由於金屬錯合物 (e.g., Cu-EDTA) 的高溶解性和高穩定性，所以並不容易透過沉澱處理金屬錯合物。因此，本研究在探討在不同的pH值下Fe和Cu之間與EDTA結合的競爭，並且在不同的水化學機制條件下，像是pH值、鐵的劑量和反應時間，研究透過二價鐵和三價鐵的置換沉澱反應過程有效的處理Cu-EDTA錯合物的可能性。研究中發現Fe(III) 在酸性pH值區域可以有效的置換Cu-EDTA錯合物中的Cu離子，但在升高的pH值下氫氧化鐵會沉澱，而有時間依賴性的Fe(III)系統會造成降低Cu去除率的影響。另一方面，Fe(II) 在鹼性pH值區域有效的置換Cu，並且Cu的置換和沉澱反應可以同時在鹼性pH區域發生，Cu的去除效率也不會跟沉澱反應的時間有關係。根據上面的結論，Fe(II)會比Fe(III)更適合作為置換沉澱反應中的置換劑。
  雖然銅離子透過置換沉澱反應過程與7mM的Fe(II) 反應10分鐘就可以完全去除，但是EDTA錯合物仍然存在於溶液中。為了去除EDTA錯合物，使用Fenton process 處理已經透過置換沉澱反應處理過的溶液。在本研究中，將溶液先Fenton process處理再使用置換沉澱反應處理 (表示為 Fenton/沉澱) 和相反的程序 (表示為置換/沉澱/Fenton) 進行比較TOC和Cu 的去除率。Fenton/沉澱 程序將Cu離子完全的去除，置換/沉澱/Fenton程序只有去除40-66% 的Cu離子。然而，置換/沉澱/Fenton程序能將TOC去除得更好，這是因為Cu也可以當作Fenton反應劑。基於上面的結果，可以得知Fenton/沉澱程序更適合有效的去除Cu離子。

Treating metal complexes (e.g., Cu-EDTA) by precipitation is difficult because of their high solubility and stabilities. Therefore, this study focused on the competition between Fe and Cu complexes with EDTA under various pH values, and the possibility for the effective treatment of Cu-EDTA complexes by replacement/precipitation processes using ferric and ferrous iron species were investigated under various water chemistry conditions, such as pH levels, iron doses, and reaction times. Fe(III) was found to be effective for replacing Cu ions in Cu-EDTA complexes at an acidic pH region, but the precipitation of ferric hydroxides at elevated pH values gave a detrimental effect on Cu removal because of its time dependency. In contrast, Fe(II) replaced Cu effectively at an alkaline pH region where both replacement and precipitation of Cu can take place simultaneously. Cu removal was effective and independent of precipitation time when Fe(II) was dosed. According to the above conclusion, Fe(II) is more suitable as a replacement agent in the replacement/precipitation reaction than Fe(III).
Although the Cu can be removed completely with 7 mM of Fe(II) for 10 min by the replacement/precipitation process, the EDTA complexes still exist in the solution. In order to remove EDTA, Fenton process was employed to treat the treated water after the replacement and precipitation reactions. In this study, the replacement/precipitation reaction after the Fenton process (denoted Fenton/precipitation process) was compared to the reverse reaction sequence (denoted as replacement/precipitation/Fenton process) of Cu and TOC removal. The former achieved complete Cu removal while the latter removed only 40-66% of Cu. However, the latter achieves a slightly better TOC removal because the Cu can act as Fenton agents. Based on the results, the replacement/precipitation of the Fenton process was more suitable for effective Cu removal.

List of Figure	V
Chapter 1 Introduction	1
Study background	1
Chapter 2 Background information	3
2.1 Chelated-copper wastewater	3
2.2 Chemical precipitation	4
2.3 Ion-exchange method	5
2.4 Fenton process	6
2.5 Replacement/precipitation reactions	8
Chapter 3 Methods and Materials	10
3.1 Chemical and materials	10
3.2 Experimental methods	10
3.2.1 Adsorption experiments (per-formed flocs)	10
3.2.2 Effects of pH	11
3.2.3 Effects of Fe dose	11
3.2.4 Effects of replacement and precipitation times	12
3.2.5 Fenton process	12
3.3 Analytical methods	13
3.3.1 Flame atomic absorption spectrometry	13
3.3.2 TOC analysis	13
Chapter 4 Results and discussion	14
4.1	Chemical equilibrium modeling	14
4.2	Adsorption experiments (per-formed flocs)	18
4.3	Effects of pH	22
4.4	Effects of Fe dose	25
4.5	Effects of replacement time	29
4.6	Effects of precipitation time	30
4.7	Fenton process	34
Chapter 5 Conclusion and suggestions	37
5.1 Conclusion	37
5.2 Suggestions	38
Reference	39

