CRYSTALINE SORBENT MATERIALS FOR WATER CAPTURE AND RELEASE

Abstract

A crystalline sorbent material of formula: A.sub.bM[M(CN).sub.6]y.Math.nH.sub.2O wherein A is a group 1 metal; b is from 0.001 to 0.3; M is a transition metal; M is iron or cobalt; y is from 0.65 to 0.80; and n is from 0 to 7. The crystalline sorbent materials of the present invention may be used in a method of capturing water. The method of the present invention utilising such crystalline sorbent materials may be used in water capture and purification processes to provide fresh water suitable for drinking or for use in agriculture. The method of the present invention may also be used to remove water as a contaminant or for use in dehumidification processes. A use of such a crystalline sorbent material is also disclosed.

Claims

1. A crystalline sorbent material of formula:
A.sub.bM[M(CN).sub.6].sub.y.Math.nH.sub.2O wherein A is a group 1 metal; b is from 0.001 to 0.3; M is a transition metal; M is iron or cobalt; y is from 0.65 to 0.80; and n is from 0 to 7.

2. The crystalline sorbent material of claim 1, wherein A is potassium.

3. The crystalline sorbent material of claim 1, wherein M is zinc.

4. The crystalline sorbent material of claim 1, wherein M is cobalt.

5. The crystalline sorbent material of claim 1, having a formula (K.sub.bZn[Co(CN).sub.6].sub.y.Math.nH.sub.2O) wherein b is from 0.001 to 0.3, y is from 0.65 to 0.80 and n is from 0 to 7.

6. The crystalline sorbent material of claim 5 wherein b is from 0.005 to 0.12.

7. The crystalline sorbent material of claim 5 wherein b is from 0.12 to 0.3.

8. The crystalline sorbent material of claim 1, having a cubic unit cell.

9. The crystalline sorbent material of claim 1, wherein the crystalline sorbent material is at least one of thermally stable or hydrolytically stable, and wherein the crystalline sorbent material does not undergo a phase transition to a hexagonal phase when heated to at least 80? C.

10. A method of preparing a crystalline sorbent material of formula:
A.sub.bM|M(CN)l.sub.y.Math.nH.sub.2O wherein A is a group 1 metal: b is from 0.001 to 0.3; M is a transition metal; M is iron or cobalt; y is from 0.65 to 0.80; and n is from 0 to 7, the method comprising the steps: (a) reacting a source of B.sub.c[M(CN).sub.6] with a source of MX.sub.x; and (b) obtaining the crystalline sorbent material; wherein B is H or a group 1 metal; c is from 2 to 4; M is a transition metal; M is iron or cobalt; X is an anion; and x is from 1 to 4.

11. The method of claim 10, wherein step (a) involves the source of B.sub.c[M(CN).sub.6] with a source of MX.sub.x in water; and step (b) involves precipitating the crystalline sorbent material from water.

12. A method of capturing water from a composition comprising water and/or water vapour, the method comprising: (i) providing a crystalline sorbent material of formula A.sub.bM[M(CN).sub.6].sub.y.Math.nH.sub.2O; and (ii) contacting the crystalline sorbent material with the composition comprising water; wherein upon contact with the composition comprising water and/or water vapour the crystalline sorbent material sorbs water; and wherein A is a group 1 metal; b is from 0.001 to 0.3, M is a transition metal, M is iron or cobalt; y is from 0.65 to 0.80; and n is from 0 to 7.

13. The method of claim 12 wherein the composition is a gaseous composition comprising water, suitably wherein the gaseous composition is air.

14. The method of claim 12 comprising a further step (iii) of releasing the captured water from the crystalline sorbent material using a suitable process such as temperature swing, humidity swing or vacuum swing.

15. The method of claim 12 wherein the crystalline sorbent material is provided on a support.

16. The method of claim 12, wherein the method further comprises A delivering water to a locus, at least in part by: at least one of transporting or storing the crystalline sorbent material; applying a stimulus to the crystalline sorbent material to effect desorption of water retained therein; and collecting desorbed water at the locus.

