| Apreutesei, R.E., Catrinescu, C. and Teodosiu, C. | Surfactant-modified natural zeolites for environmental applications in water purification.
| 2008 | Environmental Engineering and Management Journal
Vol. 7(2), pp. 149-161 | article | |
| Abstract: A review. This paper presents an overview of research related to use of surfactant modified natural zeolites (SMZ) in water and wastewater treatment. The most common natural zeolite, widely used as starting material is clinoptilolite, but other natural zeolites have also been used (chabazite, heulandite, mordenite). In the first part, the prepn. methods and the influence of process parameters on the final product properties is reviewed. The discussion is focused on the influence of surfactant concn. in the water phase related to the external cation exchange capacity of the zeolite. The phys.-chem. characterization of raw and modified zeolites by using relevant anal. methods (XRD, SEM, thermal anal., FTIR spectroscopy, DRIFTS) is also presented. Thus, an integrated view of the relation between the structure and the behavior of the modified-zeolites, covering both the compositional and the structural aspects, can be obtained. Following surfactant modification process, the chem. of zeolite surface is greatly changed, allowing zeolites to sorb not only cations and polar orgs. but also nonpolar orgs. and anions, for which untreated zeolites have little or no affinity. Consequently, the area of application of natural zeolites in water and wastewater treatment is greatly extended. The most relevant applications of surfactant-modified zeolites for the removal of anionic (chromate, phosphate, arsenate), cationic (mercury, cadmium), org. pollutants (BTEX, chlorophenol, perchloroethylene, fulvic acids, dyes, pesticides, ionizable org. solutes, PAHs) and microorganisms are reviewed. The data reported in the literature suggest that naturally occurring zeolites modified with cationic surfactants can be considered as potential sorbents for the removal of the most important categories of pollutants from polluted waters. [on SciFinder(R)] |
| Balmer, W., Bore, C. and Regis, R.C. | Uses of zeolites for a better tapwater quality.
| 2004 | Cahiers de l'Association Scientifique Europeenne pour l'Eau et la Sante
Vol. 9(1), pp. 29-48 | article | |
| Abstract: A review. The use of zeolites A, X, and Y; chabazite; mordenite; ferrierite; phillipsite; clinoptilolite; and ZSM-5 in water purifn. are discussed. [on SciFinder(R)] |
| Chmielewska, E. | New trends of application of proenvironmental and supramolecular substances in water purification technologies.
| 2009 | Vodni Hospodarstvi
Vol. 59(5), pp. 182-185 | article | |
| Abstract: A review. Recently, numerous approaches have been studied for the development of cheaper and more effective adsorbents contg. natural polymers. Among these, polysaccharides such as chitin and starch and their derivs. (chitosan, cyclodextrin) deserve particular attention. These biopolymers represent an interesting and attractive alternative as adsorbents because of their particular structure, physico-chem. characteristics, chem. stability, high reactivity and excellent selectivity towards arom. compds. and metals resulting from the presence of chem. reactive groups (hydroxyl, acetamido or amino functions) in polymer chains. Moreover, it is well known that polysaccharides which are abundant, renewable and biodegradable resources, have a capacity to assoc. by phys. and chem. interactions with a wide variety of mols. In framework of the submitted paper, some hybridized adsorption materials esp. on the base of natural clinoptilolite have been evaluated towards a broad range of pollutants (inorg. anions and azodyes). [on SciFinder(R)] |
| Chocholek, S., Czarnecka, M. and Warchol, J. | Use of clinoptilolite in environmental protection.
| 2000 | Symp. - AQUA 2000: Probl. Inz. Srodowiska, 21st, pp. 362-369 | inproceedings | |
| Abstract: A review with 19 refs. was given on the possibilities using of natural zeolite, clinoptilolite, for environmental protection. The applications were ion exchange, adsorption of gases and liqs., sorption of crude oil pollutants and catalytic properties. [on SciFinder(R)] |
| Colella, C. | Natural zeolites in environmentally friendly processes and applications.
