• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.1
• /
• pp.1-8
• /
• 2012

Numerical analysis has been carried out to investigate the fully developed flow and heat transfer characteristics of a plate heat exchanger. Multi-cell models with an inlet part and outlet part are used to perform the numerical simulation. The plate heat exchanger is characterized by a chevron angle of $20^{\circ}$ and a P/H ratio of 2.0~4.0. The working fluid is water and the Reynolds numbers range from 300 to 1,500. The correlation is given in the form of $f=CRe^m$ for the friction factor and $j=CRe^m$ for the Colburn factor. It is found that the fully developed flow starts from the third cell and the Nusselt number increases with decreasing P/H ratios.

• Resources Recycling
• /
• v.15 no.2 s.70
• /
• pp.45-49
• /
• 2006

The removal of copper ion from aqueous solution by adsorption with bone char that made from spent pig bone has been studied. This paper was studied the effects of bone char dosage and pH. The optimal results show that bone char adsorbs about 96.5 percent of copper ion in aqueous solution containing 50 mg/L as initial concentration at pH 5.0 when the bone char of 5g/L is used for 30 hours. Increase in the initial pH of the copper solution resulted in an increase in the copper ion uptake per weight of the sorbent Freundlich isotherm model was found to be applicable for the experimental data of $Cu^{2+}$.

• Korean Journal of Soil Science and Fertilizer
• /
• v.34 no.3
• /
• pp.213-236
• /
• 2001

The ionic composition of soil solution is related to a nutrient uptake by plant. Many models for estimating ionic composition of solution have been developed, and most of them have been used for calculating a content of mineral and ionic species in a geochemical point of view. An approximation model considering both cation and anion in soil solution was developed. Variables such as pH, Eh, EC, cations(K, Ca, Mg. Na, Fe, Mn, Al, $NH_4{^+}$), anions(Si, S, P, CY, $NO_3{^-}$, $HCO_3{^-}$ and chemical equilibria of ionic species in soil solution were input into Excel sheet. The activities of soluble ion, ionpairs and complexes of input element were estimated by Newton-Raphson method using conditional equilibrium constant calculated by Davies equation and special models. Equilibrium contents of insoluble minerals and complexes were also calculated.

• Clean Technology
• /
• v.23 no.4
• /
• pp.413-420
• /
• 2017

The batch experiments and response surface methodology (RSM) have been applied to the investigation of the Cs adsorption with zeolite X synthesized using coal fly ash generated from the thermal power plant. Regression equation formulated for Cs adsorption was represented as a function of response variables. The model was highly relevant because the decision coefficient ($r^2$) was 0.9630. It was confirmed from the statistical results that the removal efficiency of Cs was affected by the order of experimental factors as pH > Cs concentration > temperature. The adsorption kinetics were more accurately represented by a pseudo second-order model. The maximum adsorption capacity calculated from the Langmuir isotherm model was $151.52mg\;g^{-1}$ at 293 K. Also, according to the thermodynamic parameters calculated from Vant Hoff equation, it could be confirmed that the adsorption reaction was an endothermic reaction and a spontaneous process.

• Korean Journal of Crystallography
• /
• v.10 no.2
• /
• pp.125-129
• /
• 1999

X-선 회절법을 이용하여 1-(3 Carbamoyl-3,3-diphenylpropyl)-1-methylhexahydro-1H-azepinium iodide[이하: DIP]의 분자 및 결정구조를 규명하였다. 이 결정의 분자식은 C23H31N2O·I, 결정계는 Monoclinic이며 공간군은 P21이다. 단위포 상수는 a =8.937(1) Å, b=19.522(2) Å, c=6.485(2) Å이며, β= 105.18(2)°, V=1091.9(6) Å3, T=293(2)K, Z=2, Dc=1.45 Mgm-3이다. 회절반점들의 세기는 Enarf-Nonius CAD-4 diffractometer로 얻었으며 Mo Katjs(λ=0.71073 Å)을 사용하였다. 분자구조는 직접법으로 개략적인 분자모델을 설정하고, Fo>4σ(Fo)인 4112개의 독립 회절 데이터에 대하여 최소자승법으로 정밀화하여 최종 신뢰도 값 R=5.23%인 최종적인 분자모형을 구하였다.

• Journal of the Mineralogical Society of Korea
• /
• v.22 no.3
• /
• pp.177-189
• /
• 2009