17. (canceled)

Description

EXAMPLES

Materials and Analytical Methods

[0136] The following materials were obtained from the sources noted. Potassium hexacyanocobaltate(III) (K.sub.3[Co(CN).sub.6])Alfa Aesar; zinc sulphate heptahydrate (Zn(SO.sub.4).sub.2.Math.7H.sub.2O)Alfa Aesar; zinc nitrate hexahydrate (Zn(NO.sub.3).sub.2.Math.6H.sub.2O)Sigma Aldrich; zinc chloride (ZnCl.sub.2)Sigma Aldrich; and sulphuric acid (H.sub.2SO.sub.4, 95-97%)Sigma-Aldrich. These materials were directly used without further purification. Millipore grade water was used for the synthesis of example materials described below. Zeolite 13X, Syloid? AL-1 and Silica Gel were obtained from commercial suppliers.

Powder X-Ray Diffraction (PXRD)

[0137] PXRD patterns were recorded at room temperature on a PANalytical Empyrean? diffractometer equipped with a PIXcel.sup.3D detector operating in scanning line detector mode with an active length of 4 utilizing 255 channels. The diffractometer is outfitted with an Empyrean Cu LFF (long fine-focus) HR (9430 033 7310x) tube operated at 40 kV and 40 mA and CuK.sub.? radiation (?.sub.?=1.540598 ?) was used for diffraction experiments. Continuous scanning mode with the goniometer in the theta-theta orientation was used to collect the data. Incident beam optics included the Fixed Divergences slit with anti-scatter slit PreFIX module, with a ?? divergence slit and a ?? anti-scatter slit, as well as a 10 mm fixed incident beam mask and a Soller slit (0.04 rad). Divergent beam optics included a P7.5 anti-scatter slit, a Soller slit (0.04 rad), and a Ni-? filter. In a typical experiment, approximately 20 mg of fine powder sample was loaded on a zero background silicon disc. The data were collected from 5?-45? (2?) with a step-size of 0.01313030 and a scan time of 30 seconds per step. Raw data were analyzed using the X'Pert HighScore Plus? software V 4.1 (PANalytical, The Netherlands).

[0138] FIG. 1 shows a comparison of PXRD patterns calculated for Zn[Co(CN).sub.6].sub.0.667.Math.4H.sub.2O (termed ZnCo herein) and obtained by experiment as described above for ZnCo in the cubic phase and ZnCo in the hexagonal phase.

In-Situ Variable Temperature Powder X-Ray Diffraction (VT-PXRD)

[0139] Diffractograms at different temperature were recorded using a PANalytical X'Pert Pro-MPD diffractometer equipped with a PIXcel3D detector operating in scanning line detector mode with an active length of 4 utilizing 255 channels. Anton Paar TTK 450 stage coupled with the Anton Paar TCU 110 Temperature Control Unit was used to record the variable temperature diffractograms. The diffractometer was outfitted with a Cu LFF (long fine-focus) HR (9430 033 7300x) tube operated at 40 kV and 40 mA and CuK? radiation (??=1.54056 ?). A continuous scanning mode with the goniometer in the theta-theta orientation was used to collect the data. Incident beam optics included a fixed divergences slit, with a ?? divergence slit and a Soller slit (0.04 rad). Divergent beam optics included a P7.5 anti-scatter slit, a Soller slit (0.04 rad), and a Ni-? filter. In a typical experiment, 50 mg of sample was dried, ground into a fine powder and loaded on a sample holder made in an Anton Paar TTK 450 chamber. The data were collected from 5?-40? (2?) with a step-size of 0.01671130 and a scan time of 50 seconds per step. Raw data were analysed using the X'Pert HighScore Plus? software V 4.1 (PANalytical, The Netherlands). Each sample was heated up to 240? C. under N.sub.2 atmosphere and then cooled to room temperature.

Thermogravimetric Analysis (TGA)

[0140] TGA Thermograms were recorded under nitrogen using a TA Q50 V20.13 Build 39 instrument. Platinum pans and a flow rate of 60 mL/min for the nitrogen gas were used for the experiments. The data were collected in the high-resolution dynamic mode with a sensitivity of 1.0, a resolution of 4.0, and a temperature ramp of 10? C./min up to 550? C. The data was evaluated using the T.A. Universal Analysis suite for Windows XP/Vista Version 4.5A.

ICP-OES Analysis

[0141] ICP-OES analysis was carried out on Agilent Technologies 5100 ICP-OES instrument. In a typical experiment, samples were prepared and analysed as follows. 10 mg of each sample was dissolved in 4 mL aqua regia. A 1 mL aliquot was taken from this solution and diluted with 4 mL of 1 M HNO.sub.3. For each sample, three sets of aliquots were prepared and injected into the auto sampler. Prior to analysis, the instrument was calibrated with standard solutions of all the tested elements (Co, K, Zn and S) in the appropriate concentration range (0-250 ppm). Individual elements were identified from peaks at characteristic positions (Co, 228 nm and 238 nm; K, 769 nm; Zn, 206 nm and 334 nm) with best intensity (to avoid interference). The concentration (in ppm) of each element was calculated using standard calibration curves and is tabulated in Table 1 below.

