• Applied Chemistry for Engineering
• /
• v.7 no.3
• /
• pp.453-463
• /
• 1996

The chlorination of reagent PbS and natural ore galena with $NH_4Cl$ was investigated to find a new extraction metallurgical process of lead. The proper conditions for the chlorination of galena were that reaction temperature ; $425^{\circ}C$, $NH_4Cl$ weight ratio to galena ; 4.0 and reaction time ; 2hrs. Under these conditions, PbS was successfully chlorinated to $PbCl_2$ and the conversion was 90%. And also $NH_4Cl$ was effectively decomposed and was separated $NH_3$ and HCl. HCl was a chlorinating agent and 90% of $NH_3$ was recovered through this chlorination reaction.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.6
• /
• pp.646-653
• /
• 2003

Investigations were made on the population structure, sex ratio, growth, and recruitment patterns of Leptochela sydniensis in the southwestern coastal areas of Korea, between May 2000 and December 2001. Spawning period, fecundity, brood loss, reproductive output, and size at sexual maturity also were examined. The results of the sex ratio showed that females were more numerous than males during the overall study period. Parameters of growth were estimated using the modified von Bertalanffy growth function (VBGF) model incorporating seasonal variation into growth. Females grew somewhat faster and reached a larger size than males $(L\infty=12.80\;mm\;CL\;and\;K=0.70\;yr^{-1}\;or\;females,\and\;L\infty=12.08\;mm\;CL\;and\;K=0.69\;yr^{-1}$ for males). The structure of recruitment patterns obtained by the FiSAT program indicated one normally distributed group. Based on the occurrence of ovigerous females and the gonadosomatic index (GSI), the main spawning season was from June to August. Analysis of covariance indicated that brood loss was not observed during the incubation period. The size at which $50\%$ of females are mature is estimated as 5.48 mm CL.

• Korean Chemical Engineering Research
• /
• v.59 no.3
• /
• pp.399-409
• /
• 2021

In order to utilize dolomite as a calcium/magnesium compound material, it was prepared highly reactive calcined dolomite(CaO·MgO) using a microwave kiln (950 ℃, 60 min). The experiment was performed according to the standard of the hydration test (ASTM C 110) and hydration reactivity was analyzed as medium reactivity (max 74.1 ℃, 5 min). Experiments were performed with calcined dolomite and salt (MgCl₂·6H₂O) (a) 1:1, (b) 1:1.5, and (c) 1:2 wt% based on the hydration reaction of calcined dolomite. The result of X-ray diffraction analysis confirmed that MgO of calcined dolomite increased to Mg(OH)₂ as the salt addition ratio increased. After the separating reaction, calcium was stirred at 80 ℃, 24 hr that produced CaCl₂ of white crystal. XRD results, it was confirmed calcium chloride hydrate (CaCl₂·(H₂O)x) and CaO of calcined dolomite and salt additional reaction was separated into CaCl₂. And it was synthesized with Ca(OH)₂ 99 wt% by NaOH adding reaction to the CaCl₂ solution, and the synthesized Ca(OH)₂ was manufactured CaO through the heat treatment process. In order to prepare calcium carbonate, CaCO₃ was synthesized by adding Na₂CO₃ to CaCl₂ solution, and the shape was analyzed in cubic form with a purity of 99 wt%.

• Proceedings of the Korean Institute of Resources Recycling Conference
• /
• 2004.05a
• /
• pp.218-226
• /
• 2004

Solvent extraction and stripping experiments were conducted to separate iron from a spent $FeCl_3$ etching solution containing nickel. In the extraction, PC88A, MIBK and Alamine336 were tested as an extractant in various diluents. Alamine336 salt in toluene led to the highest extraction percentage of iron. Stripping percentage of iron from the loaded organic by Alamine336 increased with decreasing HCl conentration of stripping solution and with increasing volume ratio of aqueous to organic. In the operation of bench scale mixer-settler, 7 extraction stage with 1.0M Alamine336 salt in toluene and 10 stripping stage with 0.01M HCl solution resulted in a stripped solution with 133g/L of iron and in a raffinate with most of nickel together with a small amount of iron when the flow rate ratio of organic to aqueous was 7.

• Journal of the Korean Society of Safety
• /
• v.13 no.2
• /
• pp.109-115
• /
• 1998

Tri-cresyl phosphate(TCP) was synthesized by reaction of phosphorus chloride with mixed cresol(mixture of m-cresol, p-cresol, and others) in the presence of $AlCl_3$. Some of unwanted products and unreactants colored TCP. In order to separate TCP from these, vaccume distillation was carried twice, but colorless TCP could not be producted. Separation of unwanted materials by 2% NaOH solution was introduced before first and second distillation and optimal separation conditions such as NaOH concentration, mixing volume ratio, mixing time, and rpm were investigated for new batch separation and production of colorless TCP Optimal conditions were 2% NaOH solution, 35% mixing volume ratio of 2% NaOH solution, 1.5 hours of mixing time, and 20 rpm.

