SYNTHESIS OF ADSORPTION MATERIALS

Abstract

A process for producing zeolites comprising: a) calcining a clay material to form an amorphous material from clay components in the clay material, b) leaching the material from step (a) in a leaching solution to produce a solution containing dissolved aluminium and dissolved silica and a solid residue, c) separating the solid residue from the solution, and d) crystallising zeolites from the solution from step (c).

Claims

1. A process for producing zeolites, the process comprising: a) calcining a clay material to form an amorphous material from clay components in the clay material; b) leaching the amorphous material from step (a) in a leaching solution at 70° C. or less to produce a solution containing dissolved aluminium and dissolved silica and a solid residue; c) separating the solid residue from the solution; and d) crystallising zeolites from the solution from step (c).

2. The process as claimed in claim 1, wherein the clay material comprises kaolin clays, kaolinite (Al.sub.4Si.sub.4O.sub.10(OH).sub.8), halloysite (Al.sub.2Si.sub.2O.sub.5(OH).sub.4) and montmorillonite (Al.sub.4(Si.sub.4O.sub.10).sub.2(OH).sub.4*xH.sub.2O)), mining tailings, mining tailings from kaolin mining, coal gangue kaolin, bentonite clays and bauxite mine or flotation tailings, coal flotation tailings and bauxite.

3. The process as claimed in claim 1, wherein the calcination step includes characterising phase transformation of the clay material using in-situ high temperature XRD (x-ray diffraction) by subjecting one or more samples of clay material to programmed heating rate and time and using in-situ XRD to obtain the XRD phase transformation pattern of the clay material and determining optimum calcination temperature and calcination time.

4. The process as claimed in claim 1, wherein the calcination step involves calcining the clay material to a pre-determined temperature for a pre-determined period of time.

5. The process as claimed in claim 1, wherein the temperatures used in the calcination step is between 600° C. to 900° C. or from 625° C. to 800° C., or from 650° C. to 750° C.

6. The process as claimed in claim 1, wherein the clay material is subject to heating in the calcination step for a period of from 1 minute to 2 hours, or from 5 minutes to 1.5 hours, or from 8 minutes to 1.5 hours.

7. The process as claimed in claim 1, wherein a kaolin clay material is used in the calcination step and kaolinite is converted to metakaolin in the calcination step.

8. The process as claimed in claim 1, wherein impurity quartz, muscovite and feldspar remain essentially unchanged in the calcination step.

9. The process as claimed in claim 1, wherein in the leaching step, the amorphous material recovered from the calcination step is leached in a leaching solution to dissolve the aluminium components and the silicate components from the amorphous material and whereby impurity components that were present in the material from step (a) do not dissolve and remain as a solid residue.

10. The process as claimed in claim 1, wherein the leaching solution comprises an alkaline solution.

11. The process as claimed in claim 10, wherein the alkaline solution suitably sodium hydroxide solution or potassium hydroxide solution.

12. The process as claimed in claim 1, wherein the alkaline solution comprises a hydroxide solution having a molar content of hydroxide ions of at least 1M, or from 1M to 6M, or from 1M to 5M, or from 1M to 4M or from 2M to 6M.

13. The process as claimed in claim 1, wherein the leaching step is conducted at a temperature at which precipitation of crystallisation of zeolites or other desilication products (DSPs) is suppressed or minimised.

14. The process as claimed in claim 1, wherein the temperature used in the leaching step from 50° C. to 70° C.

15. The process as claimed in claim 1, wherein impurities, including quartz, muscovite and feldspar, do not dissolve in the leaching step but remain as solid particulates mixed with the leaching solution and the mixture of pregnant leaching solution and solid residue is subjected to a solid/liquid separation step to separate the undissolved solid residue from the pregnant leaching solution.

16. The process as claimed in claim 1, wherein the solid/liquid separation step results in a purified pregnant leach solution being obtained and the solid residue that is separated from the pregnant leach solution is discarded or subjected to a second leaching step in order to extract further aluminium and silicate components therefrom, or subject to further treatment.

17. The process as claimed in claim 1, wherein the solution from step (c) comprises a purified pregnant leach solution that contains dissolved aluminium and dissolved silicates.

18. The process as claimed in claim 17, wherein additional material is added to the pregnant leach solution to change the ratio of Al to Si in the pregnant leach solution.

