Articles de revues : « Natural Clinoptilolite »

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Matijasevic, Srdjan, Aleksandra Dakovic, Deana Iles et Sonja Milicevic. « Adsorption of uranyl ion on acid-modified zeolitic mineral clinoptilolite ». Chemical Industry 63, n^o 5 (2009) : 407–14. http://dx.doi.org/10.2298/hemind0905407m.

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In this paper, the results of adsorption of uranyl ion on acid-modified zeolitic mineral clinoptilolite are presented. Adsorption was investigated at different amounts of solid phase in suspension, as well as at different pH values. The modified clinoptilolite samples were obtained by treatment of clinoptilolite with acids: hydrochloric, oxalyc and citric. Starting and modified clinoptilolites were characterized by chemical analysis, thermal (DT/TG) analysis and by determination of cation exchange capacity, while starting and nonadsorbed amounts of uranyl ion were determined by fluorometric method. Uranyl ion adsorption experiments on natural unmodified zeolitic mineral showed that uranyl ion adsorption was low (29.2%) and that treatment of clinoptilolite with acids significantly increases the adsorption of uranyl ion (>90%). In the case of acid treated clinoptilolites, the highest adsorption of uranyl ion was achieved on clinoptilolite modified with hydrochloric acid. Kinetics of adsorption showed that adsorption of uranyl ion begins very fast and that the most of uranyl ion was adsorbed in first 30 min. Practically, there were no changes in uranyl ion adsorption within next 72 h.

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Kowalak, S., et A. Jankowska. « Natural zeolites for styrene oligomerization ». Clay Minerals 46, n^o 2 (juin 2011) : 189–95. http://dx.doi.org/10.1180/claymin.2011.046.2.189.

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AbstractHydrogen forms of natural mordenite and clinoptilolite were used as catalysts for styrene oligomerization and as matrices to hold the resultant oligomers in order to prepare intense and light-resistant pigments. In contrast to synthetic zeolites of similar pore sizes (mainly H-ZSM-5, H-mordenite), the natural zeolites did not form products with an intense (pink) colouration. H-mordenite samples treated with styrene developed some colour due to styrene oligomers (the chromophore) whereas, in treated clinoptilolites, colour formation was negligible due to the lack of access of styrene molecules into the elliptical channels. The results of catalytic tests for cracking of cumene (cumene and styrene have similar molecular sizes) were consistent with the styrene oligomerization results. They indicate a noticeable catalytic activity with natural H-mordenite and a lack of activity with clinoptilolite. On the other hand, catalytic tests for propan-2-ol decomposition indicate a high activity with both natural zeolites, which confirms the presence of acid sites and their accessibility to small alcohol molecules.

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Nik Malek, Nik Ahmad Nizam, et Siti Aishah Mohd Hanim. « Antibacterial Activity of Amine-Functionalized Silver-Loaded Natural Zeolite Clinoptilolite ». Science Letters 15, n^o 1 (3 janvier 2021) : 13. http://dx.doi.org/10.24191/sl.v15i1.11790.

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The antibacterial activity of amine-functionalized silver-loaded natural zeolite clinoptilolite was analysed against Gram-negative Escherichia coli ATCC 11229 and a comparison was made with raw clinoptilolite, silver-loaded clinoptilolite, and amine-functionalized clinoptilolite with APTES (3-Aminopropyl) triethoxysilane. Results from the characterization of the samples using Fourier transform infrared (FTIR) spectroscopy showed that the silver-loaded clinoptilolite was functionalized with APTES without affecting the original framework structure of the clinoptilolite. The antibacterial activity of the analysed samples based on disc diffusion technique (DDT) and minimum inhibition concentration (MIC) showed that the silver-loaded clinoptilolite (150 % of cation exchange capacity of clinoptilolite) had the highest antibacterial activity, as compared to amine-functionalized silver-loaded zeolite. This study showed that the functionalization of silver-loaded clinoptilolite could affect the release and action of silver ions to kill or inhibit bacterial growth. However, it showed that the natural zeolite clinoptilolite could become a good carrier system for the antibacterial metal ion, especially silver ions. Keywords: Zeolite, clinoptilolite, antibacterial agent, silver, amine-functionalization

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Nenadovic, Snezana, Ljiljana Kljajevic, Bojan Seslak, Nina Obradovic, Ivana Vukanac et Vladimir Pavlovic. « Cesium removal from aqueous solution by natural mineral clinoptilolite ». Nuclear Technology and Radiation Protection 29, n^o 2 (2014) : 135–41. http://dx.doi.org/10.2298/ntrp1402135n.

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The aim of this study was to investigate the Cs+ ions sorption on natural minerals clinoptilolite. The analysis of clinoptilolite and clinoptilolite with adsorbed Cs+ ion was con- ducted by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, and gamma spectrometry. The specific activity of naturally occurring radionuclides in clinoptilolite was determined by gamma spectrometry by using the HPGe semiconductor detector. Obtained activity concentrations ranged from 49 Bq/kg to 810 Bq/kg for 40K, 5.7 Bq/kg to 10 Bq/kg for 238U, 5.8 Bq/kg to 70 Bq/kg for 232Th(228Ac), and the presence of artificial radionuclides was not detected (137Cs < 0.02 Bq/kg). The study of the thermal decomposition of raw clinoptilolite and Cs adsorbed clinoptilolite by differential thermal analysis is presented in this paper. The activation energy of the reaction phase transformation of raw clinoptilolite is 156.7 kJ/mol, while Cs adsorbed clinoptilolite is 121.7 kJ/mol. The lower value of activation energy reaction of the phase transformation Cs adsorbed clinoptilolite indicates that Cs which is adsorbed destabilizes the crystal structure of clinoptilolite and thus facilitates the transition to the amorphous state.

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Atkovska, Katerina, Shaban Jakupi, Flakrim Aliu, Stefan Kuvendziev, Mirko Marinkovski et Kiril Lisichkov. « ADSORPTION CHARACTERISTICS OF NATURAL POROUS SORBENTS ». Knowledge International Journal 31, n^o 3 (5 juin 2019) : 647–52. http://dx.doi.org/10.35120/kij3103647a.

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Zeolites are nano-porous crystalline aluminosilicates. Natural zeolites are non-toxic and safe for humans which expand their application in different fields. Clinoptilolite is the most abundant natural zeolite with high purity that occurs in many parts of the world. It has a frame structure in which the tetrahedra of silicon [SiO4/2] and aluminium [AlO4/2]- are interconnected with oxygen bridge. Cations like K+, Na+ and Ca2+ and water are located in its pores and large cavities. Zeolites have high ion exchange capacity, selective adsorption capacity and thermal and mechanical stability.In this paper, the characterization of the natural zeolite - clinoptilolite from Bulgaria is performed. The investigated clinoptilolite was characterized in terms of its chemical composition, particle size distribution, structural morphology (SEM, XRD, FTIR) and thermal analysis. The chemical analysis show that clinoptilolite contains 69.7% of SiO2 and 11.4% of Al2O3. As specific surface area is the most important characteristic of the materials when used as adsorbents (the most common application of the zeolite) the specific surface area of clinoptilolite was obtained from data of equilibrium adsorption of water vapor at 25oC and using the BET method with nitrogen. To enhance its adsorptive properties clinoptilolite was modified (mechanically activated) and its specific surface area was also determined.

