Abiotic Reductive Dechlorination of <i>cis</i>-Dichloroethylene by Fe Species Formed during Iron- or Sulfate-Reduction

Jeong, Hoon Y.,Anantharaman, Karthik,Han, Young-Soo,Hayes, Kim F. American Chemical Society 2011 Environmental science & technology Vol.45 No.12

<P>This study investigated reductive dechlorination of <I>cis</I>-dichloroethylene (<I>cis</I>-DCE) by the reduced Fe phases obtained from in situ precipitation, which involved mixing of Fe(II), Fe(III), and S(-II) solutions. A range of redox conditions were simulated by varying the ratio of initial Fe(II) concentration ([Fe(II)]<SUB>o</SUB>) to initial Fe(III) concentration ([Fe(III)]<SUB>o</SUB>) for iron-reducing conditions (IRC) and the ratio of [Fe(II)]<SUB>o</SUB> to initial sulfide concentration ([S(-II)]<SUB>o</SUB>) for sulfate-reducing conditions (SRC). Significant dechlorination of <I>cis</I>-DCE occurred under highly reducing IRC and iron-rich SRC, suggesting that Fe (oxyhydr)oxides including green rusts are highly reactive with <I>cis</I>-DCE but that Fe sulfide as mackinawite (FeS) is nonreactive. Relative concentrations of sulfate to chloride were also varied to examine the anion impact on <I>cis</I>-DCE dechlorination. Generally, slower dechlorination occurred in the batches with higher sulfate concentrations. As indicated by higher dissolved Fe concentration, the slower dechlorination in the presence of sulfate was probably due to the decreased surface-complexed Fe(II). This study demonstrates that the chemical form of reduced Fe(II) is critical in determining the fate of <I>cis</I>-DCE under anoxic conditions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2010/esthag.2010.45.issue-12/es104387w/production/images/medium/es-2010-04387w_0002.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es104387w'>ACS Electronic Supporting Info</A></P>

Abiotic reductive dechlorination of cis-DCE by ferrous monosulfide mackinawite

Hyun, Sung Pil,Hayes, Kim F. Springer-Verlag 2015 Environmental Science and Pollution Research Vol.22 No.21

THE RELATIONSHIP BETWEEN MILK PROTEIN PHENOTYPES AND LACTATION TRAITS IN AYRSHIRES AND JERSEYS

Kim, S.,Ng-Kwai-Hang, K.F.,Hayes, J.F. Asian Australasian Association of Animal Productio 1996 Animal Bioscience Vol.9 No.6

A total of 3,610 Ayrshire and 1,711 Jersey cows were phenotyped for the genetic variants of ${\alpha}_{s1}$-casein, ${\beta}$-casein, $\chi$-casein, ${\beta}$-lactoglobulin and ${\alpha}$-lactalbumin. Least squares analyses showed possible associations between milk protein phenotypes and lactational production traits. Depending on lactation number, ${\beta}$-casein phenotypes in Ayrshires were associated with milk production ($A^2A^2$ > $A^1A^2$ > $A^1A^1$), and with milk protein content. In the third lactation, Ayrshire cows with ${\beta}$-casein $A^1A^1$ produced milk with 3.43% fat compared to 3.37% fat for ${\beta}$-casein $A^2A^2$. In Ayrshire, $\chi$-casein phenotypes affected the protein content during the three lactations (BB > AB > AA) and ${\beta}$-lactoglobulin phenotypes significantly influenced the milk fat during the first lactation (4.06% for AA and 3.97% for BB). In Jerseys, protein content of milk was influenced by phenotypes of ${\alpha}_{s1}$-casein(3.98% for CC v/s 3.86% for BB in the first lactation). In the third lactation, $\chi$-casein AA of Jersey milk contained 5.35% fat compared to 4.82% for phenotype BB. The effects of ${\beta}$-lactoglobulin phenotypes on protein content were apparent in Jerseys during the second lactation with the A variant being superior to the B (4.00% for AA v/s 3.87% for BB).

