In the s, synthetic zeolites began to replace phosphate compounds in laundry detergent powders. The high cost of synthetic zeolites precludes their use for most natural zeolite applications. Conversely, stringent product specifications prevent the large-scale use of natural zeolites for most synthetic zeolite applications. For more information on zeolites and other mineral resources, visit: minerals.
In , U. Magor U. In , world production of natural zeolite was estimated to be 2. Credit: The American Geosciences Institute. AGI was founded in , under a directive of the National Academy of Sciences, as a network of associations representing geoscientists with a diverse array of skills and knowledge of our planet.
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Skip to main content. Enter your search terms. Mineral Resource of the Month: Zeolites. Zeolites give off heat when rehydrated. An old field test to determine if a rock sample contained zeolites was to see if a rock chip heated up when placed on the tongue. Zeolites adsorb ethylene and are used to prolong the shelf-life of vegetables and fruit, which emit ethylene as they ripen.
Zeolites were used to adsorb radioactive isotopes from contaminated cooling water spilled at the Fukushima nuclear power plant after the plant was damaged in the March magnitude-9 earthquake in Japan.
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Zeolite minerals have large surface areas because of their open crystal structure — 10 grams of chabazite has roughly the same surface area as a football field about 5, square meters. Energy notes: May The American Geosciences Institute. These particles are used due to their chemical inertness, physical resilience and water retention ability [ 12 ]. Chemical analysis results of the samples confirmed by X-ray fluorescence data are shown in Table 1. Bentonite deposits are mainly formed by alteration of volcanic rock or by direct precipitation authigenesis in alkaline continental basins [ 15 ].
Deposits of bentonite can be found on almost all continents; however, the features and the properties of the material differ greatly from zone to zone. It has the special feature of swelling when in contact with water, constituting a tixotropic gel [ 14 ]. Although it is insoluble in water, it swells to approximately twelve times its volume when added to water and does not swell in organic solvents including absolute alcohol, isopropanol, glycerin and fixed oils [ 12 ]. Bentonites are classified into two groups: Na-bentonite and Ca-bentonite.
The swelling properties of Na bentonites are reater than those of Ca-bentonites and Na bentonites are preferred in landfills because they have low shrinkage and hydraulic conductivity [ 16 , 17 ]. The chemical analysis results of the natural bentonites were confirmed by X-ray fluorescence and are shown in Table 1. Solid wastes were used in the cabins were provided from containers in the -Kurupelit region of Turkey and they were collected as mixed wastes. After their organic part was separated, they were mixed until homogeneous and then divided into four groups.
These were mixed and divided again into four groups. This operation was repeated until four group of 20 kg each were obtained. Thus the organic wastes added to the cabins were identical. Physical composition of the waste mixture is shown in Table 2. Physical composition of the solid waste samples [ 18 ].
The aim of this study was to investigate the effects of natural zeolite, expanded perlite and bentonite when used as alternate liner materials in a sanitary landfill on the transmission of leachate and treatment of pollutants in the leachate. Natural materials was placed as the base of cabins is made of glass with slope; in this study the solid waste was added on top of the natural materials. No material was placed into one cabin base in order to compare with the chemical characteristic of the leachate for the removal of each material.
Contents of the laboratory scale cabins were prepared in agreement with guidelines of the Turkish Ministry of Environment and Forestry MEF. A schematic of the test apparatus is illustrated in Figure 1 and their component rates are listed in Table 3. Experimental systems were left open to atmosphere in order to imitate the characteristics of real landfills. Landfill leachate samples were analyzed for periods of one week and two weeks.
Characterization of Cement Pastes Containing Natural Zeolite as a Pozzolanic Admixture
WEF methods. Organic matter measurements were performed in reference to the standard method [ 19 ]. Cumulative and daily leachate quantities depending on precipitation in the experiments continued during 17 weeks, are shown in Figure 2 a,b. As a result there are no pollutant measurements for system 4. The chemical characteristics of system 1 are compared with the different landfill leachates in Table 4 and for each system, treatment efficiencies are given in Table 5. According to the degradation of wastes and seasonal precipitation, the amount of leachate in each system showed an increase Figure 2 a,b.
However, leachate leaking from system 3 was less than for system 1 and the highest leachate was in system 1 because of the absence of liner material. It is shown that infiltration of leachate for system 2 and system 3 decreased Not only were the pH values of system 2 lower than those of system 1, but they are also higher than system 3.