19. The process as claimed in claim 18, wherein silica gel is added to increase the amount of Si in the pregnant leach solution

20. The process as claimed in claim 17, wherein the pregnant leach solution is heated to a temperature of from 80° C. to 100° C., or about 90° C., and stirred in order to cause precipitation of zeolites.

21. The process as claimed in claim 20, wherein stirring is used to keep the zeolite particles suspended in the solution and to prevent agglomeration of the particles into overly large particles.

22. The process as claimed in claim 1, wherein a residence time of between 30 minutes and 10 hours, or between 1 hour and 5 hours, or between 1 hour and 4 hours, used in step (d).

23. The process as claimed in claim 1, wherein zeolite particles formed in step (d) are separated from the solution, washed and dried and optionally calcined.

24. The process as claimed in claim 23, wherein the solution that is separated from the zeolite is returned or recycled to the leaching step, or it may be used to conduct a second leaching step on the solid residue removed from the initial leaching step.

25. The process as claimed in claim 24, wherein make up leach solution is added to the solution recovered from the crystallisation step and/or some of the leach solution is bled off to prevent impurities from building up in the recycled solution.

26. The process as claimed in claim 1, wherein the leaching step has a residence time of less than 1 hour.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0043] Various embodiments of the invention will be described with reference to the following drawings, in which:

[0044] FIG. 1 is a flow sheet of a prior art process for synthesising zeolites from kaolin minerals;

[0045] FIG. 2 is a flow sheet of a process for synthesising zeolites from kaolin minerals in accordance with an embodiment of the present invention;

[0046] FIG. 3 shows in-situ XRD patterns of heat-treated kaolinite from 550° C. to 675° C.;

[0047] FIG. 4 shows SEM images of (a) kaolin sample and (b) meta-kaolin after heat treatment at 650° C.;

[0048] FIG. 5 shows graphs of aqueous silicate concentration against time during kaolin leaching (FIG. 5a) and metakaolin leaching (FIG. 5b);

[0049] FIG. 6 shows XRD patterns for amorphous phase and zeolite LTA using kaolin sample heating at 650° C.;

[0050] FIG. 7 shows SEM images of (a) amorphous zeolite, (b) zeolite LTA, cubic, Pm3m and (c) sodalite, wool ball shaped particles, P43n;

[0051] FIG. 8 shows in-situ XRD patterns of heat-treated feed material in Example 2;

[0052] FIG. 9 shows XRD patterns for the zeolite containing product formed in example 2. FIG. 9 also shows XRD patterns for the zeolite containing product formed in accordance with prior art methods, as described in this specification;

[0053] FIG. 10 shows XRD patterns for the zeolite LTA formed in example 2;

[0054] FIG. 11 shows XRD patterns for the Kaolinite feed and the calcined feed material in example 3;

[0055] FIG. 12 shows XRD patterns for the zeolite containing product formed in example 3;

[0056] FIG. 13 shows XRD patterns for the bauxite feed and the calcined feed material in example 4;

[0057] FIG. 14 shows XRD patterns for the zeolite containing product formed in example 4;

[0058] FIG. 15 shows XRD patterns for the coal flotation tailings feed and the calcined feed material in example 5;

[0059] FIG. 16 shows XRD patterns for the zeolite containing product formed in example 5; and

[0060] FIGS. 17 to 20 show SEM photomicrographs of the zeolite products obtained in examples 2, 3, 4 and 5, respectively.

DESCRIPTION OF EMBODIMENTS

[0061] It will be appreciated that the following examples have been provided for the purposes of illustrating preferred embodiments of the present invention. Therefore, the skilled person will understand that the present invention should not be considered to be limited solely to the features as described in the examples.

[0062] FIG. 2 shows a flow sheet of a process for synthesising zeolites from clay minerals in accordance with one embodiment of the present invention. In the flowsheet of FIG. 2, kaolin minerals 10 are fed to a calcination step 12 that is conducted in a furnace. The furnace is operated at a temperature of from 600° C. to 750° C. and the kaolin minerals are held in the furnace for a period of from 30 minutes to 1 hour. This converts the kaolinite to meta-kaolin. The meta-kaolin is fed to a leaching step 14 where is mixed with a 4M sodium hydroxide solution 16. In the leaching step 14, the aluminium and silicon components in the metakaolin are dissolved into solution to form an aluminosilicate solution (which is likely to consist of aluminates and silicates in solution). Impurities such as quartz, muscovite and feldspar do not dissolve in the leaching step 14. A solid/liquid separation step 15, such as filtration, is used to separate the pregnant leach liquor 18 from the solid impurities 20.