Intrinsic Dynamic Vapour Sorption (DVS) Measurements

[0142] Water vapour adsorption-desorption experiments at atmospheric pressure and 27? C. were performed using a DVS Intrinsic analyser (from Surface Measurement Systems). The water vapour sorption isotherms were measured using approximately 5-30 mg of sample. Pure HPLC grade water was used as the adsorbate for these measurements and temperature was maintained by enclosing the system in a temperature-controlled incubator. Prior to the sorption analysis, each sample was pre-treated at 40? C. for 6 h, followed by a cooling down at 27? C. for 60 min.

Vacuum DVS Measurements

[0143] Vacuum DVS measurements were conducted using a Surface Measurement System DVS Vacuum instrument. The DVS Vacuum instrument used for these studies measures the uptake and loss of water vapour gravimetrically. Activated and degassed samples were further degassed in-situ under high vacuum (2.Math.10.sup.?6 Torr) to establish the dry mass. Adsorption/desorption cycles were used for the determination of recyclability and working capacity of ROS-038 and Syloid? AL-1, respectively.

[0144] Recycling tests were performed in a temperature-controlled incubator at 27? C. For each material, ?135 cycles of adsorption (0.fwdarw.60% P/P.sub.0, 5 min) followed by desorption (60.fwdarw.0% P/P.sub.0, 5 min) were conducted at 27? C. Approximately 5-10 mg of sample were used for each experiment. The mass of every sample was determined by comparison with an empty reference pan and recorded by a high-resolution microbalance with a mass resolution of ?0.1 ?g. The high mass resolution and its excellent baseline stability allow the instrument to measure the adsorption and desorption of very small amounts of water molecules. The vapour partial pressure around the sample is controlled by mixing saturated and dry carrier vapour streams using electronic mass flow controllers. The temperature was maintained constant at 27?0.1? C. by enclosing the entire system in a temperature-controlled incubator. Pure water (HPLC Gradient Grade, Fisher Chemical) was used as the adsorbate for the recycling studies.

Intelligent Gravimetric Analyser (IGA) Measurements.

[0145] Water vapour adsorption-desorption experiments at atmospheric pressure (1013 mbar, 760 torr) were performed using a IGAsorp dynamic vapour sorption (DVS) analyser from Hiden Isochema Ltd., UK. Prior to the experiment, the sample was allowed to reach temperature and humidity equilibria within the chamber for a specific period of time. The sample (ca. 5-40 mg) was exposed to desired % RH (30, 60 or 0% RH) and temperatures, in the adsorption (27? C.)/desorption (49? C. or 60? C.) branches, respectively. Consequently, recyclability and regeneration profiles of water vapour adsorption and desorption were obtained.

Preparation of Crystalline Sorbent Materials

Example 1: K.SUB.0.10.Zn[Co(CN).SUB.6.].SUB.0.70..Math.4H.SUB.2.O

[0146] A solution of K.sub.3[Co(CN).sub.6] (2 mmol, 664.6 mg) in 20 mL of H.sub.2O was added to a stirred solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (2 mmol, 575.1 mg) in 20 mL of H.sub.2O. The resulting precipitate was stirred at room temperature for 30 minutes, filtered, and washed with H.sub.2O. Yield: 530 mg, ?94%. The phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at 2? (?) 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 1 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 2: K.SUB.0.009.Zn[Co(CN).SUB.6.].SUB.0.669..Math.4.5H.SUB.2.O

[0147] H.sub.3Co(CN).sub.6 was synthesised from K.sub.3[Co(CN).sub.6] by a previously reported procedure (U.S. Pat. No. 7,022,641 B2). The H.sub.3Co(CN).sub.6 produced by this method contained a small amount of potassium ion impurity (0.5-1%). A solution of H.sub.3[Co(CN).sub.6] (containing 0.5-1% potassium compared to cobalt) (1 mmol, 218 mg) in 100 mL of H.sub.2O was added dropwise to a stirred solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (1 mmol, 287 mg) in 100 mL of H.sub.2O over a period of 15 minutes. The resulting precipitate was stirred at room temperature for 30 minutes, filtered, and washed with H.sub.2O. Yield: 250 mg, ?87%.

