LPP방법에 의한 EDTA-Cu의 분해에서 Ho doped TiO2 광촉매의 첨가 = Degradation of EDTA-Cu Using Liquid Phase Plasma Method with Ho Doped TiO2 Photocatalyst

다국어 초록 (Multilingual Abstract)

The EthyleneDiamineTetraAcetic acid-Copper (EDTA-Cu) complex is a representative metal-chelate pollutant generated from various industrial processes, including nuclear facility decontamination, and is known for its high chemical stability and poor biodegradability in aquatic environments. Due to its strong coordination structure, EDTA–Cu is hardly removed by conventional wastewater treatment processes and poses potential environmental risks by enhancing metal mobility and toxicity. In this context, advanced oxidation techniques capable of decomposing such stable complexes are required. This study aimed to explore the removal possibility of the EDTA-Cu complex, a metal-chelate pollutant that is stable in aquatic environments and difficult to treat. To achieve this, the liquid phase plasma (LPP) process was applied to evaluate the degradation characteristics and efficiency of EDTA-Cu, and, at the same time, the synthesis and performance of Ho-doped TiO₂ photocatalysts were examined. Ho-doped TiO₂ catalysts were synthesized under different precursor concentrations (0.5–2.0 mM) using the LPP method, and the resulting samples were characterized by X-ray Diffraction, Transmission Electron Microscope, UV-Diffuse reflectance spectroscopy, Photoluminescence, and X-ray Photoelectron Spectroscopy analyses. The results demonstrated that Ho doping suppressed crystal growth and reduced the band gap energy of TiO₂, leading to extended light absorption into the visible region and effective inhibition of electron–hole recombination. Among the tested samples, Ho1.5-TiO₂ exhibited the lowest PL emission intensity and a reduced band gap of 2.82 eV. In the degradation experiments, it showed a reaction rate constant that was 4.1 times higher than the condition without catalyst and 1.6 times higher than bare TiO₂. In addition, the major operating parameters of the LPP process—applied voltage, frequency, and pulse width—were confirmed to have significant impacts on EDTA-Cu degradation efficiency. Under the optimized conditions (250 V, 40 kHz, 5 μs), the generation of reactive radicals and UV emission was maximized, leading to the highest degradation performance. These findings suggest that Ho doped TiO₂, when combined with the LPP process, can serve as an effective photocatalyst capable of utilizing both UV and visible light, providing a practical approach for the removal of complex metal-chelate pollutants and contributing to environmental remediation technologies.

목차 (Table of Contents)

• I. 서론 1
• Ⅱ. 이론적 배경 3
• 2.1 EDTA 및 EDTA-Cu 복합체 3
• 2.2 광촉매(Photocatalyst) 9
• 2.3 플라즈마 15
• III. 실험 재료 및 방법 18
• 3.1 시약 및 재료 18
• 3.2 Ho doped TiO2 합성 방법 19
• 3.3 EDTA-Cu 분해 실험 조건 20
• 3.4 특성 분석 방법 22
• Ⅳ. 결과 및 고찰 25
• 4.1 Ho doped TiO2의 물리화학적 특성 분석 25
• 4.2 LPP 조건에 따른 EDTA-Cu 분해 특성 41
• 4.3 Ho doped TiO2 광촉매 성능 비교 46
• 4.4 EDTA-Cu 분해 경로 48
• Ⅴ. 결론 50