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Znak, Z. О., R. V. Мnykh, М. А. Pyrih et T. V. Zhuk. « RESEARCH OF OIL SORPTION BY NATURAL CLINOPTYLOLITE ». Chemistry, Technology and Application of Substances 5, n^o 2 (1 décembre 2022) : 58–64. http://dx.doi.org/10.23939/ctas2022.02.058.

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The sorption capacity of natural clinoptilolite of the Transcarpathian field in relation to the Boryslav field oil has been studied. It is shown that the sorption of oil occurs almost immediately after its contact with clinoptilolite. This forms the absorption front, which moves up the zeolite layer. Based on the analysis of the sorption process, it was concluded that lighter fractions of oil are sorbed faster and play the role of "solvent" for heavier fractions. It is shown that the sorption capacity of initial clinoptilolite is slightly higher than that of thermally activated. It was found that with increasing dispersion of clinoptilolite the mass of sorbed oil increases significantly, but the sorption capacity of different fractions, taking into account the height of the working layer differs slightly.

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Malecky, M., M. Shivazad et A. Nikkhah. « Effects of natural zeolite (clinoptilolite) on eggshell quality ». Proceedings of the British Society of Animal Science 2005 (2005) : 168. http://dx.doi.org/10.1017/s1752756200010796.

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Using inorganic additives is one suggested approach for improvement of performance or for preventing some disorders and poisoning of farm animals. One of those which use in animal diets is zeolite. There are more than 40 types of natural zeolites, of which one of the commonest is Clinoptilolite. Clinoptilolite has a relatively constant crystalline structure and has good adsorption properties. One of the most important problems in the poultry industry is low eggshell quality, particularly at end of lay. This leads to problems such as the breaking of egg in transport. Research on this has indicated positive effects of zeolites. Adding 1.5% clinoptilolite causes a significant increase in the calcium CA concentration of serum (Hossein et al., 1994). Olver (1989) observed a significant increase in eggshell thickness when 5% clinoptilolite was added to the diet of laying hens. The purpose of present study was to investigate the effect of different dietary concentrations of clinoptilolite on some blood parameters and eggshell quality.

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Lilkov, V., O. Petrov et Y. Tzvetanova. « Rheological, porosimetric, and SEM studies of cements with additions of natural zeolites ». Clay Minerals 46, n^o 2 (juin 2011) : 225–32. http://dx.doi.org/10.1180/claymin.2011.046.2.225.

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AbstractRheological, porosimetric, and SEM studies of cements with additions of natural zeolites (chabazite, mordenite and clinoptilolite) were investigated. The addition of 5% zeolite to cement pastes had a plastifying effect. The increase in the rheological parameters of aqueous cement–zeolite suspensions began after additions of more than 10% zeolite. At a water/solid ratio (w/s) = 0.5 all compositions exhibited similar rheological behaviour for yield stress and maximum shear stress values. At lower w/s values the rheology depended on the zeolite used, decreasing in the order Sl (clinoptilolite, Nižny Hrabovec deposit, Slovakia), M (mordenite, Philipines), Bp (clinoptilolite, Beli Plast deposit, Bulgaria), NM (clinoptilolite, Saint Cloud deposit, New Mexico) and Ch (chabazite, Nasm Yan deposit, Korea).After 28 days of hydration the mixtures containing 10% Bp clinoptilolite, mordenite, and Sl clinoptilolite (up to 30%) had unchanged specific pore volumes but additions of 10% and 30% of chabazite and NM clinoptilolite and of 30% mordenite and Bp clinoptilolite lead to increases in the total specific pore volume compared to the neat cement paste. Between the 28th and 180th days of hydration the specific volume of the pores in all the cement-zeolite pastes decreased due to the filling of the pores with products from the pozzolanic reaction between the zeolites and the hydration products of the cement.The pozzolanic reaction between zeolite and the hydration products of cement is enhanced by the zeolite content in the samples and depends on the Si/Al ratio (clinoptilolite (Si/Al >4.5), mordenite (Si/Al >5), chabazite (Si/Al <2.5)) and the surface area (clinoptilolite from Slovakia has the smallest crystallites and, hence, the greatest reactive surface area).

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Szala, Barbara, Tomasz Bajda et Anna Jeleń. « Removal of chromium(VI) from aqueous solutions using zeolites modified with HDTMA and ODTMA surfactants ». Clay Minerals 50, n^o 1 (mars 2015) : 103–15. http://dx.doi.org/10.1180/claymin.2015.050.1.10.

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AbstractThe removal of Cr(VI) from aqueous solutions under various conditions was investigated using a natural clinoptilolite and a synthetic zeolite derived from fly-ash (Na-P1), modified either with hexadecyltrimethylammonium bromide (HDTMA) or octadecyltrimethylammonium bromide (ODTMA). The study was focused mainly on the impact of the properties of the zeolite on the sorption capacity, the sorption mechanism, the influence of pH and the durability of the immobilization. The zeolites were modified with HDTMA and ODTMA surfactants up to 100% and 120% of their external cation exchange capacity. Batch and column studies were conducted to evaluate the influence of pH and the initial Cr(VI) concentration on their efficiencies for removing chromates. The organo-zeolites show a significant ability to remove Cr(VI) from aqueous solutions. The amount of Cr(VI) removed by organo-clinoptilolite and organo-zeolite Na-P1 is greater at low pH values, whereas the sorption efficiency decreased with increasing pH. Sorption of Cr(VI) was more efficient with the HDTMA-modified organo-clinoptilolite (150 mmol Cr(VI)/kg) than the ODTMA-modified clinoptilolite (132 mmol Cr(VI)/kg). The maximum sorption capacity was obtained with the 1.2 × ECEC ODTMA-modified clinoptilolite (237 mmol Cr(VI)/kg). The organozeolites Na-P1 adsorbed Cr(VI) from aqueous solutions more effectively and were much more durable than the organo-clinoptilolites.

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Forughirad, Abdollah, Ataallah Bahrami, Khalil Farhadi, Anahita Fathi Azerbaijani et Fatemeh Kazemi. « COMPARATIVE OF NATURAL ZEOLITE – CLINOPTILOLITE ELIMINATION OF METAL IONS/ESPECIALLY Cu (II) WITH D-PENICILLAMINE FROM BIOLOGICAL ENVIRONMENTS ». Rudarsko-geološko-naftni zbornik 36, n^o 4 (2021) : 11–19. http://dx.doi.org/10.17794/rgn.2021.4.2.

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Clinoptilolite is used as an adsorbent to remove heavy metal cations due to its function as a molecular sieve. This molecular sieve characteristic has made it possible to study the efficiency of clinoptilolite and D-Penicillamine in a comparative way in terms of the adsorption of heavy metals (especially copper) from a biological medium. For this purpose, clinoptilolite was subjected to grinding to produce a homogenized micronized powder in two sizes with d90=75 and 150 μm. Then, initial adsorption tests in an aqueous medium were performed on 10 ppm solutions of iron, zinc, copper, cadmium and nickel cations in single cation solutions, as well as a mixture of cations. In the next step, tests were performed to evaluate the adsorption of Cu2+ on clinoptilolite under different conditions. Experiments have been performed to investigate the effect of pH, temperature (T), adsorbent dosage, time and cation concentration in a simulated biological medium. According to the results, clinoptilolite has a high ability to remove metal cations from aqueous solutions. The 99.71% removal of copper cations by clinoptilolite indicates the high ability of this mineral to remove copper from any environment. In a simulated biological medium at pH=7 and 5, the copper adsorption rate was 98.18% and 97.45% respectively, which indicates the high ability of zeolite to absorb copper cations under biological conditions. An examination of the mass balance calculations has also shown the ability to replace clinoptilolite with penicillamine; 15 mg of clinoptilolite removes 214 mg of Cu from aqueous solutions, which is equivalent to the formation of copper-penicillamine chelate.