[0063] The pregnant leach liquor 20 is then treated in a crystallisation step 22 to form zeolites. The crystallisation step 22 is conducted at a temperature of from 80 to 100° C. and for a time of 1 to 4 hours, with stirring, to cause precipitation of the zeolites. Other components that may be used in zeolite crystallisation, such as templating agents, seed particles, and the like, may also be added to the crystallisation step 22. Additional material 23 may be added to change the ratio of Al to Si. For example, silica gel may be added. The zeolite particles are then separated from the liquid phase and the zeolite particles are recovered at 24. The zeolite particles may be washed and dried, as required and calcined to remove organic templating agents, if necessary. The desilicated solution 26 is recycled to the leaching step 14. In another embodiment, the solid impurities 20 may be mixed with the desilicated solution 26 to leach further aluminium and silicon components from the solid impurities. Where recycle of leach liquor takes place, it may be necessary to add make-up leach solution and to have a bleed stream from the recycle leach solution to prevent undesired build-up of impurities.

Example 1

[0064] In this example, zeolites were synthesised in accordance with one embodiment of the present invention. Kaolinite (composition shown in Table 1), sodium hydroxide (2.2% Na.sub.2CO.sub.3 by weight) and aluminium hydroxide (99.4%) were sourced from Sigma-Aldrich. Lead nitrate (99%) and copper (II) nitrate (98%) from ThermoFisher Scientific and cobalt (II) chloride hexahydrate (98%) from Sigma-Aldrich.

TABLE-US-00001 TABLE 1 XRF Data of Kaolinite (wt. %) Samples Al.sub.2O.sub.3 SiO.sub.2 Fe.sub.2O.sub.3 TiO.sub.2 MgO Na.sub.2O LOI Kaolin 38.5 44.9 0.74 1.36 0.04 0.08 13.8

Zeolite Synthesis

[0065] Kaolin (˜20 grams) was placed into a muffle furnace preheated to the target temperatures (650° C.) for 0.5 h to obtain the calcined product (amorphous meta-kaolin). Then, 2.5 g calcined products were added into a 250 ml glass beaker (with magnetic stirring) with 200 ml of 4 M NaOH solution which has been preheated to 60° C. The slurry was leached for 15 minutes or 30 minutes then filtrated at the same temperature. 0.2 ml filtrated liquid solution was sampled with dilution of 10 fold for ICP analysis. The filtrated liquid solution was transferred into a plastic bottle (250 ml) with two steel balls for mixing. The container was then placed into a water bath preheated to target temperature (90° C.) with an agitation speed of 500 rpm for 4 hour, which is enough time for full crystallisation and formation of the zeolite LTA. Based on the liquid solution chemical composition, extra gibbsite (Al(OH).sub.3) may need to be used to make up the Al/Si mole ratio up to 1. After crystallisation, the slurry was filtered. The solid sample was washed and dried in an oven overnight for the future adsorption test. The filtrate liquid solution was recycled to use the next round of kaolin leaching. 0.2 ml of filtrate liquid solution was sampled with 10× dilution for ICP analysis. Based on the liquid solution chemical composition, an extra amount of NaOH may need to be used to make up caustic solution up to 4M. For comparison, we also use kaolin or metakaolin feed samples to synthesis the sodalite (SOD) samples and amorphous zeolite samples.

Sample Characterization

[0066] Rigaku Smartlab was used to perform the in-situ high temperature XRD analysis to determine the phase transformation of kaolin. The pulverized solid power was added in the small container made from corundum. The loaded container was placed on top of sampler holder and sealed by the dome. The heating rate was set to 50° C./minute. The holding time for each scan at each temperature was 10 minutes prior to the x-ray scan time which was approximately 15 minutes to cover the 2θ angle range of 5-40° using Cu Kα irradiation (λ=1.5406 Å) at 40 kV with a scanning speed of 0.05° per second.

[0067] The other crystalline solid phases were identified by X-ray diffraction (XRD) with a Bruker D8 Advance XRD with a LynxEye detector, and Cu Kα irradiation (λ=1.5406 Å) at 40 kV with a scanning speed of 0.050 per second over the 2θ angle range of 5−40°. The 2014 PDF database from BRUKER was used for reflection identification. The solid particle morphologies were observed by scanning electron microscopy (SEM, HITACHI SU3500) with an accelerating voltage of 5 kV and spot size of 30.

