• Economic and Environmental Geology
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• v.36 no.5
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• pp.349-356
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• 2003

As industrial activities are growing, pollutants found in the contaminated land are getting diverse. Some contaminated areas are subject to mixed wastes containing both organic and inorganic wastes such as hydrocarbon and heavy metals. This study concerns with the influence of the degradation of organic pollutants on the coexisting heavy metals, expecially for As. As mainly exists as two different oxidation state; As(III) and As(V) and the conversion between the two chemical forms may be induced by organic degradation in the soil contaminated by mixed wastes. We operated microcosm in an anaerobic chamber for 60 days, using sandy loam. The soils in the microcosm are artificially contaminated both by tetradecane and As, with different combination of As(III) and As(V); As(III):As(V) 1:1, As(III) only and As(V) only. Although not systematic, ratio of As(III)/As(Total) increase slightly at the later stage of experiment. Considering complicated geochemical reactions involving oxidation/reduction of organic materials, Mn/Fe oxides and As, the findings in the study seem to indicate the degradation of the organics is connected with the As speciation. That is to say, the As(V) can be reduced to As(III) either by direct or indirect influence induced by the organic degradation. Although Fe and Mn are good oxidising agent for the oxidation of As(III) to As(V), organic degradation may have suppressed reductive dissolution of the Fe and Mn oxides, causing the organic pollutants to retard the oxidation of As(III) to As(V) until the organic degradation ceases. The possible influence of organic degradation on the As speciation implies that the As in mixed wastes may be have elevated toxicity and mobility by partial conversion from As(V) to As(III).

• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.125-134
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• 2007

This study has been carried out in order to examine the precipitation characteristics of Fe, Mn and Al ions in coal mine drainage before removing heavy metals by using the froth flotation method. The removal rate of Fe(III), Mn(II) and Al(III) within 1 h accounted for over 99% in pH 5.0, 10.0, and $6.0{\sim}9.0$ respectively, and residual concentrations of which were under $1mgL^{-1}$. When sodium oleate as a collector was added to the solution of Fe, Mn, and Al ions, insoluble salts was not formed by the reaction of heavy metal and sodium oleate. So, we must remove the metals from coal mine drainage by using not the ion flotation method, but the precipitation flotation method

• Journal of the Korean Chemical Society
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• v.37 no.7
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• pp.648-654
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• 1993

$[M(cyclam)X_2]Y(M=Co^{3+},\;Fe^{3+},\;Mn^{3+}\;:\;X=Cl-^,\;Br^-,\;NCS^-\;:\;Y=Cl^-,\;Br^-,\;NCS^-),\;[Co(trans-14-diene)X_2]Y(X=Cl^-,\;Br^-\;:\;Y=ClO_4^-)\;and\;[Co(trans-14-diene)](ClO_4)_2$ were able to activate an molecular oxygen under sodium borohydride. 2,4-di-tert-butylphenol and 2,6-di-tert-butylphenol reacted with activated molecular oxygen to give 2,4-tert-butyl-1,6-benzoquinone(BQ) and 3,5,3',5'-tetra-tert-butyldiphenoquinone(DPQ). The saturated tetraazamacrocyclic complexes, $[Co(cyclam)X_2]Y$, were more an effective catalyst than $[Co(trans-14-diene)X_2]Y$ the unsaturated complexes in the formation of BQ and DPQ. The mole ratio of $O_2$ vs. catalyst $(O_2/M)$ for $[Co(cyclam)X_2]Y$ and [Co(trans-14-diene)X_2]Y$ was 1/1, while it was 1/2 for $[M(cyclam)Cl_2]Cl(M=Fe(III),\;Mn(III))$. The results suggested that Co(III)-macrocyclic complexes activated molecular oxygen as superoxolike ${O_2}^-$ and $[M(cyclam)Cl_2]Cl(M=Fe(III),\;Mn(III))$ activated that as peroxolike $O_2^{2-}$.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.423-429
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• 2008

Application of manganese-impregnated activated carbon(Mn-AC) in the treatment of synthetic wastewater containing both organic and inorganic contaminants was investigated. Phenol and As(III) was used as representative organic and inorganic contaminants, respectively. When the stability of Mn-AC at acidic condition was evaluated with variation of solution pH ranging from 2 to 4, Mn-AC was unstable below pH 3, while negligible dissolution of Mn was observed above pH 4. This stability test suggests a plausible applicability of Mn-AC in the treatment of wastewater above pH 4. Compared to AC-alone, the adsorption rates of phenol as well as adsorbed amounts of phenol by Mn-AC were slightly decreased due to the decrease of the surface area by impregnation. The maximum adsorbed amount of phenol by Mn-AC was corresponds to 75% of that by AC-alone from the adsorption isotherm study. The oxidation efficiency of As(III) by Mn-AC was greater than that by AC-alone at lower pHs while reverse trend was observed as pH increased above 7. From this work, it was found that Mn-AC could be used in the simultaneous treatment of both phenol and As(III).

