• Analytical Science and Technology
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• v.23 no.6
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• pp.566-571
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• 2010

This paper describes the sorption behaviors of aqueous uranium ions on the K-birnessite. K-birnessite was synthesized by adding a concentrated HCl to an aqueous solution of $KMnO_4$. Physicochemical characteristics of the K-birnessite, such as structure, specific surface area and surface charge, were investigated. K-birnessite is a layered material and the $K^+$ ions exist in the interlayer of layered K-birnessite. BET specific surface area of the K-birnessite was 38.30 m2/g. The surface charge of K-birnessite was $-1.65\;C/m^2$ at pH 5.00 and ionic strength of 0.010 M $NaClO_4$, at which the sorption experiments of uranium ions were carried out. Uranium ions were incorporated into the interlayer of the K-birnessite by cation-exchange reaction with $K^+$ ions, and the distribution coefficient is quite similar to those of common ion-exchange materials. The results might be applicable in the retardation of migration of radioactive materials from the underground disposal site of high-level radioactive waste.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.43-49
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• 2008

This study is conducted to determine the potential of zerovalent iron (ZVI), pyrolusite and birnessite to remediate water contaminated with chlorothalonil. The degradation rate of chlorothalonil by treatment of ZVI, pyrolusite and birnessite was much higher in low condition of pH. Mixing an aqueous solution of chlorothalonil with 1.0% (w/v) ZVI, pyrolusite and birnessite resulted in 4.7, 13.46 and 21.38 hours degradation half-life of chlorothalonil, respectively. Dechlorination number of chlorothalonil by treaonent of ZVI, pyrolusite and birnessite exhibited 2.85, 1.12 and 1.09, respectively. Degradation products of chlorothalonil by teartment of pyrolusite and birnessite were confirmed as trichloro-1,3-dicyanobenzene and dichloro-1,3-dicyanobenzene which were dechlorinated one and two chlorine atoms from parent chlorothalonil by GC-mass. Degradation products of chlorothalonil by ZVI were identified not only as those by pyrolusite and birnessite but as further reduced chloro-1,3-dicyanobenzene and chlorocyanobenzene.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.155-164
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• 2013

The main purpose of this research was to examine the adsorption/ion exchange characteristics of radioactive species such as cesium and strontium onto synthetic Na-birnessite (sodium-birnessite). As part of efforts to investigate the sorption behavior of cesium and strontium onto synthetic Na-birnessite, batch isotherm tests were performed under different experimental conditions. Na-birnessite was synthesized by the oxidation of $Mn^{2+}$ ions in sodium hydroxide solution. The synthetic Na-birnessite was characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) surface area analysis. Cesium and strontium concentrations were determined by atomic absorption spectroscopy (AAS). The removal efficiency of strontium by Na-birnessite was around 95 % which was much higher than that of cesium (~ 32 %). The results imply that strontium has a higher affinity for Na-birnessite than cesium because strontium, divalent cation leads to larger electrostatic attraction than monovalent cesium.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.1-8
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• 2012

The success of stabilization treatment in heavy metal contaminated sediment depends on the heavy metal bioavailability reduction through the sequestration of the heavy metals. This study was performed to assess the changes in the bioavailability of Pb or Cd in the Pb or Cd contaminated sediments by using birnessite and hydroxyapatite as stabilizing agents. The toxicity tests were carried out using a microorganism (Vibrio fischeri), an amphipod (Hyalella azteca) and an earthworm (Eisenia foetida). With Vibrio fischeri, the toxicities of both Pb and Cd were reduced by more than ten times in the presence of birnessite and hydroxyapatite compared to that of in the absence of birnessite and hydroxyapatite. The concentrations of Pb and Cd in the contaminated sediments were lethal to Hyalella azteca, however, in the presence of birnessite and hydroxyapatite more than 90%, on average, of Hyalella azteca survived. With Eisenia foetida, the bioaccumulated concentrations of both Pb and Cd were reduced by more than 75%, on average, lower with the addition of birnessite and hydroxyapatite to the contaminated sediments. These results show that the addition of birnessite and hydroxyapatite can reduce the bioavailability of Pb and Cd in contaminated sediments. In addition, the in situ and ex situ performance of birnessite and hydroxyapatite as stabilizing agents can be verified using the toxicity tests with Hyalella azteca and Eisenia foetida, respectively.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.590-592
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• 2010

Li-Mn spinel ($LiMn_2O_4$) is prepared by a hydrothermal process with K-Birnessite ($KMnO_4{\cdot}yH_2O$) as a precursor. The K-Birnessite obtained via a hydrothermal process with potassium permanganate [$KMnO_4$] and urea [$CO(NH_2)_2$] as starting materials are converted to Li-Mn spinel nanoparticles reacting with LiOH. The molar ratio of LiOH/K-Birnessite is adjusted in order to find the effect of the ratio on the structural, morphological and electrochemical performances of the Li-Mn spinel. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetry (TG) are used to investigate the crystal structure and morphology of the samples. Galvanostatic charge and discharge are carried out to measure the capacity and rate capability of the Li-Mn spinel. The capacity shows a maximum value of $117\;mAhg^{-1}$ when the molar ratio of LiOH/K-Birnessite is 0.8 and decreases with the increase of the ratio. However the rate capability is improved with the increase of the ratio due to the reduction of the particle size.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.143-152
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• 2020

