Dissolution Behavior of Steam Generator Deposit in EDTA Solution
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摘要: 为了研究化学清洗剂乙二胺四乙酸(EDTA)对模拟沉积物Fe3O4和蒸汽发生器(SG)泥渣的溶解能力,以指导化学清洗工艺选择,采用X射线荧光光谱和电感耦合等离子体发射光谱分析温度、EDTA浓度、溶解时间对模拟沉积物Fe3O4和SG泥渣的溶解效果。采用Fe3O4制备化学修饰电极,采用三电极体系开展修饰电极的循环伏安测试和交流阻抗测试。结果表明,溶液温度越高,EDTA浓度越高,对Fe3O4的溶解能力越强;溶解时间越长,模拟沉积物Fe3O4和SG泥渣的溶解率越高;由于SG泥渣和模拟沉积物Fe3O4的差异性,EDTA溶液对SG泥渣的溶解能力弱于模拟沉积物Fe3O4;修饰电极在EDTA溶液中的电化学反应过程属于扩散控制过程。
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关键词:
- 蒸汽发生器(SG) /
- Fe3O4 /
- 泥渣 /
- 化学修饰电极 /
- 乙二胺四乙酸(EDTA)
Abstract: In order to explore the solubility of chemical cleaning agent EDTA on simulated deposit Fe3O4 and steam generator sludge, and to guide the selection of chemical cleaning processes, XRF and ICP-OES were used to analyze the dissolution effects of solution temperature, EDTA concentration, and dissolution time on simulated deposit Fe3O4 and SG sludge. The chemically modified electrode was prepared by Fe3O4, and the cyclic voltammetry test and AC impedance test of the modified electrode were carried out by using a three-electrode system. The results indicate that the higher the solution temperature, the higher the EDTA concentration, and the stronger the solubility of Fe3O4. The longer the dissolution time, the higher the dissolution rate of Fe3O4 and SG sludge. Due to the differences between SG sludge and Fe3O4, EDTA solution has a weaker ability to dissolve SG sludge than Fe3O4. The electrochemical reaction process of Fe3O4 modified electrode in EDTA solution is diffusion-controlled process.-
Key words:
- Steam generator (SG) /
- Fe3O4 /
- Sludge /
- Chemically modified electrode /
- EDTA
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表 1 实验仪器
Table 1. Experimental Instruments
仪器名称 型号 XRD PANalytical X' PERT PRO SEM ZEISS Sigma 300 XRF Bruke S2 PUMA ICP-OES SPECTRO ARCOS EOP 电化学工作站 CHI 660E 表 2 SG泥渣的XRF分析结果
Table 2. XRF Analysis Results of SG Sludge
元素 Fe Cr Mn Ti Ni Zn 质量分数/% 94.91 0.79 0.69 0.54 0.52 0.33 元素 Mg Cu Si Pb Cl Mo 质量分数/% 0.76 0.27 0.61 0.26 0.11 0.05 注:因XRF测量原理限制,原子序数在Na之前的元素无法检出 表 3 SG泥渣在10% EDTA溶液中溶解8 h后滤液中金属元素含量
Table 3. Metal Element Content in the Filtrate of SG Sludge Dissolved in 10% EDTA Solution for 8 h
元素 Fe Cu Pb Zn Na 浓度/(mg·kg−1) 3044.4 80.4 17.3 11.9 20.0 元素 K Ca Mg Al 浓度/(mg·kg−1) 35.5 3.0 0.4 35.0 表 4 修饰电极在EDTA溶液中CV循环前后的EIS拟合数据
Table 4. EIS Fitting Data of Modified Electrode Before and After CV Cycling in EDTA Solution
测试条件 EDTA
浓度/%Rs/Ω C/10−5F Rp/Ω CPE1/10−5 F Rct/Ω CV循环前 2 56.23 4.31 191.7 3.12 4308 5 32.47 4.63 197.8 2.90 3696 10 22.27 4.93 189.5 2.93 3228 15 20.77 2.92 101.9 9.04 1740 CV循环后 2 66.71 3.68 153.0 3.47 4501 5 39.73 3.99 134.8 3.26 4474 10 28.51 4.48 148.8 2.89 3433 15 21.30 4.78 158.8 2.92 3589 -
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