비점오염원에서 발생하는 카드뮴의 효율적인 제거를 위한 이황화물 고분자 유기화합물과 활성탄의 처리효율 비교

김효원,고동아,Henrik R. Andersen,황유훈 대한환경공학회 2017 대한환경공학회 학술발표논문집 Vol.2017 No.11

Graphene for Controlled and Accelerated Osteogenic Differentiation of Human Mesenchymal Stem Cells

Nayak, Tapas R.,Andersen, Henrik,Makam, Venkata S.,Khaw, Clement,Bae, Sukang,Xu, Xiangfan,Ee, Pui-Lai R.,Ahn, Jong-Hyun,Hong, Byung Hee,Pastorin, Giorgia,Ö,zyilmaz, Barbaros American Chemical Society 2011 ACS NANO Vol.5 No.6

<P>Current tissue engineering approaches combine different scaffold materials with living cells to provide biological substitutes that can repair and eventually improve tissue functions. Both natural and synthetic materials have been fabricated for transplantation of stem cells and their specific differentiation into muscles, bones, and cartilages. One of the key objectives for bone regeneration therapy to be successful is to direct stem cells’ proliferation and to accelerate their differentiation in a controlled manner through the use of growth factors and osteogenic inducers. Here we show that graphene provides a promising biocompatible scaffold that does not hamper the proliferation of human mesenchymal stem cells (hMSCs) and accelerates their specific differentiation into bone cells. The differentiation rate is comparable to the one achieved with common growth factors, demonstrating graphene’s potential for stem cell research.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-6/nn200500h/production/images/medium/nn-2011-00500h_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn200500h'>ACS Electronic Supporting Info</A></P>

수처리용 반응성 나노 복합 소재 개발 및 성능 평가 기법 개발

황유훈,Paul D. Mines,Henrik R. Andersen 대한환경공학회 2016 대한환경공학회 학술발표논문집 Vol.2016 No.11

토양 및 수용액내 카드뮴 제거를 위한 고분자 황-알지네이트 복합체의 흡착성능 비교 평가

이한샘,고은초,이은비,고동아,Henrik R. Andersen,황유훈 대한환경공학회 2016 대한환경공학회 학술발표논문집 Vol.2016 No.11

나노 영가철 환원 반응성의 정량 분석을 위한 수정된 인도페놀법 적용

황유훈(Yuhoon Hwang),이원태(Wontae Lee),Henrik R. Andersen 대한환경공학회 2016 대한환경공학회지 Vol.38 No.12

나노 기술에 대한 관심이 증가함에 따라 다양한 종류의 나노 물질이 환경 정화 분야에서 활발히 연구되고 있다. 이에 따라 새롭게 개발된 나노 물질의 성능을 쉽고 신속하게 측정할 수 있는 분석법에 대한 요구가 증가하고 있다. 본 연구에서는 토양/지하수 정화 분야에서 활발히 사용되는 나노 영가철의 환원 반응성을 쉽고 신속하게 측정할 수 있는 방법으로써 수정된 인도페놀법을 제시하였다. 인도페놀법에서 한계반응물로 작용하던 암모늄과 과량으로 존재하던 페놀을 치환하여 사용함으로써 페놀류에 대한 정량 분석이 가능하도록 수정하였다. 대상으로 한 나노 영가철에 의한 환원 반응은 4-클로로페놀의 페놀로의 환원과 나이트로벤젠의 아닐린으로의 환원이었으며, 수정된 인도페놀법은 반응생성물인 페놀과 아닐린에 대하여 선택성을 나타내 분석 방법으로 사용이 가능함을 확인하였다. 민감도 향상을 위하여 발색 시약의 농도 및 반응 시간, 시료의 전처리 등의 영향에 대하여 평가하였다. 실제 시료를 대상으로 시험하였을 때, 용존 철 이온에 의한 저해 영향을 확인하여 탄산나트륨 용액 주입의 전처리를 이용하여 해결하였다. 최종적으로 개발된 분석 방법을 이용하여 나노 영가철 및 이중금속 나노영가철의 환원 반응성을 측정하였으며, 결과적으로 환원 반응 속도의 차이뿐 아니라 환원 기작의 차이도 구분할 수 있는 가능성을 보여 주어 나노 영가철의 환원과 관련된 연구 분야에서 유용하게 사용될 수 있을 것으로 사료된다. Nanoscale zero-valent iron (nZVI) has been effectively applied for environmental remediation due to its ability to reduce various toxic compounds. However, quantification of nZVI reactivity has not yet been standardized. Here, we adapted colorimetric assays for determining reductive activity of nZVIs. A modified indophenol method was suggested to determine reducing activity of nZVI. The method was originally developed to determine aqueous ammonia concentration, but it was further modified to quantify phenol and aniline. The assay focused on analysis of reduction products rather than its mother compounds, which gave more accurate quantification of reductive activity. The suggested color assay showed superior selectivity toward reduction products, phenol or aniline, in the presence of mother compounds, 4-chlorophenol or nitrobenzene. Reaction conditions, such as reagent concentration and reaction time, were optimized to maximize sensitivity. Additionally, pretreatment step using Na₂CO₃ was suggested to eliminate the interference of residual iron ions. Monometallic nZVI and bimetallic Ni/Fe were investigated with the reaction. The substrates showed graduated reactivity, and thus, reduction potency and kinetics of different materials and reaction mechanism was distinguished. The colorimetric assay based on modified indophenol reaction can be promises to be a useful and simple tool in various nZVI related research topics.