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Ramadhan, Anggara Diaz, Nindya Carolina C.S, Nuryoto Nuryoto et Teguh Kurniawan. « The Use of Natural Zeolite as A Catalyst for Esterification Reaction Between Glycerol and Oleic Acid ». Reaktor 19, n^o 4 (31 décembre 2019) : 172–79. http://dx.doi.org/10.14710/reaktor.19.4.172-179.

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Natural zeolite in Indonesia generally divided into 2 types, which are mordernite and clinoptilolite. As far the use of zeolites is very limited. This experiment tries to use both types of natural zeolites to find out its work. The purpose of this experiment is testing the performance of mordenite natural zeolite from Bayah-Indonesia and clinoptilolite from Lampung- Indonesia in the esterification reaction between glycerol and oleic acid integrated by several variable that affect the reaction. The experiment will be done by using three-neck rounded flask batch reactor. The result showed that modernite zeolite has a better performance compared to clinoptilolite zeolite. To get the oleic acid conversion of 70%, clinoptilolite zeolite needs 4% catalyst of glycerol weight and reactant ratio of 6:1 mole of glycerol/mole of oleic acid, Meanwhile the mordernite zeolite only needs 2% catalyst of glycerol weight with reactant ratio of 4:1 mole of glycerol/mole of oleic acid.Keywords: natural zeolite; glycerol; reaction; diffusion

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Faghihian, H., et M. Pirouzi. « Cis/trans-but-2-ene adsorption on natural and modified clinoptilolite ». Clay Minerals 44, n^o 3 (septembre 2009) : 405–9. http://dx.doi.org/10.1180/claymin.2009.044.3.405.

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AbstractAdsorption of cis-2-butene and trans-2-butene on clinoptilolite-rich tuff and ion-exchanged forms was investigated. Clinoptilolite samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, chemical analysis and nitrogen adsorption techniques. Adsorption isotherms for cis and trans 2-butene on purified clinoptilolite (Cp) and modified forms (Na-Cp, K-Cp, Ca-Cp and Mg-Cp) were obtained at pressures up to 2.7 atm. and at 25ºC. The results show that natural clinoptilolite has a considerable potential for separation of the two hydrocarbons. Mg-Cp samples showed maximal uptake of both cis-2-butene and trans-2-butene.

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Günal, Aytaç, et Burcu Erdoğan. « Ammonia removal by natural modified clinoptilolite ». Journal of the Serbian Chemical Society, n^o 00 (2022) : 51. http://dx.doi.org/10.2298/jsc211110051g.

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In this study, cation exchange and acid activation processes were applied to determine the effects of different cationic compositions of clinoptilolite on ammonia (NH3) adsorption properties. Thermogravimetric (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), X-ray fluorescence (XRF) and nitrogen adsorption techniques were used for the characterization of the clinoptilolite samples. As a result of ion exchange and acid activation, the amount, type, and location of exchangeable cations in the structure significantly affected the thermal properties as well as NH3 removal efficiency. Ammonia adsorption isotherms were obtained at 298 K up to 100 kPa volumetrically. In addition, NH3 adsorption capacities of the clinoptilolite samples within this study (3.823 to 5.372 mmol g-1) were compared with those of the other materials (1.77 to 12.2 mmol g-1) in terms of their textural and structural differences.

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Nikolov, Aleksander, Henk Nugteren, Ognyan Petrov, Ivan Rostovsky, Tanya Petrova et Zlatka Delcheva. « Synthesis of natural zeolite agglomerates : clinoptilolite-based geopolymers through aluminate activation ». Clay Minerals 54, n^o 4 (12 novembre 2019) : 393–400. http://dx.doi.org/10.1180/clm.2019.52.

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AbstractNatural zeolite (clinoptilolite)-based geopolymers were synthesized using alkali aluminate solution, including aluminate anodizing waste solution. The effect of calcination of the clinoptilolite sample at 900°C was investigated. The samples were studied by powder X-ray diffraction, thermal analysis, scanning electron microscopy and N2-specific surface area. The alkali aluminate-activated clinoptilolite geopolymers are characterized by satisfactory compressive strength (up to 37 MPa), low density and acceptable shrinkage. The clinoptilolite geopolymer obtained contains an X-ray amorphous phase and newly formed phillipsite and zeolite NaP. The presence of zeolite phases in the geopolymer agglomerate could be beneficial in products with specific qualities and properties, such as ion exchange, passive cooling, antimicrobial activity, etc.

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Cinar, S., et B. Beler-Baykal. « Ion exchange with natural zeolites : an alternative for water softening ? » Water Science and Technology 51, n^o 11 (1 juin 2005) : 71–77. http://dx.doi.org/10.2166/wst.2005.0392.

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Possibility of using natural zeolites for water softening was investigated. Quantitative data regarding separation of calcium from water at various levels of hardness through ion exchange with the ammonium selective natural zeolite clinoptilolite is reported. Capacity of the zeolite towards calcium removal in the presence of ammonium at low concentrations and calcium at higher concentrations, and breakthrough characteristics are presented. The results have revealed that removal of calcium, and hence hardness, through ion exchange with clinoptilolite under those circumstances is a promising alternative, with surface capacities reaching 11 mg calcium/g clinoptilolite.

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Hosseini, Asieh, Alireza Ebadollahi-Natanzi, Mohammad Foroughi et Seyed V. Shetab-Boushehri. « Barium- and Bismuth-loaded Clinoptilolite Micro- and Nano-Particles as Proposed New Efficient Contrast Agents ». Combinatorial Chemistry & ; High Throughput Screening 23, n^o 3 (19 mai 2020) : 191–95. http://dx.doi.org/10.2174/1386207323666200218113537.

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Aim and Objective: Clinoptilolite is one of the natural zeolites. Clinoptilolite particles have a high surface area, negative surface charge, cation adsorption and exchange capacities. Barium sulfate (BaSO4) and bismuth subnitrate (Bi5H9N4O22) suspensions have been used for upper and lower gastrointestinal imaging but Ba2+ and Bi3+ ions are toxic. In the present study, the feasibility of the application of Ba2+- and Bi3+-loaded clinoptilolite micro- and nano-particles in medical imaging was investigated. Materials and Methods: Nanoparticles and microparticles of natural clinoptilolite were loaded with Ba2+ and Bi3+ ions. Radiopacities of loaded particles were measured and compared with those of BaSO4 and Bi5H9N4O22. Results: Ba2+- and Bi3+-loaded clinoptilolite nanoparticles and microparticles showed more intense X-ray opacities than BaSO4 and Bi5H9N4O22 with equimolar concentrations. Moreover, Ba2+- and Bi3+-loaded clinoptilolite nanoparticles more intensely absorbed X-ray than respective loaded microparticles. Conclusion: The present study proposes Ba2+- and Bi3+-loaded clinoptilolite nanoparticles and microparticles as new, safe, efficient, and inexpensive contrast agents.

