• Applied Chemistry for Engineering
• /
• v.10 no.1
• /
• pp.51-57
• /
• 1999

Adsorption characteristics of Ni(II), Co(II) and Ag(I) ions on the Amberite IRN 77 cation exchange resin have been studied to suggest the guide-line for the optimum operation of demineralization process in primary coolant system during the shut-down period of pressurized water reactor(PWR). The adsorption mechanism of each metal ion, Ni(II), Co(II) or Ag(I) ion, on a cation exchange resin was well coincided with Langmuir isotherm. The adsorption and treatment capacities of $H^+$-form resin were higher than those of $Li^+$-form resin. In the continuous ion exchange process for the solution of multi-component system, the selectivity of the resin was in increasing order of Ni(II)${\approx}$Co(II)>Ag(I). In addition, the increase of the flow rate decreased the treatment capacity of the resin as well as the slope of the breakthrough curve.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11a
• /
• pp.110-114
• /
• 2010

Li-incorporated mesoporous $TiO_2$ materials with various pore-sized istributions were synthesized by using triblockcopolymers via a sol-gel process in a queous solution. The properties of the se materials were characterized by HR-TEM, XRD, and BET analysis. All particles have spherical morphology with a diameterrange of $1-3{\mu}m$. The mesoporous $TiO_2$ materials calcined at $400^{\circ}C$ and their specific surface area, average pore size and crystallite sizes were 210 $m^2g^{-1}$, 6.4 nm and 8.8 nm respectively. The Li-incorporated mesoporous $TiO_2$ were tested for $CO_2$ adsorption and its adsorption capacity is 90mg/g. The Li-incorporated mesoporous $TiO_2$ ar eobserved to be thermally stable, recyclable and greens or bent for $CO_2$ capture. The effect of bimetallic $ZrLiTiO_2$ is also studied for $CO_2$ adsorption.

• Carbon letters
• /
• v.28
• /
• pp.116-120
• /
• 2018

Nitrogen-doped carbons have attracted much attention due to their novel application in relation to gas storage. In this study, nitrogen-doped porous carbons were synthesized using SBA-15 as a template, polypyrrole as the carbon and nitrogen precursor, and KOH as an activating agent. The effect of the activation temperature ($600-850^{\circ}C$) on the $CO_2$ adsorption capacity of the obtained porous carbons was studied. Characterization of the resulting carbons showed that they were micro-/meso-porous carbon materials with a well-developed pore structure that varied with the activation temperature. The highest surface area of $1488m^2g^{-1}$ was achieved at an activation temperature of $800^{\circ}C$ (AC-800). The nitrogen content of the activated carbon decreased from 4.74 to 1.39 wt% with an increase in the activation temperature from 600 to $850^{\circ}C$. This shows that nitrogen is oxidized and more easily removed than carbon during the activation process, which indicates that C-N bonds are more easily ruptured at higher temperatures. Furthermore, $CO_2$ adsorption isotherms showed that AC-800 exhibited the best $CO_2$ adsorption capacity of $110mg\;g^{-1}$ at 298 K and 1 bar.

• Nuclear Engineering and Technology
• /
• v.46 no.6
• /
• pp.847-856
• /
• 2014

Spent resin waste containing a high concentration of $^{14}C$ radionuclide cannot be disposed of directly. A fundamental study on selective $^{14}C$ stripping, especially from the IRN-150 mixed bed resin, was carried out. In single ion-exchange equilibrium isotherm experiments, the ion adsorption capacity of the fresh resin for non-radioactive $HCO_3{^-}$ ion, as the chemical form of $^{14}C$, was evaluated as 11mg-C/g-resin. Adsorption affinity of anions to the resin was derived in order of $NO_3{^-}$ > $HCO_3{^-}{\geq}H_2PO_4{^-}$. Thus the competitive adsorption affinity of $NO_3{^-}$ ion in binary systems appeared far higher than that of $HCO_3{^-}$ or $H_2PO_4{^-}$, and the selective desorption of $HCO_3{^-}$ from the resin was very effective. On one hand, the affinity of $Co^{2+}$ and $Cs^+$ for the resin remained relatively higher than that of other cations in the same stripping solution. Desorption of $Cs^+$ was minimized when the summation of the metal ions in the spent resin and the other cations in solution was near saturation and the pH value was maintained above 4.5. Among the various solutions tested, from the view-point of the simple second waste process, $NH_4H_2PO_4$ solution was preferable for the stripping of $^{14}C$ from the spent resin.

• Journal of the Mineralogical Society of Korea
• /
• v.23 no.3
• /
• pp.183-189
• /
• 2010

It is of importance to separate Ni(II) and Co(II) from Mg(II) in solution which was leached from nickel laterite ore. In order to investigate the possibility of separating Ni(II) and Co(II) from Mg(II), adsorption behavior of the three metals from individual and mixed sulfate solutions was investigated by using Diphonix resin. The concentration of each metal in solution was fixed at 100 ppm and the pH of the sulfuric acid solution was changed from 5 to 7. At ambient temperature, the adsorption behavior of the three metal ions followed Langmuir adsorption isotherm. The loading capacity of Diphonix resin for the three metal ions was obtained from the Langmuir isotherm. Since adsorption behavior of the three metal ions from the mixed solution was similar to each other, it was found to be difficult to separate Ni(II) and Co(II) from Mg(II) by using Diphonix resin.

