• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.260-268
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• 2021

Adsorption is the most promising technology used to adsorb CO2 to reduce its concentration in the atmosphere due to its functional effectiveness. Various porous materials have been extensively synthesized to boost CO2 adsorption efficiency, for example, zeolite. Here, we report the synthesis process of zeolite adsorbent impregnated with amine, combining the benefit of these two substances. We compared conventional heating with microwave-assisted heating by varying concentrations of monoethanolamine in methanol (10% v/v and 40% v/v) as a liquid solution. The results showed that monoethanolamine impregnation helps significantly increase adsorption capacity, where adsorption occurs as a physisorption and not as chemisorption due to the adsorbent's steric hindrance effect. The highest adsorption capacity of 0.3649 mmol CO2 / gram adsorbent was reached by microwave exposure for 10 minutes. This work also reveals that a decrease in CO2 adsorption capacity was observed at a longer exposure period, and it reached a constant 40-minute adsorption rate. Impregnating activated zeolite with 40% monoethanolamine for 10 minutes in addition to microwave exposure (0.8973 mmol CO2 / gram adsorbent) is the maximum adsorption ability achieved.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.123-130
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• 2005

Zeolite X adsorbents with large surface area were prepared for using oxygen PSA adsorbent. Selective adsorption performance of nitrogen on the synthesized zeolite X adsorbent was improved by the cation exchange of adsorbent. The zeolite X which had over $650m^2/g$ surface area was synthesized at the conditions of $SiO_2\;:\;Na_2O\;:\;H_2O\;:\;Al_2O_3$ = 2.5 : 3.5 : 150 : 1 mole ratio, $98^{\circ}C$ temperature and 18 h synthesized time in 50 L reactor. The metal ions Li, Ag, Ca, Br, Sr, etc. were investigated for ion exchange with zeolite X. Ag ion was showed the highest ion exchange rate among these metal ions and all metal ions were exchanged with Na ion at equivalent rate. Compared with the NaX adsorbent, the ion exchanged zeolite X adsorbent remarkably improved its adsorption performance of nitrogen at the conditions of $10{\sim}40^{\circ}C$ temperature and 0~9 atm pressure. At an equilibrium pressure under 0.5 atm, adsorption performance of nitrogen on the ion exchanged zeolite adsorbent increased in the order of Ag > Li > Ca > Sr> Ba > K, whereas at an equilibrium pressure over 1 atm showed in the order of Li > Ag > Ca > Sr > Ba > K. Nitrogen/oxygen separation factor of Li ion exchanged zeolite X adsorbent was 13.023 at the partial pressure of nitrogen/oxygen gas mixture similar to air and $20^{\circ}C$ adsorption temperature.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.273-278
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• 2007

The honeycomb adsorbents and adsorption process for carbon dioxide removal from fuel gas were investigated. Zeolite paper was made with Na-X zeolite powder and ceramic fiber as raw materials. $Li^+$, $Ca^{2+}$ or $K^+$ ion exchanges for Na-X zeolite and additional Na-X coating were performed on zeolite paper for increasing the carbon dioxide adsorption capacity, after that the adsorption characteristics of the samples were analyzed. Among the ion exchanged samples, $Li^+$ ion exchanged zeolite paper was most promising but its carbon dioxide adsorption capacity was less than expected for process application. However, additional Na-X coating was found to be an effective method for increasing the carbon dioxide adsorption capacity of the zeolite paper for process application. The carbon dioxide breakthrough test of the honeycomb adsorbent prepared with the zeolite paper was studied, and fuel gas treatment capacity was calculated when the honeycomb adsorbent was used in the rotary adsorption process.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.494-503
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• 2013

In this study, $CO_2$ adsorbent was produced for minimizing energy loss due to ventilation within the building. For improved selectivity about low concentration of $CO_2$ in multiple-use facilities, the ball type adsorbent was modified from a commercial zeolite, alumina, alkali metals and activated carbon with mixing LiOH, binder, and $H_2O$. We measured specific surface area, pore characteristic, and crystal structure of the modified adsorbent. Effects of alkalization on the absorptive properties of the adsorbents were investigated. Continuous column tests (2,000 ppm) and batch chamber tests ($4m^3$, 5,000ppm) showed that the modified adsorbent indicated about the selectivity of $CO_2$ more than 9.7% (0.613 mmol/g) compared with ordinary adsorbents and $CO_2$ removal efficiency of 88.8% within l hour, respectively. It was estimated that the modified adsorbent was applicable to indoor environments.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.99-110
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• 2004

In order to investigate the performance of carbon dioxide PSA over zeolite adsorbent, the present study showed results of isotherm measurement, cyclic operation of 3-bed apparatus, and the corresponding numerical simulation. The experiment data of bed temperature, purity, recovery were matched well with that of numerical simulation. Purity of both gas and adsorbent phase increased rapidly with rinse rate but the degree of increase was retarded for large rinse rate The total amount of adsorbed increased only 10% even if rinse rate was enlarged to 4 times. Optimal rinse rate was 7N㎥/hr in this study. The heating rinse led to augments in recovery and productivity, possibly thanks to ease of description resulting from increased volumetric rinse rate and temperature rise in the column.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.1-11
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• 2005