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Alsawalha, Murad. « Overview of Current and Future Perspectives of Saudi Arabian Natural Clinoptilolite Zeolite : A Case Review ». Journal of Chemistry 2019 (3 mars 2019) : 1–16. http://dx.doi.org/10.1155/2019/3153471.

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After a thorough review of existing studies of clinoptilolite zeolites, three areas for potential investigation of the Saudi Arabian zeolites were found. They are the characterizations, the catalytic activity, active sites, and uses of natural clinoptilolite zeolites. First, no analysis is available worldwide to compare the percentage weight of local zeolites with those sourced from other countries, nor does one exist for the establishment on the zeolite conversion of MBOH with water on acidic catalysts at lower temperatures. Secondly, a review of current literature on the topic revealed that basic and active sites of Saudi Arabian zeolites have yet to be examined. Future investigation of zeolite catalytic activity can be achieved by methyl butynol test reaction (MBOH) and absorption-desorption of ammonia. In the characterization of a range of international materials, the methyl butynol test reaction was utilized, including on natural zeolites, natural clays, and synthesized hydrotalcites. However, the catalytic performance of natural Saudi Arabian clinoptilolite zeolites by test reaction of MBOH conversion has not been yet investigated. Therefore, this article also includes an outline of the general testing conditions and parameters required to execute the accurate characterization of local Saudi clinoptilolite under optimal test conditions. Likewise, knowledge of the important active acidic centers of local materials is prescribed. This can be ascertained by determining the conditions together with the test parameters for the application of the “temperature-programmed desorption of ammonia” method in order to obtain an accurate determination of local Saudi clinoptilolite acidic centers. Additionally, an outline of the catalytic activity of worldwide clinoptilolite is given in this article together with kinetic investigations of other sources for the clinoptilolite zeolite in order to form the basis for the testing of local Saudi clinoptilolite. The percentage average of chemical composition (Wt.%) of natural clinoptilolite from various countries is also included. Finally, a future research plan is proposed here. This will form the basis for a complete study or survey to be compiled detailing the modifications needed to increase the surface areas for Saudi natural clinoptilolite zeolites using different methods of modifications. This could enhance its application as acid catalysts for use in the retardation of coke formation and for membrane separation on cationic exchange.

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Rodríguez-Iznaga, Inocente, Marina G. Shelyapina et Vitalii Petranovskii. « Ion Exchange in Natural Clinoptilolite : Aspects Related to Its Structure and Applications ». Minerals 12, n^o 12 (17 décembre 2022) : 1628. http://dx.doi.org/10.3390/min12121628.

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Clinoptilolite is one of the most common, widespread and abundant zeolites in nature. Its availability, low cost, and outstanding ion exchange properties make clinoptilolite an excellent candidate for both direct use and various modifications to create new low-cost functional materials for sustainable development. Specific applications in which clinoptilolite is already being used include water treatment and heavy metal ion removal, agricultural purposes, storage and conversion of unwanted gaseous emissions into the atmosphere, production of catalysts and photocatalysts, bioactive materials, and a number of others. Unlike some other zeolites, clinoptilolite is difficult to synthesize, which is why most publications refer to this zeolite in its natural form, either directly from the deposit or after applying various processes to this mineral to improve its properties. Among the modification methods used, ion exchange stands out. This review is devoted to the study of ion exchange processes in natural clinoptilolite with two goals: first, as its strategic property for use in processes in which cation exchange is fundamentally necessary; second, as a way to modify it to create composite materials with predetermined desired properties.

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Sheydaei, Mohsen, Ali Balanejad Gasemsoltanlu et Asadollah Beiraghi. « Optimization of ultrasonic-assisted copper ion removal from polluted water by a natural clinoptilolite nanostructure through a central composite design ». Clay Minerals 54, n^o 4 (23 septembre 2019) : 339–47. http://dx.doi.org/10.1180/clm.2019.46.

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AbstractA natural clinoptilolite nanostructure (CNS) along with ultrasonic irradiation was used to remove Cu2+ ions from polluted water. In the first part of this work, natural clinoptilolite was converted to CNS by ball milling. The natural clinoptilolite and prepared CNS samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction, N2 adsorption/desorption and pH at the point of zero charge analyses. The SEM images showed the development of CNS from natural clinoptilolite by ball milling. The N2 adsorption/desorption and FTIR spectroscopy confirmed the greater specific surface area, pore volume and number of surface groups of the CNS compared to the natural clinoptilolite. In addition, the crystalline phase of the CNS was the same as the natural clinoptilolite. In the second part of this work, the ultrasonic-assisted sorption of Cu2+ ions from polluted water by CNS was investigated. These experiments were optimized with response surface methodology based on central composite designs. The effects of initial pH of solution, CNS dosage, sonication time and temperature on Cu2+ ion-removal efficiency were investigated. By using a CNS dosage of 500 mg L−1, an initial pH of 6, a sonication time of 12 min and a sonication temperature of 45°C as optimal conditions, 97% of Cu2+ ions were removed from contaminated water. The initial pH was the most effective variable. Ultrasonic-assisted sorption of Cu2+ was more effective than sorption alone, onto the CNS.

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Kasture, M. W., P. N. Joshi, H. S. Sorti, V. V. Joshi, A. L. Choudhari et V. P. Shiralkar. « Sorption Properties of the Natural, K and Partially Deammoniated (H/NH4) Forms of Clinoptilolite ». Adsorption Science & ; Technology 16, n^o 2 (mars 1998) : 135–51. http://dx.doi.org/10.1177/026361749801600207.

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A sample collected from the Aurangabad District, Maharashtra, India was characterized by XRD, IR, TG and DTA methods, and by chemical analysis, as a calcium-rich clinoptilolite. Two different methods involving exchange with KOH or NH4Cl led to the formation of K-clinoptilolite (K-Clino) and H/NH4-clinoptilolite (H/NH4-Clino). Water sorption studies were carried out on the parent clinoptilolite (P-Clino), K-Clino and H/NH4-Clino at five different temperatures in the range 303–423 K. Different adsorption models were applied to the data obtained from such sorption studies. Thermodynamic parameters such as the chemical potential were also computed from the sorption data and their significance is discussed.

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Çelik, M. S., B. Özdemir, M. Turan, I. Koyuncu, G. Atesok et H. Z. Sarikaya. « Removal of ammonia by natural clay minerals using fixed and fluidised bed column reactors ». Water Supply 1, n^o 1 (1 janvier 2001) : 81–88. http://dx.doi.org/10.2166/ws.2001.0010.

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A series of fixed and fluidised bed ion exchange column runs were conducted to identify the ability of natural clay minerals, sepiolite and clinoptilolite, to remove ammonia from a contaminated drinking water reservoir. Ion exchange column tests using both fixed and fluidised bed were initially carried out with synthetic water composed of NH4Cl. Breakthrough curves as a function of flow rate, particle size, and initial ammonia concentration reveal that sepiolite does not have as high ion exchange capacity as clinoptilolite but maintains a steady adsorption up to higher bed volumes. The adsorption capacity was modified by using regeneration cycles at both acidic and alkaline pH. Furthermore, fluidised bed runs with clinoptilolite utilising water and air as fluidiser resulted in inferior results compared to those of fixed bed runs. This was respectively ascribed to the presence of ammonia in the circulating water and competition of exchangeable ions released in water and the ability of air to adsorb nitrogen. Tests conducted with natural raw water contaminated with sewage indicated that clinoptilolite adsorbs ammonia the same as the synthetic water. Regenerated clinoptilolite is capable of removing ammonia from both synthetic and actual raw water at a much higher rate than the untreated clinoptilolite.