The Relationship between Milk Protein Phenotypes and Lactation Traits in Brown Swiss and Canadienne

Kim, S.,Ng-Kwai-Hang, K.F.,Hayes, J.F. Asian Australasian Association of Animal Productio 1998 Animal Bioscience Vol.11 No.3

A total of 1033 Brown Swiss and 610 Canadienne cows were phenotyped for the genetic variants ${\alpha}_{s1}$-casein, ${\beta}$-casein, ${\kappa}$-casein, ${\beta}$-lactoglobulin and ${\alpha}$-lactalbumin. In Brown Swiss, frequency distributions were: 97.3% B and 2.7% C variant of ${\alpha}_{s1}$-casein; 31.6% $A^1$, 51.8% $A^2$, 0.5% $A^3$ and 16.1% B variant of ${\beta}$-casein; 70.4% A, 29.3% B, and 0.3% C variant of ${\kappa}$-casein; 41.7% A and 58.3% B variant of ${\beta}$-lactoglobulin; and 100% B variant of ${\alpha}$-lactalbumin. Corresponding frequencies in Canadienne for those five milk proteins were: 98.6 and 1.4%;58.5, 33.5, 0.08 and 7.9%; 78.8, 21.1 and 0.1%, 42.4 and 57.6%; and 100%. Analysis of variance by least squares showed possible association between milk protein phenotypes and some lactational production traits. There were no significant association of phenotypes of ${\alpha}_{s1}$-casein, ${\beta}$-casein and ${\beta}$-lactoglobulin with milk yield, fat yield, protein yield, fat percentage and protein percentage in both breeds during the three lactations. In the Brown Swiss, ${\kappa}$-casein phenotype was associated with 305-day fat yield and protein yield during the first lactation. ${\kappa}$-Casein AB was associated with higher milk, fat and protein yield during the second lactation. During the third lactation, ${\beta}$-lactoglobulin AA in Canadienne cows was associated with higher protein content in the milk (3.70%) when compared to phenotypes AB (3.54%) and BB (3.64%).

The Importance of Reaction Mechanisms in Interpreting the Arsenic Reactive Transport of FeS-coated Sand Column

Han, Young-Soo,Demond, Avery H.,Hayes, Kim F. Korean Society of Soil and Groundwater Environment 2015 지하수토양환경 Vol.20 No.5

FeS, as a natural reduced iron mineral, has been recognized to be a viable reactive material for As(III) sequestration in natural and engineered systems. In this study, FeS-coated sand packed columns were tested to evaluate the As(III) removal capacities under anaerobic conditions at pH 5, 7 and 9. The column obtained As(III) removal capacity was then compared with the capacity result obtained from batch reactors. In the comparison, two different approaches were used. The first approach was used the total As(III) removal capacity which method was proved to be useful for interpreting pH 5 system. The second approach was used to consider sorption non-linearity and proved to be useful for interpreting the pH 9. The results demonstrated that a mechanistic understanding of the different removal processes at different pH conditions is important to interpret the column experimental results. At pH 5, where the precipitation of arsenic sulfide plays the major role in the removal of arsenic, the column shows a greater removal efficiency than the batch system due to the continuous dissolution of sulfide and precipitation of arsenic sulfide. At pH 9, where adsorption mainly governs the arsenic removal, the sorption nonlinearity should be considered in the estimation of the column capacity. This study highlighted the importance of understanding reaction mechanism to predict column performance using batch-obtained experimental results.

The Importance of Reaction Mechanisms in Interpreting the Arsenic Reactive Transport of FeS-coated Sand Column

한영수,Avery H. Demond,Kim F. Hayes 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.5

FeS, as a natural reduced iron mineral, has been recognized to be a viable reactive material for As(III) sequestration in natural and engineered systems. In this study, FeS-coated sand packed columns were tested to evaluate the As(III) removal capacities under anaerobic conditions at pH 5, 7 and 9. The column obtained As(III) removal capacity was then compared with the capacity result obtained from batch reactors. In the comparison, two different approaches were used. The first approach was used the total As(III) removal capacity which method was proved to be useful for interpreting pH 5 system. The second approach was used to consider sorption non-linearity and proved to be useful for interpreting the pH 9. The results demonstrated that a mechanistic understanding of the different removal processes at different pH conditions is important to interpret the column experimental results. At pH 5, where the precipitation of arsenic sulfide plays the major role in the removal of arsenic, the column shows a greater removal efficiency than the batch system due to the continuous dissolution of sulfide and precipitation of arsenic sulfide. At pH 9, where adsorption mainly governs the arsenic removal, the sorption nonlinearity should be considered in the estimation of the column capacity. This study highlighted the importance of understanding reaction mechanism to predict column performance using batch-obtained experimental results.

