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SYNTHESIS AND APPLICATION OF MAGNETIC COMPOSITES FOR CONTAMINANT REMOVAL IN AQUEOUS SOLUTIONS
수중 오염물질 제거를 위한 자성복합체의 합성과 적용

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dc.contributor.advisor김성배-
dc.contributor.author이창구-
dc.date.accessioned2017-07-13T17:42:44Z-
dc.date.available2017-07-13T17:42:44Z-
dc.date.issued2014-02-
dc.identifier.other000000018684-
dc.identifier.urihttps://hdl.handle.net/10371/121067-
dc.description학위논문 (박사)-- 서울대학교 대학원 : 생태조경.지역시스템공학부(지역시스템공학전공), 2014. 2. 김성배.-
dc.description.abstract본 논문에서는 자성 복합체를 합성하여 특성을 분석해 보았으며, 흡착제로써 수중 셀레늄, 크롬, 비소 및 인 제거에 적용해 보았다. 본 연구에서 제시하는 자성 복합체에는 탄소 나노튜브/산화철 자성 나노복합체와 자성 알긴산-층상이중수산화물 복합체를 포함한다.
탄소 나노튜브/산화철 자성 나노복합체는 탄소 나노튜브 표면에 산화철 나노입자를 화학적으로 공침하여 제조하였다. 합성된 자성 나노 복합체를 주사전자현미경(SEM), 투과전자현미경(TEM), 질소 흡•탈착, 푸리에 변환 적외선분광기(FTIR), 영전위점(pHPZC), 에너지 분산형 X-선 분광기(EDS), X-선 회절 분석기(XRD), X-선 광전자 분석기(XPS), 그리고 진동 시료 자력계(VSM)와 같은 다양한 분석 기술을 통해 분석해 보았다. 나노 복합체에 의한 오염물질 제거는 회분 실험과 전량 여과 실험을 통해 확인하였다. 흡착 특성은 동역학 모델과 평형 모델, 그리고 열역학적 분석을 이용하여 분석하고 정량화 하였다.
분석 결과 산화된 탄소 나노튜브 표면에 나노 크기의 산화철 입자가 6에서 17 nm 범위로 균일하게 성장해 있는 것으로 나타났다. XRD 피크는 산화철 나노입자가 입방형 산화철 형태인 자적철과 침철석임을 나타냈다. 자성 나노복합체는 38.37 emu/g의 포화 자력과 15.66 Oe의 보자력을 가지고 있으며, 영구 자석에 의해 쉽게 분리 될 수 있다.
주어진 실험 조건(함유량 = 1g/L, 초기 농도 = 10 mg/L, 반응 시간 = 4 h, 온도 = 30°C)에서 탄소 나노뷰트/산화철 자성 나노복합체의 흡착 용량은 비산염 9.55 mg/g, 아셀렌산염 8.12 mg/g, 아비산염 7.10 mg/g, 크롬산염 5.93 mg/g, 그리고 셀렌산염 3.82 mg/g 순으로 감소했다. 분석 결과 유사 2차 모델이 동역학 실험 설명에 최적인 것으로 나타났다. 평형 실험의 경우, 프로인드리히 등온식과 레들리히-피터슨 등온식이 잘 맞았다. XPS 분석 결과 셀렌산염과 아셀렌산염은 자성 복합체 표면에서 철의 산화와 함께 환원되는 것으로 나타났다. 연속 추출 실험은 57.8%의 크롬(VI)이 철 산화물 부분(F3)에 존재함을 보였다. 비산염은 흡착 여과 공정에서 자성 복합체에 의해 효과적으로 제거 되었다.
자성 알기산-층상이중수산화물 복합체는 분말 형태의 하소된 마그네슘-알루미늄 층상이중수산화물(LDH)과 자성 산화철을 알긴산 하이드로겔로 포획하여 제조하였다. 자성 복합체는 1.5±0.1 mm의 입자 크기를 가지며 외부 자기장에 따라 자성 특성을 나타내었다. 자성 복합체(2% 자성 산화철과 6% 하소 마그네슘-알루미늄 층상이중수산화물)의 흡착 용량은 주어진 조건(흡착제 함유량 = 3 0mL 용액에 0.05 g, 초기 농도 = 10 mg/L, 반응 시간 = 24 h)에서 인산염에 대해 4.99 mg/g 그리고 크롬산염에 대해 1.61 mg/g이었다. 자성 복합체는 자력 분리에 의해 재사용 될 수 있다.