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Wei, Wei, Duan Lian-Yun et Xie You-Chang. « Dispersion of Urea in Natural Clinoptilolite ». Acta Physico-Chimica Sinica 16, n^o 05 (2000) : 472–75. http://dx.doi.org/10.3866/pku.whxb20000520.

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Pogorelov, A. G., A. I. Panait, A. A. Gulin, A. A. Stankevich, V. N. Pogorelova et G. R. Ivanitskii. « Natural Clinoptilolite Nanoparticles Coated with Phosphatidylcholine ». Doklady Biochemistry and Biophysics 505, n^o 1 (août 2022) : 156–59. http://dx.doi.org/10.1134/s160767292204007x.

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Rahimi, Monireh, et Jafar Mahmoudi. « Heavy Metals Removal from Aqueous Solution by Modified Natural Zeolites Using Central Composite Design ». Periodica Polytechnica Chemical Engineering 64, n^o 1 (27 mai 2019) : 106–15. http://dx.doi.org/10.3311/ppch.13093.

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Removal of heavy metals including Pb, Co, Cr and Zn from an aqueous solution was investigated using modified clinoptilolite zeolites as adsorbents. The adsorbents were characterized by X-ray, FTIR, SEM and BET. The central composite design defined under response surface methodology was applied for design of experiments. According to the results, clinoptilolite/MgO showed higher capacity for absorption of lead (98.38 %) in comparison to clinoptilolite/NaOH. The removal percentage of Co, Cr and Zn was obtained 89.51 %, 81.07 % and 78.24 %, respectively, using clinoptilolite/MgO. Moreover, the equilibrium experimental data well fitted the Freundlich isotherm model, as compared with the Langmuir isotherm. The results show that the complete regeneration of adsorbents can be achieved at room temperature using NaCl (0.35 M).

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Ji, Zhi Yong, Jun Sheng Yuan et Min Su. « Modification of Natural Clinoptilolite and its Uptake of NH₄⁺ ». Advanced Materials Research 178 (décembre 2010) : 191–95. http://dx.doi.org/10.4028/www.scientific.net/amr.178.191.

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Natural clinoptilolite collected from Chicheng of Hebei province in China, was treated with physical modification using sodium/ammonium salts, chemical modification using NaOH or NaAlO2, and physicochemical modification using NaOH or NaAlO2 and NaCl in order, respectively. And its adsorption capacity of NH4+ in different conditions was investigated. The results show that modified clinoptilolite has the same crystal structure, and the clinoptilolite modified with NaOH or NaAlO2 has good uptake of ammonia ion; the concentration of NaAlO2 has apparent influence on the removal of ammonia nitrogen, and the perfect concentration is 0.1 mol/L and the uptake could reach 0.92 mmol/g in the 100 mg/L NH4+ solution; the existence of K+、Na+、Ca2+、Mg2+ decreases the uptake of ammonia ion on clinoptilolite modified with 0.1 mol/L NaAlO2.

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Milyovich, S. S., V. I. Gomonaj, I. P. Stercho et S. V. Kremsa. « SORPTION OF FERUM IONS ON NATURAL AND MODIFIED CLINOPTYLOLITE. INFLUENCE OF OXYDANTS ». Scientific Bulletin of the Uzhhorod University. Series «Chemistry» 46, n^o 2 (10 février 2022) : 86–91. http://dx.doi.org/10.24144/2414-0260.2021.2.86-91.

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The health of the population depends on the state of the environment, so the study of opportunities to improve the condition of water, air and soil does not lose its actual. The presence of substances in waters in concentrations is higher than the maximum permissible concentration can be caused by both human economic activity and the peculiarities of the geological structure of the lithosphere of the region. For example, high iron content is observed in the natural waters of many regions of the world. Although iron is an important element in human life, its excess in the body can cause many diseases. Removal of iron ions from water has a high cost, so reducing the cost of this process is an urgent issue. One of the options to reduce the cost of the process is to use natural zeolites, such as clinoptilolite. One of the largest deposits of clinoptilolite in Europe is located in the village Sokyrnytsia, Transcarpatian region. In this work, the sorption of iron ions on the natural clinoptilolite of the Sokyrnytsia deposit and its modified forms under static conditions has been studied. Any of the proposed modification methods has a positive effect on the sorption properties of clinoptilolite with respect to iron ions, the amount of Fe ions sorption increases for hydrogen form by 30%, ammonium form by 60% and sodium form by 65% are shown. The influence of oxidants (hydrogen peroxide) on the sorption of iron ions on clinoptilolite of the Sokyrnytsia deposit (Ukraine) has been studied. The significant influence of iron oxidation before sorption on the growth of its extraction from water by natural clinoptilolite is shown, which is confirmed by thermodynamic calculations performed by the semi-empirical method GFN2- xTB (density functional theory), which indicate that only ion exchange reaction involving Fe3+. And if the exchange ion is a Na+ ion, ion exchange sorption can occur with both Fe3+ and Fe2+. Isotherms of ion-exchange sorption of iron in the range of concentrations from 0.05 mmol/l to 1 mmol/l are well described by the Langmuir equation. Sorption isotherms in the coordinates 1 / A = f (1 / C) are linear. Keywords: clinoptilolite; iron; ion exchange; oxydants.

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Omerasevic, Mia, Jovana Ruzic, Nikola Vukovic, Uros Jovanovic, Miljana Mirkovic, Vesna Maksimovic et Vera Dondur. « Removal of Cs ions from aqueous solutions by using matrices of natural clinoptilolite and its safe disposal ». Science of Sintering 48, n^o 1 (2016) : 101–7. http://dx.doi.org/10.2298/sos1601101o.

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The possibility to use natural zeolite - clinoptilolite as a host material for radioactive Cs immobilization has been investigated. Cs-exchanged form of clinoptilolite which was prepared by treatment of clinoptilolite powder with 0.25 M CsCl solution was compacted. Both, powder and powder compact of exchanged clinoptilolite were thermally treated at 1200?C. The XRPD analysis showed that Cs was successfully immobilized after heat treatment by formation of stable cesium dodecaoxo-alumopentasilicate in both, powder sample and compact. The newly formed compound showed satisfactory Cs ions retention during leaching test. The sintered compact showed somewhat better resistance to Cs leaching than the thermally treated powder. The compressive strength of sintered compact was close to 200 MPa which is more than enough for easy handling and safe storage.

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Dimowa, L. T., O. E. Petrov, N. I. Djourelov et B. L. Shivachev. « Structural study of Zn-exchanged natural clinoptilolite using powder XRD and positron annihilation data ». Clay Minerals 50, n^o 1 (mars 2015) : 41–54. http://dx.doi.org/10.1180/claymin.2015.050.1.05.

