• Korean Chemical Engineering Research
• /
• v.47 no.3
• /
• pp.373-379
• /
• 2009

Cesium carbonate was used as an adsorbent to capture carbon dioxide from gaseous stream of carbon dioxide, nitrogen, and moisture in a fixed-bed to obtain the breakthrough data of $CO_2$. The deactivation model in the non-catalytic heterogeneous reaction systems is used to analyze the sorption kinetics among carbon dioxide, carbonate, and moisture using the experimental breakthrough data. The experimental breakthrough data are fitted very well to the deactivation model than the adsorption isotherm models in the literature.

• Advances in environmental research
• /
• v.1 no.2
• /
• pp.167-179
• /
• 2012

Pistachio shell (Pistacia vera) (PS), a low-cost material, has been utilized for the removal of the Cr(VI) ions after treatment with citric acid. Batch experimental steps were applied to obtain Cr(VI) ion adsorption details for the equilibrium between Cr(VI) and modified pistachio shell (MPS). The influences of contact time, pH, adsorbent dose and initial chromium concentration on the adsorption performance of MPS was investigated in detail. The results displayed that adsorption of Cr(VI) by MPS reached to equilibrium after 2 h and after that a little change of Cr(VI) removal efficiency was observed. The sorption percent is higher at lower pH and lower chromium concentration. Two possible mechanisms for reduction of Cr(VI) to Cr(III) can be suggested in Cr(VI) removal. In the first mechanism, Cr(VI) is reduced to Cr(III) by surface electron-donor groups of the adsorbent and the reduced Cr(III) forms complexes with adsorbent or remains in the solution. This Cr(III) is not adsorbed by adsorbent at pH 1.8. But in second mechanism, the adsorption-coupled reduction of Cr(VI) to Cr(III) occurred on the adsorbent sites. The equilibrium sorption capacity of Cr(VI) ion after 2 h was 64.35 mg/g for MPS.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.1
• /
• pp.27-36
• /
• 2007

Milled Korean pine (Pinus densiflora) wood was used to evaluate its adsorption capacity of Cu(II) ions from aqueous solution by running a series of batch experiments. Prior to the tests, the milled woods were pretreated with 1N NaOH, 1N $NHO_3$, and distilled water, respectively, to examine the effect of pretreatment. Within the tested pH range in this study between 3 and 6, copper adsorption efficiency of NaOH-treated wood(96~99%) was superior than $NHO_3$-treated wood(19~31%) and distilled water-treated wood(18~35%). Adsorption behavior of copper onto both raw and $NHO_3$-treated woods was mainly attributed to interaction with carboxylic acid group. For NaOH-treated wood, carboxylate ion produced by hydrolysis was a major functional group responsible for Cu sorption. NaOH treatment of wood changed the ester and carboxylic acid groups into carboxylate group, whereas $NHO_3$ treatment did not affect the production of functional groups which could bind copper. A pseudo second-order kinetic model fitted well for the sorption of copper ion onto NaOH-treated wood. A batch isotherm test using NaOH-treated wood showed that equilibrium sorption data were better represented by the Langmuir model than the Freundlich model.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.1
• /
• pp.113-119
• /
• 2009

The feasibility of using cork oak bark for phosphorus removal from wastewater was evaluated in this study. Recently, development of more cost-effective media while maintaining high efficiency in pollutants removal has received concern. Barks have a negative surface charge and, hence, tend to show a high affinity to bind cations, and they need to undergo chemical modification to increase their adsorption capacity of anions. Bark was hydrolyzed by HCl solution and it received modification using an aqueous solution of high molecular weight polyethylenimine(PEI). Surface modification with HCl and PEI resulted in a decrease of specific surface area of the bark from $1.932 m^2/g$ to $1.094 m^2/g$. The adsorption experiments were carried out in batch tests and the data were fitted to the Langmuir isotherm and Freundlich isotherm equations. Phosphate removal rate was higher at the lower solution pH possibly due to the form of phosphate ion in solution. For the initial phosphate concentration of 10 mg/L, maximum adsorption was 20.88 mg P/g at pH 3 and 12.02 mg P/g at pH 5. Mechanism of phosphorus sorption onto the HCl-PEI bark was examined through FT-IR spectrometer. Ion exchange between $NH^+$ and $H_2PO_4{^-}$ appeared to be a key mechanism of phosphate adsorption onto the HCl-PEI bark surface.

• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.6
• /
• pp.369-373
• /
• 2008

Special concern has been given to the elevated arsenic content in soils because of its high mobility and toxicity. Layered double hydroxide (LDH) which has a high anionic exchange capacity is another potential anion adsorbent for toxic anions such as arsenic, chromate and selenium etc. The uptake of arsenate from aqueous solutions by the calcined Mg-Al LDH has been investigated. The sorption capacity was about 530 mmol/kg. Sorption isotherm was defined as L-type in which arsenate was removed by LDH through anion uptake reaction. Arsenate sorption by the calcined Mg-Al LDH was occurred by reconstruction of LDH's framework. Competitive adsorption revealed that Mg-Al LDH had higher selectivity for arsenate than for sulfate. These results strongly suggest that calcined Mg-Al LDH has a promising potential for efficient removal of toxic metal oxides like arsenates from aqueous environments.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.5
• /
• pp.521-525
• /
• 2001

Screening tests of different fucoidan fractions from Sporophylls of Undazia pinnatifida, Laminaria religiosa, Hizikia fusiforme and Sagassum fulvellum revealed that the highest biosorptive Pb and Cd uptake fraction was Undaria finnatifida Fr-3.0 prepared by dissolving the precipitated complex (crude fucoidan and cetylpyridinum chloride) with 3.0 M $CaCl_2$ solution, The Pb and Cd uptake by Undaria finnatifida Fr-3.0 was quantitatively evaluated using sorption isotherms and Langmuir sorption model. The Pb and Cd uptake by Undaria finnatifida Fr-3.0 increased with increasing pH values at high equilibrium residual concentration. The highest experimentally observed Pb and Cd uptake value in the sorption isotherm for pH 5.5 were 94 mg/g (at $C_f=164\;mg/L$) and 64 mg/g (at $C_f=197\;mg/L$) respectively, and $q_{max}$ of Pb and Cd calculated by Langmuir sorption model were 178 mg/g and 122 mg/g, respectively. In the low equilibrium concentration range, up to 20 mg/L, the Pb uptake remained unchanged in the presence of Cd, but decreased at higher equilibrium concentration range.

• Korean Journal of Food Science and Technology
• /
• v.17 no.2
• /
• pp.101-106
• /
• 1985

Dried soymilk residue(SMR) which was prepared by washing with ethanol and acetone, followed by drying at $60^{\circ}C$ was investigated for its sorption characteristics and the relationship between moisture content and water activity when it was mixed with wheat flour. During storage at $20^{\circ}C$ and various RH, an excess sorption phenomena was observed for solvent treated and dried SMR before equilibrium reached. A simple equation of log(dw/dt)=b log t+log a, where t is storage time(hr) and w is %$(H_2O)$ was drived for sorption or desorption rate of dried SMR at RH range of 12%-92%. From sorption isothermifigure, the moisture content(Mi) could be calculated from water activity by the equation of Mi=b Aw+a. The proposed equation was proved to have better fitness than those of the Smith isotherm equation or Lang and Steinberg equation for the mixture of dried SMR and wheat flour.

• Nuclear Engineering and Technology
• /
• v.54 no.2
• /
• pp.627-636
• /
• 2022

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO₃ solutions using antimony oxide (Sb₂O₃) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca²⁺ or Ni²⁺ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co²⁺ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol^-1.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1992.04a
• /
• pp.13-18
• /
• 1992

Moisture movement which is controlled by water potential and permeability of concrete is a very important phenomenon which affects the shrinkage of concrete. Thermocouple psychrometer were used to measure the moisture potentials in concrete. Based on the measured moisture potentials, three method have been proposed to calculate hycraulic conductivity and diffusivity. And also the hystresis of sorption isotherm due to drying and wetting cycle has been crawn.

• Applied Biological Chemistry
• /
• v.33 no.1
• /
• pp.14-17
• /
• 1990

Seven varieties of soybeans(Paldal, Danyeob, Jangbaek, Baegun, Jangyeob and 2 cultivars of Local 1 and Local 2) were investigated to compare the sorption characteristics during storage of various relative humidities. The sorption isotherm curve determined at RH range of $33{\sim}92\;%$ and $4^{\circ}C$ and $25^{\circ}C$ showed that moisture contents of soybeans was higher at $4^{\circ}C$ than those values at $25^{\circ}C$ for overall water activities of 0.33{\sim}0.92$. The Paldal was the highest moisture content at $4^{\circ}C$ while that value of Baegun was the highest at $25^{\circ}C$. The change in moisture content with storage time was expressed by log(dw/dt)=b log(t)+log a and the value of (dw/dt)${\times}10^3$ was decreased logarithmically. The Paldal was comparatively the highest initial absorption rate and the value of -b in seven varieties decreased as the relative humidity increased from 33 % to 92 %.