• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.622-625
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• 2005

본 연구의 목적은 동해 울릉분지 천부퇴적층의 공극수와 메탄의 특징 및 상호작용을 규명하는데 있다. 울릉분지에서 채취한 코어에서 공극수를 추출하여 분석한 결과, 공극수의 황산염 농도가 퇴적물의 심도가 증가할수록 감소하며, 감소하는 경향은 크게 세 가지 (직선성, concave down, upward kink)로 나뉨을 알 수 있었다. 이는 모든 코어에서 황산염 환원작용이 일어나고 있음을 지시한다 황산염 농도의 수직적 구배를 이용하여 SMI (sulfate-methane interface) 심도를 계산하면, 남부울릉분지가 북부울릉분지보다 낮은 값을 갖는다. 반면에 메탄 농도는 퇴적물의 심도가 증가할수록 전반적으로 증가하며, 공간적으로는 남부 울릉분지가 북부울릉보지보다 높다. 또한 남부울릉분지에서 메탄가스 농도는 SMI 심도 아래에서 급격히 증가한다 메탄가스의 탄소 안정동위원소$(\delta^{13}C)$ 분석 값들은 대부분 $-60\%_{\circ}$이하로서 이는 메탄가스가 열기원 보다는 박테리아기원임을 지시해준다 또한 남부 울릉분지에서 메탄의 탄소 안정동위원소 분석 값들은 메탄농도가 증가할수록 낮은 값을 보여 주는 데 이러한 결과들은 남부 울릉분지에서 무산소 메탄 산화작용이 일어나고 있음을 지시하고, 메탄의 상향 분산 (diffusion)량이 북부 울릉분지보다 많이 일어난다는 것을 의미한다. 공극수내 황산염 이온 농도 구배와 메탄가스 농도를 종합적으로 고려할 때, 울릉분지에서 가스하이드레이트의 부존가능성은 북부 울룽분지보다 남부 울릉분지가 높은 것으로 추정된다.

• Resources Recycling
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• v.30 no.3
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• pp.55-62
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• 2021

In Korea, a good recycled product (GR) certification system was introduced in 1997 to improve resource and energy use efficiency. However, in industry and society, recycled products are not used well because of the lack of awareness of recycled materials. In this study, the status of domestic and international quality standards for nickel materials was investigated, and the purity and electrochemical properties of nickel sulfate prepared from ore and nickel sulfate recovered from waste lithium-ion batteries were evaluated during the electroplating process. As a result of the test, it was found that there is no quality difference between recycled nickel sulfate and high-purity nickel sulfate reagents when used in the electroplating industry.

• Journal of the Korean Geotechnical Society
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• v.39 no.8
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• pp.7-16
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• 2023

This study aimed to evaluate the sulfate removal capacity of the enzyme-induced carbonate precipitation (EICP) technique through the chemical precipitation of sulfate with calcium ions. The optimal EICP recipe was obtained to retain the excess calcium cations in the solution for the generation of a sufficient amount of calcium carbonate (CaCO₃) mineral. The effect of gypsum precipitation on the EICP-treated sand specimen was investigated by measuring the shear wave velocity and by visual inspection via scanning electron microscopy. The EICP solution using soybean crude urease, as an alternative to laboratory-grade purified urease, exhibited a lower sulfate removal efficiency at a similar CaCO₃ production rate compared with the optimal EICP recipe because of soybean impurities.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.526-527
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• 2010

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.309-314
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• 1984

The species and equilibria of uranium and vanadium have been investigated in the various concentration of perchloric, hydrochloric and sulfuric acid by anion exchange chromatography. In the concentration range of $0.01\;{\sim}\;0.5M$ hydrochloric and $0.01\;{\sim}\;0.5M$ perchloric acid, uranium seems to be $UO_2^{2+}$species and in higher concentration than 0.5M hydrochloric acid $UO_2^{2+}$seems to form the chloride complex ion as $UO_2Cl^+$, $UO_2Cl_2$, $UO_2Cl_3^-$ and $UO_2Cl_4^{2-}$ according to the increase of the hydrochloric acid concentration. In the dilute(0.01N) sulfuric acid the adsorbability of uranium on anion exchange resin is strong and then decreases with increasing the sulfuric acid concentration. From this result we conclude that $UO_26{2+}$ formed the complex ion as $UO_2(SO_4)_2^{2-}$. In the perchloric acid of $0.01\;{\sim}\;0.5N$ concentration the existing equilibrium of vanadium and its constant calculated at $20^{\circ}C$ is $1.9{\times}108$ for $H_2V_{10}O_{28}^{4-}$ + $14H^+$ = $10VO_2^+ + 8H_2O$. The elution behaviors of vanadium in the hydrochloric and sulfuric acid are smiliar to those in perchloric acid.