Iron (oxyhydr)oxides commonly form as secondary minerals of high reactivity and large surface area resulting from alteration and weathering of primary minerals, and they are efficient sorbents for inorganic and organic contaminants. Accordingly, they have a great potential in industrial applications and are also of substantial interest in environmental sciences. Goethite (${\alpha}$-FeOOH) is one of the most ubiquitous and stable forms of iron (oxyhydr)oxides in terrestrial soils, sediments, and ore deposits, as well as a common weathering product in rocks of all types. This study focused on adsorption reaction as a main mechanism in scavenging arsenic using goethite. Goethite was synthesized in the laboratory to get high purity, and a variety of mineralogical and physicochemical features of goethite were measured and related to adsorption characteristics of arsenic. To compare differences in adsorption reactions between arsenic species, in addition, a variety of experiments to acquire adsorption isotherm, adsorption edges, and adsorption kinetics were accomplished. The point of zero charge (PZC) of the laboratory-synthesized goethite was measured to be 7.6, which value seems to be relatively higher, compared to those of other iron (oxyhydr)oxides. Its specific surface area appeared to be $29.2\;m^2/g$ and it is relatively smaller than those of other (oxyhydr)oxides. As a result, it was speculated that goethite shows a smaller adsorption capacity. It is likely that the affinity of goethite is much more larger for As(III) (arsenite) than for As(V) (arsenate), because As(III) was observed to be much more adsorbed on goethite than As(V) in equivalent pH conditions. When the adsorption of each arsenic species onto goethite was characterized in various of pH, the adsorption of As(III) was largest in neutral pH range (7.0~9.0) and decreased in both acidic and alkaline pH conditions. In the case of As(V), the adsorption appeared to be highest in the lowest pH condition, and then decreased with an increase of pH. This peculiarity of arsenic adsorption onto goethite might be caused by macroscopic electrostatic interactions due to variation in chemical speciation of arsenic and surface charge of goethite, and also it is significantly affected by change in pH. Parabolic diffusion model was adequate to effectively evaluate arsenic adsorption on goethite, and the regression results show that the kinetic constant of As(V) is larger than that of As(III).

• Clean Technology
• /
• v.27 no.3
• /
• pp.261-268
• /
• 2021

Equilibrium, kinetics, and thermodynamics of adsorption of acid black 1 (AB1) by coal-based granular activated carbon (CGAC) were investigated with the adsorption variables of initial concentration of dye, contact time, temperature, and pH. The adsorption reaction of AB1 by activated carbon was caused by electrostatic attraction between the surface (H⁺) of activated carbon and the sulfite ions (SO₃^-) and nitrite ions (NO₂^-) possessed by AB1, and the degree of reaction was highest at pH 3 (97.7%). The isothermal data of AB1 were best fitted with Freundlich isotherm model. From the calculated separation factor (1/n) of Freundlich, it was confirmed that adsorption of AB1 by activated carbon could be very effective. The heat of adsorption in the Temkin model suggested a physical adsorption process (< 20 J mol^-1). The kinetic experiment favored the pseudo second order model, and the equilibrium adsorption amount estimated from the model agreed to that given by the experiments (error < 9.73% ). Intraparticle diffusion was a rate controlling step in this adsorption process. From the activation energy and enthalpy change, it was confirmed that the adsorption reaction is an endothermic reaction proceeding with physical adsorption. The entropy change was positive because of an active reaction at the solid-liquid interface during adsorption of AB1 on the activated carbon surface. The free energy change indicated that the spontaneity of the adsorption reaction increased as the temperature increased.

• Journal of Environmental Science International
• /
• v.13 no.3
• /
• pp.297-300
• /
• 2004

We have been proposed model equation which is able to predict the trihalomethane producing concentration formation, that is one of byproduct, in the water treatment processes. In proposed model, the effects of trihalomethane factors like chlorine contact time, pH, temperature, TOC and UV-254 are considered. The concentration of the trihalomethane produced is proportion to the contact with chlorine, pH of water, temperature of water TOC and UV-254, respectively. This proposed model could be predicted the formed concentration of trihalomethanes by trihalomethane factors.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.322-324
• /
• 1999

This paper presents the methodology of measuring the 22.9[kV] bus load characteristics for verifying the bus load model developed with equivalent load aggregation of load components, and the analysis of 22.9[kV] load data.

• Applied Chemistry for Engineering
• /
• v.30 no.4
• /
• pp.421-428
• /
• 2019

This paper describes a methode to extract yellow pigment from curcuma and turmeric containing natural color curcumin whose target color indexes of L, a, and b were 87.0 7.43, and 88.2, respectively. The pH range and extraction temperature used for the reaction surface analysis method were from pH 3 to pH 7 and between 40 and $70^{\circ}C$, respectively for both natural products. A central synthesis planning model combined with the method was used to obtain optimal extraction conditions to produce the color close to target. Results and regression equations show that the color space and difference of curcuma and turmeric have the greatest influence on the value. In the case of curcuma, the optimum conditions to satisfy all of the response theoretical values of color coordinates of L (74.67), a (5.69), and b (70.08) were at the pH and temperature of 3.43 and $54.8^{\circ}C$, respectively. The experimentally obtained L, a, and b, values under optimal conditions were 72.92, 5.32, and 72.17, respectively. For the case of turmeric, theoretical numerical color coordinates of L, a, and b, under the pH of 5.22 and temperature of $50.4^{\circ}C$ were 82.02, 7.43, and 72.86 respectively. Whereas, the experiment results were L (81.85), a (5.39), and b (71.58). Both cases showed an error range within 1%. Therefore, it is possible to obtain a low error rate when applying the central synthesis planning model to the reaction surface analysis method as an optimization process of the dye extraction of natural raw materials.