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논문 기본 정보

자료유형
학위논문
저자정보

임선미 (부경대학교, 부경대학교 대학원)

지도교수
박이슬
발행연도
2023
저작권
부경대학교 논문은 저작권에 의해 보호받습니다.

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이 논문의 연구 히스토리 (2)

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Oxalic acid used to be obtained via the oxidation of carbohydrates using nitric acid and catalysts. This process produces a variety of nitrogen oxides during oxidation and requires a separation process due to various intermediates. It results in increasing the harmfulness and complexity of the process. Recently, the electrochemical reduction of carbon dioxide to obtain oxalic acid was suggested as an environmentally friendly and efficient technology for oxalic acid production. In this electrochemical conversion system, zinc oxalate (ZnC2O4) was obtained by the reaction of Zn2+ ions produced by Zn oxidation and oxalate ion from CO2 reduction. ZnC2O4 can be converted again to oxalic acid with strong acid and heat. In this study, we proposed a system that can easily convert ZnC2O4 to oxalic acid without using strong acid and can separate easily. In addition, it is also further converted to glycolic acid which is a high-value-added chemical. ZnC2O4 was effectively separated into Zn(OH)2 powder and oxalate solution through a chemical treatment and vacuum filtration process. And Zn(OH)2 and oxalate were electrochemically converted to zinc and glycolic acid, respectively.
In addition, this study also conducted research on the development of electrodes for selective electrochemical conversion from oxalic acid to glycolic acid. The electrochemical reduction of oxalic acid was performed at TiO2 nanotubes (TNT) electrode in an aqueous medium under potentiostatic control in a two-compartment cell. The competing H2 evolution was almost non-existent at an applied potential of -1.0 V vs. Ag/AgCl. Thus, conversion of oxalic acid was achieved with 46.8 % and faradaic (98 %) yield for 3 hours. The selectivity of glycolic acid (GC) formation over that of glyoxylic acid (GO) is controlled by the length of the TNTs. A high selectivity was obtained with H2O2-TNTs (GC/GO ≈ 10). The physical properties of the TNTs, such as length, uniformity, and mechanical strength, were controlled by varying anodization time and the electrolyte composition. In addition, the modification of the TNTs was attempted using surface treatments, metal doping, and so on. With zinc-doped TNT electrode, higher conversion of oxalic acid was achieved with 55 % and Faradaic (95.8 %) yield for 3 hours.

목차

Ⅰ. 서론 1
1. 연구 배경 1
1.1 옥살산 (Oxalic acid) 1
1.2 옥살산에서 글리콜산으로의 전기화학적 환원 3
2. 연구 목적 7
Ⅱ. 이론 8
1. TiO2 nanotube (TNT) 전극 제조 메커니즘 8
2. 전환율 및 패러데이 효율 계산 11
Ⅲ. 실험 방법 12
1. 옥살산에서 글리콜산으로의 선택적 전기화학 전환을 위한 전극 개발 12
1.1 전극 제조 12
1.1.1 TiO2 nanotube (TNT) electrode 12
1.1.2 TiO2 film electrode 15
1.1.3 TiO2/TNT electrode 16
1.1.4 Metal doped TNT electrode 17
1.2 Characterization 및 전기화학적 분석 20
2. 아연옥살레이트에서 글리콜산으로의 전환을 위한 반응 시스템 개발 23
Ⅳ. 결과 및 고찰 26
1. 옥살산에서 글리콜산으로의 선택적 전기화학 전환을 위한 전극 개발 26
1.1 기존 전극과의 비교 및 실험 변수 평가 26
1.1.1 TiO2 film 전극 및 Pt 전극과의 비교 26
1.1.2 실험 변수 평가 29
1.2 양극 산화 조건에 따른 옥살산 전환 평가 34
1.2.1 양극 산화 시간 34
1.2.2 양극 산화 전해질 50
1.2.3 열처리 온도 65
1.3 개질된 TNT 전극을 이용한 옥살산 전환 평가 69
1.3.1 TiO2 나노입자 표면처리 영향 69
1.3.2 TiO2 표면처리 74
1.3.3 Metal Doping 79
2. 아연옥살레이트에서 글리콜산으로의 전환을 위한 반응 시스템 개발 90
2.1 Zinc-oxalate 용해 및 전환 90
2.2 Zinc 회수 (recovery) 96
2.3 Oxalate에서 글리콜산으로의 전환 98
Ⅴ. 결론 101
VI. 참고문헌 103

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