• Journal of Environmental Science International
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• v.10 no.6
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• pp.451-459
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• 2001

Adsorption characteristics of triadimefon and diniconazole(pesticide) by natural zeolite($CLI_N$) and several synthetic zeolites were Investigated. The synthetic zeolites used En this study were as follows: Faujasite synthesized from coal fly ash($FAU_F$); Zeolite synthesized from the mixture of FAU and Na-Pl synthesized from the ratio of Cheju scoria 6 to coal fly ash 4 by weight($(FAU + Na-Pl)_{SF}$); waste fluid catalytic cracking catalyst($FCC_W$). The distribution coefficient, $K_D$ and Freundlich constant, $K_F$ decreased in the fellowing sequence : $FCC_W ＞ FAU_F ＞ (FAU + Na-Pl)_{SF} ＞CLI_N$ among the zeolites. The distribution coefficient and the adsorption capacity of $(FAU + Na-Pl)_{SF}$ for pesticides were 4.4 and 2.6 times higher for triamefon, and 2.0 and 2.4 times higher for diniconazole than those of $CLI_N$, respectively.

• Journal of Environmental Science International
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• v.31 no.12
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• pp.1103-1115
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• 2022

The adsorption characteristics of four pesticides (phosphamidon, fenitrothion, triadimefon, and diniconazole) on natural clinoptilolite (CLI_N) and three synthetic zeolites were investigated. The synthetic zeolites included faujasite (FAU_F) synthesized from coal fly ash; the mixture of FAU and Na-P1 (FAU + Na-P1)_SF synthesized using Jeju scoria and coal fly ash at the ratio of 1.5 by weight; and waste fluid catalytic cracking catalyst (FCC_W). The distribution coefficient, K_D and the Freundlich constant, K_F decreased in the following sequence: FCC_W > FAU_F > (FAU + Na-P1)_SF > CLI_N among the zeolites and diniconazole>fenitrothion> triadimefon> phosphamidon among the pesticides. The pesticide adsorptivity increased with increasing temperature for FAU_F, (FAU+Na-P1)_SF and FCC_W, however, it decreased for CLI_N, regardless of the type of pesticide. The adsorptivity of pesticides was independent of pH for phosphamidon, fenitrothion and triadimefon, whereas it decreased with increasing pH for diniconazole, regardless of zeolite type.

• Clean Technology
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• v.30 no.3
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• pp.248-257
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• 2024

Carbon dioxide is an undesired component of biogas and landfill gas. As a result, it needs to be removed from these mixtures in order to increase their heating value and reduce corrosion during treatment. Zeolites are a class of microporous materials that can be used as adsorbents for the separation of carbon dioxide from gas mixtures. In this work, the pure gas adsorption isotherms of methane and carbon dioxide and the selectivity of their mixture onto LTA-4A, FAU-13X and FAU-NaY adsorbents at temperatures of 273, 298 and 323 K and pressures up to 30 bars were calculated by the Monte Carlo method. Also, the influence of a flexible framework in a set of zeolites on the separation of methane and carbon dioxide was studied. Carbon dioxide adsorption onto the zeolites used in this work was more favorable than methane adsorption. The FAU-13X adsorbent had the highest adsorption capacity among the studied adsorbents. However, the selectivity of carbon dioxide over methane for LTA-4A was the highest. The adsorption capacities of a rigid framework were higher than those of a flexible framework. The influence of the framework flexibility in FAU on adsorption capacity was small. In contrast, its influence on selectivity seemed to be much larger.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.132-138
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• 2003

The effect of synthesis condition, type of starting materials, mole ratio, mixing. aging, and crystallization temperature and time, on the size of FAU-type zeolite has been studied. Different mixing route may lead to the different phase of zeolite even with the same starting materials. In general, the size of particles is smaller after aging, especially at lower aging temperature. Two step mixture gel preparation method resulted to not only the reduction of crystallization time but also that of particle size, but without the aging of two mixture gels before the preparation of the overall gel in the second step, only the crystallization time was reduced, not the particle size. The FAU-type zeolite with average particle size 0.4$\mu$m and BET surface area 838 $m^2$/g was obtained from starting materials of liquid sodium silicate, sodium aluminate, and sodium hydroxide with two step preparation of mixture gel, aging of the mixture gels in two steps, which effectively reduced the crystallization time and particle size.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.160-168
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• 2014

In the present study, water vapor adsorption was evaluated at 298.15K for 9 different zeolites having LTA, FAU, CHA, and RHO frameworks, and then effect of framework type, Si/Al molar ratio, and alkali ion type on water up-take was investigated. Zeolites showed water up-takes which were increased in an order of $RHO<CHA{\approx}LTA<FAU$ frameworks. NaY zeolite having FAU framework showed a water up-take of 406 mg/g at p/po=0.5. The up-take was a little larger than that of 13X zeolite with the same framework. Among LTA zeolites, Ca-type 5A zeolite showed the highest water adsorption (282 mg/g at p/po=0.5) which could be explained by the large pore volume. Both CHA zeolite with a Si/Al molar ratio of 2.35 and RHO zeolite with a Si/Al molar ratio of 3.56 showed considerable water up-takes, even though the Si/Al molar ratio was much larger than that of LTA zeolite. In the present study, it is announced that in addition to FAU and LTA zeolites, CHA and RHO zeolites can be a promising dehumidification adsorbent.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.202.2-202
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• 2003

