• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.740-746
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• 2009

In the present study, the drowning-out crystallization of L(+)-calcium lactate was investigated in order to develop the crystallization separation process. The crystallization of the calcium lactate was induced by injecting the alcoholic anti-solvent into the aqueous solution of calcium lactate and the control of the calcium lactate crystal size during the crystallization was primarily investigated under the consideration of the anti-solvent species, anti-solvent composition and agitation speed as the key operating factors. Alcohols of methanol, ethanol, n-propanol and i-propanol were used as the anti-solvent for the drowning-out crystallization. Prior to the crystallization experiment, the solubility of calcium lactate in the water-alcohol mixture was measured along with the variation of the alcohol species and composition, which was necessary to estimate the supersaturation level of the crystallization. By the drowning-out crystallization, the calcium lactate crystals of the fabric shape were obtained. Using the ethanol as the antisolvent, the fabric crystals close to the needle shape were produced. However, the hairy crystals were obtained by using the propanol as the anti-solvent. Due to such morphological features, the crystals was highly apt to form the aggregates. The aggregation of the crystals was intensified as increasing the alcohol fraction in the water-alcohol mixture. Meanwhile, the agitation caused the breakage of crystals, resulting in the decrease of the crystal size. Therefore, the crystal size in the crystallization was predominantly determined by the competition between the crystal aggregation and breakage.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.730-736
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• 2015

Cyclotrimethylene trinitramine (RDX) is a high explosive commonly used for military applications. Submicronization of RDX particles has been a critical issue in order to alleviate the unintended and accidental stimuli toward safer and more powerful performances. The purpose of this study is to optimize experimental variables for drowning-out crystallization applied to produce submicron RDX particles. Effects of RDX concentration, anti-solvent temperature and anti-solvent mass were analyzed by the central composite rotatable design. The adjusted determination coefficient of regression model was calculated to be 0.9984 having the p-value less than 0.01. Response surface plots based on the central composite rotatable design determined the optimum conditions such as RDX concentration of 3 wt%, anti-solvent temperature of $0.2^{\circ}C$ and anti-solvent mass of 266 g. The optimum and experimental diameters of RDX particles were measured to be $0.53{\mu}m$ and $0.53{\mu}m$, respectively. The regression model satisfactorily predicts the average diameter of RDX particles prepared by drowning-out crystallization. Structure of RDX crystals was found to be ${\alpha}$-form by X-ray diffraction analysis and FT-IR spectroscopy.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.158-164
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• 2016

Spherical DADNE/AP (1,1-diamino-2,2-dinitroethylen/ammonium perchlorate) energetic composites were produced by drowning-out/agglomeration (D/A). The agglomeration of DADNE with AP particles was found to be affected by the amount of the bridging liquid, stirring velocity and residence time. The composites appeared to grow dramatically with the amount of bridging liquid which triggers agglomeration. As the stirring velocity and the residence time increased, the size of composites increased and then tended to decrease. Thermal gravimetric analysis showed that the addition of DADNE activates the low temperature decomposition (LTD) of AP. For the neat AP, the only about 30 wt% of AP was found to decompose at the LTD. On the other hand, it was found that 70 wt% of AP decomposed when DADNE was added by physical mixing and 90 wt% of AP decomposed when the DADNE/AP composites were prepared by the D/A method.

• KSBB Journal
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• v.21 no.3
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• pp.199-203
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• 2006

Precipitation and reactive distillation were employed to recover lactic acid from fermentation broth. Lime was initially added to fermentation broth in order to convert soluble lactic acid to an insoluble calcium lactate form. Drowning-out crystallization was used to decrease the solubility of calcium lactate by adding ethanol as a co-precipitant. In the ideal solution of organic acids as well as fermentation broth, precipitation experiments were performed with varying amounts of ethanol. Precipitation process was followed by reactive distillation. Carboxylate salts formed in the previous precipitation process were mixed with carbon dioxide and triethylamine to precipitate as calcium carbonate. The remaining liquid was distilled for 1 hr at different temperatures. Triethylamine and water were recovered from the top of the distiller, while organic acids, inducing lactic acid as a main component remained in feeding bottle. The yield of recovered lactic acid was 67.5% with the purity of 99.7%.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.4
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• pp.69-76
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• 2015

Recently, environmental sustainability of the transitional explosives and propellants is an issue of growing importance in energetic materials. For examples, ammonium perchlorate(AP) as an solid propellants oxidizer could create a poisonous gas and atmospheric pollutions, such as HCl. Among the several oxidizers, hydrazinium nitroformate(HNF) is an effective candidate substance for eco-friendly oxidizer, which has high density, pressure index, and less smog generating property during combustion for the Divert and Attitude Control System(DACS). This study was confirmed a synthesis through various conditions, was performed for the essential data of solubility the crystallization process. Also, crystallization process such as cooling, drowning-out and sonication were performed.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.214-220
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• 2017

The spherical Al/RDX/AP composites with an average size of $550{\mu}m$ were successfully prepared by drowning-out/agglomeration (D/A) process. The surface morphology and dispersion of Al particles of those composites were investigated using SEM and EDS (energy dispersive spectrometry). As a result of thermal analysis, the onset temperature of thermal decomposition of the Al/RDX/AP composites by the D/A process was found to decrease about $50^{\circ}C$ and their thermal stability was shown to be relatively enhanced due to the increase of activation energy compared to those of using the physical mixing method. In the first decomposition region of AP, Prout-Tompkins model was shown to describe well the thermal decomposition of both composites by the physical mixing and D/A process. On the other hand, in the second decomposition region of AP, the decomposition mechanisms of composites by the physical mixing and D/A process were explained by the zero-order and contracting volume model, respectively.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.178-185
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• 2019

Three spherical quaternary composites composed of metal/metal oxide/high explosive/oxidizer were prepared by a crystallization/agglomeration process. From the characteristics of composites by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the shortening of the decomposition zone of high explosives in the quaternary composite was observed, which may be attributed to the autocatalytic reaction caused by $ClO_2$ or HCl which are ammonium perchlorate (AP) degradation products. The activation energy analysis showed that the activation energy abruptly decreases at the end of the decomposition zone of high explosives, and it was considered to be caused by $HNO_2$ which is common in decomposition products of high explosives. The activation energy predicted from complex pyrolysis results by the distributed activation energy model (DAEM) showed much better in accuracy than those by model-fitting methods such as Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa models.