본 연구를 통해 자성 복합체가 수중 셀레늄, 크롬, 비소, 그리고 인 제거에 효과적인 것으로 밝혀졌다. 이러한 결과로부터 본 연구에서 개발된 자성 복합체가 첨단 수처리 시스템에 적용될 수 있을 것으로 보여진다.
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dc.description.abstractThis thesis deals with the synthesis, characterization, and application of magnetic composites as adsorbents for selenium, chromium, arsenic, and phosphorous removal from aqueous solutions. The magnetic composites presented in this study include carbon nanotube/ iron oxide magnetic nanocomposites and magnetic alginate–layered double hydroxide composites.
Carbon nanotube/ iron oxide magnetic nanocomposites were prepared using chemical co-precipitation of iron oxide nanoparticles on surface of carbon nanotube. The synthesized magnetic nanocomposites were characterized by various analytical techniques such as SEM, TEM, nitrogen sorption, FTIR, pHPZC, EDS, XRD, XPS, and VSM. The removal of the contaminants by the nanocomposites materials was verified by batch experiments and full filtration test. The adsorption properties were analyzed and quantified using kinetic and equilibrium models and thermodynamic analysis.
These analyses indicated that nano–sized iron oxide particles grown on the surface of oxidized carbon nanotube has diameters ranging from 6 to 17 nm, regularly. XRD peaks showed that iron oxide nanoparticles were classified as a cubic iron oxide phase, i.e., maghemite and goethite. The magnetic nanocomposites have a magnetic saturation of 39.37 emu/g and a coercivity of 15.66 Oe, can be easily separated by permanent magnet.
The sorption capacities of carbon nanotube/iron oxide magnetic nanocomposites were in decreasing order: 9.55 mg/g for arsenate, 8.12 mg/g for selenite, 7.10 mg/g for arsenite, 5.93 mg/g for chromate, and 3.82 mg/g for selenate under given experimental conditions (dosage = 1 g/L, initial concentration = 10 mg/L, reaction time = 4 h, and temperature = 30°C). The results indicated that the pseudo second order model was most suitable for describing the kinetic experiments. In case of equilibrium test, the Freundlich and Redlich-Peterson isotherms were fitted well. XPS analysis revealed that selenite and selenate were reduced on the surface of magnetic nanocomposites, accompanied with iron oxidation. Sequencing extraction experiments showed that 57.8% of Cr(VI) was present in fraction of iron oxides (F3). Arsenate was removed by magnetic nanocomposites in the adsorptive filtration process, effectively.
Magnetic alginate–layered double hydroxide composites were prepared by entrapping powdered forms of both calcined Mg–Al LDHs and magnetic iron oxide into an alginate hydrogel. The magnetic composites had a particle size of 1.5±0.1 mm and showed magnetic properties under an external magnetic field. The sorption capacity of magnetic composites (2% magnetic iron oxide and 6% calcined Mg–Al LDHs) was 4.99 mg/g for phosphate and 1.61 mg/g for chromate under given conditions (adsorbent dose = 0.05 g in 30 mL solution, initial concentration = 10 mg/L, reaction time = 24 h). The magnetic composite material could be reused by magnetic separation.
Therefore, this study elucidated that the magnetic composites removed selenium, chromium, arsenic, and phosphorous from aqueous solutions, effectively. These results also demonstrate that the magnetic composites developed in this study can be applied to advanced water treatment system.