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.7-10
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• 2001

Adsorption of the pesticides (phosphamidon, fenitrothion, triadimefon and diniconazole) in natural zeolite (CL $I_{N}$) and several synthetic zeolites was incestigated. The pesticides were not adsorbed on zeolites (Na-Pl, SOD, ANA, JBW and CAN) synthesized from Jeju scoria. The distribution coefficient ( $K_{D}$) and the Freundlich constant ( $K_{F}$) decreased in the following sequences. FC $C_{W}$ (waste catalytic cracking catalyst)>FA $U_{F}$ (FAU Synthesized from coal fly ash)>(FAU+Na-Pl)$_{SF}$ (the mixture of FAU and Na-Pl synthesized from the ratio of Jeju scoria 6 to coal fly ash 4 by weight)>CL $I_{N}$ among the zeolites; diniconazole>fenitrothion> triadimefon>phosphamidon. As the temperature was increased, the amount of pesticide adsorbed per unit mass of zeolite increased for FC $C_{W}$, FA $U_{F}$ and (FAU+Na-Pl)$_{SF}$ but it decreased for CL $I_{N}$, for all the pesticides used in this study. It was independent of pH for phosphamidon, fenitrothion and triadimefon, but decresed as pH was increased for all the zeolites used in this study.y.udy.y.y.y.y.y.y.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.485-491
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• 2015

This paper shows the design improvement and test model of FAU (Frequency Analysis Unit) in PDD (Partial Discharge Diagnosis system) for 800kV GIS (Gas Insulated Switchgear). We found some problems during operation of previous FAU, such as the aging of fiber-optic converter that can cause communication error, the malfunction of signal analysis circuit etc. And then we solved those problems by design improvement and verified the performance through type test. To monitor partial discharge, the performance of UHF sensor is important but the performance of frequency analysis unit is also very important. So we solved communication error, the malfunction of signal analysis circuit and then increased the operation reliability of FAU by improving fiber-optic converter and signal analysis circuit. Accredited testing laboratory carried out the performance verification test according to performance test criteria and procedure of reliability test standards, IEC-60225, 61000 and 60068 etc. We confirmed the test results which correspond with the performance test criteria.

• Safety and Health at Work
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• v.11 no.4
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• pp.385-396
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• 2020

Teachers are facing various job demands with psychosocial aspects being fundamental due to the nature of the occupation. Although teachers' work is associated with different psychosocial health risks, little is known on how to identify and tackle those. Thus, a systematic literature search as per the PRISMA statement was conducted via MEDLINE (PubMed), PSYNDEX (PubPsych), and ScienceDirect. Two reviewers independently screened 2261 titles and abstracts and 169 full-texts. According to the inclusion criteria established a priori, articles from peer-reviewed journals (English or German) on psychosocial risk management in teachers were incorporated. Despite a comprehensive and sensitive search, only four publications could be identified, outlining a process to implement risk management and different assessment tools. Taken together, data presented in the articles were scarce. Recommendations for process steps and the assessment of psychosocial risks can be derived from the findings. To implement effective psychosocial risk management in the teaching profession, further research is needed, though. Effective and practicable approaches, which are accepted by the target group, should be further developed and investigated. Relevant causes of occupational strain in the teaching profession must be identified and assessed reliably. Low-threshold interventions should be implemented, and the outcome must be evaluated afterward.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.243-249
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• 2014

Three single crystals of fully dehydrated $Co^{2+}$-exchanged zeolite Y (Si/Al = 1.56) were prepared by the exchange of $Na_{75}$-Y ($|Na_{75}|[Si_{117}Al_{75}O_{384}]$-FAU) with aqueous streams 0.05 M in $Co(NO_3)_2$, pH = 5.1, at 294 K for 6 h, 12 h, and 18 h, respectively, followed by vacuum dehydration at 673 K. Their single-crystal structures were determined by synchrotron X-ray diffraction techniques in the cubic space group Fd3m at 100(1) K. They were refined to the final error indices $R_1/wR_2$ = 0.0437/0.1165, 0.0450/0.1228, and 0.0469/0.1278, respectively. Their unit-cell formulas are $|Co_{29.1}Na_{11.8}H_{5.0}|[Si_{117}Al_{75}O_{384}]$-FAU, $|Co_{29.8}Na_{11.0}H_{4.4}|[Si_{117}Al_{75}O_{384}]$-FAU, and $|Co_{30.3}Na_{9.5}H_{4.9}|[Si_{117}Al_{75}O_{384}]$-FAU, respectively. In all three crystals, $Co^{2+}$ ions occupy sites I, I' and II; $Na^+$ ions are also at site II. The tendency of $Co^{2+}$ exchange slightly increases with increasing contact time as $Na^+$ content and the unit cell constant of the zeolite framework decrease.