• Title, Summary, Keyword: chlorides

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The Synthesis of Surfactant of N-Alkyl Nicotinates (N-알킬 니코틴산염류(酸鹽類) 계면활성제(界面活性劑)의 합성(合成))

  • Nam, Ki-Dae;Jeong, No-Hee;Lee, Chang-Seoup;Lee, Seung-Yeol
    • Journal of the Korean Applied Science and Technology
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    • v.7 no.2
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    • pp.11-18
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    • 1990
  • N-alkyl carboxy pyridinium chlorides such as N-lauryl carboxy-pyridinium chloride, N-myristyl carboxy pyridinium chloride, N-cetyl carboxy pyridinium chloride and N-stearyl carboxy pyridinium chloride were synthesized by the reaction of nicotinic acid and isonicotinic acid with long chain alkyl chlorides, and N-alkyl pyrinium carboxylates such as N-lauryl pyridinium carboxylate, N-myristyl pyridinium carboxylate. N-cetyl pyridinium carboxylate and N-stearyl pyridinium carboxylate were prepared from N-alkyl carboxy pyridinium chlorides. These reaction products could be separated by both column chromatogrphy, and paper chromatography, and there dissociation constants of N-alkyl pyridinium carboxylates were found to pKa $1.0{\times}10^{13}{\sim}6,31{\times}10^{14}$.

Effect of Corrosion Inhibitor for Reinforcing Steel in Concrete Containing Chlorides (염화물을 함유한 콘크리트 중의 철근방식을 위한 방청제의 효과)

  • 문한영;김성수
    • Magazine of the Korea Concrete Institute
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    • v.10 no.6
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    • pp.325-333
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    • 1998
  • Under the seawater environment, the reinforced concrete structure is deteriorated due to physical and chemical attacks. The main deterioration mechanism is the chloride corrosion of reinforcing steel. The corrosion inhibitors have been used to protect the rebars from corrosion which are susceptible to chlorides in concrete. However, there is not clear conclusion about corrosion inhibitors yet. In this study, it is made the accelerated experiment with 3 kinds of corrosion inhibitors for various chloride ingresses. It is estimated corrosion inhibitors that inhibitors by Half-Cell Potential, corrosion area ratio and weight loss ratio. It is concluded that inhibitors are not effective to corrosion inhibition for excessive chloride ingress. However, the effect of inhibition is directly proportional ot contents of corrosion inhibitors in some chloride ingress.

Synthesis and Surface Activity of New Quaternary Ammonium Salts Prepared from 2-Chloromethyl-5-(2-Phenylthiazol-4-yl)-1,3,4-Oxadiazole (2-클로로메틸-5-(2-Phenylthiazol-4-yl)-1,3,4-옥사디아졸의 새로운 4급 암모늄염의 합성과 계면활성도)

  • Bae, Sun Kun;Yeon, Young Heum
    • Applied Chemistry for Engineering
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    • v.17 no.3
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    • pp.286-290
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    • 2006
  • New quaternary ammonium chlorides, [alkyldimethyl-[5-(2-phenylthiazol-4-yl]-1,3,4-oxadizol-2-ylmethyl]quaternary ammonium chlorides (ADOQACs): 6] were obtained with high yields by the reaction of compound 5 with N,N-dimethylalkyl amines in isopropyl alcohol. The structures and physical properties of the synthesized compounds were investigated and those surface-active properties were measured. The surface tension ($\gamma_{cmc}$) and the minimal inhibitory concentration (MIC) of compound 6 were found to be influenced by the number of alkyl chain carbon. Especially, compounds 6c and 6d exhibited high anti-bacterial activities and good surface-active properties.

Integrated Modeling of Chloride Binding Isotherm of Concrete Based on Physical and Chemical Mechanisms (물리화학적 메커니즘에 기이한 큰크리트의 염화물 흡착 등온에 대한 모델링)

  • Yoon, In-Seok
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.537-540
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    • 2006
  • Over the past few decades, a considerable number of studies on the durability of concrete have been carried out extensively. A lot of improvements have been achieved especially in modeling of ionic flows. However, the majority of these researches have not dealt with the chloride binding isotherm based on the mechanism, although chloride binding capacity can significantly impact on the total service life of concrete under marine environment. The purpose of this study is to develop the model of chloride binding isotherm based on the individual mechanism. It is well known that chlorides ions in concrete can be present; free chlorides dissolved in the pore solution, chemical bound chlorides reacted with the hydration compounds of cement, and physical bound attracted to the surface of C-S-H grains. First, sub-model for water soluble chloride content is suggested as a function of pore solution and degree of saturation. Second, chemical model is suggested separately to estimate the response of binding capacity due to C-S-H and Friedel's salt. Finally, physical bound chloride content is estimated to consider a surface area of C-S-H nano-grains and the distance limited by the Van der Waals force. The new model of chloride binding isotherm suggested in this study is based on their intrinsic binding mechanisms and hydration reaction of concrete. Accordingly, it is possible to characterize chloride binding isotherm at the arbitrary stage of hydration time and arbitrary location from the surface of concrete. Comparative study with experimental data of published literature is accomplished to validity this model.

