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>

Nanoporous networks as effective stabilisation matrices for nanoscale zero-valent iron and groundwater pollutant removal

Mines, P. D.,Byun, J.,Hwang, Y.,Patel, H. A.,Andersen, H. R.,Yavuz, C. T. The Royal Society of Chemistry 2016 Journal of Materials Chemistry A Vol.4 No.2

<P>Nanoscale zero-valent iron (nZVI), with its reductive potentials and wide availability, offers degradative remediation of environmental contaminants. Rapid aggregation and deactivation hinder its application in real-life conditions. Here, we show that by caging nZVI into the micropores of porous networks, in particular Covalent Organic Polymers (COPs), we dramatically improved its stability and adsorption capacity, while still maintaining its reactivity. We probed the nZVI activity by monitoring azo bond reduction and Fenton type degradation of the naphthol blue black azo dye. We found that depending on the wettability of the host COP, the adsorption kinetics and dye degradation capacities changed. The hierarchical porous network of the COP structures enhanced the transport by temporarily holding azo dyes giving enough time and contact for the nZVI to act to break them. nZVI was also found to be more protected from the oxidative conditions since access is gated by the pore openings of COPs.</P>

Granular activated carbon with grafted nanoporous polymer enhances nanoscale zero-valent iron impregnation and water contaminant removal

Mines, Paul D.,Uthuppu, Basil,Thirion, Damien,Jakobsen, Mogens H.,Yavuz, Cafer T.,Andersen, Henrik R.,Hwang, Yuhoon Elsevier 2018 Chemical engineering journal Vol.339 No.-

<P><B>Abstract</B></P> <P>Granular activated carbon was customized with a chemical grafting procedure of a nanoporous polymeric network for the purpose of nanoscale zero-valent iron impregnation and subsequent water contaminant remediation. Characterization of the prepared composite material revealed that not only was the polymer attachment and iron impregnation successful, but also that the polymeric shell acted as a protective barrier against the effects of oxidation from the surrounding environment, nearly 99% of total iron content was in the form of zero-valent iron. When applied towards the remediation of two common water contaminants, nitrobenzene and nitrate, the composite material exploited the qualities of both the activated carbon and the polymeric network to work together in a synergistic manner. In that the increased protection from oxidation allowed for increased reactivity of the nanoscale zero-valent iron, and that the adsorption abilities of both the carbon and the polymer achieved a higher amount of total removal of the contaminants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanoporous polymeric networks are chemically grafted to activated carbon granules. </LI> <LI> Hybrid polymer/carbon composites are impregnated with nanoscale zero-valent iron. </LI> <LI> Composite materials increase nZVI content and protect against oxidation. </LI> <LI> Materials provide effective simultaneous adsorption and degradation of pollutants. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Covalent organic polymer functionalization of activated carbon surfaces through acyl chloride for environmental clean-up

Mines, P.D.,Thirion, D.,Uthuppu, B.,Hwang, Y.,Jakobsen, M.H.,Andersen, H.R.,Yavuz, C.T. Elsevier 2017 Chemical engineering journal Vol.309 No.-

Nanoporous networks of covalent organic polymers (COPs) are successfully grafted on the surfaces of activated carbons, through a series of surface modification techniques, including acyl chloride formation by thionyl chloride. Hybrid composites of activated carbon functionalized with COPs exhibit a core-shell formation of COP material grafted to the outer layers of activated carbon. This general method brings features of both COPs and porous carbons together for target-specific environmental remediation applications, which was corroborated with successful adsorption tests for organic dyes and metals.

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.

Disulfide polymer grafted porous carbon composites for heavy metal removal from stormwater runoff

Ko, Dongah,Mines, Paul D.,Jakobsen, Mogens H.,Yavuz, Cafer T.,Hansen, Hans Chr. B.,Andersen, Henrik R. Elsevier 2018 Chemical engineering journal Vol.348 No.-

<P><B>Abstract</B></P> <P>The emerging concern of heavy metal pollution derived from stormwater runoff has triggered a demand for effective heavy metal sorbents. To be an effective sorbent, high affinity along with rapid sorption kinetics for environmental relevant concentrations of heavy metals is important. Herein, we have introduced a new composite suitable for trace metal concentration removal, which consists of cheap and common granular activated carbon covered with polymers containing soft bases, thiols, through acyl chlorination (DiS-AC). Material characterization demonstrated that the polymer was successfully grafted and grown onto the surface of the carbon substrate. The distribution coefficient for Cd<SUP>2+</SUP> bonding was 89·10<SUP>3</SUP> L/kg at a solution concentration of 0.35 mg/L, which is notably higher than sorption affinities for Cd<SUP>2+</SUP> seen in conventional sorbents. The sorption isotherm is well described by the Freundlich isotherm and within an hour, half of the initial trace (0.2 mg/L) concentration of Cd<SUP>2+</SUP> was removed by the DiS-AC at a sorbent loading of 2 g/L. Therefore, the novel material DiS-AC promises to be an ideal candidate for filters treating stormwater runoff.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The novel disulfide polymer grafted activated carbon composites were devised. </LI> <LI> Covalent bonds between disulfide polymer and carbon substrate have been proven. </LI> <LI> DiS-AC showed rapid kinetics on removing heavy metal in overall range of pH 6–8. </LI> <LI> DiS-AC showed high affinity towards even for trace amount of heavy metal in water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</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

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.

Experimental study of the atmospheric neutrino backgrounds forp→e+π0searches in water Cherenkov detectors

Mine, S.,Alcaraz, J. L.,Andringa, S.,Aoki, S.,Argyriades, J.,Asakura, K.,Ashie, R.,Berghaus, F.,Berns, H.,Bhang, H.,Blondel, A.,Borghi, S.,Bouchez, J.,Burguet-Castell, J.,Casper, D.,Catala, J.,Cavata, American Physical Society 2008 PHYSICAL REVIEW D - Vol.77 No.3

렝보의 <취정선>의 타롯트점에 의한 연구

閔熹植 漢陽大學校 人文科學大學 1984 人文論叢 Vol.7 No.-

Le but de cette etude est de faire des recherches sur<le bateau ivre> de Rimbaud en se basant sur l'occultisme, surtout le signe de Tarot. Nous abons constate que les recherches sur la technique de ia Poesie de Rimbaud sont relativement nombreuses, par contre les recherches sur des rapports entre L'occultisme et la Poese de Rimbaud sont tres rares, bien que ce theme, chez Rimbaud, soit tres important. Il serait donc tres interessant de porter notre etude sur le domaine de l'occultisme pour en decouvrir la vraie valeur de poesie de Rimbaud. Une analyse minitieuse sur <le bateau ivre> de Rimbaud nous permettra de demontrer que Rimbaud n'est pas seulement le symboliste, mais encore qu'il est un temoinage d'une grande valeur poetique contemporaine. Nous avons deviee notre etude en deux parties. Dans la premiere, nous nous sommes efforces d'analyser <le bateau iver> en tenant compte de la position de ce poeme dans le courant de la poesis symboliste. Ensuite, nous avons examine la genese de ce poeme. Dans la deuxieme, nous avons etudie le symbol de Tarot ainsi que les rapports existant entre (le bateau iver) a travers le Tarot d'une part, le texte d'autre part. De la nous en sommes venus a faire un rapprochment du torot avec <le bateau ivre.> Enfin il s'agit d'ecIairer le symbole de <le bateau ivre> en tenant compte du tarot. En conclusion, nous avons constate que dans l'univers de Rimbaud, il y a la tendance prophetique sur son epoques.