[0148] The K.sup.+ in H.sub.3[Co(CN).sub.6] was found to be as follows, as quantified by ICP-OES.

[0149] ICP-OES analysis of H.sub.3[Co(CN).sub.6]:

TABLE-US-00001 Sample Co (ppm) K (ppm) Co Molar K Molar K/Co Calculated formula H.sub.3Co(CN).sub.6 110.37 4.01 1.872 0.102 0.054 K.sub.0.054H.sub.3[Co(CN).sub.6]

[0150] FIG. 2 shows a comparison of PXRD patterns calculated for ZnCo (using the data provided in Roque et al. 2007 cited above) and obtained by experiment as described above for Example 1 (as synthesized) and Example 9 (as synthesized) measured at 25? C. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 2 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 3: K.SUB.0.02.Zn[Co(CN).SUB.6.].SUB.0.676..Math.4.2H.SUB.2.O

[0151] A solution of K.sub.3[Co(CN).sub.6] (1 mmol, 332 mg) in 10 mL of H.sub.2O was added dropwise to a stirred solution of in Zn(NO.sub.3).sub.2.Math.6H.sub.2O (1.8 mmol, 535 mg) 10 mL of H.sub.2O over a period of 15 minutes. The resulting precipitate was stirred at room temperature for 24 hours, filtered, and washed with H.sub.2O. Yield: 400 mg, ?77%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 3 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 4: K.SUB.0.03.Zn[Co(CN).SUB.6.].SUB.0.677..Math.4H.SUB.2.O

[0152] A solution of K.sub.3[Co(CN).sub.6] (1 mmol, 332 mg) in 100 mL of H.sub.2O was added to a stirred solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (1 mmol, 287 mg) in 100 mL of H.sub.2O. The resulting precipitate was stirred at room temperature for 30 minutes and left undisturbed for 24 hours, then filtered and washed with H.sub.2O. Yield: 190 mg, ?66%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 4 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 5: K.SUB.0.06.Zn[Co(CN).SUB.6.].SUB.0.688..Math.3.5H.SUB.2.O

[0153] 2.4 g of polyvinylpyrrolidone (PVP) was added to a solution Zn(NO.sub.3).sub.2.Math.6H.sub.2O (0.71 mmol, 214 mg) in 80 mL H.sub.2O and stirred until the solution cleared. To this, a solution of K.sub.3[Co(CN).sub.6] (0.4 mmol, 132.9 mg) in 80 mL of H.sub.2O and was added dropwise for a period of 30 minutes. The resulting mixture was further stirred for 30 minutes, filtered, and washed with H.sub.2O. Yield: 150 mg, ?76%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 5 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 6: K.SUB.0.11.Zn[Co(CN).SUB.6.].SUB.0.702..Math.3.8H.SUB.2.O

[0154] K.sub.3[Co(CN).sub.6] (1.52 mmol, 521 mg) and ZnCl.sub.2 (2.28 mmol, 317 mg) were taken as solids and 50 mL of H.sub.2O was added, stirred for 10 minutes. The resulting suspension was shaken on a benchtop shaker for 24 hrs (400 rpm). The slurry was centrifuged and the resulting solid was washed 3 times with distilled water, air dried. Yield: 650 mg, ?98%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 6 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 7: K.SUB.0.12.Zn[Co(CN).SUB.6.].SUB.0.709..Math.3.5H.SUB.2.O

[0155] A solution of K.sub.3[Co(CN).sub.6] (2 mmol, 664.6 mg) in 10 mL of H.sub.2O was added to a stirred solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (2 mmol, 575.1 mg) in 10 mL of H.sub.2O. The resulting precipitate was stirred at room temperature for 30 minutes, filtered, and washed with H.sub.2O. Yield: 503 mg, ?89%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 7 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 8: K.SUB.0.13.Zn[Co(CN).SUB.6.].SUB.0.711..Math.4H.SUB.2.O

[0156] A solution of K.sub.3[Co(CN).sub.6] (2 mmol, 664.6 mg) in 5 mL of H.sub.2O was added to a stirred solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (2 mmol, 575.1 mg) in 5 mL of H.sub.2O. The resulting precipitate was stirred at room temperature for 30 minutes, filtered, and washed with H.sub.2O. Yield: 540 mg, ?92%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 8 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 9: K.SUB.0.25.Zn[Co(CN).SUB.6.].SUB.0.75..Math.3.8H.SUB.2.O