This study applied EK method to remediate contaminated soil by lead (Pb), tried increasing efficiency of remediation using adsorbent (apatite and zeolite) as enhanced EK remediation method to overcome the limit of traditional EK remediation method. Adsorption tests on Pb were practiced to extract EK, making different concentration of contaminated soil, voltage condition, operating time etc., transferring Pb-ion into the position of adsorbent, then tried immobilization. On this results, the efficiency of remediation is different on its test conditions. In addition, the efficiency of remediation was not only improved by adding electrode revεrsal and install position of adsorbent but also satisfied TCLP regulation of EPA in USA through the whole sample range. Finally, absorption and immobilization capacity of apatite and zeolite proved on its excellence and confirmed the possibility of application of apatite and zeolite as enhanced EK remediation method.

• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.63-70
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• 1999

A study on the zeolite synthesized of bituminous coal fly ash from power plant has been carried out to reuse industrial waste. The synthesized zeolite was proved to be 4A type by means of the X-ray diffraction analysis and the degree of crystallinity was found to be higher than 90%. Then the synthesized zeolite was used as an adsorbent to remove the heavy metal ions in the CU, Pb, and Cd containing wastewater and water. Also, adsorption characteristics and kinetics of synthesized zeolite in the each metal ion solutions were studied. In each ion solutions, the adsorbed amounts of Pb, Cd, and Cu to the unit weight of synthesized zeolite were 141.6, 118.8, and 131.4mg/g respectively when each metal ion concentration was 500mg/L solution. The adsorption kinetics was fitted well to the Freundlich isotherms. The value of l/n for Pb, Cd, and Cu and 0.27, 0.50, and 0.66, respectively. Those results showed that the synthesized zeolite could be used as an adsorbent to remove single heavy metal ions in the wastewater and water. The heats of adsorption, H values of Pb, Cd, and Cu were 4.87, 14.95, and 18.23kacl/mol by the Henry-van't Hoff equation.

• Membrane and Water Treatment
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• v.14 no.3
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• pp.121-128
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• 2023

This study introduces a NaOH/Zn-assisted hydrothermal method for the synthesis of zeolites derived from coal ash (CA). A zeolite/Zn adsorbent is successfully prepared by the activation of CA with NaOH and Zn; it is characterized by a high surface area and a negative surface charge.Methylene blue (MB) and methyl orange (MO) are selected as dye pollutants, and their adsorption onto the zeolite/Zn adsorbent is investigated. Results show the high adsorption capacities of MB and MO and that the negative surface charge facilitates electrostatic interactions between the adsorbates and adsorbents. The zeolite/Zn adsorbents shows the selective adsorption of positively charged dye MB via electrostatic interactions between the =NH+ group (positive dipole) and the oxygen functional group of the adsorbents (negative dipole). The selectivity for the positively charged dye is sufficiently high, with the removal efficiency reaching 99.41% within 10 min. By contrast, the negatively charged dye MO exhibits negligible absorption. These findings confirm the role of electrostatic interactions in the adsorption of MB, in addition to the effect of a large surface area. The results of this study are expected to facilitate the development of simple, eco-friendly, and cost-effective zeolite-based adsorptive composites from CA residuals for the selective removal of dye pollutants from CA waste.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.663-669
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• 2009

The honeycomb adsorbent was prepared for adsorbing and seadsorbent was prepared by using zeolite sheet, which contained zeolite as component. The steady-state adsorption properties and surface morphologies were analyzed and breakthrough characteristics were ananlyzed by providing 16% carbon dioxide mixed gas. By thermal regeneration, carbon dioxide concentration properties were analyzed, and the adsorptive separation process was compared between thermal swing adsorption and pressure swing adsorption after adsorbent temperature change during heating. The breakthrough results of the honeycomb showed possibility parating carbon dioxide from combustion exhaust gas, which had deep impact on climate change, and the characteristics of the adsorbent were studied. Na-X zeolite was coated on a honeycomb prepared with ceramic sheet or active carbon sheet so that the two honycomb can be used at high temperature. Third honeycomb of rotary adsorptive concentration process.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.450-457
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• 2015

In this research a adsorbent, PVA-Zeolite bead, was prepared by immobilizing zeolite with PVA. The results of XRD and SEM analysis showed that the prepared PVA-Zeolite beads had porous structure and the zeolite particles were in mobilized within the internal matrix of the beads. The adsorption properties of Sr ion and Cs ion with the adsorbent were studied by different parameters such as effect of pH, adsorption rate, and adsorption isotherm. The adsorption of Sr ion and Cs ion reached equilibrium after 540 minutes. The adsorption kinetics of both ions by the PVA-Zeolite beads were fitted well by the pseudo-second-order model more than pseudo-first-order model. The equilibrium data fitted well with Langmuir isotherm model. The maximum adsorption capacities of Sr ion and Cs ion calculated from Langmuir isotherm model were 52.08 mg/g and 58.14 mg/g, respectively. The external mass transfer step was very fast compared to the intra-particle diffusion step in the adsorption process of Cs ion and Sr ion by the PVA-Zeolite beads. This result implied that the rate controlling step was the intra-particle diffusion step.