系统，本系统中利用活性炭纤维（ACF）和不锈钢（SS）作为阴极。在反应体系中通入O2，ACF阴极 表面接受电子生成H2O2，强化CN-的氧化。反应75 min时，CN-的去除率是91%，Cu离子的去除率也可达到80%以上。CN-主要氧化为CNO-；60%的Cu(I)离子沉积在ACF表面，15%左 右的Cu(I)沉积在SS表面。 （4）H2O2-电芬顿处理含有CN-、Cu2+与Ni2+等重金属离子和有机物的实际电镀废水。单独电混凝对CN-，Cu2+、Ni2+以及COD的去 除能力均有限。相比而言，一定浓度H2O2预氧化30分钟后，CN-浓度从75 mg/L降到15 mg/L。H2O2-电混凝组合处理30分钟后， CN-， Cu2+、Ni2+浓度分别低于0.3, 0.5 and 1.5 mg/L，COD也得到了有效去除与矿化。实验结果表明，H2O2氧化-电芬顿方法可有效去除电镀废水中的CN-、重金属和有机物。 |
| 英文摘要 | Recently, heavy metal pollution was paid more and more attention. Eelctroplating wastewater contain not only heavy metals such as Cu, Ni, and Cr but also CN-, P2O74-, EDTA etc. The heavy metal complexes cannot be removed by conventional methods such as coagulation, sedimentation, etc. In this paper, Cu(CN)32- was selected as targeted pollutants. Oxidation of Cu(CN)32- by H2O2 was investigated in details. Furthermore, effect of EDTA or P2O74- on the H2O2 oxidation of Cu(CN)32- was furthermore investigated. The electrochemical system with activated carbon fibre (ACF) and stainless steel (SS) assembling cathode is built for the Cu(CN)32- treatment. in-situ generated H2O2 at cathode surface enhanced the cyanide oxidation and copper recovery. Finally, the effluent from a electroplating workshop was treated by a combined process of H2O2 oxidation followed by an electrochemical Fenton process. The main results and conclusions were following: (1) Firstly, H2O2 oxidation of Cu(CN)32- was studied in details. The results indicated that with the oxidation of cyanide into cyanate, Cu(CN)2- formed firstly. The continuous oxidation of cyanide from Cu(CN)2- and the attendant dissociation of Cu(CN)2- led to progressive liberation of Cu(I). Cu(I) was oxidized into Cu(II) with formation of hydroxyl radicals (HO?) or Cu(III). The formation of superoxo-cupric complex between Cu(II) and H2O2 occurred in alkaline conditions. H2O2 was decomposed into O2 due to catalysis of Cu(II) species. Cu(CN)32- was destroyed completely with excess of H2O2. (2) In the presence of EDTA or P4O74-, oxidation of Cu(CN)32- was significantly enhanced. 4.0 mM cyanide was nearly oxidized by 4.8 mM H2O2 in the presence of 1.0 mM EDTA. Otherwise, 18.0 mM H2O2 was needed. The strong bonding of Cu(II) to EDTA suppressed decomposition of H2O2 into O2 and enhanced the effective utilization of H2O2 for cyanide destruction. By contrast, complexation of Cu(II) with pyrophosphate enhanced the catalytic redox reaction (Cu(I)/Cu(II) or Cu(I)/Cu(III)), improving cyanide oxidation.Cu(CN)32- oxidation was more favored at pH 9.5 and 11.0 than at pH 12.0. With the increase of H2O2 dose, rate of Cu(CN)32-oxidation was accelerated. Oxidation of Cu(CN)32-was accelerated with CN-/Cu(I) decreasing from 4.0 to 2.8. (3) Cu(CN)32- was efficiently destructed in an electrochemical reactor with activated carbon fiber and stainless steel assembling cathodes. O2 accepted electron at ACF surface, leading to the H2O2 geneartion. Cyanide was converted into cyanate. 80% of copper was reduced at the ACF and SS surface as Cu2O. (4) H2O2 pre-oxidation followed by anodic Fenton process efficiently treated a real electroplating wastewater containing heavy metals, cyanide, and organic contaminants. Remove of cyanide, copper, nickel, and COD was limited by the electrocoagulation process. In the H2O2 oxidation followed by an EC process, the concentration of total cyanide, Ni and Cu was decreased to be less than 0.3, 0.5 and 1.5 mg/Lwith an efficient COD removal. Meantime, organic contaminants were efficiently mineralized. |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34490]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 陈发源. 强化H2O2氧化水中Cu(CN)32-的机制与方法[D]. 北京. 中国科学院研究生院. 2014. |
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