Birnessite is a layered manganese oxide mineral with ~7 Å of d-spacing. Because of its high cation exchange capacity, birnessite greatly impacts the chemical compositions of ground water and fluids in sediment pores. Understanding the cation exchange mechanisms requires atomistic investigations of the crystal structures and coordination environments of hydrated cations in the interlayer. In this study, we conducted classical molecular dynamics (MD) simulations, an atomistic simulation method of computational mineralogy, for triclinic Na-birnessite and K-birnessite whose chemical formula are from previous experiments. We report our MD simulation results of the crystal structures, coordination environments of Na⁺ and K⁺, and the polytypes of birnessite and compare them with available experimental results. The simulation results well reproduced experimental lattice parameters and provided atomic level information for the interlayer cation and water molecule sites that are difficult to distinguish in X-ray experiments. We also report that the polytype of the Mn octahedral sheets is identical between Na- and K-birnessite, but the cation positions differ from each other, demonstrating a correlation between the coordination environment of the interlayer cations and the crystal lattice parameters. This study shows that MD simulations are very promising in elucidating ion exchange reactions of birnessite.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.384-389
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• 1998

The herbicide propanil and its metabolite, DCA were incubated with oxidative catalysts in the presence or absence of humic monomers to evaluate the incorporation of them into humic substances. Propanil and DCA underwent little or no transformation by oxidatve catalysts in the absence of humic monomers. In the presence of humic monomers, the most effective co-substrate for transformation of propanil was syringic acid by laccase and HRP, that of DCA was catechol by laccase and HRP, and protocatechuic acid by birnessite. The transformation of DCA was the highest when it was incubated with catechol at pH 8.0 during 24 hrs by laccase, and with catechol at pH 3.0 during 2 hrs by HRP, and with protocatechuic acid at pH 5.0 during 2 hrs by birnessite. The DCA transformation increased with increasing concentration of humic monomers. The transformation of DCA was increased with about 5 times when it was incubated with lactase and birnessite together than lactase alone, but that of it was not effected when it was incubated with HRP and birnessite together. When DCA was incubated with dissolved organic carbon in the presence of oxidative catalysts, the transformation of it was not increased by laccase and birnessite but increased by HRP.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.49-52
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• 2005

In this study, abiotic transformation of 1-naphthol via oxidative-coupling reaction was evaluated using Mn oxide which is ubiquitous in natural soils. The transformation of 1-naphthol catalyzed by synthetic birnessite $({\delta}-MnO_2)$ followed pseudo-lst order reaction, and the rate constants was in the range of $0.053{\sim}0.13\;min^{-1}$ with birnessite loadings of $12.5{\sim}50\;mg/20\;mL$. Since the oxidation of 1-naphthol was occurred on the reactive surface of the oxide particles, the rate constants with various birnessite loadings were correlated with birnessite surface area concentration. The correlation showed a strong linearity, which confirms the supposition of the surface reaction. From the correlation, therefore, the surface area normalized rate constant, $k_{surf}$, was determined to be 0.032 $L/m^2\;min$.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.545-554
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• 2017

Birnessite is one of the dominant Mn (oxyhydr)oxide phases commonly found in soil and deep ocean environments. It typically occurs as nano-sized and poorly crystalline aggregates in the natural environment. It is well known that birnessite participates in a wide variety of bio/geochemical reactions as a reactive mineral phase with structural defects, cation vacancies, and mixed valences of structural Mn. These various bio/geochemical reactions control not only the fate and transport of inorganic and organic substances in the environment, but also the formation of diverse Mn (oxyhydr)oxides through birnessite transformation. This review assessed and discussed about the phase transformation of birnessite under a wide range of environmental conditions and about the potential geochemical factors controlling the corresponding reactions in the literature. Birnessite transformation to other types of Mn (oxyhydr)oxides were affected by dissolved Mn(II), dissolved oxygen, solution pH, and co-existing cation (i.e., $Mg^{2+}$). However, there still have been many issues to be unraveled on the complex bio/geochemical processes involved in the phase transformation of birnessite. Future work on the detail mechanisms of birnessite transformation should be further investigated.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.547-554
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• 2010

In this study, new manganese oxide (i.e., black-birnessite) particles with nanostructures were prepared and its physico-chemical properties and oxidative-transformation efficiency on 1,4-naphthoquinine(1,4-NPQ) in the presence of reactive mediator was investigated. The results were also compared with that of the manganese oxide (i.e., brown-birnessite) particles synthesized by classical McKenzie method. Analysis of XRD and SEM data show that the particles are a single phase corresponding to a birnessite-based manganese oxide with cotton ball-like shapes containing nanofibers. In batch experiments, removals of 1,4-NPQ by the black-birnessite follows pseudo-first-order kinetics and the rate constant values obtained are greater about 2.3 times than that of the brown-birnessite in spite of its lower surface area (41.0 vs 19.80 $m^2/g$). The results can be explained by the higher crystallinity and nano structured features of the back-birnessite particles, which give higher reactivity for the removals of the quinone compound. HPLC analysis of the reaction products confirmed that the balck-birnessites removed 1,4-NPQ through cross-coupling reaction in the presence of catechol as a reactive mediator.