Application Of Natural Zeolites Research Articles

Effects of the application of natural zeolite on the growth and nutrient status of radish (Raphanus sativus L.)

SummaryThe unique cation exchange, adsorption, hydration-dehydration, and catalytic properties of natural zeolites, and their abundance, have promoted their use in agriculture as soil amendments and slow-release fertilisers. This research was conducted to investigate the effects of natural Iranian zeolite on vegetative growth and the nutrient status of radish (Raphanus sativus L. cv. Cherry Belle). The experiment was performed as a completely randomised design with six treatments (0, 20, 40, 60, 80, or 100 g zeolite kg−1 soil) and four replicates. The results indicated that zeolite increased leaf number and leaf area, shoot fresh weight (FW), the diameter and FW of edible roots, the number, length and FW of fibrous roots, and harvest index. The use of zeolite also increased the concentrations of nitrogen (N) and potassium (K) in shoot tissues, and the cation-exchange capacity of the medium. It was concluded that zeolite had a pronounced positive effect on vegetative growth in radish. Zeolite may be recommended as a soil amendment for vegetable crops such as radish to decrease nutrient leaching.

SURFACTANT-MODIFIED NATURAL ZEOLITES FOR ENVIRONMENTAL APPLICATIONS IN WATER PURIFICATION

Abstract 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 (chabasite, heulandite, mordenite). In the first part, the preparation methods and the influence of process parameters on the final product properties is reviewed. The discussion is focused on the influence of surfactant concentration in the water phase related to the external cation exchange capacity of the zeolite. The physical-chemical characterization of raw and modified zeolites by using relevant analytical methods (XRD, SEM, thermal analysis, 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 chemistry of zeolite surface is greatly changed, allowing zeolites to sorb not only cations and polar organics but also nonpolar organics 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), organic pollutants (BTEX, chlorophenol, perchloroethylene, fulvic acids, dyes, pesticides, ionisable organic 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.

The potential application of natural zeolite for greywater treatment

Natural zeolites are good potential material for water and wastewater treatment. It is due to the advantages of low cost, ion-exchange and adsorption capability of the natural zeolites. It can also be modified and regenerated. This paper thus looks at efforts made in exploring the potential application of natural zeolites and modified natural zeolites in water and wastewater treatment especially for reducing or removing contaminants in greywater, a type of wastewater originated from bathrooms and laundries in household. The material to be reviewed in this paper includes (i) major greywater contaminants and (ii) the potential of natural zeolites for greywater treatment.

Remoção de metais pesados em solução por zeólitas naturais: revisão crítica

Nesta síntese são discutidos os resultados de trabalhos publicados nos últimos anos referentes à aplicação das zeólitas naturais na remoção de metais pesados em solução. A seqüência de seletividade iônica, bem como os parâmetros associados à eficiência de adsorção e capacidade de troca catiônica (CTC), estão inteiramente relacionados à estrutura cristalina das zeólitas e às características químicas dos íons encontrados em solução. Cabe ressaltar que, algumas variáveis externas como temperatura, pH e concentração iônica inicial podem interferir no processo de remoção de metais, assim como na seqüência de seletividade iônica. De forma geral, íons com menor energia de hidratação possuem maior preferência pelos sítios de troca disponíveis nas estruturas das zeólitas. A eficiência de remoção de íons de maior energia de hidratação, por sua vez, pode ser controlada pela sua concentração na solução: quanto menor, melhor. Verifica-se, portanto, que as zeólitas naturais possuem grande potencial de aplicação em tratamentos de efluentes contaminados com metais pesados.