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dc.description.tableofcontentsABSTRACT i
CONTENTS v
LIST OF TABLES ix
LIST OF FIGURES xiii
Chapter 1 Introduction 1
1.1. Background 3
1.2. Objective 14
Chapter 2 Literature Review 17
2.1. Nanoadsorbents and their Composites 19
2.1.1. Carbon nanotubes 19
2.1.2. Magnetic iron oxide nanoparticles 20
2.1.3. Carbon nanotube/iron oxide nanocomposites 21
2.1.4. Layered double hydroxides and magentic polymer composites 22
2.2. Anionic Aqueous Contaminants 29
2.2.1. Selenium 29
2.2.2. Chromium 30
2.2.3. Arsenic 30
2.2.4. Phosphorus 31
Chapter 3 Synthesis and Characterization of Magnetic Composites 33
3.1. Carbon Nanotube/Iron Oxide Magnetic Nanocomposites 35
3.1.1. Synthesis and characterization methods 35
3.1.2. Surface characterization 39
3.1.3. X-ray analysis 48
3.1.4. Magnetic properties 55
3.2. Magnetic Alginate-Layered Double Hydroxide Composites 58
3.2.1. Synthesis and characterization methods 59
3.2.2. Surface characterization 65
3.2.3. X-ray analysis 70
3.2.4. Magnetic properties 77
Chapter 4 Selenate and Selenite Removal by Carbon Nanotube/ Iron Oxide Magnetic Nanocomposites 81
4.1. Materials and Methods 83
4.1.1. Selenium removal experiments 83
4.1.2. XPS analysis 84
4.1.3. Data analysis 88
4.2. Results and Discussion 92
4.2.1. Characteristics of selenium sorption 92
4.2.2. Adsorption kinetic, isotherm and thermodynamic analysis 96
4.2.3. XPS analysis for selenium adsorption 107
Chapter 5 Use of Carbon Nanotube/Iron Oxide Magnetic Nanocomposites for Removal of Chromium in Aqueous Solution 111
5.1. Materials and Methods 114
5.1.1. Chromate removal experiments 114
5.1.2. Sequential extraction 115
5.2. Results and Discussion 118
5.2.1. Characteristics of chromate sorption 118
5.2.2. Adsorption kinetic, isotherm and thermodynamic analysis 123
5.2.3. Chromate fractions in magnetic nanocomposites 134
Chapter 6 Arsenate and Arsenite Removal by Carbon Nanotube/Iron Oxide Magnetic Nanocomposites 137
6.1. Materials and Methods 139
6.1.1. Arsenic removal experiments 139
6.1.2. Adsorptive filtration experiments 141
6.2. Results and Discussion 144
6.2.1. Characteristics of arsenic sorption 144
6.2.2. Adsorption kinetic, isotherm and thermodynamic analysis 147
6.2.3. Filtration study 157
Chapter 7 Magnetic Alginate-Layered Double Hydroxide Composites for Phosphate Removal 161
7.1. Materials and Methods 164
7.1.1 Phosphate removal experiments 164
7.2. Results and Discussion 166
7.2.1. Characteristics of phosphate sorption 166
7.2.2. Adsorption kinetics and equilibrium isotherms 174
Chapter 8 Removal of Chromate from Aqueous Solution Using Magnetic Alginate-Layered Double Hydroxide Composites 183
8.1. Materials and Methods 185
8.1.1 Chromate removal experiments 185
8.2. Results and Discussion 187
8.2.1. Characteristics of chromate sorption 187
8.2.2. Adsorption kinetics and equilibrium isotherms 196
Chapter 9 General Conclusions and Recommendations 205
9.1 General conclusions 207
9.2. Recommendations 212
REFERENCES 215
NOMENCLATURE 235
국 문 초 록 237
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dc.formatapplication/pdf-
dc.format.extent4131010 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectAdsorbents-
dc.subjectArsenic removal-
dc.subjectCarbon nanotubes-
dc.subjectChromium removal-
dc.subjectIron oxide nanoparticles-
dc.subjectLayered double hydroxides-
dc.subjectMagnetic composites-
dc.subjectPhosphorous removal-
dc.subjectSelenium removal-
dc.subject.ddc712-
dc.titleSYNTHESIS AND APPLICATION OF MAGNETIC COMPOSITES FOR CONTAMINANT REMOVAL IN AQUEOUS SOLUTIONS-
dc.title.alternative수중 오염물질 제거를 위한 자성복합체의 합성과 적용-
dc.typeThesis-
dc.contributor.AlternativeAuthorCHANG-GU LEE-
dc.description.degreeDoctor-
dc.citation.pagesxx, 238-
dc.contributor.affiliation농업생명과학대학 생태조경.지역시스템공학부(지역시스템공학전공)-
dc.date.awarded2014-02-
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College of Agriculture and Life Sciences (농업생명과학대학)Dept. of Landscape Architecture and Rural System Engineering (생태조경·지역시스템공학부)Theses (Ph.D. / Sc.D._생태조경·지역시스템공학부)
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