| 1999 | Studies in Surface Science and Catalysis
Vol. 125(Porous Materials in Environmentally Friendly Processes), pp. 641-655 | article | |
| Abstract: A review with 90 refs. concerning the occurrence, features, and environmental uses of the major sedimentary zeolites (chabazite, clinoptilolite, mordenite, phillipsite) is given. Topics discussed include: materials (clinoptilolite-rich tuff deposits, mordenite-rich tuff deposits, phillipsite- and/or chabazite-rich deposits); and environmental uses of natural zeolites (natural zeolites in soil amendment, cement manuf., wastewater purifn., adsorption and catalysis). [on SciFinder(R)] |
| Dlugopolska, K., Ruman, T., Pogocki, D. and Danilczuk, M. | Medical applications of molecular sieves.
| 2009 | Wiadomosci Chemiczne
Vol. 63(11-12), pp. 1073-1088 | article | |
| Abstract: A review. Mol. sieves are porous cryst. materials, mostly synthetic or natural zeolites, that contain well-defined pores of precise and uniform size. The term zeolite originally described natural cryst. aluminosilicates, but now includes many different materials such as aluminophosphates or gallium silicates. For decades the microporous and mesoporous zeolite materials have been considered for medical use due to their biol. properties and stability in biol. environments. Zeolites have been studied as drug carriers, dietary supplements, antimicrobial agents, or adjuvants in anticancer therapy. Zeolite nanocrystals can be combined in situ with superparamagnetic magnetite (Fe3O4) nanoparticles in the hydrothernmal synthesis procedure. High enzyme adsorption and good biocatalytic performance can be seen with magnetite/zeolite composite nanoparticles. Zeolite of the CuX type can be used as a carrier for the antitumor drug cyclophosphamide. In vivo tests show that the antitumor effects of the CuX zeolite-cyclophosphamide system are similar to those of cyclophosphamide alone. Ion-exchanged zeolites can be also used for storage and delivery of nitric oxide (NO). Zeolite surface coatings offer antimicrobial protection via controlled release of antimicrobial agents that can be applied to different surfaces or incorporated in various polymer types. Zeolitic materials and drugs can be given simultaneously to patients without loss of individual pharmaceutical effects of each product. Zeolite matrix can also stabilize erythromycin solns. A com. product with diisopropylsebacate/ethanol soln. of 4% erythromycin and zinc acetate (Zineryt) has been compared to analogical system where active compds. were loaded into a porous material. Natural clinoptilolite is the main active component of the antidiarrheal drug acting as adsorbent of bile acids, aflatoxin B and glucose. Clinoptilolite can be also used in adjuvant anticancer therapy. The new antacid drug Neutacid with neutralizing capacity from purified natural zeolite-clinoptilolite from Cuba can be used in treatment of hyperacidity in patients with gastric dyspepsia and gastric/duodenal ulcer. Mesoporous material MCM-41 with pore size tunability and functionalization can encapsulate various drug mols. and release them in controlled manner. Zeolites contg. silver ions are used as antimicrobial agents. Zeolites are the main ingredient of com. anti-hemorrhagic agents. [on SciFinder(R)] |
| Dragan, E.S., Dinu, M.V. and Mihai, M. | Separations by multicomponent ionic systems based on natural and synthetic polycations.