Copper(Ⅱ) Sorption Mechanism on Kaolinite : An EPR and EXAFS Study 전자상자성공명 및 EXAFS 연구

Hyun, Sung Pil,Kim, F. Hayes 한국광물학회 2004 한국광물학회지 Vol.17 No.1

캐올리나이트(KGa-lb) 표면에 수착된 구리를 전자상자성공명(electron paramagnetic resonance)과 ExAFS (extended X-ray absorption fine structure) 분광법을 이용하여 연구하였다. 수착된 구리는 상온에서 g_(iso)=2.19의 등방성 전자상자성공명 흡수 신호를 보여 준다. 77 K에서 이러한 등방성 신호는 g_(∥)=2.40, g_(i)=2.08, 그리고 A_(∥)=131 G의 전사상자성공명 파라미터를 가지는 축대칭 이방성 신호로 바뀐다. 전자상자성공명 분석 결과로부터 수착된 구리 이온이 찌그러진 CuO_(6) 팔면체구조의 외부권착물을 형성함을 알 수 있다. 수착 실험에서 용액의 pH가 증가함에 따라 수착된 구리의 양은 증가하였다. 그러나 등방성 신호는 수착된 구리의 양에 단순 비례하지는 않았다. 수착된 구리 이온이 높은 pH 조건에서 표면 침전을 형성함을 가정함으로써 이러한 불일치를 해소할 수 있다. EXAFS 결과로부터 이러한 표면 침전의 존재를 확인할 수 있었다. 최적의 fitting 결과는 수착된 구리 이온이 1.96Å 거리에 결합된 4개의 수평 방향 산소와 2.31 Å 거리에 결합된 2개의 축방향 산소로 이뤄진 첫 번째 산소 껍질과 함께 3.08 Å 거리에 평균 6.8개의 구리 이웃 원자들을 가짐을 보여준다. 이 연구는 캐올리나이트에 수착된 구리 이온의 국소 환경이 용액의 pH와 표면 농도에 따라 변화하며 그러한 변화를 연구하는데 전자상자성공명과 EXAFS가 효과적으로 활용될 수 있음을 보여 준다. Copper(Ⅱ) sorbed on kaolinite (KGa-1b) was studied using electron paramagnetic resonance (EPR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The sorbed copper(Ⅱ) had an isotropic EPR signal with g_(iso)= 2.19 at room temperature. At 77 K, the isotropic signal converted to an axially symmetric anisotropic signal with g_(∥) = 2.40, g_(l) = 2.08, and A_(∥) = 131 G. These EPR results suggest that the sorbed copper(II) forms an outer-sphere surface complex with a tetragonally distorted CuO_(6) octahedral structure on the kaolinite. In the sorption measurement, the amount of sorbed copper increased with increasing pH of the solution. However, the intensity of the isotropic EPR line was not directly proportional to the amount of sorbed copper. This discrepancy was resolved by assuming the formation of a surface precipitate at higher pH that is invisible by EPR. The EXAFS data confirmed the existence of the surface precipitate. The best fit for the EXAFS of the sorbed copper showed that each copper on the kaolinite had 6.8 copper neighbors located 3.08 A from it, in addition to the first shell oxygen neighbors, including 4 equatorial 0 at 1.96 A and 2 axial 0 at 2.31 A. This work shows that the local environment of the copper sorbed on the kaolinite changes as a function of pH and surface loading, and that the EPR and EXAFS are useful in studying such changes.

Assessing Abiotic Reductive Dechlorination of cis-DCE by Reduced Fe Species Forming under Various Redox Conditions

정훈영,Karthik Anantharaman,Sung Pil Hyun,Kim F. Hayes 대한지질학회 2010 대한지질학회 학술대회 Vol.2010 No.

매키노아이트 (FeS1-x)에 의한 우라늄(VI) 환원을 통한 우라니나이트 형성

현성필(Sung Pil Hyun),James A. Davis,Kim F. Hayes 한국암석학회 2012 한국암석학회 학술발표회 논문집 Vol.2012 No.5