The Reconstruction of Natural Zeolites: A New Approach to Announce Old Materials by their Synthesis
Moreover, pH values in system 3 are the highest among all the systems. In the first phase of the leachate formation, the pH is over 8 and it drops to 6 because of existence of organic acids in the second phase. The highest pH value of system 2 is 7. SWANA [ 21 ] reported that due to organic acids, low pH values caused increased metal solubility and electrical conductivity EC that can be used as an indicator of the abundance of these dissolved inorganic species or total concentration of ions [ 22 ].
EC values increased versus time and the lowest recorded value 6. After the EC of system 4 reached the highest value In addition to this, the EC values of system 1 and system 3 increased in during the course of time but system 3 recorded higher values than system 2. The EC values of system 2 and system 3 varied between 2. Nitrate concentrations of each system are shown in Figure 5. Increases in nitrate concentrations depending on time were observed in each system and the concentration variations of the different materials are close to straight lines.
Nitrate removal of the systems is very high and removal efficiencies are Using natural zeolite as a liner material in landfills is more effective than using expanded perlite. The lowest concentrations of the leachate with respect to natural zeolite and expanded perlite utilization are 2. As shown in Figure 6 , firstly, the concentration of NH 4 -N for system 1 increased and became fixed and then dropped in.
As Johannessen [ 23 ] mentioned, high concentrations of NH 4 -N represenrt a third phase for degradation of waste. Although NH 4 -N was observed at low levels in system 2 and its maximum level was measured at The removal efficiency for system 2 was NH 4 -N levels in system 3 were higher than in system 1. Whereas the ammonium concentration decreased in system 1, in system 3 it increased.
Therefore treatment performance for system 3 was lower than for system 2. According to Figure 7 , the phosphate concentration of leachate for system 2 and system 3 was lower than in system 1 and changed versus time. Variable values from The phosphate removal efficiencies were However using natural zeolite and expanded perlite reduced this to 1, By this means removal efficiency is The amount of organic matter builds up over time and the increasing organic matters in leachate originate organic acids.
According to Figure 9 , natural zeolite is more effective than expanded perlite and removal efficiency was Moreover, natural zeolite achieved effective removal of NH 4 -N and organic matter Although natural zeolite was not effective reducing leachate quantity, natural zeolite and expanded perlite show good performance for in-situ leachate treatment.
On the other hand, due to the swelling feature of bentonite when it contacts water, no leachate was obtained from system 4. If natural zeolite and expanded perlite is used together in different proportions, both accumulated leachate quantity and removal of NH 4 -N, COD and organic matter can be increased. In addition this, the swelling featuree of bentonite can be used to fill up the spaces between of natural zeolite and expanded perlite particles.
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Even if the rate of filling with bentonite is low, it will serve to both decrease both percolation of leachate and increase the removal efficiency of pollutants. National Center for Biotechnology Information , U. Published online May 3. Find articles by Osman Nuri Ergun. Author information Article notes Copyright and License information Disclaimer. This article has been cited by other articles in PMC. Abstract The potential long term environmental impacts of a landfill on groundwater quality depend on its liner material properties.
Keywords: landfill liner, leachate treatment, natural zeolite, perlite, bentonite. Introduction The sanitary landfill plays most important role in the solid waste disposal because it is an economical and final solution. Materials and Methods 2. Properties of the Materials 2.
Natural Zeolite Zeolites are crystalline aluminosilicates of alkali or alkali earth elements, such as sodium, potassium, and calcium [ 11 ] and possess three dimensional frameworks of SiO 4 and AlO 4 tetrahedra linked by shared oxygen [ 12 ]. Table 1 Results of chemical analysis of the bentonite, natural zeolite and expanded perlite used in experiment.
Open in a separate window. Obtaining and Preparing of the Solid Wastes Sample to Experiments Solid wastes were used in the cabins were provided from containers in the -Kurupelit region of Turkey and they were collected as mixed wastes. Table 2 Physical composition of the solid waste samples [ 18 ]. Figure 1.
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Table 3 Components and their rates in the test apparatus. Zeolite 7. Experimental Results Cumulative and daily leachate quantities depending on precipitation in the experiments continued during 17 weeks, are shown in Figure 2 a,b. Figure 2.