Using natural zeolite for the improvement of soil salinity and crop yield

The effects of natural zeolite (clinoptilolite) on salinity and the presence of harmful salts in the soil on Raphanus sativus L. were studied. Six soil treatments were studied: (1) control, (2) NaCl, (3) Na2SO4, (4) natural zeolite, (5) natural zeolite + NaCl and (6) natural zeolite + Na2SO4. Five seeds of radish were planted in each pot. Each treatment had 10 repetitions. After 50 days under equal condition some parameters consisting of number of leaf (NL), total leaf area (TLA), total fresh weight (TFW), total dry weight (TDW), root fresh weight (RFW), air fresh weight (AFW), root dry weight (RDW) and air dry weight (ADW) were determined. Results showed that using clinoptilolite may improve soil quality and increase crop yield. Application of natural zeolite in radish cultivation seems to increase the final product and also retain the harmful salt, such that salts do not pass through the roots to the plants.

Use of natural zeolite at different doses and dosage procedures in batch and continuous anaerobic digestion of synthetic and swine wastes

The aim of the present work was to study the behavior of conventional digesters working while adding natural zeolite to the anaerobic treatment of swine wastes. High nitrogen concentrations (3 g/l) were also applied when synthetic media was used as feed in anaerobic reactors operating in batch mode. Three sets of experiments were carried out. The first experiment was carried out in batch mode, in order to find the most appropriate zeolite doses for the digester operation. One gram per litre of zeolite was found to be the dose that produced the best reactor performance. The second experiment was carried out using three reactors operating with swine wastes at three different hydraulic retention times (HRT): 10, 20 and 30 days. From this experiment, an HRT of 20 days was selected for the following continuous experiments. For the third experiment, the digesters operated in four different ways using synthetic waste and a zeolite dose of 1 g/l, with different procedures for zeolite addition: (1) not adding natural zeolite; (2) adding zeolite at the start-up of anaerobic digestion; (3) adding natural zeolite at the start-up of the anaerobic digestion and again when the steady-state was reached; (4) adding natural zeolite on a daily basis. Finally, from these results, a fourth experiment was carried out using swine waste and the same zeolite doses and digesters, operating: (1) without adding natural zeolite; (2) adding natural zeolite at the start-up of the digestion; (3) adding natural zeolite on a daily basis. It was found that the application of natural zeolite allowed for a 17–20% increase in organic matter removal with respect to the experiments carried out where natural zeolite was not added. A daily methane production increase of 11.1–30.8% with respect to the reactors working where no natural zeolite was added. The daily addition of zeolite with the influent fed to the digesters was found to be the most appropriate procedure for dosage of this material on the basis of TCOD removal efficiencies and methane productions achieved in the process. It was also demonstrated that when zeolite was added, the digester did not need more frequent cleaning.

Application of natural zeolites: understanding the properties at a molecular scale

Application of natural zeolites: understanding the properties at a molecular scale

The application of natural zeolites for mercury removal: from laboratory tests to industrial scale

The paper discusses the application of natural zeolites from clinoptilolite group for mercury removal from industrial effluents from copper smelter and refinery. The experiments included studies on sorption mechanisms (adsorption or ion-exchange) and sorption equilibria. The dominating mechanism of sorption with zeolite was found to be ion exchange and the maximum sorption capacity was evaluated as 1.21 meq/g sorbent. Three cation-exchange groups were identified and deprotonation acidity constants (p K a) 3.1, 7.3 and 10.7 were determined. The results of model experiments were verified by the treatment of the industrial effluent containing elevated levels of Hg 2+ ions on the laboratory as well as on full-plant scale. Laboratory and industrial scale experiments showed that zeolite was capable of mercury ions removal from the effluent. Currently, the company uses the proposed method for effluents treatment.