• Korean Journal of Materials Research
• /
• v.31 no.12
• /
• pp.704-709
• /
• 2021

In the flux used in the batch galvanizing process, the effect of the component ratio of NH₄Cl to ZnCl₂ on the microstructure, coating adhesion, and corrosion resistance of Zn-Mg-Al ternary alloy-coated steel is evaluated. Many defects such as cracks and bare spots are formed inside the Zn-Mg-Al coating layer during treatment with the flux composition generally used for Zn coating. Deterioration of the coating property is due to the formation of AlCl_x mixture generated by the reaction of Al element and chloride in the flux. The coatability of the Zn-Mg-Al alloy coating is improved by increasing the content of ZnCl₂ in the flux to reduce the amount of chlorine reacting with Al while maintaining the flux effect and the coating adhesion is improved as the component ratio of NH₄Cl to ZnCl₂ decreases. Zn-Mg-Al alloy-coated steel products treated with the optimized flux composition of NH₄Cl·3ZnCl₂ show superior corrosion resistance compared to Zn-coated steel products, even with a coating weight of 60 %.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.607-611
• /
• 1991

The stereochemical ratio cis and trans isomer of the hydration reaction of trans-$[Co(en)(tmd)Cl_2]^+$ complex ion were studied with varing temperature by the spectrophotometric method. It was observed that the ratio of cis-isomer was about 30%, and the intermediate was rearranged. And in order to investigate this mechanism more clearly, stability energy profile, interaction diagram and orbital correlation diagram were calculated by the EHT method. By the calculation, the mechanism of cis-isomer was in good agreement with the experimental results, and it was estimated that the hydration reaction was carried through some distorted square pyramid (sp).

• Membrane Journal
• /
• v.28 no.4
• /
• pp.271-278
• /
• 2018

In this study, the carbon electrodes using activated carbon fibers (ACFs) were prepared for the capacitive deionization process. The Polyvinylidene fluoride (PVDF) was used as the binder and the mixed ACFs with proper solvent was cast on the commercial graphite sheets to prepare the carbon electrodes. At this moment, the different particle sizes of ACFs were applied and the mixing ratio of solvent, PVDF and ACFs, 80 : 2 : 18 and 80 : 5 : 15, were used for the electrode preparation. Then their salt removal efficiencies were characterized under the various operating conditions, adsorption potential and time, desorption potential and time, concentration of feed NaCl solution and flow rate as well. Typically, the salt removal efficiency of 53.6% were obtained at the particle size below $32{\mu}m$, mixing ratio 80 : 2 : 18, adsorption 1.2 V and 3 min, desorption -0.1V and 1 min, and 15 mL/min flow rate of NaCl 100 mg/L.

• Applied Chemistry for Engineering
• /
• v.28 no.6
• /
• pp.663-669
• /
• 2017

Activated carbons were prepared from waste citrus peels using KOH, NaOH, and $ZnCl_2$ as activating chemicals. They were prepared at optimal conditions including the chemical ratio of 300%, activation time of 1.5h, and activation temperature of $900^{\circ}C$ for KOH, $700^{\circ}C$ for NaOH, and $600^{\circ}C$ for $ZnCl_2$, which were named as ACK, ACN, and ACZ, respectively. Using the activated carbons, their adsorption characteristics for three target gases such as acetone, benzene, and methylmercaptan (MM) were carried out in a batch reactor. The adsorption behavior of activated carbons for three target gases followed the Freundlich model better than the Langmuir. And the experimental kinetic data followed a pseudo-second-order kinetic model more than pseudo-first-order one. Following the intraparticle diffusion model suggested that the external mass transfer and particle diffusion were occurred simultaneously during the adsorption process.

• Applied Chemistry for Engineering
• /
• v.9 no.1
• /
• pp.82-88
• /
• 1998

In an effort to obtain high efficiency in air cooled absorption heat pump, a new working fluid has developed with the addition of $LiNO_3$ and LiCl to the conventional solution of $LiBr-H_2O$. The solubility and vapor pressure of the multicomponent salts solution developed in this work were measured and compared with the results of $LiBr-H_2O$ solution. It was observed that there exists an optimal molar ratio of the inorganic salts in terms of solubility. The molar ratio of LiBr, $LiNO_3$ and LiCl was found to be about 5:1 in the $LiBr-LiNO_3$ mixture, and in the case of $LiBr-LiNO_3-LiCl$ mixture, the molar ratio of LiBr, $LiNO_3$ and LiCl was found to be around 5:1:2. The vapor pressure of the multicomponent salts solution of the optimal molar ratio was increased with adding $LiNO_3$, while decreased with adding LiCl.