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Theoretical Studies on the Nucleophilic Substitution Reactions of 1-Phenylethyl Chlorides

  • 김왕기;류왕선;박형연;한인석;김창곤;이익준
    • Bulletin of the Korean Chemical Society
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    • v.18 no.8
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    • pp.868-873
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    • 1997
  • Nucleophilic substitution reactions of 1-phenylethyl chlorides (1-PEC; YC6H4CH(CH3)Cl) with phenoxides (XC6H4O-) and thiophenoxides (XC6H4S-) are investigated theoretically using the PM3 method. The Bronsted α and β values are greater for the phenoxides indicating a more advanced reaction in the transition state (TS) than for the thiophenoxides. This is supported by a greater magnitude of ρX (- 6.4 ∼ - 7.4) and ρXY (- 0.76) for the phenoxides than for the thiophenoxides (ρX = - 3.6 ∼ - 4.4 and ρXY = - 0.60). The percentage bond order changes, %Δn≠, suggest that the extents of bond making and breaking are similar for the phenoxides and hence the TS is symmetrical, but bond making is somewhat greater than bond cleavage for the thiophenoxides indicating an unsymmetrical TS. The reactions in the gas phase for both nucleophile series proceed by a SN2 mechanism with a tight TS and negative charge development on the reaction center carbon, Cα. The reactions in water investigated with model systems of benzyl and 1-phenylethyl chlorides using the Cramer-Truhlar solvation model (PM3-SM3) indicate that the reactions of 1-PEC are far more complex due to enhanced stabilization of the carbocation by the methyl substitution for a benzylic hydrogen.

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Facile Synthesis of Dendritic Benzyl Chlorides from Their Alcohols with Methanesulfonyl Chloride/$Et_3N$ (덴드리틱 벤질 클로라이드의 효율적인 합성)

  • Lee, Jae-Wook;Han, Seung-Choul;Kim, Hee-Joo;Kim, Jung-Hwan;Lee, Un-Yup;Kim, Byoung-Ki;Sung, Sae-Reum;Kang, Hwa-Shin;Kim, Ji-Hyeon;Huh, Do-Sung
    • Polymer Korea
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    • v.31 no.5
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    • pp.417-421
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    • 2007
  • A successful rapid synthesis of dendritic benzyl chlorides from dendritic benzyl alcohols using methanesulfonyl chloride/$Et_3N$ as activating agents was described. In this method, each dendritic benzyl chloride can be prepared in one pot: no isolation of intermediate mesylated dendrons is required. The key steps in the syntheses of dendritic benzyl chlorides were the mesylation of the hydroxymethyl group followed by the chlorination by in-situ generated triethylammonium chloride.

Density Functional Theory Study of Silicon Chlorides for Atomic Layer Deposition of Silicon Nitride Thin Films

  • Yusup, Luchana L.;Woo, Sung-Joo;Park, Jae-Min;Lee, Won-Jun
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.211.1-211.1
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    • 2014
  • Recently, the scaling of conventional planar NAND flash devices is facing its limits by decreasing numbers of electron stored in the floating gate and increasing difficulties in patterning. Three-dimensional vertical NAND devices have been proposed to overcome these issues. Atomic layer deposition (ALD) is the most promising method to deposit charge trap layer of vertical NAND devices, SiN, with excellent quality due to not only its self-limiting growth characteristics but also low process temperature. ALD of silicon nitride were studied using NH3 and silicon chloride precursors, such as SiCl4[1], SiH2Cl2[2], Si2Cl6[3], and Si3Cl8. However, the reaction mechanism of ALD silicon nitride process was rarely reported. In the present study, we used density functional theory (DFT) method to calculate the reaction of silicon chloride precursors with a silicon nitride surface. DFT is a quantum mechanical modeling method to investigate the electronic structure of many-body systems, in particular atoms, molecules, and the condensed phases. The bond dissociation energy of each precursor was calculated and compared with each other. The different reactivities of silicon chlorides precursors were discussed using the calculated results.