Removal of Heavy Metal Ions in Wastewater Using Zeolite Minerals

All the applications of natural zeolites make use of one or more of their physical and chemical properties: adsorption, ion-exchange and related molecular sieve properties, dehydration and rehydration, and siliceous composition. Accordingly, the applications of zeolite have been carried out in the various aspects because of its large cation exchange capacity and adsorption properties. In this paper, the adsorption effect of heavy metal ions in wastewater on zeolite mineral by batch adsorption process is studied. The amounts of adsorbed ions were variable by original pH and ionic concentration, especially original pH of solution had an important effect on the adsorption. In case of low pH solution, e.g. below 3.0, clinoptilolite adsorbed <TEX>$Pb^{2+}$</TEX> ,<TEX>$ Cd ^{2+ }$</TEX> , <TEX>$Cu^{2+}$</TEX> and <TEX>$Zn^{ 2+}$</TEX> , but mordenite almost did not adsorb except <TEX>$Pb^{2+}$</TEX> . Under the same conditions, these ions were more adsorbed on clinoptilolite than on mordenite mineral. The velocity of adsorption was relatively fast and it was confirmed by shaking test that the equilibrium of adsorption could be attained in about one hour. The species of exchangeable cation of zeolite had an effect on its removing ability and zeolite of the sodium-exchanged type was the best.

Applications of Natural Zeolites in Water and Wastewater Treatment

The world is faced with increasing demands for high-quality drinking water and for removal of contaminants from municipal, agricultural, and industrial wastewaters. Treatment is required to obtain drinking water from most natural resources as well as from wastewaters with varying amounts of impurities. These impurities may occur in a variety of forms including large particles such as microorganisms or suspended solids or as dissolved or colloidal inorganic and organic substances. This chapter provides an overview of the use of natural zeolites in removal of impurities from water or wastewater (Murphy et al. 1978, Tarasevich 1994, Kallo 1995). Most technologies using natural zeolites for water purification are based on the unique cation-exchange behavior of zeolites through which dissolved cations can be removed from water by exchanging with cations on a zeolite’s exchange sites (see Pabalan and Bertetti, this volume). The most common cation in waters affecting human and animal health is NH4+. It can be removed by exchanging with biologically acceptable cations such as Na+, K+, Mg2+, Ca2+ or H+ residing on the exchange sites of the zeolite. Fortunately, many natural zeolites (e.g. clinoptilolite, mordenite, phillipsite, chabazite) are selective for NH4+ ( vide infra ), meaning that they will exchange NH4+ even in the presence of larger amounts of competing cations. Clinoptilolite and mordenite are also selective for transition metals (e.g. Cu2+, Ag+, Zn2+, Cd2+, Hg2+, Pb2+, Cr3+, Mo2+, Mn2+, Co2+, Ni2+), which are often present in industrial waters and can be very toxic even in concentration as low as several mg/L. As emphasized in discussions of radioactive waste treatments, both clinoptilolite and mordenite …

Natural Zeolites in Solar Energy Heating, Cooling, and Energy Storage

This chapter describes the use of zeolites in solar energy storage and in solar energy heating and cooling applications. This chapter concentrates on natural zeolites, but considerable work has also been done with synthetic zeolites, especially zeolite 13X. The chapter begins with a review of energy storage applications of natural zeolites, both for short-term (day-to-night) and long-term (seasonal) storage. It then discusses the use of zeolites in heating and cooling cycles. Open cycles are considered first, where the zeolite is open to the ambient air and is used mainly for air dehumidification followed by evaporative cooling. This is followed by a discussion of closed-cycle systems, where the zeolite and the working refrigerant gas are sealed in an airtight container, which excludes all other impurity gases. The pressure in the closed-cycle systems is not ambient but is determined by the condensation and evaporation pressures of the refrigerant. The chapter concludes with a brief description of the needs and directions for future research in this field. For this reason it describes the thermodynamic analysis of open and closed cycles, the approximations involved in the analysis, and the appropriate application of the Clausius-Clapeyron equation to determine the isosteric heat of adsorption for various gases on natural and modified or synthetic zeolites. Solar energy is intermittent by nature. The sun shines during the day whereas the need for heat in homes is largest at night, when the ambient temperature is lowest. To overcome the time lag between supply and demand, people have used day-to-night averaging of solar energy since very early times. Throughout human history, homes in hot climates were built with thick walls of large thermal mass that warmed slowly during the day (keeping the home cool) and released the stored heat during the night. Zeolitic tuffs have been used for centuries as …

Application of natural zeolites for preconcentration of arsenic species in water samples.

