• Resources Recycling
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• v.12 no.5
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• pp.10-15
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• 2003

In this study, the separation of rare earths and aluminium from the dried powder of waste cerium polishing slurry was investigated. Since cerium oxide, 40％ of rare earths, is the most stable state in rare earth, the dissolution of cerium oxide in acid solution is not easy. Therefore the dissolution process of cerium oxide by sulfation was examined in order to increase the recovery of rare earth. The rare earths could be separated from aluminum by double salt precipitation using sodium sulfate.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.444-449
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• 2010

In this study, the petroleum sulfonate(PS) was synthesized from pyolyzed fuel oil by sulfonation reaction with sulfuric acid. The PS synthesized had surfactant behaviors relating to the interfacial properties such as surface tension, surface adsorption, and wetting, etc. These interfacial properties were affected by the sulfonation ratio in the synthesis. As the sulfonation ratio increased, the surface tension of the PS aqueous solution decreased. However, when the ratio was too high, the surface tension was increased due to the extremely higher value of hydrophilicity of PS. At the optimum sulfonation ratio, the PS had a good wettability on the cement particles and a good fluidity of the cement mortar with a high adsorption.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.289-298
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• 1996

Eight kinds of poly(oxyethylene, oxyisopropylene) dodecyl ethers were synthesized by adding ethylene oxide and isopropylene oxide with each 5 and 10 moles alternatively on dodecanol. The addition of EO and PO for eight kinds of sodium poly(oxyethylene, oxyisopropylene) dodecyl ether sulfates was identified with HPLC, $^1H$ NMR, hydroxy value, and IR spectrum. In order to verify the sulfation the number of EO and PO molecules was obtained by spectra and Epton method. The yields of products sulfated by chlorosulfonic acid were 90~96%.

• Clean Technology
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• v.4 no.2
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• pp.23-31
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• 1998

Photo-sensitized oxidation of benzene in aqueous solution was conducted with persulfate, nitrate, nitrite, sulfate and chloride as sensitizers.In the photo-sensitized oxidation of benzene persulfate, nitrate and nitrite could act as sensitizers, while no detectable effects could be observed with sulfate and chloride. With increasing nitrite concentration the photo-sensitized oxidation of benzene ran through a maximum value and decreased thereafter with increasing nitrite concentration. A build-up of nitrite ions seemed to scavenge hydroxyl radicals. When nitrite was present with other ions, nitrite inhibited the photo-sensitized oxidation of benzene. Phenol and biphenyl were identified as intermediate.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.05a
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• pp.55-58
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• 1997

대기오염의 주요원인은 소각로 연소가스와 자동차의 배기가스로 이들 이동 오염원에서 배출되는 오염가스는 일산화탄소, 탄화수소, 질소 및 황산화물 둥이고 이들은 공기중의 산소와 반응하여 광화학반응을하여 오존을 생성하며 기타 미세먼지, 수분과 반응하여 스모그를 생성하여 인체의 호흡기 계통 질병을 유발케한다. (중략)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.5
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• pp.222-228
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• 2019

In this study, we carried out the experiment to prepare lithium carbonate powder through gas-liquid reactions with a lithium-containing solution and $CO_2$ gas using lithium hydroxide, lithium chloride, and lithium sulfate. Thermodynamically, the carbonation reaction of a lithium-containing solution showed that aqueous reaction of lithium hydroxide occurs spontaneously, but aqueous reactions of lithium chloride and lithium sulfate does not occur spontaneously. In the case of lithium hydroxide solution, the recovery rate of lithium carbonate was 69.8 % at room temperature ($25^{\circ}C$), and increased to 89.4 % at $60^{\circ}C$. In the case of lithium chloride and lithium sulfate solution, lithium carbonate could be prepared using sodium hydroxide as an additive, but the recovery rates were 19.2 % and 16.7 %, respectively.

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.407-412
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• 1998

This study was carried out to investigate the optimum leaching conditions for the sulfation and water leaching, and separation of cerium from rare earth elements in leached solution by acid-adjusting method. The optimum conditions for the sulfation and water leaching from bastnasite concentrates are that the equivalent ration of sulfuric acid to concentrates is 2.5, calcination temperature and time are $600^{\circ}C$ and 2 hrs respectively, and the pulp density in the water leaching is 9.1%. The yield of rare earth oxide is about 93% at the above condition. The process of recovery of cerium hydroxide from leached solution by acid-adjusting method was carried out as following steps. The first step is the oxidation of the solution at pH 5 by using twice the equivalent of $H_2O_2$ solution as an oxidant. The second step is the precipitation to obtain cerium complex salt and cerium hydroxide after lowering the solution to pH 2. The last step is the oxidation-precipitation by using equivalent of $H_2O_2$ solution. From these results, it was possible to prepare cerium hydroxide with the yield of 60% and the quality of 80%.

• Magazine of the Korea Concrete Institute
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• v.7 no.2
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• pp.175-182
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• 1995

Styrene-Maleic anhydride copolymer (SMA) was prepared by the radical copolmerization of styrene and maleic anhydride using ${\alpha}-{\alpha}'$ azobis(isobutyronitrile) as an initiatrr. SMA was further reacted with m-amino phenol to obtain aminophenol-substituted SMR (mSMA). Sulfonated SMA and mSMA were also prepared by the reaction of copolymers with sulfuric acid The copolyniers were characterized by infrared spectroscopy. It was found from the results of elemental analysis that the substitution degree of aminophenol in the mSMR is 44% and the degree is lowered to 35% after sulfonation. The percentage of copolymers adsorbed on the surface of cement particles was increased with a decrease of added copolymers. While, the arnourit of sulfonated SMA absorbed on the surface of cement particles was larger than that of the sulfonated mSMA The copolymers synthesized in this study are probably expected as a high range water reducer for coiicxte.

• Resources Recycling
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• v.25 no.5
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• pp.57-63
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• 2016

This study were carried out sulfation roasting and selective leaching test for the effective recovery of copper component in concentrate obtained by froth floatation of Autrallian low grade copper ore. The optimum conditions of sulfation roasting were temp. $450^{\circ}C$, $Na_2SO_4$ 2 mole ratio and time 1.5 h, and then selective leaching were room temperature and $H_2O$ or 1M $H_2SO_4$ solutions. Leaching efficiency of optimum sulfation product were 90 wt.% of copper, 20 wt.% of iron and 15wt.% of nickel elements. In this results, it was possible to selective decomposition leaching of the copper component under optimum conditions in this research.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.135-143
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• 2010

본 연구에서는 대기오염물질인 유해 황산화물 가스를 이산화티탄 촉매 반응기와 연면 방전 반응기를 조합한 반응기에서 플라즈마 방전반응에 의하여 주파수 변화, 체류시간, 전극의 굵기, 첨가 모의가스 등의 공정 변수를 변화 시켜 분해제거 실험을 하였다. 실험 결과 황산화물의 분해제거 실험에서 주파수 10kHz에서 소비전력 19W에서 분해제거율은 99%이었으며 이산화티탄 촉매반응기를 부착한 경우가 없는 경우보다 5%이상 증가효과가 이었다. 첨가가스로 메탄을 첨가한 경우 분해제거율이 증가하였고, 산소농도가 높아질수록 증가하였다 또한 이산화 탄소를 첨가한 경우 분해율은 감소하였다.