Reductive degradation of perfluorinated compounds in water using Mg-aminoclay coated nanoscale zero valent iron

Arvaniti, Olga S.,Hwang, Yuhoon,Andersen, Henrik R.,Stasinakis, Athanasios S.,Thomaidis, Nikolaos S.,Aloupi, Maria Elsevier 2015 Chemical engineering journal Vol.262 No.-

<P><B>Abstract</B></P> <P>Perfluorinated compounds (PFCs) are extremely persistent micropollutants that are detected worldwide. We studied the removal of PFCs (perfluorooctanoic acid; PFOA, perfluorononanoic acid; PFNA, perfluorodecanoic acid; PFDA and perfluorooctane sulfonate; PFOS) from water by different types of nanoscale zero-valent iron (nZVI). Batch experiments showed that an iron dose of 1gL<SUP>−1</SUP> in the form of Mg-aminoclay (MgAC) coated nZVI, at an initial pH of 3.0 effectively removed 38–96% of individual PFCs. An increasing order of removal efficiency was observed of PFOA<PFNA<PFOS≈PFDA. Compared to this, PFCs removal was less than 27% using a commercial air stabilized nZVI or freshly synthesized uncoated nZVI, under the same experimental conditions. The effectiveness of PFCs removal by MgAC coated nZVI was further investigated at various initial pH, nZVI dosage, temperature and age of the nZVI. A maximum removal was observed for all PFCs with high nZVI concentration, freshly synthesized nZVI, low pH and low temperature. A mass balance experiment with PFOS in a higher concentration of nZVI revealed that the removal was due to both sorption and degradation. Fluoride production partially matched the observed degradation, while no organic byproducts were detected using LC–QTOF–MS.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Different nanosized zero valent iron (nZVI) types were tested for PFCs degradation. </LI> <LI> Only nZVI coated with a cationic surface modifier removed PFCs effectively. </LI> <LI> The order of PFCs degradability was PFOA<PFNA<PFOS≈PFDA. </LI> <LI> Low pH and temperature favored degradation of PFCs by surface modified nZVI. </LI> <LI> Fluoride formation confirmed PFCs degradation while partial sorption was observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis of covalent organic polymers for removing heavy metal ions with strong affinity

Dongah Ko,Mogens H. Jakobsen,Yuhoon Hwang,Cafer T. Yavuz,Henrik R. Andersen 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

Mines, Paul D.,Kaarsholm, Kamilla M. S.,Droumpali, Ariadni,Andersen, Henrik R.,Lee, Wontae,Hwang, Yuhoon Springer-Verlag 2017 JOURNAL OF NANOPARTICLE RESEARCH Vol.19 No.9

<P>Remediation of contaminated groundwater by nanoscale zero-valent iron (nZVI) is widely becoming a leading environmentally friendly solution throughout the globe. Since a wide range of various nZVIcontaining materials have been developed for effective remediation, it is necessary to determine an appropriate way to terminate the reactivity of any nZVI-containing material for a practical experimental procedure. In this study, bimetallic Ni/Fe-NPs were prepared to enhance overall reduction kinetics owing to the catalytic reactivity of nickel on the surface of nZVI. We have tested several chemical strategies in order to terminate nZVI reactivity without altering the concentration of volatile compounds in the solution. The strategies include surface passivation in alkaline conditions by addition of carbonate, and consumption of nZVI by a reaction competitor. Four halogenated chemicals, trichloroethylene, 1,1,1-trichloroethane, atrazine, and 4-chlorophenol, were selected and tested as model groundwater contaminants. Addition of carbonate to passivate the nZVI surface was not effective for trichloroethylene. Nitrate and then bromate were applied to competitively consume nZVI by their faster reduction kinetics. Bromate proved to be more effective than nitrate, subsequently terminating nZVI reactivity for all four of the tested halogenated compounds. Furthermore, the suggested termination method using bromate was successfully applied to obtain trichloroethylene reduction kinetics. Herein, we report the simple and effective method to terminate the reactivity of nZVI by addition of a reducing reactivity competitor.</P>

