Facile and Green Synthesis of Zinc Oxide Nanoparticles Using Plant Extracts and Its In vitro Photocatalytic Activity

유영춘 경희대학교 대학원 2021 국내박사

A green biosynthetic approach of zinc oxide nanoparticles using coprecipitation method with dried fruit extract of Amomum longiligulare (A. longiligulare) is reported in this study, as it is plant- derived reducing agent. For configuration of Al-ZnO NPs (Amomum longiligulare - Zinc Oxide Nano Particles), the absorption of wavelength of nanoparticles was observed by UV–vis spectra at 354 nm. XRD (X-ray diffraction) micrograph and FETEM (Field-Emission Transmission Electron Microscopy) determined the morphological structure of green synthesized Al-ZnO. The chemical functional group, elemental mapping, and crystallization of nanoparticles were characterized by FTIR (Fourier Transform Infrared Spectroscopy), and EDX (Energy dispersive X-ray spectroscopy). The photocatalytic activity of Al- ZnO NPs was confirmed by photodegradation of methylene blue and malachite green dyes under 356 nm of UV light irradiation in aqueous solution. The degradation of MB with Al-ZnO NPs was completed with approximately 66 % in 60 min, whereas MG degradation was measured around 38.1% by 60 min by Al-ZnO NPs, respectively. The kinetic reaction rate as stated by first-order reaction of photocatalytic degradation of MB (Methylene Blue) and MG (Malachite Green) with Al-ZnO NPs were found to be 0.014 min−1 and 0.008 min−1 respectively. Therefore, phytochemicals of A. longiligulare extract have capability to act as a reducing agent in biosynthesis of zinc nanoparticles and is suitable to produce cost-efficient and eco-friendly photocatalyst. In addition, we have also studied the photocatalytic activity of Stevia rebaudiana leaves, which is a well-known medicinal plant for its non-caloric bio-sweetener. To enhance its value addition, employed first time for synthesis and stabilization of ZnO nanoparticles. The characterization using UV-Spec, FE-TEM, XRD, DLS revealed that SR-ZnO (ZnO particles obtained from S. rebaudiana) were flower-shape, 500–1,000nm sizes, hydrodynamic diameter Z-average of polydisperse SR-ZnO was 582.35±52.40nm with a PDI of 0.33±0.002. Furthermore, 76% degradation of methylene blue dye within 30min exposure to SR-ZnO and plant extract under UV light indicates that it could be utilized as an efficient photocatalyst for waste- water treatment. Finally, we have also further synthesized Zinc Oxide Nanoparticles from Hippophae rhamnoides leaves extract via co precipitation method. Synthesized nanoparticles from leaves extract having ability to generate electron–hole (ē–h+) between the band gap of ZnO due to works as a photo catalyst in de- gradation of (Eosin Y, Malachite Green) textile dye. The photo catalysts were characterized with the UV–vis spectrometer, Field emission transmission electron microscopy (FE-TEM), Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), Dynamic light scattering (DLS) analysis. The UV analysis confirmed the formation of ZnO nanoparticles at 374 nm. The FE-TEM images indicates that it is having flower like shape. The XRD data confirmed the size, and it is about 20.17 nm. The photocatalytic activity of the Synthesized NPs was evaluated using the Eosin Y and Malachite Green dye under UV irradiation. Our study found that it has ability to degrade dye about 95% and 89% respectively. So, Hippophae rhamnoides Leaves Zinc oxide nanoparticles (Hr- L-ZnO –NPs) can be a better photo catalyst for the treatment of polluted water through textile industry. In this study, the photocatalytic activity and dye degradation of biosynthesized zinc oxide nanoparticle from three different plants such as Amomum longiligulare, Stevia rebaudiana and Hippophae rhamnoides has been studied and reported.

North Korea and the United States, 1955-1972 : a study of North Korea's hostility toward the United States

Chun UMI 1990 국내박사

접착 길이와 하중 형태가 표면 부착된 광섬유 브래그 격자 센서의 변형률 전달률에 미치는 영향에 관한 연구

권현석 한국과학기술원 2017 국내석사

상용 항공기 좌석 경량화를 위한 소재 대체 설계 기술 연구

이상훈 한국과학기술원 2017 국내석사

Enhanced resistance of OG POSS-filled composites against atomic oxygen

최충현 Korea Advanced Institute of Science and Technology 2019 국내박사

Improvement of the sinking performance of the Vietnamese tuna purse seine

Dinh, Xuan Hung Pukyong National University 2016 국내석사

Tethered and contactless power transfer systems for mobile devices with high reliability