• Clean Technology
• /
• v.7 no.1
• /
• pp.51-63
• /
• 2001

In this study, PSA, known as the most economic process, was used to recover $CO_2$ from the power-plant flue gas. Activated carbon and zeolite molecular sieve 13X were used as adsorbent. Activated carbon has been deemed inadequated adsorbent for separating $CO_2$ from the flue gas. However, highly concentrated $CO_2$ could be obtained as a product on the activated carbon adsorbent using the new operating cycle modifying the rinse step. Also, the recovery of $CO_2$ was improved using double-layered adsorption column packed with the activated carbon and the zeolite 13X simultaneously. Adsorption column was filled with the activated carbon in the feed-end side, and the zeolite 13X in the product-end side. The recovery of $CO_2$ increased about 40% with only 25% zeolite, and increased 67% with 50% zeolite at the experimental conditions of 13% $CO_2$ concentration, 10 SLPM flow rate and 2.2 atm adsorption pressure.

• Journal of the Korean Chemical Society
• /
• v.66 no.5
• /
• pp.416-419
• /
• 2022

• Membrane and Water Treatment
• /
• v.14 no.1
• /
• pp.1-10
• /
• 2023

This study explored the feasibility of calcium-rich food waste, Mactra veneriformis shells (MVS), as an adsorbent for phosphate removal, and its removal efficiency was enhanced by the thermal activation process. The CaCO3 in MVS was converted to CaO by thermal activation (>800 ℃), which is more favorable for adsorbing phosphate. Thermal activation did not noticeably influence the specific surface area of MVS. The MVS thermally activated at 800 ℃ (MVS-800), showed the highest phosphate adsorption capacity, was used for further adsorption experiments, including kinetics, equilibrium isotherms, and thermodynamic adsorption. The effects of environmental factors, including pH, competing anions, and adsorbent dosage, were also studied. Phosphate adsorption by MVS-800 reached equilibrium within 48h, and the kinetic adsorption data were well explained by the pseudo-first-order model. The Langmuir model was a better fit for phosphate adsorption by MVS-800 than the Freundlich model, and the maximum adsorption capacity of MVS-800 obtained via the Langmuir model was 188.86 mg/g. Phosphate adsorption is an endothermic and involuntary process. As the pH increased, the phosphate adsorption decreased, and a sharp decrease was observed between pH 7 and 9. The presence of anions had a negative impact on phosphate removal, and their impact followed the decreasing order CO₃^2- > SO₄²- > NO₃^- > Cl^-. The increase in adsorbent dosage increased phosphate removal percentage, and 6.67 g/L of MVS-800 dose achieved 99.9% of phosphate removal. It can be concluded that the thermally treated MVS-800 can be used as an effective adsorbent for removing phosphate.

• Korean Chemical Engineering Research
• /
• v.46 no.4
• /
• pp.783-791
• /
• 2008

The dynamic characteristics of adsorption using an adsorption bed packed with Li-X zeolite (UOP) were studied through the breakthrough experiments of $H_2/CH_4$ (90:10 vol%), $H_2/CO$ (90:10 vol%) and $H_2/CO_2$ (80:20 vol%) mixtures. Effects of feed flow rate (6.24~10.24 LPM) and adsorption pressure (6.1 bar~10.1 bar) in the Li-X zeolite bed with 2.7 cm of inside diameter and 80 cm of bed length were observed. The smaller feed rate or the higher operating pressure, resulted in the longer of the breakthrough time and the breakthrough curve have tailing due to temperature variance in the bed. The adsorption dynamics of the Li-X zeolite bed were predicted by using LDF model with feed flow and pressure dependent diffusivity. The prediction and experimental data were analyzed with a nonisothermal, nonadiabatic model, dual-site langmuir (DSL) isotherm

• Korean Journal of Environmental Agriculture
• /
• v.16 no.4
• /
• pp.320-326
• /
• 1997

In order to elucidate the degradation characteristics of the herbicide imazapyr in soil, mineralization to $^{14}CO_2$and adsorption were investigated using eight types of soils with the different physico-chemical properties. The results obtained were as follows: 1. During the incubation period of 12 weeks after the treatment of imazapyr, the amounts of $^{14}CO_2$ evolved from 8 types of soils with different properties ranged from 1.5 to 4.9% of the originally applied $^{14}C$ activities. Soil C, G, and H with low pH and high organic matter showed low $^{14}CO_2$evolution, whereas soil B and D with high pH and low organic matter did high $^{14}CO_2$ evolution. 2. Time for reaching the equilibrium concentrations in the adsorption experiment of imazapyr in soils was about 3 hours at $25^{\circ}c$ in soil C, D, G, and H. Imazapyr was adsorbed in the range of 0.25${\sim}$28.32% in soils with different physico-chemical properties. Among the soil parameters, organic matter content was the most influential in imazapyr adsorption on soil. The Freundlich adsorption coefficient $(K_f)$ increased 5.5 to 25.6 times as organic matter content increased 2.0 to 21.3 times. Hence it seems that the extent to which soil organic matter contributes to imazapyr adsorption is greater than that of clay mineral. $K_f$ values for the soils tested were 0.44, 0.08, 0.65, and 2.05 in soil C, D, G, and H, respectively. In all the soils tested, $K_f$ values had a strong resemblance to K_$K_d$.