Zeolites of the clinoptilolite type produced in Mexico and Hungary were investigated with respect to their sorption efficiency for various redox species of arsenic. Long-term experiments showed that arsenate remains stable for a long period in spiked deionised water and drinking water, as well as in the surface water of the Biela valley in Saxony, Germany. Both clinoptilolites are able to decrease the initial arsenic concentration of 200 microg l(-1) by more than 75% in deionised, drinking, ground and surface waters. In the case of the Mexican zeolite, both the arsenite and the arsenate concentrations (200 microg l(-1)) can be lowered from 200 microg l(-1) to 10 microg l(-1), which is the World Health Organisation's (WHO's) recommended maximum level. It was found that the presence of cations and anions in the natural waters of Biela, Germany, and Zimapán, Mexico, did not reduce the efficiency of the selected zeolites. The Hungarian zeolite removed 75% of the arsenate in the Zimapán water and only 50% when the sample was first acidified. This zeolite totally desorbed the fixed arsenic into a water volume that was half the volume in the adsorption experiment.

96/05985 Preparation of activated carbons with mesopores by use of organometallics

A brief information about occurrences, properties, and application of natural zeolites in Georgia is given. Ion exchange, thermal and catalytic properties of clinoptilolite and phillipsite have been studied. Application of natural zeolites for desiccation of solvents is considered.

Natural zeolite utilisation in pollution control: A review of applications to metals' effluents

AbstractThis paper assesses the potential of natural zeolite utilization as a low‐cost ion‐exchange and sorbent material in pollution control and recovery of metals. The improvement of the purity of natural zeolites coupled with their chemical modification capabilities in order to provide specific properties may provide a cost‐effective alternative for the treatment of heavy metal contaminated soil and water. The application of natural zeolites in industrial pollution control is becoming important and the level of technical effort is increasingly expanding. The extent of application is unlikely to be related solely to their low cost, but also to improved properties and performance characteristics, which will advance the practical implementation of natural zeolites' technology.

Application of natural zeolites for the reduction of ammonia emissions during the composting of organic wastes in a laboratory composting simulator

Ammonia losses from composting of unchopped and chopped straw-pig slurry mixtures were studied in a laboratory composting simulator. Ammonia emissions were reduced when pig slurry was composted with chopped straw. Chopped straw was more easily degraded by the microorganisms because its surface area was higher than that of the unchopped straw. An average of 84·88% of initial NH 4-N was immobilized and incorporated into the organic-N fraction. Zeolite clinoptilolite was very effective in trapping the ammonia lost during the composting process. The zeolite sample was placed inside the composting simulator, in the spent-air stream, just after the air had passed through the composting material. Reduction in the effectiveness of ammonia adsorption in zeolites was related to their water adsorption. The connentration of ammonia in the airstream played an important role in the ammonia adsorption. The zeolite amount required to retain 80% of N-losses was 53 g kg −1 of fresh chopped straw-pig slurry mixture, while the amount was 82 g kg −1 of fresh mixture when unchopped straw was used. The combination of mixing the pig slurry with an easily degradable straw and covering the composting material with zeolite minerals is a very effective procedure for reducing ammonia emissions.

Natural zeolites: mineralogy and applications

After a brief description of the crystallochemical peculiarities of zeolites, which enable them to be used in many technological fields, the present and potential applications of natural zeolites are reviewed. The possibility of using Italian chabazite and phillipsite to reduce problems connected with nitrogen pollution is considered

Application of natural zeolites for air separation

The application for air separation purposes of modified versins of clinoptilolite and mordenite containing tuffs, deposited in the Tokaj Mountains (Hungary), is demonstrated. The importance of adsorption kinetics in the design of any pressure swinging adsorption (PSA) operation is shown.

Sodium-aluminium-silicates in the washing process Part II: Cleansing action of natural zeolites

The following factors are decisive for the application of natural zeolites: Particle size Ion-exchange capacity and kinetics Purity

The Application of Natural Zeolites in Animal Science and Aquaculture

The Application of Natural Zeolites in Animal Science and Aquaculture