[0068] Characterisation of the solution samples was performed using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES).

Results

Thermal Activation of Kaolin

[0069] Accurately determining the kaolin to amorphous transition temperature is especially useful in the synthesis process in relation to energy costs. Most previous researchers utilise Thermo Gravimetric Analysis (TGA) to determine the phase transition temperature and time. Previously, most of the research implemented the thermo gravimetric (TG) method for estimation of weight loss of kaolin samples. Based on the chemical formula as shown in equation 3, the weight loss is around 14% if pure kaolin is fully de-hydroxylated. However, most kaolin samples contain impurities and the weight loss technique is not highly accurate. This causes the thermal activation normally reported to be over a wide temperate range from 550 to 1000° C., which typically overestimates the calcination time from 1 to 12 hours. Here, we implemented the methodology of in-situ high temperature XRD to monitor the phase transformation of kaolin with programmed heating rate (5˜200° C. per minute) and short scan time (5˜16 minutes). Instead of measuring the weight loss, the intensity change of key phase peaks at (001) and (002) planes of kaolin were recorded with different temperatures and heating times. The kaolin sample has no significant change under 500° C. As shown in FIG. 3, the sample at 550° C. still has the characteristic peaks of kaolinite and the impurity anatase (2Θ=25.33°). The intensity of the kaolinite crystal plane peaks decreases with increasing temperature. At 625° C., the peaks at range 20˜220 and 35˜40° for kaolin phase are not detectable while crystal plane peaks at (001) and (002) are still detectable. At 650° C., the XRD patterns only show the anatase peaks. This indicates that the kaolinite was fully dehydroxylated into x-ray amorphous phase. The dehydroxylation to the amorphous phase that occurs in the temperature range of 600-675° C. is shown in Equation 3.

Al.sub.2[Si.sub.2O.sub.5](OH).sub.4.fwdarw.Al.sub.2O.sub.3.2SiO.sub.2+2H.sub.2O  (3)

[0070] SEM images indicate that meta-kaolin started to lose the edge sheet structure of the kaolin as shown in FIG. 4 but still have the layer structure of crystals which is indicative of lack of long range crystalline structure.

Hydrothermal Synthesis of Zeolites

[0071] In the synthesis process used in this example, kaolinite or metakaolin dissolves into highly alkaline solution then re-precipitates as insoluble sodium aluminate silicates known as zeolites based on equation 1 and 2.

[0072] FIG. 5a shows leaching/dissolution of a kaolin feed material with a 4M NaOH solution. A can be seen from FIG. 5, the kaolin dissolves quite slowly in the leaching solution. The silicate concentration in solution increases as the kaolin dissolves. However, desilication products (DSP) start to precipitate after about 50 minutes and this leads to the silicate concentration in solution decreasing due to precipitation of the DSP. In contrast, when metakaolin is sent to the leaching test, the metakaolin dissolves very quickly and almost complete dissolution is obtained after 10 to 15 minutes. DSP starts to precipitate after about 25 to 30 minutes, with a maximum concentration of silica in solution being obtained between 10 minutes and 30 minutes. Therefore, by leaching metakaolin at 70° C. for a period of from 10 minutes to 30 minutes, loss of silicates to DSP in the leaching step can be avoided. It will be appreciated that any DSP that precipitates in the leaching step will precipitate onto the solid impurities that do not dissolve in the leaching solution. As it is necessary to separate the undissolved solid impurities from the leaching solution prior to zeolite crystallisation in order to obtain pure zeolite, the DSP that precipitates in the leaching step will precipitate onto the solid impurity particles and this will represent a loss of yield. In FIG. 5, the silicate concentration in solution (expressed as g/L SiO.sub.2) is monitored and the kaolin and DSP are calculated from a mass balance.

[0073] For zeolites made from a feed material in which the solid samples were heated at 650° C., as shown in FIG. 6, zeolite LTA is the only phase. The SEM image reveal the cubic structure of zeolite LTA shape as shown in FIG. 7.

Example 2

[0074] A material having the composition as set out in Table 2 was used as the feed material in this example.

TABLE-US-00002 TABLE 2 XRF data of main chemical composition and loss on ignition of feed samples(%) Al.sub.2O.sub.3 TiO.sub.2 Fe.sub.2O.sub.3 K.sub.2O SiO.sub.2 LOI 32.9 1.0 1.3 0.9 51.1 13.0

[0075] The feed material was subjected to the following processing:

Thermal Activation Stage:

[0076] 25 gram samples were placed in ceramic containers and transferred into a muffle furnace, followed by preheating them to the target temperature of 750° C. for 1.5 h. FIG. 8 shows XRD patterns for the feed material and the calcined feed material.

