• Membrane Journal
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• v.27 no.6
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• pp.469-476
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• 2017

Membrane separation is a technology of low energy consumption. Membranes made of zeolites are of great interest because their fixed and open pores in the size of small molecules inside crystalline structures allow separation processes under harsh conditions. While zeolite NaA (LTA-type) is industrially used for dewatering of organic solvents, its pore size and thermal and hydrothermal stability can be tuned by exchange of framework and extra-framework elements. SOD with pores of only 0.28 nm is of great interest for $H_2$- und $H_2O$-separation and also can be tuned by ion exchange. Zeolites open the opportunity to create membranes of adapted separation behavior for small molecules in conditions of surrounding technical processes.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.33-47
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• 2003

Various applied-mineralogical characterization including measurements of surface area, size distribution, swelling index, and viscosity were done for some domestic bentonites in order to decipher the rheological properties and their controlling factors. The bentonites, which are Ca-type and relatively low-grade (rnontmorillonite contents: 30 ∼ 75 wt%), occur mostly as subhedral lamellas with the size range of 2 ∼ 4 $\mu\textrm{m}$. The size distribution of mineral fractions in bentonite suspension is dominant in the range of 10 ∼ 100 $\mu\textrm{m}$, and though rather complicated, exhibits roughly bimodal patterns. The feature is more conspicuous in the case of zeolitic bentonite. The bentonites have surface areas ranging 269 ∼ 735 $\m^2$/g, which are measured by EGME adsorption method. The EGME surface areas are nearly proportional to the rnontmorillonite contents, moisture contents, or total CEC. In the surface area measurements, zeolitic bentonites have slightly higher values than those zeolite- free types. The measured swelling index and viscosity of domestic bentonites are comparatively low in values. The swelling values of bentonites were measured to be 250∼500% at maximum by progressively mixing amounts of 2 ∼ 5 wt% Na$_2$CO$_3$, which varies depending on the contents of rnontmorillonite and other impurities, especially zeolite. Much amount of sodium carbonate is required for optimum swelling property of zeolitic bentonited which has usually strong Na- exchanged capacity. The bentonites, which are comparatively feldspar-rich and low in size and crystallinity, tend to be higher in viscosity values. Tn addition, the viscosity is largely higher in case of the bentonites with higher pH in suspension. However, the rheological properties of bentonites such as swelling index and viscosity do not show any obvious relationships with rnontmorillonite contents and mean particle size in suspension. In contrast, roughly speaking, the swelling index of bentonites is reversely proportional to the values of surface area which can be regarded as a collective physico-chemical parameter encompassing all the effects caused by mineral composition, surface charge, particle size, morphological farm, and etc. in bentonites. Thus, the rheological properties in bentonite suspension appear to be rather complicated characteristics which mainly depend on the flocculation of clay particles and the mode of particle association, i.e. quasicrystals, controlled by surface charge, morphology, size, and texture of rnon-tmorillonite, and which partly affected by the finer impurities such as zeolite.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.647-651
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• 1995

A tylosin-hyperproductive mutant of S. fradiae MNU20 was isolated among 3500 strains obtaincd from either MNNG- or UV-treated Streptomyces fradiae NRRL2702. The composition of optimal medium for tylosin production was formulated as followed as: 4 g soluble starch, 1 g glucose, 1 g corn steep liquor, 7.5 ml soy bean oil, 0.2 g KH$_{2}$PO$_{4}$, 1 g Na$_{2}$S$_{2}$O$_{3}$$\cdot $5H$_{2}$O, 2 g CaCO$_{3}$, 2 g NaCl, 0.001 g CoCl$_{2}$$\cdot $6H$_{2}$O in 1 liter of distilled water. With the optimal medium, S. fradiae MNU20 was able to produce 159 mg tylosin (g biomass)$^{-1}$, indicating that tylosin productivity of Streptomyces fradiae NRRL2702 was increased 14 times higher by mutation. When the effect of valine, succinate, and natural zeolite on tylosin production was investigated by using the optimal medium, these substances essentially enhanced tylosin production and their addition time during culture period appeared to be critical for the increase of tylosin production.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.509-512
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• 2009