• Resources Recycling
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• v.21 no.6
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• pp.58-64
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• 2012

A study on the solvent extraction for the separation and recovery of Ni and Li from the leaching solution of active cathode materials of Li-ion batteries was investigated using PC88A(2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester). The experimental parameters, such as the pH of the solution, concentration of extractant and phase ratio were observed. Experimental results showed that the extraction percent of Ni and Li and separation factor of Ni/Li were increased with increasing the equilibrium pH. More than 99.4% of Ni and 28.7% of Li were extracted in eq. pH 8.5 by 25% PC88A and the separation factor of Ni/Li was 411.6. From the analysis of McCabe-Thiele diagram, 99% of Ni was extracted by three extraction stages at phase ratio(A/O) of 1.5. Stripping of Ni and Li from the loaded organic phases can be accomplished by sulfuric acid as a stripping reagent and 50-60g/L of $H_2SO_4$ was effective for the stripping of Ni.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.409-414
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• 2006

Sulfur-oxidizing bacteria were enumerated and isolated from a steady-state anaerobic master culture reactor (MCR) operated for over six months under a semi-continuous mode and nitrate-limiting conditions using thiosulfate as an electron donor. Most are Gram-negative bacteria, which have sizes up to 12 m. Strains AD1 and AD2 were isolated from the plate count agar (PCA), and strains BD1 and BD2 from the solid thiosulfate/nitrate medium. Based on the morphological, physiological, FAME and 16S rDNA sequence analyses, the two dominant strains, AD1 and AD2, were identified as Paracoccus denitrificans and Paracoccus versutus (formerly Thiobacillus versutus), respectively. From the physiological results, glucose was assimilated by both strains AD1 and AD2. Heterotrophic growth of strains AD1 and AD2 could be a more efficient way of obtaining a greater amount of biomass for use as an inoculum. Even though facultative autotrophic bacteria grow under heterotrophic conditions, autotrophic denitrification would not be reduced.

• Resources Recycling
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• v.31 no.2
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• pp.40-48
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• 2022

In this study, the effects of solution components were investigated in the recovery of vanadium as ammonium metavanadate from vanadium-ore-salt roasting-water leaching solution. The vanadium-containing solution is strongly alkaline (pH 13), so the pH must be lowered to 9 or less to increase the ammonium metavanadate precipitation efficiency. However, in the process of adjusting the solution pH using sulfuric acid, aluminum ions are co-precipitated, which must be removed first. In this study, aluminum was precipitated in the form of an aluminum-silicate compound using sodium silicate, and the conditions for minimizing vanadium loss in this process were investigated. After aluminum removal, the silicate was precipitated and removed by adjusting the solution pH to 9 or less using sulfuric acid. In this process, the concentration and addition rate of sulfuric acid have a significant influence on the loss of vanadium, and vanadium loss was minimized as much as possible by slowly adding dilute sulfuric acid. Ammonium metavanadate was precipitated using three equivalents of ammonium chloride at room temperature from the aluminum-free, aqueous solution of vanadium following the pH adjustment process. The recovery yield of vanadium in the form of ammonium metavanadate exceeded 81%. After washing the product, vanadium pentoxide with 98.6% purity was obtained following heat treatment at 550 ℃ for 2 hours.

• Land and Housing Review
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• v.4 no.1
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• pp.119-124
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• 2013

Generally, the characteristic of nanofiltration membranes were catagorized into charged membrane, sieve effect, interaction between membarnes and target solutes. This study aims to investigate the effect item of heavy metal separation with view of charge nanofiltration membranes. The experiments of nanofiltration were conducted by nanofiltration set-up with operational pressure of 0.24 MPa at $25^{\circ}C$ by using synthetic wastewater containing 0.1mg/L of Cr, Fe, Cu, Zn, As, Sn, Pb. Nanofiltration membranes rejected heavy metals much better than chloride, sulfate and TOC, of which concentration in synthetic wastewater was higher than that of heavy metals. To consider rejection characteristics of various metals by nanofiltration membranes, separation coefficient, which is the molar conductivity ratio of the metal permeation rate to the chloride ion or TOC permeation rate, was introduced. In spite of different materials and different nominal salt rejection of nanofiltration membrane used, the separation coefficients of metals were nearly the same. These phenomena were observed in the relationship between the molar conductivity and the separation coefficient for heavy metals.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.403-407
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• 1975

The rate constant for the $N_2H_4-Br_2$ reaction has been measured in sulfuric acid media by direct mixing method and chronopotentiometric method. The former gave 105 mole-1 l sec-1 whereas the latter 103 mole-1 l sec-1. It has been inferred that the former represents the rate constant for $N_2H_4-Br_2$ {\rightarrow} $N_2H_2$ and the latter for $N_2H_2+Br_2$ {\rightarrow} X. When the concentrations of KBr and $H_2SO_4$ are both high, drastic reduction of rate constant has been observed.