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2684-2688
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• 2014

Two two-dimensional cyanide- and phenoxo-bridged heterometallic M(II)-Mn(III) (M = Ni, Pd) coordination polymers $\{[Mn(saltmen)]_4[Ni(CN)_4]\}(ClO_4)_2{\cdot}CH_3OH{\cdot}H_2O$ (1) and $\{[Mn(saltmen)]_4[Pd(CN)_4]\}(ClO_4)_2{\cdot}CH_3CN{\cdot}H_2O$ (2) ($saltmen^{2-}$ = N,N'-(1,1,2,2-tetramethylethylene)bis(salicylideneaminato)dianion) have been obtained by using $K_2[M(CN)_4]$ as building blocks and a salen-tpye Schiff-base manganese(III) compound as assembling segment. Single X-ray analysis reveals their isostrutural cyanide-bridged $MMn_4$ pentanuclear cationic structure. The four Schiff base manganese units of the pentanuclear entity are self-complementary through the phenoxo oxygen atoms from the neighboring complex, therefore forming cyanide- and phenoxo-bridged 2D sheet-like structure. Investigation over magnetic susceptibilities reveals the overall ferromagnetic coupling between the adjacent Mn(III) ions bridged by the phenoxo oxygen atoms with J = 2.13 and $2.21cm^{-1}$ for complexes 1 and 2, respectively.

• Korean Journal of Materials Research
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• v.14 no.4
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• pp.235-238
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• 2004

The LT-MBE (low temperature molecular beam epitaxy) allows to dope GaAs with Mn over its solubility limit. A 75 urn thick GaMnAs layers are grown on a low temperature grown LT-GaAs buffer layer at a substrate temperature of $260^{\circ}C$ by varying Mn contents ranged from 0.03 to 0.05. The typical growth rate for GaMnAs layer is fixed at 0.97 $\mu\textrm{m}$/h and the V/III ratio is varied from 25 to 34. The electrical and magnetic properties are investigated by Hall effect and superconducting quantum interference device(SQUID) measurements, respectively. Double crystal X-ray diffraction(DCXRD) is also performed to investigate the crystallinity of GaMnAs layers. The $T_{c}$ of the $Ga_{l-x}$ /$Mn_{x}$ As films grown by LT-MBE are enhanced from 38 K to 65 K as x increases from 0.03 into 0.05 whereas the $T_{c}$ becomes lower to 45 K when the V/III ratio increases up to 34 at the same composition of x=0.05. This means that the ferromagnetic exchange coupling between Mn-ion and a hole is affected by the growth condition of the enhanced V/III ratio in which the excess-As and As-antisite defects may be easily incorporated into GaMnAs layer.

• Journal of the Korean Applied Science and Technology
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• v.15 no.2
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• pp.41-48
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• 1998

The catalytic oxidations of several cycloolefins in $CH_2Cl_2$ were been investigated using Mn(III)-, Fe(III)-porphyrin complexes as a catalyst and sodium hypochlorite as a terminal oxidant. Porphyrins were $(p-CH_3O)TTP,\;(p-CH_3)TTP,$ TPP, (p-F)TPP, (p-Cl)TPP and $(F_{20})TPP$ (TPP = tetraphenylporphyrin), and olefins were cyclopentene, cyclohexene and cycloheptene. The substrate conversion yield was discussed according to the substituent effects of metalloporphyrin. The conversion yield of substrate by changing the substituent of TPP increased in the order of $p-CH_3O$ < $p-CH_3$ < H < p-F < p-Cl, which was consistent with the sequence of $4{\sigma}$ values of TPP. The conversion of cycloalkene followed the order of $C_5\;<\;C_6\;<\;C_7$.

• Journal of the Korean Applied Science and Technology
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• v.19 no.3
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• pp.206-212
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• 2002

The catalytic activities of several metalloporphyrin, wherein the porphyrins are TPP(5,lO,l5,20-Tetraphenyl-21H,23H-porphyrin) and (p-X)TPP (X =$CH_{3}O$, $CH_{3}$, F, Cl), are reported for the oxidation of styrene and it's derivatives. The electronic effects of substrates and porphyrins on the catalytic activity of metalloporphyrin containing the transition metal ion such as Mn(III) was discussed. Investigating the correlation between the Michaelis-Menten's rate parameters and the substituent constants, we are going to analyze the influences on the changes of catalytic activity or rate determining step during the processes of the formation and the dissociation of the M-oxo-olefin.

• Resources Recycling
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• v.26 no.4
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• pp.34-41
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• 2017

The effect of Mn(II) concentration on the anodic reactions occurring on a Pb-Ag electrode in sulfuric acid solutions has been studied by potentiostatic oxidation in the potential range of 1.8 to 2.0 V. High oxidation potentials and low initial concentrations of Mn(II) resulted in higher concentrations of soluble Mn(III) ions which were obtained from spectrophotometric analysis of the solution after oxidation. $MnO_2$ was deposited on the electrode by electrochemical oxidation of Mn(II) at 1.8 and 1.9 V, while it was formed by disproportionation of Mn(III) at 2.0 V. No $PbO_2$ was formed in the presence of Mn(II) during potentiostatic oxidation treatment for two hours at 1.8 V. Chemical reduction of $PbO_2$ with Mn(II) led to a decrease in the amount of $PbO_2$ as Mn(II) concentration increased at 1.9 and 2.0 V.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.619-626
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• 2009

The objective of this study was to evaluate the efficiency of Fe and Mn oxides coated granular activated carbons (FMOCGs) for the removal of arsenite and arsenate by oxidation and adsorption mechanisms using surface characterization and batch adsorption experiments. Within four manufactured adsorbents, Fe and Mn contents of FMOCG-1 was the highest (178.12 mg Fe/g and 11.25 mg Mn/g). In kinetic results, As(III) was removed by oxidation and adsorption with FMOCGs. Removal of arsenic by FMOCGs increased as pH value of the solution decreased. The adsorption isotherm results were well fitted with Langmuir isotherm. Adsorption amount of As(V) onto FMOCGs was higher than that of As(III) and the maximum adsorption capacities of FMOCGs for As(III) and As(V) were 1.38~8.44 mg/g and 2.91~9.63 mg/g, respectively.