配體的存在如EDTA 為處理金屬汙染的廢水帶來困難。電化學程序廣泛用於金屬汙染物的廢水處理以及金屬回收。在本研究中，銅回收是透過添加Fe(II) 或Fe(III) 離子作為替代季的置換和電沉積程序系統中的陽極為塗有釕和銥(Ti/Ru-Ir)的鈦板，陰極為不銹鋼板。
電壓、pH、鐵添加速率、鐵添加時間和陰極表面積對同時去除有機物和重金屬的影響在本研究中系統性的探討。隨著電壓的降低，銅的去除效率從20 V 的44.8%降至1 V 時的93.9 %。相反地，Cu(II) 的陰極回收率隨電壓的增加而增加，在1V 時為2.1 %，在20 V 時達到38.2 %。結果顯示，在低電壓下，釋放的Cu(II) 離子主要通過化學沉澱去除，而在高電壓下，則是以沉積去除。在固定電壓1 V 和3V 的實驗過程中觀察到綠色的汙泥，表明Fe(II) 可能以Fe(OH)2 的形式沉澱。
相反地，在10、15 和20 V 的固定電壓下觀察到褐色汙泥，表Fe(II) 被氧化成Fe(III)，然後沉澱為Fe(OH)3。同時，隨著電壓的增加，總有機碳去除量增加。與除銅效率相反，回收效率隨電壓的增加而增加。

The presence of ligands such as EDTA causes difficulties for the treatment of metal-contaminated wastewaters. Electrochemical processes have been widely used for metal-contaminated wastewaters treatment as well as for the recovery of metals. In the present work, a replacement and electrodeposition processes with the addition of either Fe(II) or Fe(III) ions as a replacement agent were studied for copper recovery. A titanium plate coated with ruthenium and iridium (Ti/Ru-Ir) is employed as anode and a
stainless-steel plate as a cathode. The effects of voltage, pH, iron dosing rate, iron dosing time, and surface area of the cathode on the simultaneous removal of organic matters and heavy metals were systematically investigated. The removal efficiency of copper increased with decreasing of the voltage from 44.79 % at 20 V to 93.87 % at 1 V. In contrast, the cathodic recovery of Cu increased with increasing voltage, reaching 2.08 % at 1 V to 38.2 % at 20 V. The results elucidated that at the low voltage the liberated Cu (II) ions were mainly removed by chemical precipitation and by deposition at high voltage. A greenish sludge was observed during the experimentation for a fixed voltages of 1 V and
3 V, indicating that Fe(II) could precipitate as Fe(OH)2. In contrast, brownish sludge was observed for fixed voltages of 10, 15, and 20 V, indicating that Fe(II) is oxidized to Fe(III) followed by the precipitation to Fe(OH)3. At the same time with the increase of voltage, the increase of total organic carbon removal is observed. Contrary to copper removal efficiency, the recovery efficiency increases with
increasing voltage.

CONTENTS
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .i
中文摘要 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iii
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Literature reviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 CuEDTA complexation . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Replacement-precipitation process . . . . . . . . . . . . . . . . . . . . . 7
2.3 CuEDTA removal by electrocoagulation process . . . . . . . . . . . . . 10
2.4 Photoelectrocatalytic process for CuEDTA removal . . . . . . . . . . . 11
2.5 Removal of CuEDTA by microelectrolysis process . . . . . . . . . . . . 13
2.6 CuEDTA removal by electrodeposition method . . . . . . . . . . . . . . 15
3 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1 Chemicals and wastewater . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 Electrodes materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3 Experimental setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4 Experimental methods . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.4.1 Fe(III) as a replacement agent . . . . . . . . . . . . . . . . . . . 21
3.4.2 Fe(II) as a replacement agent . . . . . . . . . . . . . . . . . . . 22
3.4.3 Copper recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.4.4 Current efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.5 Analytical methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.5.1 Flame atomic absorption spectrometry (AAS) . . . . . . . . . . 26
3.5.2 TOC analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.1 Fe(III) as replacement agent . . . . . . . . . . . . . . . . . . . . . . . . 28
4.2 Fe(II) as replacement agent . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2.1 Effect of voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2.2 Effect of dissolved oxygen . . . . . . . . . . . . . . . . . . . . . 37
4.2.3 Effect of pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2.4 Effects of Fe dosage . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.2.5 Effect of Fe dosing rate . . . . . . . . . . . . . . . . . . . . . . . 46
4.2.6 Effect of cathode surface area . . . . . . . . . . . . . . . . . . . 50
5 Conclusions and recommendations . . . . . . . . . . . . . . . . . . . . . . . . 55
5.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.2 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

LIST OF TABLES
2.1 Stability constant for complexation of metals ions by EDTA . . . . . . 4
2.2 Electrodeposition process for Cu recovery . . . . . . . . . . . . . . . . . 17
3.1 Chemicals material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