영가철이 고정된 입상활성탄 제조를 위한 최적 합성조건 도출

황유훈(Yuhoon Hwang),Paul D. Mines,이원태(Wontae Lee),Henrik R. Andersen 대한환경공학회 2016 대한환경공학회지 Vol.38 No.9

나노 영가철은 산화환원기작을 통하여 염소계 유기화합물과 같은 물질을 효과적으로 처리할 수 있다고 알려져 있지만, 작은 사이즈로 인하여 회수가 어려운 단점으로 인하여 실제 수처리 공정에서는 유출 등의 우려로 널리 적용되지 못하였다. 이와 같은 한계를 극복하기 위하여 활성탄과 같은 담체에 고정화 하여 사용하는 연구가 활발히 진행되었다. 본 연구에서는 활성탄에 영가철의 고정화 시 대표적으로 사용되는 고온 및 상온의 두 가지 경로에 대해 평가하였으며, 결과를 바탕으로 최적의 합성 조건을 도출하였다. 효과적인 나노영가철/입상활성탄 복합체를 합성하기 위해서는 높은 철 함량과 더불어 영가철의 분율을 높이는 것이 중요하며, 이를 위해서는 합성 과정에서 형성되는 철 산화물 및 수산화물의 형성을 억제하는 것이 중요한 것으로 나타났다. 또한 영가철의 분율을 높이기 위한 환원 시간 및 중간 건조 과정의 유무 등 합성 조건의 영향을 살펴보았으며, 그 결과 중간 건조 과정 없이 바로 NaBH4를 이용한 환원 조건을 약 2시간 이상 유지하는 것이 최적 조건임을 확인하였다. 합성된 나노영가철/입상활성탄 복합체는 활성탄의 흡착 능력과 영가철의 환원 능력을 동시에 보유함으로써 나이트로벤젠과 같은 환원이 가능한 오염물질의 제거에 효과적으로 나타났다. Nanoscale zero valent iron (nZVI) has been intensively studied for the treatment of a plethora of pollutants through reductive reaction, however, the nano size should be of concern when nZVI is considered for water treatment, due to difficulties in recovery. The loss of nZVI causes not only economical loss, but also potential risk to human health and environment. Thus, the immobilization onto coarse or structured support is essential. In this study, two representative processes for nZVI immobilization on granular activated carbon (GAC) were evaluated, and optimized conditions for synthesizing Fe/GAC composite were suggested. Both total iron content and Fe<SUP>0</SUP> content can be significantly affected by preparation processes, therefore, it was important to avoid oxidation during preparation to achieve higher reduction capacity. Synthesis conditions such as reduction time and existence of intermediate drying step were investigated to improve Fe<SUP>0</SUP> content of Fe/GAC composites. The optimal condition was two hours of NaBH4 reduction without intermediate drying process. The prepared Fe/GAC composite showed synergistic effect of the adsorption capability of the GAC and the degradation capability of the nZVI, which make this composite a very effective material for environmental remediation.

Estimating dehalogenation reactivity of nanoscale zero-valent iron by simple colorimetric assay by way of 4-chlorophenol reduction

Paul D. Mines,Kamilla M.S. Kaarsholm,Ariadni Droumpali,Henrik R. Andersen,Yuhoon Hwang 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.2

A number of different nanoscale zero-valent iron (nZVI) materials have been prepared and compared depending on the desired properties for the particular application, but different physicochemical properties of this prepared nZVI make it difficult to universally compare and standardize them to the same scale. In this study, we aimed to demonstrate a simple microplate-based colorimetric assay using 4-chlorophenol as an indicator with respect to the remediation of real treatment targets, such as trichloroethylene (TCE), 1,1,1-trichloroethane (TCA), and atrazine. Effect of nickel contents on 4-chlorophenol reduction was successfully investigated by the miniaturized colorimetric assay. In the same manner, the effect of nickel contents on dehalogenation of TCE, TCA, and atrazine was investigated and the pseudo-first-order kinetic constants were compared with the results for 4-chlorophenol. The similar pattern could be observed between 4-chlorophenol reduction obtained by colorimetric assay and TCE, TCA, atrazine reduction obtained by a traditional chromatographic method. The reaction kinetics does not match perfectly, but the degree of reaction can be estimated. Therefore, the colorimetric assay can be a useful and simple screening tool to determine nZVI reactivity toward halogenated organics before it is applied to a particular remediation site.