• Membrane Journal
• /
• v.9 no.2
• /
• pp.97-106
• /
• 1999

A and 2SM-5 type zeoli tic crystal films were synthesized on porous supports from the reaction mixture of 1.9 ${SiO}_2$1.5 $Na_20-Al_2O_3-40$ $H_20$ and $Si0_2$-0.l3 $Na_2O$-52 $H_20$-O.l2 TPAOH composition, respectively. The zeolite films were characterized by XRD and SEM. The 2SM -5 crystals grown on the porous matrix were very closely bound together. It was so difficult to obtain the perfectly intergrown crystals in the case of A-type zeolite and this crystal was transformed into P-type zeolite membrane with a prolonged reaction time. The densely intergrown A type zeolite crystal membrane could be also synthesized by the hydrothermal treatment at 100$^{\cirt}C$ after pressing the reaction mixture without addition of water. The pervaporation performance of the synthesized porous inorganic membranes was investigated for alcohol and water mixtures. A-type zeolite membrane crystallized as a thin film showed the selective \'Jermeability of water from the mixtures through the molecular sieving activity of micropores.

• Korean Journal of Materials Research
• /
• v.5 no.5
• /
• pp.620-624
• /
• 1995

To study the acid and base properties of chemical-treated natural zeolite, FT-IR analysis was performed by the adsorption of pyridne and pyrrole and thermo-gravimetric analysis was done by the adsorption of NH$_{3}$. These solid catalysts have two acid sites, which are related to the Bronsted and Lewis acid sites, respectively. HIC-treatment led to the increased acidity and the maintained basicity.Acidity of NaHO-treatment samples also increased with thr NaOH-treatment but basicity decreased. The p-xylene selectivity on the chemical-treatment zelite was higher than that on the untreated zeolite.

• Applied Chemistry for Engineering
• /
• v.20 no.1
• /
• pp.80-86
• /
• 2009

In this study, binderless zeolite BaX granule, an effective adsorbent for the separation of p-xylene was made. This adsorbent which has a sufficient strength, high specific surface area and selectivity to p-xylene was prepared by various steps, such as granulation process, calcination, binderless treatment, ion-exchange, and activation. In the granulation, the concentration of colloidal silica solution was controlled in order to confirm the effect of $SiO_2$ contents after binderless treatment. As a result, we confirmed that the compressive strength of granule after binderless treatment was increasing with increasing proportion of $SiO_2$ in the granule. And then Na-ion in granule was exchanged with Ba-ion by successive batch ion-exchange process. And then prepared adsorbents were tested for p-xylene separation by batch adsorption at $90^{\circ}C$. As a results of batch adsortion test, we confirmed that prepared adsorbents have a high selectivity to p-xylene. Also, it could be conformed that the prepared binderless zeolite BaX has a sufficient compressive strength (0.450 kgf), high specific surface area $(647.57m^2/g)$, high crystallinity (98.5% compared with zeolite NaX powder), and selectivity to p-xylene.

• Proceedings of the KAIS Fall Conference
• /
• 2005.05a
• /
• pp.321-323
• /
• 2005

중수숭급기 충진재의 부식원인인 염분 유입 및 열분해로 인한 산화물 형성 과정 조사를 위해 zeolite 의 열분해 및 염분 유입을 조사하였다. 그리고 원자력 발소의 dryer 모사 장치를 만들어 열분해 특성 조사 실험을 하였다. zeolite 열분해 특성 조사 결과 zeolite에 고온의 증기를 통과시키면 가수분해가 일어나 구조가 바뀌게 되며, $500\~700^{\circ}C$에서 완전히 열분해 된다. 그리고 열분해가 일어난 zeolite에 염분이 유입되면, zeolite의 $H^+$와 염분의 $Na^+$ 가 자리바꿈을 하게 되고, 수중에 $H^+$ 와 $Cl^-$ 가 존재하여 HCl이 형성될 것으로 조사되었고, 실험 결과 pH가 4.5, 4.53, 4.72, 4.64, 4.86, 5.03, 4.61로 낮게 측정되었다.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.5
• /
• pp.401-418
• /
• 2000