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Chloride diffusion in concrete associated with single, dual and multi cation types

  • Song, Zijian;Jiang, Linhua;Zhang, Ziming
    • Computers and Concrete
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    • v.17 no.1
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    • pp.53-66
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    • 2016
  • Currently, most of the investigations on chloride diffusion were based on the experiments and simulations concerning single cation type chlorides. Chloride diffusion associated with dual or multi cation types was rarely studied. In this paper, several groups of diffusion experiments are conducted using chloride solutions containing single, dual and multi cation types. A multi-ionic model is also proposed to simulate the chloride diffusion behavior in the experimental tests. The MATLAB software is used to numerically solve the nonlinear PDEs in the multi-ionic model. The experimental and simulated results show that the chloride diffusion behavior associated with different cation types is significantly different. When the single cation type chlorides are adopted, it is found that the bound rates of chloride ions combined with divalent cations are greater than those combined with monovalent cations. When the dual/multi cation type chlorides are adopted, the chloride bound rates increase with the $Ca^{2+}/Mg^{2+}$ percentage in the source solutions. This evidence indicates that the divalent cations would markedly enhance the chloride binding capacity and reduce the chloride diffusivity. Moreover, on the basis of the analysis, it is also found that the complicated cation types in source solutions are beneficial to reducing the chloride diffusivity.

Effect of Coating Materials for Steel on the Threshold of Corrosive Amount of Airborne Chlorides and the Evaluation of Their Corrosion Speeds (강재마감별 부식개시 임계 비래염분량 및 부식속도 평가)

  • Cho, Gyu-Hwan;Lim, Myung-Hyun;Park, Dong-Cheon
    • Journal of the Korea Institute of Building Construction
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    • v.15 no.2
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    • pp.143-151
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    • 2015
  • Many studies have investigated the airborne chlorides that can weaken the overall durability of the concrete structures due to the corrosion of steel materials, but most of the studies have aimed to examine weathering by exposing various construction materials to the actual oceanic environment. However, with the exposure test, it was difficult to find the threshold of precise corrosive amount of airborne chlorides due to diverse deteriorating environmental factors such as ultraviolet ray, acid rain, floating material from industrial pollution as well as airborne chlorides. Therefore, in this study, an airborne chloride simulator was set up, in oder to conduct a corrosion accelerating test for steels coated by five different finishing materials. As results, it was found that the corrosion began to be observed at $0.58{\sim}0.73mg/dm^2$ for no-coated steel, at $7.89{\sim}8.46mg/dm^2$for urethane-coated steel, at $57.95{\sim}69.48mg/dm^2$ for red lead-coated steel, and at $80.73{\sim}89.35mg/dm^2$ for stainless-coated steel, respectively. Hence, these specific data can be considered as the threshold ranges of corrosion for each coating material for steel.

Investigation of Water-Washing Process Parameters for Removal of Alkali Metals and Chlorides from Electric Arc Furnace Dust (EAFD) (전기 제강로 분진(EAFD)으로부터 알칼리 금속 및 염화물 제거를 위한 수 세척 공정 운영인자 조사)

  • Lee, Han Saem;Park, Da so mi;Ha, Jong Gil;Shin, Hyun Sang
    • Journal of Korean Society of Environmental Engineers
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    • v.39 no.11
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    • pp.626-633
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    • 2017
  • The present study investigated the effect of a water-washing process, which is part of the acid hydrometallurgical process for recovery of high purity of zinc, on the removal of alkali metals and chlorides (Na, K, Ca, Cl) from Electric arc furnace dust (EAFD). Two EAFD samples with different properties were characterized by particle size, XRD and element analysis, and their washing efficiencies (%) on alkali metals and chlorides were compared according to pH, washing time, liquid to solid (L/S) ratio and number of washings. The results show that the alkali metals and chlorides could be effectively removed by the washing (at L/S ration of 3 for more than 30 min., pH 10~11) while minimizing loss of zinc (<0.1%), in which the washing efficiency was Na-78%, K-76%, Cl >99%, respectively. Na and K could be removed up to 97% and 89% respectively by 3 times of repeated washings. With increased sample volume (10 times) of the mixed (1:1, w/w) sample with two types of EAFD, it was confirmed that the pH(10~11) can be used as the main process control parameter for the washing of the alkali metals regardless of EAFD properties.