LIST OF FIGURES
2.1 Copper species as a function of pH at chemical equilibrium using the modelling software Mineql+. Temperature = 25oC. Initial concentration of Cu = 1 mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 EDTA species as a function of pH at chemical equilibrium using the modelling software Mineql+. Temperature = 25 oC. Initial concentration of Cu = 1 mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 CuEDTA species as a function of pH at chemical equilibrium using the modelling software Mineql+. Temperature = 25oC. Initial concentration of Cu = 1 mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 CuEDTA and Fe(II)EDTA species as a function of pH at chemical equilibrium using the modelling software Mineql+. Temperature = 25oC. Initial concentration of Cu, Fe(II), and EDTA = 1 mg/L. . . . . . . 9
2.5 CuEDTA and Fe(III)EDTA species as a function of pH at chemical equilibrium using the modelling software Mineql+. Temperature = 25oC. Initial concentration of Cu, Fe(III), and EDTA = 1 mg/L. . . . . . 10
3.1 Schematic diagram of the experimental setup . . . . . . . . . . . . . . . 21
4.1 Removal efficiency of Cu and TOC from CuEDTA wastewater as a function of voltage, with controlled pH value of 3, a reaction time of 75 min, and Cu:EDTA:Fe(III) molar ratio = 1:1:6. The system was under N2 purging conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.2 Removal efficiency of Cu and TOC from CuEDTA wastewater as a function of voltage, with controlled pH value of 8, a reaction time of 75 min, and Cu:EDTA:Fe(III) molar ratio = 1:1:6. The system was under N2 purging conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3 Current efficiency as a function of voltage, with controlled pH value of 3 and 8, a reaction time of 75 min, Cu:EDTA:Fe(III) molar ratio = 1:1:6, and current varying from 0.01 A to 1.24 A at pH 3 and form 0.01 to 1.84 A at pH 8. The system was under N2 purging conditions. . . . . 33
4.4 Removal efficiency of Cu and TOC from CuEDTA wastewater as a function of voltage, with a reaction time of 75 min, control pH of 8, and final Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under N2
purging conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.5 Current efficiency as a function of voltage, with controlled pH value of 8, a reaction time of 75 min, Cu:EDTA:Fe(III) molar ratio = 1:1:6,
and current varying from 0.015 A to 1.18 A. The system was under N2 purging conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.6 Effect of dissolved oxygen on Cu and TOC removal from CuEDTA wastewater by comparison of system with and without nitrogen purging, with a reaction time of 75 min, control pH of 8, voltage fixed at 20 V, and final Cu:EDTA:Fe(II) molar ratio = 1:1:6. . . . . . . . . . . . . . . 39
4.7 Removal efficiency of Cu and TOC from CuEDTA wastewater as a function of pH, with a reaction time of 75 min, voltage fixed at 20 V, and Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under N2 purging conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.8 Current efficiency as a function of pH, fixed voltage at 20 V, a reaction
time of 75 min, Cu:EDTA:Fe(III) molar ratio = 1:1:6, and current varying from 1.075 A to 1.62 A. The system was under N2 purging conditions. 42
4.9 Dissolved Fe as a function of pH, with addition of Fe by syringe pump for 70 min and a reaction time of 75 min, a fixed voltage at 20 V, and Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under N2 purging conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.10 Sludge collected at different control pH values . . . . . . . . . . . . . . 43
4.11 Fe(II) species as a function of pH at chemical equilibrium using the modelling software Mineql+. Temperature = 25oC. Initial concentration of Cu = 1 mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.12 Removal efficiency of Cu and TOC from CuEDTA wastewater as a function of Fe molar ratio, with a reaction time of 75 min, pH controlled at 8 voltage fixed at 20 V, and Cu:EDTA:Fe(II) molar ratio ranging from 0 to 10.The system was under N2 purging conditions. . . . . . . . . . . 46
4.13 Cu removal and recovery and TOC removal from CuEDTA wastewater as a function of Fe dosing time, pH controlled at 8 voltage fixed at 20V, and Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under N2 purging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.14 Current efficiency as a function of reaction time, controlled pH value of 8, fixed voltage at 20 V, a reaction time varying from 40 to 180 min, Cu:EDTA:Fe(III) molar ratio = 1:1:6, and current varying from 1.46 A to 1.76 A. The system was under N2 purging conditions. . . . . . . . . 49
4.15 Removal and recovery efficiency of Cu and TOC as a function of Fe dosing time, pH controlled at 8, voltage fixed at 20 V,reaction time of 180 min, and Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under N2 purging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.16 Cu removal from CuEDTA wastewater as a function of voltage, with comparison of initial and larger surface area of cathode, a reaction time of 75 min, pH controlled at 8, and final Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under nitrogen purging. . . . . . . . . . . . . . . 52
4.17 Cu recovered from CuEDTA wastewater as a function of voltage, with comparison of initial and larger surface area of cathode, a reaction time of 75 min, pH controlled at 8, and final Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under nitrogen purging. . . . . . . . . . . . . . . 53
4.18 TOC removal from CuEDTA wastewater as a function of voltage, with comparison of initial and larger surface area of cathode, a reaction time of 75 min, pH controlled at 8, and final Cu:EDTA:Fe(II) molar ratio = 1:1:6. The system was under nitrogen purging conditions. . . . . . . . . 54
5.1 Graphical abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

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