구범우 Korea Advanced Institute of Science and Technology 2018 국내박사

Electrical properties of trilayer graphene

이용진 ProQuest LLC UMI Dissertation Publishing 2015 국내박사

Radar-absorbing structure with the metallic material coated dielectric fabric

남영우 Korea Advanced Institute of Science and Technology 2018 국내박사

Multiple success criteria optimization for developing a sustainable and affordable housing model

Saidu, Aliyu Ibrahim University of Seoul 2020 국내석사

전 세계의 도시들은 주택 붕괴의 참담한 현장으로 가득 차 있다. 불법 정착, 빈민가 등 열악한 환경은 나이지리아 도시에서 흔히 볼 수 있는 풍경이다. 급증하는 도시의 인구를 위해 신규 주택 사업을 계획하고, 자금을 조달하는데 시간이 걸리기 때문에, 정부는 기존 주택 재고에 대한 투자를 소홀히 하는 경향이 있다. 게다가 정부의 주택 정책은 대부분 현재와 미래의 주택 수요를 충족하는 지속 가능한 전략이 부족하기에 시간의 시험을 견딜 수 없다. 그 결과, 우리는 사회적, 경제적으로 부정적인 영향이 주택문제에 직면하고 있으며, 확장으로 인해 환경이 악화되고 있다. 최근 정치 및 학문적 논쟁은 지속가능성에 초점을 맞추고 있는데, 지속가능성은 정부로 하여금 이러한 사회적, 경제적, 환경적인 부정적 요소들을 외부적으로 개입시키고 시정하도록 자극하고 있다. 이러한 지속가능성에 대한 새로운 관심은 주택 공급을 확대할 뿐만 아니라, 다음 세대의 주택 수용에 영향을 주지 않으면서 희소 자원의 활용과 환경보호를 통해 저소득층의 주거생활의 질을 향상시키게 될 것이다. 이 연구는 더 나은 의사결정 과정을 향상시키며 지속가능하고 합리적인 주택 모델을 달성하기 위한 실용적인 다중 성공 기준을 확립하는 것을 목표로 한다. 연구의 첫 번째 수행은 문서 내용 분석이었는데, 이 분석은 여러가지 성공 기준을 생성하고 전문 평가자에 의한 검증과 분석 계층적 프로세스를 통해 최종사용자의 응답에 의한 평가를 동시에 진행하였다. 따라서 두 그룹 사이의 “이견에 대한 합의” 과정을 용이하게 하기 위해 절충 분석을 실시했다. 그 결과는 주택 이해관계자들 간의 의견 불일치와 합의를 보여준다. 따라서 최적화된 일련의 다중 성공 기준이 도출되었다. 즉, 유틸리티, 경제성, 기술, 커뮤니티, 적응성, 수용성, 접근성 및 보안등이 기준으로 도출되었다. 결론적으로 연구는 국가 및 지역 주택 당국이 정의를 강화하고 민주 이해당사자들의 참여를 장려, 독립적인 지속 가능한 평가 시스템을 구축, 지속 가능한 생계 운영을 위한 가계의 교육과 인식에 대한 투자를 권고한다. Cities globally are replete with deplorable sites of decaying housing. The illegal settlement, slums, and environmental squalor are the usual scenery in our urban landscape. Because it takes time to initiate, plan, and fund new housing projects for a rapidly growing population, governments tend to neglect to invest in the existing housing stock. Additionally, governments' housing policies mostly lack sustainable strategies that meet current and future housing needs; thus, they are unable to stand the test of time. As a consequence, we are faced with housing problems that have a negative social and economic impact and by extension degrading the immediate environment. Recently, the political and academic debate centers on sustainability, which has given governments the impetus to intervene and correct these social, economic and environmental negative externalities. This renewed interest in sustainability will not only expand the housing supply but also to improve the quality of residential livelihood of the low-income household, through the utilization of scarce resources and protecting the environment without compromising the housing needs of the coming generations. The study aims to establish practical multiple success criteria for achieving a sustainable and affordable housing model that will enhance better decision-making process. The first conduct of the study was a Document Content Analysis, which generated multiple success criteria, followed by a validation by professional evaluators, through an Analytical Hierarchy Process, and simultaneously testing the evaluated by Households (end users) respondents. Therefore, a trade-off analysis was conducted to facilitate the "agree to disagree" process between the two groups. The Results show disagreements and consensus amongst the housing stakeholders; thus an optimized set of multiple success criteria was derived, namely: Utility, Affordability, Technology, Community, Adaptability, Acceptability, Accessibility, and Security. Finally, the study recommends that national and local housing authorities should be well defined and strengthened, encourage democratic stakeholder participation, establish independent sustainable rating systems, and investments in education and awareness for a household in running a sustainable livelihood, amongst others.