[0157] A solution of K.sub.3[Co(CN).sub.6] (0.34 mol, 114.9 g) in 517 mL of H.sub.2O was added to a stirred solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (0.34 mol, 99.42 g) in 517 mL of H.sub.2O. The resulting precipitate was stirred at room temperature for 4 h, filtered, and washed with H.sub.2O. Yield: ?100 g, ?98%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 9 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 10: Scale-Up Synthesis of Example 1K.SUB.0.10.Zn[Co(CN).SUB.6.].SUB.0.70..Math.4H.SUB.2.O

[0158] A solution of K.sub.3[Co(CN).sub.6] (180 mmol, 59.81 g) in 1.8 L of H.sub.2O was added to a stirred solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (180 mmol, 51.76 g) in 1.8 L of H.sub.2O. The resulting precipitate was stirred at room temperature for 30 minutes, filtered, and washed with H.sub.2O. Yield: 49.15 g, ?97%. The cubic phase purity of the material was confirmed by identifying the respective PXRD peaks of PBA at the following characteristic 2?(?) positions: 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 (see FIG. 2). The composition of Example 10 was determined by ICP-OES analysis as described above and the results are shown in Table 1. The number of water molecules was calculated from TGA data.

Example 11ROS038X Paper Composite was Made by Using a Material Prepared as Described in Example 10

[0159] A mixture of multiple cellulose and non-cellulose fibres are combined with the sorbent material of Example 10, proprietary binders (i.e. acrylic based binding system in whole or in part combined with PVOH based binders) and blended into a water slurry. The slurry was funneled through a common paper making press system comprising various stages of water removal via temperature and pressure applied to the slurry, until a flat paper can be rolled for delivery to the rotor manufacturer. FIG. 3 shows scanning electron microscopy images of this paper composite (in 3 ?m and 10 ?m magnification).

Comparative Example 1ZnCo

[0160] An aqueous solution of Zn(SO.sub.4).sub.2.Math.7H.sub.2O (0.01M, 287 mg in 100 mL H.sub.2O) was dropwise mixed with H.sub.3[Co(CN).sub.6] (0.01M, 218 mg in 100 mL of H.sub.2O) and the resulting precipitate was stirred for 30 minutes and left on bench for 1 week. The precipitate was separated from the mother liquor by centrifugation and the solid fraction was washed with distilled water and then air-dried. Yield, 230 mg, ?81%. The phase purity of the material was confirmed by identifying the respective peaks of PBA at 2? (?) 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 in PXRD. X-ray dispersed-energy spectroscopy (EDX) analyses shows that the atomic metal ratio (Zn:Co) was close to 3:2 which is very good agreement with ZnCo reported in Roque et al. 2007 (cited above). Chemical composition was determined by ICP-OES analysis:

ICP-OES Analysis of ZnCo:

[0161]

TABLE-US-00002 Co Zn K* Co Zn K* Sample (ppm) (ppm) (ppm) Molar Molar Molar K/Zn Co/Zn Calculated formula ZnCo 62.06 103.62 0.3 1.053 1.584 0.007 0.004 0.664 Zn[Co(CN).sub.6].sub.0.664 .Math. 4H.sub.2O *Note: The amount of K.sup.+ detected here is negligible. This K.sup.+ comes from the starting material H.sub.3[Co(CN).sub.6] which has 0.5-1% K.sup.+ impurity as mentioned above.

EDX Analysis of ZnCo:

[0162]

TABLE-US-00003 Element Atomic % Zn:Co Zn 60.78 1.56 Co 38.83 K 0.40

Comparative Example 2Zn.SUB.3-a.Fe.SUB.a.[Co(CN).SUB.6.].SUB.2..Math.nH.SUB.2.OFeZnCo

[0163] A solution of K.sub.3[Co(CN).sub.6] (1 mmol, 332.33 mg) in 100 mL of H.sub.2O was added to a mixed solution of FeSO.sub.4.Math.7H.sub.2O (1.8 mmol, 501 mg in 100 mL H.sub.2O) and Zn(SO.sub.4).sub.2.Math.7H.sub.2O (3.6 mmol, 1.036 g in 100 mL H.sub.2O). The resulting precipitate was filtered by using membrane filter paper and washed with distilled H.sub.2O. Yield, 310 mg, ?77%. The phase purity of the material was confirmed by identifying the respective peaks of PBA at 2? (?) 14.9, 17.3, 24.5, 28.8, 35, 39.2, 43.2 in PXRD. Chemical composition was determined by ICP-OES analysis:

ICP-OES Analysis of ZnFeCo:

[0164]

TABLE-US-00004 Co Zn Fe Co Zn Fe Sample (ppm) (ppm) (ppm) Molar Molar Molar Fe/Co Zn/Co Calculated formula ZnFeCo 77.23 90.29 33.53 1.310 1.380 0.600 0.458 1.053 Zn.sub.2.1Fe.sub.0.9[Co(CN).sub.6].sub.2 .Math. yH.sub.2O

TABLE-US-00005 TABLE 1 Chemical compositions of ROS-038X and ROS-038Y from ICP-OES analysis. Example Co (ppm) Zn (ppm) K (ppm) Co Molar Zn Molar K Molar K/Zn Co/Zn Calculated formula 1 80.52 127.00 8.05 1.366 1.941 0.205 0.100 0.700 K.sub.0.10Zn[Co(CN)6]0.70 .Math. 4H.sub.2O 2 85.72 142.06 0.76 1.454 2.171 0.019 0.009 0.669 K.sub.0.009Zn[Co(CN)6]0.669 .Math. 4.2H.sub.2O 3 79.58 130.57 1.59 1.350 1.996 0.040 0.020 0.676 K.sub.0.02Zn[Co(CN)6]0.676 .Math. 4.2H.sub.2O 4 81.00 132.50 2.89 1.374 2.025 0.074 0.030 0.678 K.sub.0.03Zn[Co(CN)6]0.677 .Math. 4H.sub.2O 5 76.62 123.10 5.10 1.300 1.883 0.130 0.060 0.689 K.sub.0.06Zn[Co(CN)6]0.688 .Math. 3.5H.sub.2O 6 84.27 133.24 9.01 1.430 2.036 0.230 0.113 0.702 K.sub.0.11Zn[Co(CN)6]0.702 .Math. 3.8H.sub.2O 7 78.00 122.00 9.15 1.323 1.865 0.234 0.125 0.709 K.sub.0.12Zn[Co(CN)6]0.709 .Math. 3.5H.sub.2O 8 72.33 113.03 9.09 1.227 1.728 0.232 0.134 0.710 K.sub.0.13Zn[Co(CN)6]0.711 .Math. 4H.sub.2O 9 90.62 132.43 19.52 1.537 2.024 0.499 0.246 0.759 K.sub.0.25Zn[Co(CN)6]0.75 .Math. 3.8H.sub.2O 10 - Scale-up of 78.80 124.29 7.68 1.339 1.900 0.196 0.103 0.704 K.sub.0.10Zn[Co(CN)6]0.70 .Math. 4H.sub.2O Example 1

Performance Testing

Thermal Stability Test

[0165] The thermal stability of the cubic phase of the Example 1 material (termed ROS-038X) was confirmed by variable temperature Powder X-ray Diffraction (VT-PXRD) in the range of 25? C.-240? C. FIG. 4 shows the VT-PXRD patterns of Example 1 from 25? C. to 240? C. (measured under N.sub.2 flow), obtained as described above. The results confirm that the cubic phase of Example 1 is stable even at 240? C. in air and under vacuum. The unit cell was observed to have slightly shrunk after losing water molecules at around 80? C.

Water Vapour Sorption StudiesWater Uptake

[0166] Water sorption isotherms were collected at 27? C. in the humidity range of 0-90% RH using an SMS Intrinsic DVS instrument as described above. FIG. 5 shows the water sorption isotherms of Example 1 (ROS-038X), Example 9 (ROS-038Y), Syloid? AL-1 and Zeolite 13X measured at 27? C. The filled and open symbols represent the adsorption and desorption branch, respectively. Instrument: Intrinsic-DVS. dm/dt (%/min)<0.05. FIG. 6 shows water uptake in wt. % (at 60% RH and 27? C.) Vs. K.sup.+ content of the example material for Examples 1-9. Examples 1-6 (termed ROS-038X material) were observed to exhibit higher water uptake than Examples 7-9 (termed ROS-038Y material) (see FIG. 5) and a correlation between K.sup.+ content and water uptake was evident (FIG. 6). Specifically, for K.sup.+ content in the range of 0.009-0.12 of Examples 1-6 water uptake was ?30 wt. %. A drop in water uptake at K.sup.+=0.12 and above in Examples 7-9 was observed, indicating that the ROS-038X and ROS-038Y materials have distinct structures (or phases).