Leaching and Aging Stage:

[0077] The synthetic caustic liquor (50 mL) with caustic concentration 4M was magnetically stirred at 300-500 rpm in a 150 mL Erlenmeyer flask and sealed with Parafilm to prevent excessive liquid loss from evaporation. The solution was heated by a hotplate with a feedback controller. When the set-point temperature at 60° C. was reached, the activated solid samples (1.5 g) were added to the heated solution. Once the leaching reaction was completed in 1 hour, solids and liquids were separated through vacuum filtration. The filtrate solution will be used for the precipitation of the Zeolite 4A product.

Crystallization Stage:

[0078] The obtained solution from the leaching test was transferred into 100 or 200 ml Teflon bottle or steel container. To synthesis different types of zeolites, extra silica or aluminium source will be added into solution to balance molar ratio of SiO.sub.2/Al.sub.2O.sub.3. Then, the bottle was placed in the water bath with temperature of 90° C. for 2˜4 hours. The solid was filtrated and washed with DI water until pH value <9. The solid product was dried in an oven at 105° C. for 2˜4 hours.

[0079] FIG. 9 shows XRD patterns for the zeolite containing product formed in example 2. FIG. 9 also shows XRD patterns for the zeolite containing product formed in accordance with prior art methods, as described in this specification. As can be seen from FIG. 9, the zeolite containing product formed in accordance with an embodiment of the present invention has much lower levels of other components than the zeolite containing product formed in accordance with prior art methods. FIG. 10 shows XRD patterns for the zeolite LTA formed in example 2

Example 3

[0080] A material having the composition as set out in Table 2 was used as the feed material in this example.

TABLE-US-00003 TABLE 2 XRF data of main chemical composition and loss on ignition of feed samples(%) Al.sub.2O.sub.3 TiO.sub.2 Fe.sub.2O.sub.3 K.sub.2O SiO.sub.2 LOI 37.0 1.3 1.8 0.9 45.3 13.6

[0081] The feed material was subjected to the following processing:

Thermal Activation Stage:

[0082] 5 gram samples were placed in ceramic containers and transferred into a muffle furnace, followed by preheating them to the target temperature of 650° C. for 1 h.

Leaching and Aging Stage:

[0083] The synthetic caustic liquor (50 mL) with caustic concentration 4M was magnetically stirred at 300-500 rpm in a 150 mL Erlenmeyer flask and sealed with Parafilm to prevent excessive liquid loss from evaporation. The solution was heated by a hotplate with a feedback controller. When the set-point temperature at 70° C. was reached, the activated solid samples (1 g) were added to the heated solution. Once the leaching reaction was completed in 0.5 hour, solids and liquids were separated through vacuum filtration. The filtrate solution will be used for the precipitation of the zeolite 4A product.

Crystallization Stage:

[0084] The obtained solution from leaching test was transferred into 100 or 200 ml Teflon bottle or steel container. To synthesis different types of zeolites, the extra silica or aluminium source will be added into solution to balance molar ratio of SiO.sub.2/Al.sub.2O.sub.3. Then, the bottle was placed in the water bath with temperature of 90° C. for 2 hours. The solid was filtrated and washed with DI water until pH value <9. The solid product was dried in an oven at 105° C. for 2˜4 hours.

[0085] FIG. 11 shows XRD patterns for the kaolinite feed material and the calcined kaolinite. FIG. 12 shows XRD patterns of the zeolite formed in this example. The zeolite is predominantly zeolite LTA.

Example 4

[0086] This example uses a high silica bauxite as a feed material. The high silica bauxite had a composition as shown in Table 4:

TABLE-US-00004 TABLE 4 Composition of high silica bauxite material used as feed in example 4: Al.sub.2O.sub.3 TiO.sub.2 Fe.sub.2O.sub.3 K.sub.2O SiO.sub.2 LOI 39.3 1.9 24.7 0.1 14.2 19.8

[0087] The high silica bauxite feed comprised gibbsite, boehmite, haematite, kaolinite, quartz, anatase and organics. The feed material was subjected to the following processing:

Thermal Activation Stage:

[0088] 10 gram samples were placed in ceramic containers and transferred into a muffle furnace, followed by preheating them to the target temperature of 650° C. for 1 h. FIG. 13 shows XRD patterns for the bauxite feed material and the calcined bauxite feed material.