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AbstractZn-exchanged natural clinoptilolite was studied by powder X-ray diffraction and positron annihilation lifetime spectroscopy. The original clinoptilolite tuff was subjected to size fractionation by sedimentation and dissolution of cristobalite (opal-C). After Zn2+-exchange the purified clinoptilolite sample contained 2.2 Zn2+ ions per unit cell. Structural details obtained by Rietveld refinement showed that the Zn2+ cations are located in three sites (Zn1, Zn2 and Zn3) in the channels of the clinoptilolite. Site Zn1 is located in the centre of channel-A (Mg2+-M4 site). Site Zn2 is in channel-B, next to the calcium M2 position. A new Zn3 site is located in channel-A, in imminent proximity to Zn1. Positron Annihilation Lifetime Spectroscopy (PALS) was employed to assess the Zn exchange. As the cation content influences the free volume of the channels, the ionexchange process can be monitored by PALS. The results suggest the existence of two sizes of cavities, in accordance with the structural refinement.

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Nadaroglu, Hayrunnisa, Ekrem Kalkan, Neslihan Celebi et Esen Tasgin. « Removal of Reactive Black 5 from wastewater using natural clinoptilolite modified with apolaccase ». Clay Minerals 50, n^o 1 (mars 2015) : 65–76. http://dx.doi.org/10.1180/claymin.2015.050.1.07.

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AbstractIn this study, a clinoptilolite modified with apolaccase was used to adsorb Reactive Black 5 (RB5) dye from aqueous solution using the batch procedure. The influences of pH, contact time, temperature and absorbent dosage on the adsorption were investigated. The optimum adsorption was obtained at pH = 6, contact time = 60 min, temperature = 25ºC and adsorbent dosages of 1.62 and 1.59 mg/50 mL per gram of clinoptilolite and of apolaccase-modified clinoptilolite (LMC), respectively). The adsorption experimental data fitted both the Langmuir and Freundlich isotherm models well. In addition, pseudo-first-order and pseudo-second-order kinetics were used to study the kinetics of RB5 dye adsorption onto natural clinoptilolite and LMC. Adsorption appears to follow pseudo-second-order kinetics with a high correlation coefficient. Thermodynamic parameters such as changes in the free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) of adsorption were calculated. The thermodynamic parameters indicate that the adsorption of RB5 dye onto LMC was less spontaneous, feasible and endothermic. The LMC can be used as an alternative low-cost adsorbent for the dye removal from aqueous solutions.

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VITOROVIC, G., B. SLAVATA et K. STOSIC. « The effect of clinoptilolite on 137 Cs binding in broiler chickens ». Agricultural and Food Science 11, n^o 2 (2 janvier 2002) : 137–41. http://dx.doi.org/10.23986/afsci.5716.

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The objective of this study was to evaluate the 137 Cs binding capacity of clinoptilolite.In the first in vitro experiment we investigated sorption of 137 Cs to natural and modified forms of clinoptilolite in highly acid solution,prepared to be similar to that of the gut of pigs (pH =2 3)at 37 ºC.In the second in vivo experiment 137 Cs binding to a modified form of clinoptilolite was studied in orally contaminated broiler chickens.137 Cs sorption in the high acidity solution depended on clinoptilolite concentration and varied between 30 85 %of the initial activity.In the chickens,three hours after 137 Cs administration,there was 67%and 63%lower accumulation of 137 Cs in meat and edible organs (respectively)and seven hours after 137 Cs administration,there was 69% and 49% lower accumulation of 137 Cs in meat and edible organs (respectively)compared to the controls with no clinoptilolite added in food. Natural and modified forms of clinoptilolite have been shown to high sorption efficiency towards 137 Cs ions and could be recommended as possible radiocaesium binders in domestic animals.;

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Retajczyk, Monika, Agnieszka Wróblewska, Alicja Szymańska et Beata Michalkiewicz. « Isomerization of limonene over natural zeolite-clinoptilolite ». Clay Minerals 54, n^o 2 (22 avril 2019) : 121–29. http://dx.doi.org/10.1180/clm.2019.18.

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AbstractThe isomerization of limonene over natural the zeolite, clinoptilolite, was studied. The main products of limonene isomerization were terpinolene, α-terpinene, γ-terpinene and p-cymene. These products have numerous applications in the cosmetic, food and pharmaceutical industries. The main parameters affecting limonene isomerization were reaction time, temperature and catalyst content. These parameters varied within the following ranges: reaction time 15–1440 min; temperature 155–175°C; and catalyst content 5–15 wt.%. Terpinolene was obtained after reaction for 60 min at 175°C using 10 wt.% catalyst. p-Cymene was produced using similar conditions as for terpinolene except for a longer reaction time of 1440 min. The use of optimum experimental conditions allowed the greatest amounts of the desired products to be obtained in the shortest time.

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Li, Zhaohui. « Sorption Kinetics of Hexadecyltrimethylammonium on Natural Clinoptilolite ». Langmuir 15, n^o 19 (septembre 1999) : 6438–45. http://dx.doi.org/10.1021/la981535x.

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Dyer, Alan, et Kevin J. White. « Cation diffusion in the natural zeolite clinoptilolite ». Thermochimica Acta 340-341 (décembre 1999) : 341–48. http://dx.doi.org/10.1016/s0040-6031(99)00280-4.

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Katranas, Theodoros K., Athanasios G. Vlessidis, Vassilis A. Tsiatouras, Kostas S. Triantafyllidis et Nicholaos P. Evmiridis. « Dehydrogenation of propane over natural clinoptilolite zeolites ». Microporous and Mesoporous Materials 61, n^o 1-3 (juillet 2003) : 189–98. http://dx.doi.org/10.1016/s1387-1811(03)00367-6.

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Rodríguez-Fuentes, Gerardo, Aramis Rivera Denis, María A. Barrios Álvarez et Antonio Iraizoz Colarte. « Antacid drug based on purified natural clinoptilolite ». Microporous and Mesoporous Materials 94, n^o 1-3 (septembre 2006) : 200–207. http://dx.doi.org/10.1016/j.micromeso.2006.03.032.

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Dyer, A., et K. J. White. « The manganese content of a natural clinoptilolite ». Zeolites 5, n^o 2 (mars 1985) : 71–73. http://dx.doi.org/10.1016/0144-2449(85)90076-4.

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Yang, Sanyuan, Alexandra Navrotsky et Rick Wilkin. « Thermodynamics of ion-exchanged and natural clinoptilolite ». American Mineralogist 86, n^o 4 (avril 2001) : 438–47. http://dx.doi.org/10.2138/am-2001-0407.

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Copcia, Violeta Elena, Camelia Luchian, Simona Dunca, Nicolae Bilba et Claudia Mihaela Hristodor. « Antibacterial activity of silver-modified natural clinoptilolite ». Journal of Materials Science 46, n^o 22 (novembre 2011) : 7121–28. http://dx.doi.org/10.1007/s10853-011-5635-0.

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Kepák, F., S. Koutová, M. Kočiřík et A. Zikánová. « Removal of RuO4 vapors on natural clinoptilolite ». Journal of Radioanalytical and Nuclear Chemistry Articles 159, n^o 2 (juin 1992) : 317–34. http://dx.doi.org/10.1007/bf02040726.