1. Production of the artificial zeolite from coal ash Coal fly ash is mainly composed of several oxides including $SiO_2$ and $Al_2O_3$ derived from inorganic compounds remained after burning. As minor components, $Fe_2O_3$ and oxides of Mg, Ca, P, Ti (trace) are also contained in the ash. These components are presented as glass form resulting from fusion in the process of the combustion of coal. In other word, coal ash may refer to a kind of aluminosilicate glass that is known to easily change to zeolite-like materials by hydrothermal reaction. Lots of hot seawater is disposing near thermal power plants after cooling turbine generator periodically. Using seawater in the hydrothermal reaction caused to produce low price artificial zeolite by reduction of sodium hydroxide consumption, heating energy and water cost. As coal ash were reacted hydrothermally, peaks of quartz and mullite in the ash were weakened and disappeared, and new Na-Pl peaks were appeared strengthily. Si-O-Si bonding of the bituminous coal ash was changed to Si-O-Al (and $Fe^{3+}$) bonding by the reaction. Therefore the produced Na-Pl type zeolite had high CEC of 276.7 $cmol^+{\cdot}kg^{-1}$ and well developed molecular sieve structure with low concentration of heavy metals. 2. Utilization of the artificial zeolite in agro-environment The artificial zeolite(1g) could remove 123.5 mg of zinc, 164.7 mg copper, 184.4 mg cadmium and 350.6 mg lead in the synthetic wastewater. The removability is higher 2.8 times in zinc, 3.3 times in copper, 4.7 times in cadmium and 4.8 times in lead than natural zeolite and charcoal powder. When the heavy metals were treated at the ratio of 150 $kg{\cdot}ha^{-1}$ to the rice plant, various growth inhibition were observed; brownish discoloration and death of leaf sheath, growth inhibition in culm length, number of panicles and grains, grain ripening and rice yield. But these growth inhibition was greatly alleviated by the application of artificial zeolite, therefore, rice yield increased $1.1{\sim}3.2$ times according to the metal kind. In addition, the concentration of heavy metals in the brown rice also lowered by $27{\sim}75%$. Artificial Granular Zeolites (AGZ) was developed for the purification of wastewater. Canon exchange capacity was 126.8 $cmol^+{\cdot}kg^{-1}$. AGZ had Na-Pl peaks mainly with some minor $C_3S$ peaks in X-ray diffractogram. In addition, AGZs had various pore structure that may be adhere the suspended solid and offer microbiological niche to decompose organic pollutants. AGZ could remove ammonium, orthophosphate and heavy metals simultaneously. Mixing ratio of artificial zeolite in AGZs was related positively with removal efficiency of $NH_4\;^+$ and negatively with that of $PO_4\;^{3-}$. Root growth of rice seedling was inhibited severely in the mine wastewater because of strong acidity and high concentration of heavy metals. As AGZ(1 kg) stayed in the wastewater(100L) for 4days, water quality turned into safely for agricultural usage and rice seedlings grew normally.

• Journal of Environmental Science International
• /
• v.29 no.7
• /
• pp.739-748
• /
• 2020

The characteristics of heavy metal ion (Ni²⁺, Zn²⁺, and Cr³⁺) adsorption by zeolite synthesized from Jeju scoria using the fusion and hydrothermal method, were studied. The synthetic zeolite was identified as a Na-A zeolite by X-ray diffraction analysis and scanning electron microscopy images. The equilibrium of heavy metal ion adsorption by synthetic zeolite was reached within 60 min for Ni²⁺ and Zn²⁺, and 90 min for Cr³⁺. The uptake of heavy metal ions increased with increasing pH in the range of pH 3-6 and the uptake decreased in the order of Cr³⁺ > Zn²⁺ > Ni²⁺. For initial heavy metal concentrations of 20-250 mg/L at nonadjusted pH, the adsoption of heavy metal ions was well described by the pseudo second-order kinetic model and was well fitted by the Langmuir isotherm model. The maximum uptake of heavy metal ions obtained from the Langmuir model, decreased in the order of Zn²⁺ > Ni²⁺ > Cr³⁺, differing from the effect of pH on the uptake, which was mainly based on the different pH of the solutions.

• Korean Journal of Soil Science and Fertilizer
• /
• v.31 no.2
• /
• pp.95-106
• /
• 1998

To reduce the environmental contamination and to utilize fly ash massively produced from the coal power plant every year, we synthesized the artificial zeolite using fly ash treated with alkaline, and then analyzed the mineralogical and morphological properties by X-ray, IR, and SEM. The amount of $NH_4{^+}$, $K^+$, and $H_2PO_4{^-}$ adsorbed by the fly ash and the artificial zeolite were determined with reaction time, amount of adsorbate used, ion concentrations. The results obtained from the pot experiments packed with the top soil, amended with granulated artificial zeolite which was made by treatment of 4% polyvinylalcohol, showed that CEC of the artificial zeolite was $257.7cmol^+kg^{-1}$, that was almost 36 times greater than that of fly ash. The ratio of $SiO_2/Al_2O_3$ decreased but the amount of Na increased. The physico-chemical properties analyzed by X-ray, IT, and SEM represented that the artificial zeolite synthesized had a similar morphological structure to that of the natural zeolite. The structures of the artificial zeolite had a significantly enlarged surface having a lot of pores, while the fly ash looked like spherical smooth shape with having not pores on the surface. Thus, the artificial zeolite was successfully synthesized. The results of adsorption isotherms of fly ash and artificial zeolite showed that the amount of $NH_4{^+}$, $K^+$, and $H_2PO_4{^-}$ adsorbed increased as the equilibrium concentration increased, while $NH_4{^+}$ was strongly adsorbed on the surface of fly ash and artificial zeolite than that of $K^+$. The most distinctive growth of Chinese cabbage was found from the top soil(NPK + soils + 20% of granulated artificial zeolite + 5% of compost). Therefore, we concluded that one of the most effective methods to effectively recycle a fly ash was to make the artificial zeolite as we did in this experiment.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.2
• /
• pp.66-73
• /
• 2017

This study was to evaluate the influential parameters such as intial Cs concentration, reaction temperature, contact time and pH variation of solution on Cs adsorption. Using the experimental data, adsorption kinetics, isotherms and thermodynamic properties were analyzed. The Cs ion adsorption of the zeolite X was effective in the range from pH 5 to 10 and reached equilibrium after 60 minutes. The adsorption kinetics and isotherms of Cs ion with the zeolite X was described well by the pseudo-second-order kinetic and Langmuir isotherm model. The maximum adsorption capacities of Cs ion calculated from Langmuir isotherm model at 293~333 K were from 303.03 mg/g to 333.33 mg/g. It was found that thermodynamic property of Cs ion absorption on the zeolite X was spontaneous and endothermic reaction. The experimental data were fitted a second-order polynomial equation by the multiple regression analysis. The values of the dependent variable calculated by this best fitted model equation were in very good agreement with the experimentally obtained values.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1997.06a
• /
• pp.27-32
• /
• 1997

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