Leaching and Aging Stage:

[0089] The synthetic caustic liquor (50 mL) with caustic concentration 4M was magnetically stirred at 300-500 rpm in a 150 mL Erlenmeyer flask and sealed with Parafilm to prevent excessive liquid loss from evaporation. The solution was heated by a hotplate with a feedback controller. When the set-point temperature at 60° C. was reached, the activated solid samples (2.5 g) were added to the heated solution. Once the leaching reaction was completed in 0.5 hour, solids and liquids were separated through vacuum filtration. The filtrate solution will be used for the precipitation of 4A product.

[0090] With this feed material, the solid impurities 20 resulting from the leaching step 14 shown in FIG. 2 comprise desilicated bauxite that can be fed to a Bayer process plant/alumina refinery. As the bauxite has had silica removed therefrom, some processing difficulties arising in the Bayer process plant/alumina refinery from having excess silica in the bauxite feed, such as excessive sodium hydroxide consumption and precipitation of desilication products on heat exchange surfaces causing fouling, can be reduced.

Crystallization Stage:

[0091] The obtained solution from leaching test will be transferred into 100 or 200 ml Teflon bottle or steel container. To synthesis different types of zeolites, the extra silica or aluminium source will be added into solution to balance molar ratio of SiO.sub.2/Al.sub.2O.sub.3. Then, the bottle was placed in the water bath with temperature of 90° C. for 2 hours. The solid was filtrated and washed with DI water until pH value <9. The solid product was dried in an oven at 105° C. for 2˜4 hours.

[0092] FIG. 14 shows XRD patterns of the zeolite formed in this example. The zeolite is predominantly zeolite LTA.

Example 5

[0093] In this example, coal flotation tailings were used as a feed material. A full analysis of this feed material has not been completed but it is expected that it will contain around 20% Al.sub.2O.sub.3. The coal flotation tailings were treated with the following steps:

Thermal Activation Stage:

[0094] 15 gram samples were placed in ceramic containers and transferred into a muffle furnace, followed by preheating them to the target temperature of 650° C. for 1 h. FIG. 15 shows the XRD patterns for the coal tailings feed product and the coal tailings after calcination.

Leaching and Aging Stage:

[0095] The synthetic caustic liquor (50 mL) with caustic concentration 4M was magnetically stirred at 300-500 rpm in a 150 mL Erlenmeyer flask and sealed with Parafilm to prevent excessive liquid loss from evaporation. The solution was heated by a hotplate with a feedback controller. When the set-point temperature at 70° C. was reached, the activated solid samples (1.5 g) were added to the heated solution. Once the leaching reaction was completed in 0.5 hour, solids and liquids were separated through vacuum filtration. The filtrate solution will be used for the precipitation of product.

Crystallization Stage:

[0096] The obtained solution from leaching test will be transferred into 100 or 200 ml Teflon bottle or steel container. To synthesis different types of zeolites, the extra silica or aluminium source will be added into solution to balance molar ratio of SiO.sub.2/Al.sub.2O.sub.3. Then, the bottle was placed in the water bath with temperature of 90° C. for 2 hours. The solid was filtrated and washed with DI water until pH value <9. The solid product was dried in an oven at 105° C. for 2˜4 hours. FIG. 16 shows XRD patterns of the zeolite formed in this example. The zeolite is predominantly zeolite LTA.

[0097] FIGS. 17 to 20 show SEM photomicrographs of the zeolite products obtained in examples 2, 3, 4 and 5, respectively.

[0098] Zeolites produced in accordance with the present invention can be used to remove heavy metals from solution. Indeed, the present inventors have conducted experimental test that show heavy metal ions, such as Cu, Pb and Co, can be removed from solution using zeolites produced in accordance with the present invention.

[0099] The zeolites produced in accordance with the present invention can also be used in any other applications in which the zeolites are known to be useful. Examples include gas separation, detergents, ethanol drying, water absorption and heavy metal absorption, and catalysis. The skilled person will understand that the final use for the zeolites produced in accordance with the present invention is not limited to any of the above-mentioned uses but can extend to any possible use for zeolites.

[0100] In the present specification and claims (if any), the word ‘comprising’ and its derivatives including ‘comprises’ and ‘comprise’ include each of the stated integers but does not exclude the inclusion of one or more further integers.

[0101] Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0102] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.