Powder diffraction patterns of the zeolite mesolite ($Na_{5.33}Ca_{5.33}Al_{16}Si_{24}O_{80}{\cdot}21.33H_2O$), with a natrolite framework topology were measured as a function of pressure up to 5.0 GPa using a diamond-anvil cell and a $200{\mu}m$-focused monochromatic synchrotron X-ray. Under the hydrostatic conditions mediated by pore-penetrating alcohol and water mixture, the elastic behavior of mesolite is characterized by continuous volume expansion between ca. 0.5 and 1.5 GPa, which results from expansion in the ab-plane and contraction along the c-axis. Subsequent to this anomalous behavior, changes in the powder diffraction patterns suggest possible reentrant order-disorder transition. The ordered layers of sodium- and calcium-containing channels in a 1:2 ratio along the b-axis attribute to the $3b_{natrolite}$ cell below 1.5 GPa. When the volume expansion is completed above 1.5 GPa, such characteristic ordering reflections disappear and the $b_{natrolite}$ cell persists with marginal volume contraction up to ca. 2.5 GPa. Further increase in pressure leads to progressive volume contraction and appears to generate another set of superlattice reflections in the $3c_{natrolite}$ cell. This suggests that mesolite in the pressure-induced hydration state experiences order-disorder-order transition involving the motions of sodium and calcium cations either through cross-channel diffusion or within the respective channels.

• Journal of Environmental Science International
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• v.31 no.2
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• pp.171-180
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• 2022

Zeolitic material, Z-Y3, was synthesized from coal fly ash (CFA) under low-alkaline conditions (NaOH/CFA ratio = 0.3 and NaOH solution concentrations of 0.0, 0.5, and 1.0 M) using a fusion/hydrothermal method. The adsorption capacities of the fabricated Z-Y3 samples for Cs and Sr ions and the desorption capacity of Na ions were evaluated. The XRD patterns of the Z-Y3 sample fabricated using a 1.0 M NaOH solution (Z-Y3 (1.0 M)) indicated the successful synthesis of a zeolitic material, because the diffraction peaks of Z-Y3 coincided with those of the Na-A zeolite in the 2θ range of 7.18-34.18. Moreover, the SEM images revealed that morphology of the Z-Y3 (1.0 M) sample, which presented zeolitic materials characteristics, consisted of sharp-edged cubes. The adsorption isotherms of Cs and Sr ions on all the fabricated Z-Y3 samples were described using the Langmuir model, and the maximum adsorption capacities of Cs and Sr were calculated to be 0.14-0.94 mmol/g and 0.19-0.78 mmol/g, respectively. The desorption of Na ions from the Cs and Sr ions adsorbed Z-Y3 samples followed the Langmuir desorption model. The maximum desorption capacities of Na ions from the Cs and Sr ions adsorbed Z-Y3 (1.0 M) samples were 1.28 and 1.49 mmol/g, respectively.

• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.283-293
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• 2003