| 2011 | Ion Exchange and Solvent Extraction
Vol. 20, pp. 233-291 | article | |
| Abstract: A review. Heavy metals, fine suspensions, and org. matter emitted by industrial processes such as paper processing, paint and pigment prodn., textile manufg., food and cosmetics operations, electronics fabrication, mines, and ceramic prodn. are very dangerous pollutants. Synthetic and, more increasingly, polymers from renewable sources are used alone or in complex systems to enhance the efficiency of sepn. processes. Multicomponent ionic systems may present a better approach. Their enhanced mech., thermal, and adsorption properties are comparable to those of their components alone. This chapter summarizes our investigations of novel materials based on chitosan: (1) composites with clinoptilolite (a common natural zeolite) and their applications for removing heavy metal ions (Cu2+, Co2+, and Ni2+); and (2) prepn. of pos. charged nonstoichiometric interpolyelectrolyte complexes as colloidal dispersions and their efficiency in solid and liq. sepns. in comparison to chitosan alone. The adsorption capacity of the chitosan-clinoptilolite composite abruptly increases up to a zeolite content of ∼20 wt%. The max. adsorption capacities are 9.04 mmol/g for Cu2+, 6.4 mmol/g for Ni2+, and 3.4 mmol/g for Co2+. One advantage of using nonstoichiometric interpolyelectrolyte complexes as specialized flocculants is the broadness of the flocculation window-more than double at an optimum dose lower than that of chitosan. Some synthetic polycations were also used to prep. novel multicomponent ionic systems with better efficiency in sepn. processes than other polycations. [on SciFinder(R)] |
| Gajowiak, A. and Majdan, M. | Use of zeolite adsorbents for the removal of uranyl ions from aqueous solutions.
| 2011 | Przemysl Chemiczny
Vol. 90(3), pp. 417-423 | article | |
| Abstract: A review is given on different adsorbent types used in removal of uranyl ions from aq. solns. A special attention is paid to natural and modified zeolites. The sorption process and parameters playing role in the process are described. [on SciFinder(R)] |
| Godelitsas, A. and Armbruster, T. | HEU-type zeolites modified by transition elements and lead.
| 2003 | Microporous and Mesoporous Materials
Vol. 61(1-3), pp. 3-24 | article | |
| Abstract: A review; research on pure samples of HEU-type zeolites modified by d- and f-block transition elements and Pb is reviewed. The interest on such modified HEU-type zeolites mainly arises from their use in pollution abatement, and for their potential catalytic properties. In addn., new composite materials composed of transition-metal loaded crystals with org. complexes stabilized on the zeolite substrate are gaining importance for versatile applications. If sorption is governed by ion-exchange, the structural distribution of the transition elements can be detd. by single-crystal XRD. In more complicated cases, where an intense metal accumulation is obsd. on the surface of the crystals, the structural characteristics can only be defined using a combination of microscopic, spectroscopic, and thermal techniques. Detailed crystal-structure information is available for HEU-type crystals completely cation exchanged by Ag+, Pb2+, Cd2+, Mn2+, and Cu2+. Cd2+, Cu2+ and Mn2+ mainly occupy two extra-framework sites: one in the center of the ten-membered ring, octahedrally coordinated by six H2O mols., and one in the eight-membered ring, coordinated to framework oxygen and addnl. H2O. Ag+ and Pb2+ do not occupy the center of the ten-membered ring but are shifted towards the framework walls. Complementary microscopic, spectroscopic, and thermal data (e.g. SEM-EDS, IR, EPR, NMR, EXAFS, XPS, RBS, DTA, TPD) on heulandite and clinoptilolite interacted with Co, Ni, Cu, Pd and Hg indicated non-homoionic and non-stoichiometric metal-loading. Excessive accumulation on the crystal surface, due to adsorption and surface pptn. phenomena, was commonly obsd. Only very low incorporation of trivalent ions of lanthanides/rare-earth elements into the heulandite channel system was exptl. achieved. Th4+- and UO22+-ions interact significantly with heulandite but the metal sorption is mainly attributed to adsorption and surface pptn. processes. [on SciFinder(R)] |
| Hoeffner, S., Conner, J. and Spence, R. | Stabilization/solidification additives.