List of Figure
Fig. 1 EDTA speciation in Fe(III)- based system as a function of pH. Modeled using Mineql+. Cu concentration is 1mM. EDTA:Cu:Fe(III) molar ratio of 1:1:1.	15
Fig. 2 Cu speciation in Fe(III)- based system as a function of pH. Modeled using Mineql+. Cu concentration is 1mM. EDTA:Cu:Fe(III) molar ratio of 1:1:1.	16
Fig. 3 Fe(III) speciation in Fe(III)- based system as a function of pH. Modeled using Mineql+. Cu concentration is 1mM. EDTA:Cu:Fe(III) molar ratio of 1:1:1.	16
Fig. 4 EDTA in Fe(II)-EDTA system as a function of pH. Modeled using Mineql+. Cu concentration is 1mM. EDTA:Cu:Fe(III) molar ratio of 1:1:1.	17
Fig. 5 Cu and TOC removals from Cu/EDTA solutions as a function of pH using pre-formed Ferric hydroxide flocs. Experimental conditions: Cu concentration = 1 mM; Cu:EDTA:Fe molar ratio = 1:1:5.	19
Fig. 6 Cu and TOC removals from Cu/EDTA solutions as a function of pH using pre-formed Ferrous hydroxide flocs. Experimental conditions: Cu concentration = 1 mM; Cu:EDTA:Fe molar ratio = 1:1:5.	20
Fig. 7 Effect of TOC removal on the removal efficiencies of Cu	20
Fig. 8 X-ray photoelectron spectroscopy analyses of three solid samples containing Cu species. (A) Survey spectra and (B-D) Cu 2p3/2 spectra and their convolution of (B) sample A, (C) sample B, and (D) sample C.	21
Fig. 9 Effects of pH on the removal efficiencies of Cu. Cu:EDTA:Fe molar ratio= 1:1:5. Initial Cu concentration = 1 mM.	23
Fig. 10 Effects of pH on the removal efficiencies of TOC. Cu:EDTA:Fe molar ratio= 1:1:5. Initial Cu concentration = 1 mM.	24
Fig. 11 Effects of pH on the removal efficiencies of dissolved Fe. Cu:EDTA:Fe molar ratio= 1:1:5. Initial Cu concentration = 1 mM.	25
Fig. 12 Effect of Cu:EDTA:Fe(III) molar ratio on the removal efficiencies of Cu and TOC, and percentage of Fe precipitated. Experimental condition: Initial Cu concentration = 1 mM; pH 3 and reaction time of 10 min for replacement reaction; pH of 8 and reaction time of 20 min for precipitation reaction.	27
Fig. 13 Effect of dissolved Fe on the removal efficencies of Cu.	27
Fig. 14 Effect of Cu:EDTA:Fe(II) molar ratio on the removal efficiencies of Cu and TOC, and percentage of Fe precipitated. Experimental condition: Initial Cu concentration = 1 mM; pH 3 and reaction time of 10 min for replacement reaction; pH of 8 and reaction time of 20 min for precipitation reaction.	28
Fig. 15 Effects of precipitation time on the removal efficiencies of Cu, dissolved Fe and TOC.	29
Fig. 16 Effects of precipitation time on the removal efficiencies of Fe(III), Cu and TOC, and the percentage of Fe precipitated. Replacement pH and time were 3.0 for 10 min, respectively. Precipitation pH = 8. Cu:EDTA:Fe(III) molar ratio = 1:1:5. Initial Cu concentration = 1 mM.	31
Fig. 17 Effect of Cu removed on the residual of Fe.	32
Fig. 18 Effects of precipitation time on the removal efficiencies of Cu and TOC, and the percentage of Fe precipitated. Replacement pH and time were 3.0 for 10 min, respectively. Precipitation pH = 8. Cu:EDTA:Fe(II) molar ratio = 1:1:5. Initial Cu concentration = 1 mM.	33
Fig. 19 Effects of metal-to-H2O2 molar ratio on the removal of TOC. In the Fenton/precipitaiton reactions, the Fenton process occurred at pH 3.0 with a reaction time of 1 hr and then, precipitation reaction proceeded at pH 7.0 with a reaction time of 30 min. Initial Cu and EDTA concentrations were the same as 1 mM.	36
Fig. 20 Effects of metal-to-H2O2 molar ratio on the removal of Cu. In the Fenton/precipitation reactions, the Fenton process occurred at pH 3.0 with a reaction time of 1 hr and then, precipitation reaction proceeded at pH 7.0 with a reaction time of 30 min. Initial Cu and EDTA concentrations were the same as 1 mM.	36

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