Domestic water treatment plants operate the rapid and slow filtering system using the filtering sands. Most of them are composed of beach sands, which have less sorption capacity of heavy metals as well as organic contaminants. Therefore, the development of fortified functional filtering materials with high removal capacity of organic and inorganic contaminants is needed to prevent the unexpected load of contaminated source water. This study aims to test the hydrochemical change and the removing capacity of heavy metals such as Cd, Cu, and Pb on the Jumunjin sand, feldspathic sand(weathering product of Jecheon granite), feldspathic mixing sand I(feldspathic sand mixed with 10 wt% zeolite), and feldspathic mixing sand II (feldspathic sand mixed with 20 wt% zeolite). Feldspathic mixing sand I and II showed the eruption of higher amounts of cations and anions compared with the Jumunjin sand and feldspathic sand. They also showed higher eruption of Si, Ca, $SO_4$ ions than that of Al, $NO_3$, Fe, K, Mg, and P. Feldspathic mixing sand II caused higher eruption of some cations of Na, Ca, Al than feldspathic mixing sud I, which is the result controlled by the dissolution of zeolite. Jumunjin sand and feldspathic sand showed very weak sorption of Cd, Cu and Pb. In contrast to this, feldspathic mixing sand I and II showed the high sorption and removal capacity of the increasing order of Cd, Cu and Pb. Feldspathic mixing sand II including 20% zeolite showed a fortified removal capacity of some heavy metals. Therefore, feldspathic mixing sand mixed with some contents of zeolite could be used as the fortified filtering materials for the water filtering and purification in the domestic water treatment plants.

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

• The Korean Journal of Ecology
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• v.15 no.1
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• pp.67-73
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• 1992

This study was carried out to investigate the effects of soil improver on the population density and composition of microarthropods in the upland which cultivated pepper consecutively. We have treated soil improver sucf as zeolite, compost, ca, sio2 , and integrated improvement i. e. treated zeolite, compost, ca, and deep cultivate ; 20 cm. We sampled soil to collect soil microarthropods from a week to 15 months after treament at each site by soil-corer and extracted 48 hours in berlese- tullgren funnel. We have classified 16 families, 35 species diversity index of soil microarthropods are highe in the integrated improver and compost site than those found in any other sites. We suggest that soil improvement effrcts of integrated improved site are influenced by compost.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.263-269
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• 2002

This study was conducted to know the removal characteristics of ammonia nitrogen by commercially available cation exchange resins. Eight acidic cation exchange resins were investigated in batch reactors. Among them, the most effective resin for ammonia removal in solution was PK228, which was a strong acidic resin of $Na^{+}$ type. PK228 was compared with activated carbon and natural zeolite. The effects of cation exchange capacity, ammonia concentration, resin amount, temperature and pH on ammonia removal by PK228 were investigated in batch reactor, and the effect of effluent velocity in continuous column reactor. Strong acidic resins of porous type were more effective than week acidic resins or gel type resins for ammonia removal in solution. PK228 was more effective than activated carbon and natural zeolite for ammonia removal in batch reactor. With increasing initial ammonia concentration, the amount of ammonia removed by PK228 increased, but the proportion of removed ammonia to initial ammonia concentration decreased. The effect or temperature on ammonia removal by PK228 was very slight. The ammonia removal to acidic solution was more effective than that at basic solution. With decreasing effluent velocity of solution through column, breakthrough point extended, and ammonia removal capacity increased.d.

• Journal of Environmental Science International
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• v.20 no.6
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• pp.729-736
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• 2011

This work is to compare the experiment results by a continuous fixed-bed adsorption of water vapor, acetone vapor, and toluene vapor on zeolite 13X (SAU) and silica-alumina (SAK). SAU and SAK have very different pore structure but similar composition as inorganic adsorbent. The relationship between the equilibrium adsorption capacity and specific pore size range were studied. Adsorption of water vapor was more suitable on SAU than SAK because SAU has relatively more developed pores around $5\;\AA$ than SAK in the pore range of $10\sim100\;\AA$. Adsorption of acetone vapor was more suitable on SAK than SAU because SAK has relatively more developed pores around $5\sim10\;\AA$ than SAK in the pore range of less than $10\;\AA$. Adsorption of toluene vapor was more suitable on SAK than SAU because SAK has relatively more developed pores in the pore range of $10\sim100\;\AA$ than SAK. Adsorption capacity of the adsorbent was closely related to the surface area generated in the specific pore size region. But it was difficult to distinguish the relationships between adsorption capacity and micro area, and the external surface area of adsorbent.