| 2005 | Stab. Solidif. Hazard., Radioact., Mixed Wastes, pp. 177-198 | inproceedings | |
| Abstract: A review concerning additives examd. for waste stabilization/solidification processes and applied at treatment, storage, and disposal facilities is given. Topics discussed include: metal stabilization (pH control and buffering; speciation/pptn./re-speciation [S2-, S, and organo-S compds.; sol. silicates and rice hull ash; carbonates; phosphates and trisodium phosphate; FeSO4 co-pptn.; other inorg. complexing agents]; oxidn./redn.; sorption and ion exchange [illite clay, cryst. silicotitanate, clinoptilolite and other zeolites, vermiculite and other sorbents]); non-metals and orgs.; org. stabilization; additives and treatment methods for organometallic and complexed compds.; processing and anti-inhibition aids (control agents, retarders, water-reducing agents, viscosity control agents, additives which increase strength or improve other phys. properties); and multi-talented or multi-purpose reagents. [on SciFinder(R)] |
| Inglezakis, V.J. | Solubility-normalized Dubinin-Astakhov adsorption isotherm for ion-exchange systems.
| 2007 | Microporous and Mesoporous Materials
Vol. 103(1-3), pp. 72-81 | article | |
| Abstract: The well-known Dubinin-Radushkevich adsorption isotherm is extensively used for vapor adsorption on activated carbon and its use was extended to cover the cases of the adsorption of org. compds. from aq. solns. and the ion exchange of metals on several porous materials. In the later cases, the use of the Dubinin-Radushkevich adsorption isotherm is questionable as it is not taking into account the pore structure of the materials used. In the present paper the more general Dubinin-Astakhov adsorption isotherm was used modified by introducing a soly.-normalized adsorption potential. Then, it was applied in exptl. isotherms to det. adsorption energy and heterogeneity parameter for the ion exchange of Pb2+ in the zeolite clinoptilolite. The Dubinin-Astakhov adsorption isotherm represents the exptl. data well and in the same time provides the heterogeneity parameter of the material which is an important adsorbent phys. parameter as well as the adsorption energy. The calcd. values were n = 5.2 and E ≃ 18 kJ/mol, resp. An extended review is conducted by applying the proposed isotherm in exptl. data found in the literature for clinoptilolite cation exchange systems (22 exptl. isotherms, 175 equil. points). The av. value of the heterogeneity parameter is n = 5.84 (35.8% deviation) with a range of 2.1-10.4. The heterogeneity parameter value is strongly influenced from the structure of the adsorbent and in lesser extend from the cation exchanged. The av. value of the adsorption energy is E = 16.7 (19.2% deviation) with a range of 9.47-21.74 kJ/mol. [on SciFinder(R)] |
| Karimova, A.M., Groisman, E.B. and Tsykina, N.M. | Deep treatment of wastewater from leather goods manufacturing plant.
| 2009 | Vodosnabzhenie i Sanitarnaya Tekhnika(1, Suppl., Ochistka Prirodnykh i Stochnykh Vod), pp. 46-48 | article | |
| Abstract: A review is given on a contemporary method of leather goods manufg. plant wastewater treatment using clinoptilolite as a natural sorbent found in Uzbekistan. This method involves phys. and chem. wastewater treatment, followed by addnl. treatment in air basins and ponds with abundant aquatic vegetation. Regeneration of clinoptilolite is performed using NaCl and NaOH. [on SciFinder(R)] |
| Komiyama, M. | Surface observation and structural characterization of zeolites by atomic force microscopy.
| 1993 | Zeoraito
Vol. 10(4), pp. 201-6 | article | |
Abstract: Reports on surface observations of 6 natural zeolites (clinoptilolite, scolecite, faujasite, stilbite, heulandite, and chabazite) by at. force microscopy (AFM) were reviewed. 8 Refs. These works appear to have achieved atomistic resoln., although there seems to be some controversy as to the interpretation of the AFM images obtained. The surface structures of these natural zeolites, including the ones possibly caused by adsorption, were discussed in light of the AFM images obtained under various liqs. as well as under ambient conditions. [on SciFinder(R)]
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