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Vasylechko, Volodymyr O., Viktor O. Fedorenko, Oleksandr M. Gromyko, Galyna V. Gryshchouk, Yaroslav M. Kalychak, Olga A. Zaporozhets et Mariya T. Lototska. « Solid phase extractive preconcentration of silver from aqueous samples and antimicrobial properties of the clinoptilolite–Ag composite ». Adsorption Science & ; Technology 35, n^o 7-8 (25 avril 2017) : 602–11. http://dx.doi.org/10.1177/0263617417703509.

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Sorptive properties of the Transcarpathian clinoptilolite compared to Ag(I) were studied in a dynamic way. The sorptive capacity value of clinoptilolite under the optimal conditions is 11.7 mg of Ag per 1 g of zeolite. The solid-phase extraction procedure with natural clinoptilolite thermally activated at 550℃ was used to preconcentrate trace amounts of silver ions in aqueous solutions to be finally determined by the atomic absorption method. It was established that the Ag–clinoptilolite composite has a powerful antimicrobial effect against gram-negative bacteria and yeasts as well as affects significantly vital activity of Staphylococcus aureus.

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Nikashina, V. A., A. N. Streletsky, I. V. Kolbanev, I. N. Meshkova, V. G. Grinev, I. B. Serova, T. S. Yusupov et L. G. Shumskaya. « Properties of mechanically activated natural clinoptilolite and chabazite ». Clay Minerals 46, n^o 2 (juin 2011) : 329–37. http://dx.doi.org/10.1180/claymin.2011.046.2.329.

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AbstractThe effect of mechanical activation on the ion-exchange selectivity of natural zeolites from Russia, namely clinoptilolite-bearing tuffs and chabazites, was studied. The structural modifications and thermal properties were investigated, and the specific surface area and porosity of mechanically activated zeolites were determined. At activation doses of up to 1.0 kJ g–1 the main processes are the breakdown of the zeolite particles and pore structure changes. At greater activation doses amorphization takes place. It was shown that during the initial stage of activation in most cases the clinoptilolite selectivity for Sr2+ increased slightly and then decreased; the selectivity for Cu2+ increased 100 times; and the selectivity of chabazite-1 for Sr2+ increased 300 times.

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Alvarez-Aguiñaga, Edith A., María P. Elizalde-González et Sergio A. Sabinas-Hernández. « Unpredicted photocatalytic activity of clinoptilolite–mordenite natural zeolite ». RSC Advances 10, n^o 64 (2020) : 39251–60. http://dx.doi.org/10.1039/d0ra06421a.

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Clinoptilolite + mordenite are self-photocatalytic in the decomposition of caffeine under UV-irradiation because endogenous iron originates photoinduced species and intermediates are confined in zeolite nanopores.

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Dosa, Melodj, Nadia Grifasi, Camilla Galletti, Debora Fino et Marco Piumetti. « Natural Zeolite Clinoptilolite Application in Wastewater Treatment : Methylene Blue, Zinc and Cadmium Abatement Tests and Kinetic Studies ». Materials 15, n^o 22 (18 novembre 2022) : 8191. http://dx.doi.org/10.3390/ma15228191.

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In recent decades, several abatement techniques have been proposed for organic dyes and metal cations. In this scenario, adsorption is the most known and studied. Clinoptilolite was considered, since it is a zeolite with a relatively low cost (100–600 $ tons−1) compared to the most well-known adsorbent used in wastewater treatment. In this work, Clinoptilolite was used for the adsorption of Methylene Blue (MB) at three different concentrations, namely, 100, 200, and 250 ppm. Furthermore, the adsorption capacity of the natural zeolite was compared with that of Activated Charcoal (250 ppm of MB). The two adsorbents were characterized by complementary techniques, such as N2 physisorption at −196 °C, X-ray diffraction, and field emission scanning electron microscopy. During the adsorption tests, Clinoptilolite exhibited the best adsorption capacities at 100 ppm: the abatement reached 98% (t = 15 min). Both Clinoptilolite and Activated Charcoal, at 250 ppm, exhibited the same adsorption capacities, namely, 96%. Finally, at 250 ppm MB, the adsorption capacity of Clinoptilolite was analyzed with the copresence of Zn2+ and Cd2+ (10 ppm), and the adsorption capacities were compared with those of Activated Charcoal. The results showed that both adsorbents achieved 100% MB abatement (t = 40 min). However, cation adsorption reached a plateau after 120 min (Zn2+ = 86% and 57%; Cd2+ = 53% and 50%, for Activated Charcoal and Clinoptilolite, respectively) due to the preferential adsorption of MB molecules. Furthermore, kinetic studies were performed to fully investigate the adsorption mechanism. It was evidenced that the pseudo-second-order kinetic model is effective in describing the adsorption mechanism of both adsorbents, highlighting the chemical interaction between the adsorbent and adsorbate.

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MYAKUSH, Oksana, et Leonid SYSA. « FEATURES OF EXTRACTION OF COPPER, ZINC AND NICKEL IONS FROM AQUEOUS SOLUTIONS BY NATURAL SORBENTS, ACTIVATED MICROWAVES ». Proceedings of the Shevchenko Scientific Society. Series Сhemical Sciences 2020, n^o 60 (25 février 2020) : 55–67. http://dx.doi.org/10.37827/ntsh.chem.2020.60.055.

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The article is a continuation of a series of scientific works of the authors on the study of the influence of microwave irradiation on the sorption parameters of natural sorbents in the processes of purification of natural and wastewater. Using the atomic absorption method, the sorption ability of the natural sorbent clinoptilolite (zeolite type of structure) to remove Copper, Zinc and Nickel ions from aqueous solutions was studied. It was found that different variants of microwave activation of this mineral (series «Nat», «Stim» and «DIR») lead to a significant increase in the sorption capacity of clinoptilolite by ions of these heavy metals. It is shown that in comparison with similar activation schemes of another natural sorbent of bentonite (clay material), the improvement of sorption parameters of clinoptilolite with respect to heavy metals is not as significant as in the case of bentonite. It is confirmed that in almost all solutions the deposition of heavy metals on clinoptilolite occurs according to the Langmuir or Langmuir-Freundlich model. A similar situation was observed in previous works of the authors on the deposition of heavy metals on bentonite. Using scanning electron microscopy, energy dispersion spectroscopy and X-ray phase analysis, it was found that the deposition of heavy metals on both bentonite and clinoptilolite occurs not only in the form of monolayers of hydrated ions in sorbent micropores (classical model), but also in the form of individual compounds. metals. It has been suggested that the action of microwaves on these sorbents in aqueous solutions improves the structure of their micropores and affects the surface charge, so some parts of the adsorbent become active centers of crystallization of new phases - heavy metal compounds. During adsorption of heavy metal by natural bentonite or clinoptilolite, low-energy adsorption centers predominate, whereas in the case of microwave-irradiated samples of these sorbents, the experimental data correspond to a symmetric quasi-Gaussian distribution of adsorption energy where low- and high-energy regions are present. This fact indicates that electromagnetic treatment stimulates the formation of new adsorption centers.

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Akgün, Yasemin, et Talha Yılmaz. « The Heat Storage Capacities of Mortars Containing Clinoptilolite Blended Cements ». Academic Perspective Procedia 2, n^o 3 (22 novembre 2019) : 758–67. http://dx.doi.org/10.33793/acperpro.02.03.83.