[0167] As revealed by the results of FIG. 5, the ROS-038X material Example 1 adsorbs ca. 30 wt. % at 60% RH and ca. 27 wt. % at 30% RH. To assess the performance of ROS-038X as a desiccant against commercially used materials, Zeolite 13X and Syloid? AL-1 were tested under the same conditions. Syloid? AL-1 showed water uptake of ca. 30 wt. % at 60% RH and ca. 14 wt. % at 30% RH, an isotherm profile that is poorly suited for the intended purpose of efficient water vapour sorption. In particular, the water uptake of Example 1 (ROS-038X) is twice that of Syloid? AL-1 at 30% RH. The other commercial desiccant, Zeolite 13X shows a water uptake of ca. 5 wt. % at 30% RH and of ca. 7 wt. % at 60% RH, much lower than the values measured for Example 1 (ROS-038X).

[0168] For comparison, the ZnCo and FeZnCo materials were similarly tested for their water sorption performance. The results are shown in FIGS. 7 and 8. The ZnCo material showed a similar performance to ROS-038X, but of course is unstable to heat and so would not be effective in most practical applications. The FeZnCo material showed significantly lower water sorption than ROS-038X.

Water Vapour Sorption StudiesRecyclability

[0169] Sorbent recyclability tests that simulate a vacuum swing process (test conditions: adsorption 0.fwdarw.60% P/P.sub.0, 5 min; desorption 60.fwdarw.0% P/P.sub.0, 5 min) were performed at 27? C. using an SMS Vacuum DVS on the material of Example 1, using the procedure described above. FIG. 9 shows the results of these water cycling experiments of Example 1 (ROS-038X) for 135 cycles. Adsorption conditions were from 0% P/P.sub.0 to 60% P/P.sub.0 at 27? C. over 5 min. Desorption conditions were from 60% P/P.sub.0 to 0% P/P.sub.0 at 27? C. over 5 min. Before starting the cycling tests, the sample was in-situ preactivated at 0% P/P.sub.0 and 50? C. for 3 hours and at 27? C. for 1 h in the Vacuum-DVS instrument. Mass at the end of first 0% P/P.sub.0 stage: 5.3 mg. In a 10 min cycle of adsorption/desorption, Example 1 (ROS-038X) exhibited a working capacity of 30 wt. % while maintaining performance for >135 cycles (see FIG. 9). Under the same conditions, Syloid? AL-1 showed a working capacity of 23 wt. %. Example 1 (ROS-038X) therefore has higher working capacity than Syloid? AL-1. The comparative example FeZnCo sorbent material was similarly tested and the results are shown in FIG. 10.

[0170] The paper composite Example 11 was manufactured as described above using the material of Example 10 (ROS-038X) and tested using the SMS Vacuum DVS under the same conditions as those used for the Example 1 (ROS-038X) powder described above. FIG. 11 shows these water cycling experiments of Example 11 (ROS-038X) paper composite for 135 cycles. Adsorption conditions were from 0% P/P.sub.0 to 60% P/P.sub.0 at 27? C. over 5 min. Desorption conditions were from 60% P/P.sub.0 to 0% P/P.sub.0 at 27? C. over 5 min. Before starting the cycling tests, the paper was in-situ preactivated at 0% P/P.sub.0 and 50? C. for 3 hours and at 27? C. for 1 h in the Vacuum-DVS instrument. Mass at the end of first 0% P/P.sub.0 stage: 6.6 mg. As shown in FIG. 11, the working capacity of ROS-038X paper Example 11 is ca. 21 wt. % and its performance is retained for >135 cycles.

[0171] Sorbent recyclability tests that simulate a temperature and humidity swing that mimics a real world recycling process were performed using an IGA vapour sorption analyser on the material of Example 1 (ROS-038X) as well as on Syloid? AL-1, using the procedure described above. FIG. 12 shows the comparative results of these water cycling experiments of Example 1 (ROS-038X) vs. Syloid? AL-1 for 17 cycles. Adsorption conditions were from 0% RH to 60% RH at 27? C. over 14 min. Desorption conditions were from 60% RH to 0% RH at 49? C. over 20 min (FIG. 12). Before starting the cycling tests, the sample was in-situ preactivated at 0% RH and 50? C. under dry air for 1 hours and at 27? C. for 1 h in the IGA instrument. Mass at the end of first 0% RH stage: 6.5 mg. In a 34 min cycle of adsorption/desorption, Example 1 (ROS-038X) exhibits a working capacity of 30.2 wt. % (at 49? C.) while maintaining the performance for >17 cycles (see FIG. 12, Table 2). Under the same conditions, Syloid? AL-1 showed a working capacity of 14.6 wt. % (see FIG. 12, Table 2). The deliverability of water (L/(kg-day)) overtime for each to these materials are shown in the Table 2. Example 1 (ROS-038X) therefore has superior working capacity and deliverability of water (12.79 L/(kg-day)) compared to Syloid? AL-1 (6.17 L/(kg-day)).

TABLE-US-00006 TABLE 2 Comparison of working capacities and deliverability of water for ROS-038X and Syloid? AL-1 under temperature and humidity swing test. Sorbent (Test condition: 0% .fwdarw.60% RH @27? C. for 14 min. Working capacity Deliverability 60% .fwdarw. 0% RH @49? C. for 20 Adsorption Desorption (wt. %) (L/(kg .Math. day) min) (min) (min) (After 17 cycles) (After 17 cycles) ROS-038X 14 20 30.2 12.79 Syloid? AL-1 14 20 14.6 6.17 ROS-038X paper composite 14 20 21.3 9.04 Syloid? AL-1 paper composite 14 20 7.6 3.20

[0172] Temperature and humidity swing recycling tests were performed on the paper composite Example 11 (manufactured using the material of Example 10 (ROS-038X)) using the IGA vapour sorption analyser under the same conditions as those used for the Example 1 (ROS-038X) powder described above. FIG. 13 shows these water cycling experiments of Example 11 (ROS-038X) paper composite for 17 cycles. Adsorption conditions were from 0% RH to 60% RH at 27? C. over 14 min. Desorption conditions were from 60% RH to 0% RH at 49? C. over 20 min. Before starting the cycling tests, the paper composites was in-situ preactivated at 0% RH and 50? C. under dry air for 3 hours and at 27? C. for 1 h in the IGA instrument. Mass at the end of first 0% RH stage: 7.8 mg. As shown in FIG. 13 and Table 2, the working capacity (wt. %) of ROS-038X paper composite Example 11 is ca. 21.3 wt. % and its performance is retained for >17 cycles. The deliverability of water is 9.04 L/(kg-day).

[0173] The ROS-038X material therefore exhibits superior water harvesting and dehumidification performance compared to leading commercial desiccants. Moreover, these results demonstrate that the ROS-038X material can be prepared at scale by a green synthesis method (slurrying in water), an important requirement for large scale production and end use of desiccants.

[0174] In summary, the present invention provides crystalline sorbent materials which have favourable water uptake capacity and sorption/desorption kinetics for use as water capture materials whilst having structural stability and recyclability in water capture over many cycles. Furthermore the crystalline sorbent materials described herein can be obtained on a large scale from a process having a low environmental impact. Therefore the crystalline sorbent materials of the present invention may provide sorbent materials for water capture processes which are advantageous over known sorbent materials.

[0175] Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

[0176] Throughout this specification, the term comprising or comprises means including the component(s) specified but not to the exclusion of the presence of other components. The term consisting essentially of or consists essentially of means including the components specified but excluding other components except for materials present as impurities, unavoidable materials present as a result of processes used to provide the components, and components added for a purpose other than achieving the technical effect of the invention. Typically, when referring to compositions, a composition consisting essentially of a set of components will comprise less than 5% by weight, typically less than 3% by weight, more typically less than 1% by weight of non-specified components.

[0177] The term consisting of or consists of means including the components specified but excluding addition of other components.

[0178] Whenever appropriate, depending upon the context, the use of the term comprises or comprising may also be taken to encompass or include the meaning consists essentially of or consisting essentially of, and may also be taken to include the meaning consists of or 10 consisting of.

[0179] For the avoidance of doubt, wherein amounts of components in a composition are described in wt. %, this means the weight percentage of the specified component in relation to the whole composition referred to. For example, wherein the sorbent composition comprises from 10 to 90 wt. % of the crystalline sorbent material means that from 10 to 90 wt. % of the sorbent composition is 15 provided by the crystalline sorbent material.

[0180] The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each aspect or exemplary embodiment of the invention as set out herein are also to be read as applicable to any other aspect or exemplary embodiments of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each exemplary embodiment of the invention as interchangeable and combinable between different exemplary embodiments.

[0181] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0182] All of the features disclosed in this specification (including any accompanying claims, and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are 30 mutually exclusive.

[0183] Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Therefore unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0184] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.