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Recently, the studies on the heat storage capabilities of building materials for energy efficient building design are becoming more widespread. In this study, the heat storage capacities of mortars produced with blended cement containing clinoptilolite that is the most valuanle of the natural zeolite minerals were investigated. The clinoptilolite which is used as replacement material and has the highest purity rate (96% purity) in the world was obtained from Manisa-G&ouml;rdes region. Firstly, the mortar samples containing clinoptilolite blended cements at 0, 10, 30 and 50% replacement ratios were produced. And then, the physical, chemical, mechanical, petrographic properties, thermal conductivity and heat storage capacities of clinoptilolite rock were determined. The compressive strengths and thermal performance tests were performed on the mortar samples containing clinoptilolite blended cements. The test results were compared amongst themselves and with each other. According to the test results, it was concluded that heat storage capabilities of the mortars containing clinoptilolite blended cements could be improved.

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Zuliyana, Said, Alrozi Rasyidah, Senusi Faraziehan et Mohamad Anuar Kamaruddin. « Removal of Binary Metal (Nickel and Lead) Ions from Aqueous Solution Using Natural and Modified Clinoptilolite ». Applied Mechanics and Materials 661 (octobre 2014) : 45–50. http://dx.doi.org/10.4028/www.scientific.net/amm.661.45.

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In this study, adsorption of binary metal (Ni(II) and Pb(II)) ions from aqueous solution by using natural (NC), acid-modified (AC) and base-modified (BC) clinoptilolite were investigated to determine the effects of adsorbent dosage, metal solution’s pH and initial metal solution concentration. From the adsorption studies, the optimum dosage of adsorbent was found to be 2.0g for all adsorbents (NC, AC and BC) specifically for removal of Pb(II). In contrast, optimum dosage of for removal of Ni(II) was found to be 2.0g for NC and 4.0g for both AC and BC, respectively. The average pH for Ni(II) and Pb(II) ion solutions were 6. It was further observed that, the percentage removal of Ni(II) was largely influenced by the presence of lead due to the preference of Pb2+ ions by the natural and modified clinoptilolites.

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Ghazi, Noor Azhana, Nik Ahmad Nizam Nik Malek et Hamdan Salehhuddin. « Cytostatic Activity of Clinoptilolite against Human Cervical Cancer Cell Lines Using Three Different Media-Sterilization Techniques ». Advanced Materials Research 626 (décembre 2012) : 667–71. http://dx.doi.org/10.4028/www.scientific.net/amr.626.667.

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Clinoptilolite has been proven useful in cancer therapy in the last decade. The use of natural zeolite such as clinoptilolite requires some purification of the raw material before it can be applied in biomedical applications, yet microorganism contamination is still viewed as a possible issue for most researchers. Therefore, the clinoptilolite-treated media must undergo filter sterilization process prior to its use in any in vitro research of human cell studies. The aim of this study was to determine whether clinoptilolite cytostatic effect on cervical cancer (HeLa) cells will differ when a different media-sterilization technique is used on the clinoptilolite-treated medium. Comparison of the effect of clinoptilolite-treated medium on cell cytostatic activity was made between three sterilization methods; heat sterilization using an autoclave, UV radiation and filter sterilization. Results showed that there were inhibition of HeLa cell growth after clinoptilolite treatment in all three media-sterilization techniques. Significant differences were shown in all except between sterilizing using UV radiation and filter sterilization. This proved that in vitro cytostatic activity of clinoptilolite on human cervical cancer cells may be affected if different sterilization methods are used to sterilize the pre-treated media. Nonetheless, filter sterilization is still the preferred choice for sterilizing treated-media in cell culture. Keywords: Zeolite, clinoptilolite, cytotoxicity, cancer cell lines, sterilization.

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Czapik, Przemysław. « The Impact of Ions Contained in Concrete Pore Solutions on Natural Zeolites ». Materials 16, n^o 4 (8 février 2023) : 1416. http://dx.doi.org/10.3390/ma16041416.

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This article investigates the relationships between different chemical compositions of simulated cement concrete pore solutions and changes on the surface of zeolite rock with potassium clinoptilolite as its main component. The changes were studied using X-ray diffraction (XRD), thermal analysis (DTA-TG) and scanning electron microscopy (SEM). Zeolite powder samples and a ground section of 16–64 mm grain were tested. The simulated pore solutions were based on Ca, Na, K hydroxides and K2SO4. It was found that 100% of Ca(OH)2 in the systems could react between 7 and 180 days of hydration due to pozzolanic and side reactions. As the degree of clinoptilolite conversion increased, it became more difficult to detect it in X-ray patterns. At the same time, various microstructural changes could be observed. As a result of the reactions that occurred, hydrated calcium silicates, sulfate and carbonate compounds were formed. Potassium hydroxide had a more substantial effect on clinoptilolite reactivity than sodium hydroxide. This effect can be enhanced by the presence of SO23− ions in the solution.

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Di, Yonghao, Xiangwei Zhang, Xinlin Wang et Shuilin Zheng. « Construction of BiOCl/Clinoptilolite Composite Photocatalyst for Boosting Formaldehyde Removal ». Materials 14, n^o 21 (28 octobre 2021) : 6469. http://dx.doi.org/10.3390/ma14216469.

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Binary composite was synthesized via coupling BiOCl with alkali leached natural clinoptilolite (40B0/CN), which showed retarded recombination of photo-generated carriers. The clinoptilolite was pretreated with alkali leaching, resulting in a larger pore size and high cation exchange capacity. The modified clinoptilolite was more feasible for the growth of BiOCl and to promote the adsorption ability for formaldehyde (HCHO). In addition, the cation exchange capacity was conducive to anchor Bi3+, further leading to the reduction of the particle size of BiOCl. The carrier effect of alkali leached natural clinoptilolite promoted the amorphous transformation of BiOCl at low temperature, which simultaneously produced more distortions and defects in the BiOCl lattice. The 40B0/CN composite exhibited the superior light absorption ability with a narrower band gap. The photocatalytic degradation rate for HCHO of 40B0/CN under solar light reached 87.7%, and the reaction rate constant was 0.0166 min−1, which was 1.6 times higher than that of BiOCl. This paper gave a deep insight into photocatalytic technology to efficiently degrade formaldehyde.

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Chmielewská, Eva. « CLINOPTILOLITE TUFF AND OTHER ZEOLITE ADDED VALUE PRODUCTS AS SUSTAINED COMMODITIES IN TRADITIONAL WATER AND WASTE MANAGEMENT ». Green Chemistry & ; Technology Letters 2, n^o 2 (6 juin 2016) : 115–20. http://dx.doi.org/10.18510/gctl.2016.2212.

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Coagulation/flocculation and ion exchange onto natural zeolite clinoptilolite are reviewed and discussed in this paper based on their pilot or industrial applications. Surface water purification by means of chemical coagulation and flocculation supported by the powdered natural zeolite was carried out industrially to save drinking water reservoir (upper part of Ondava river) settled by about ten thousands inhabitants. Therefore, several other surface water samples from the Slovakian reservoirs potentially impacted by contamination were examined to treat with alum coagulation/flocculation and powdered clinoptilolite tuff addition at the laboratory, respectively. Ammonia removal from tannery wastewater using the clinoptilolite tuff with chemical regeneration and regenerant recovery by air stripping, carried out in pilot measure during the several months at the mixed Wastewater Treatment Facility in Otrokovice - WTFO is discussed and evaluated, respectively.

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