ADSORPTION AND REMOVAL OF 4-METHYLIMIDAZOLE

Abstract

A method for removing 4-methylimidazole (4-MEI) from solution may include contacting an alkaline earth metal silicate with a solution containing 4-MEI and adsorbing at least some of the 4-MEI using the alkaline earth metal silicate. The method may further include removing at least some of the alkaline earth metal silicate having the adsorbed 4-MEI from the solution. The alkaline earth metal silicate may include magnesium silicate or calcium silicate. A method for removing 4-MEI from solution may include contacting an adsorbent clay material with a solution containing 4-MEI and adsorbing at least some of the 4-MEI using the adsorbent clay material. The method may further include removing at least some of the adsorbent clay material having the adsorbed 4-MEI from the solution. The adsorbent clay material may include smectite, bentonite, or an activated or un-activated AOCS day material.

Claims

1. A method for removing 4-methylimidazole (4-MEI) from solution, the method comprising: contacting an alkaline earth metal silicate with a solution containing 4-MEI; and adsorbing at least some of the 4-MEI using the alkaline earth metal silicate.

2. The method of claim 1, further comprising: removing at least some of the alkaline earth metal silicate having the adsorbed 4-MEI from the solution.

3. The method of claim 1, wherein the alkaline earth metal silicate is chosen from the group consisting of magnesium silicate or calcium silicate.

4. The method of claim 1, wherein the alkaline earth metal silicate is a hydrated alkaline earth metal silicate.

5. The method of claim 1, wherein the alkaline earth metal silicate is a synthetic magnesium silicate.

6. The method of claim 1, wherein the alkaline earth metal silicate is a diatomite-derived magnesium silicate.

7. The method of claim 1, wherein the alkaline earth metal silicate has a 4-MEI adsorption capacity greater than or equal to about 2000 g/g based on 25 ml of 50 ppm 4-MEI solution.

8-10. (canceled)

11. The method of claim 1, wherein the alkaline earth metal silicate has a 4-MEI adsorption capacity greater than or equal to about 500 g/g based on 25 ml of 10 ppm 4-MEI solution.

12-14. (canceled)

15. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 35 wt % to about 95 wt % of silica.

16. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 35 wt % to about 80 wt % of silica.

17. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 65 wt % to about 80 wt % of silica.

18. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 5 wt % to about 45 wt % of magnesium oxide.

19. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 10 wt % to about 30 wt % of magnesium oxide.

20. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 20 wt % to about 25 wt % of magnesium oxide.

21. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 0.1 to about 1.5 of magnesium oxide to silica molar ratios (MgO:SiO.sub.2).

22. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 0.35 to about 0.45 of magnesium oxide to silica molar ratios (MgO:SiO.sub.2).

23. The method of claim 1 wherein the alkaline earth metal silicate comprises from about 0.1 wt % to about 60 wt % of calcium oxide.

24. The method of claim 1, wherein the alkaline earth metal silicate comprises from about 25 wt % to about 60 wt % of calcium oxide.

25. The method of claim 1, wherein the alkaline earth metal silicate comprises less than or equal to about 5 wt % of alumina.

26. (canceled)

27. The method of claim 1, wherein the alkaline earth metal silicate comprises less than about 2 wt % of iron oxide.

28-44. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 shows exemplary adsorption of 4-MEI from solution at various loading quantities of adsorbent.

[0013] FIG. 2 shows exemplary adsorption of 4-MEI from solution at various loading quantities of adsorbents.

[0014] FIG. 3 shows exemplary adsorption of 4-MEI from an exemplary soft drink (PEPSI).

[0015] FIG. 4 shows exemplary adsorption of 4-MEI from an exemplary soft drink (PEPSI).

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0016] According to some embodiments, a method for removing 4-methylimidazole (4-MEI) from solution may include contacting an alkaline earth metal silicate with a solution containing 4-MEI and adsorbing at least some of the 4-MEI using the alkaline earth metal silicate. According to some embodiments, the method may further include removing at least some of the alkaline earth metal silicate having the adsorbed 4-MeI from the solution.

[0017] According to some embodiments, the alkaline earth metal silicate may include the class of synthetic silicates which comprise, in chemical combination, silicon and an alkaline earth metal. The silicon may include silica (SiO.sub.2). The alkaline earth metal may include an alkaline earth metal oxide, such as, for example, magnesium oxide, calcium oxide, or lime. The alkaline earth metal silicate may include, for example, magnesium silicate or calcium silicate. For example, the magnesium silicate may include synthetic magnesium silicate or diatomite-derived magnesium silicate. According to some embodiments, the alkaline earth metal silicate may include a hydrated alkaline earth metal silicate. According to some embodiments, the alkaline earth metal silicate may be in particulate, powder, granule, pellet form, or embedded in filter cloth or other filter media.

[0018] According to some embodiments, the alkaline earth metal silicate may be chosen from the group consisting of magnesium silicate or calcium silicate. According to some embodiments, the alkaline earth metal silicate may be a diatomite-derived magnesium silicate.

[0019] According to some embodiments, the alkaline earth metal silicate may have a 4-MEI adsorption capacity greater than or equal to about 2000 g/g based on 25 ml of 50 ppm 4-MeI solution. For example, the alkaline earth metal silicate may have a 4-MEI adsorption capacity greater than or equal to about 3000 g/g based on 25 ml of 50 ppm 4-MeI solution, greater than or equal to about 3500 g/g based on 25 ml of 50 ppm 4-MEI solution, or greater than or equal to about 4000 g/g based on 25 ml of 50 ppm 4-MEI solution.

[0020] According to some embodiments, the alkaline earth metal silicate may have a 4-MEI adsorption capacity greater than or equal to about 500 g/g based on 25 ml of 10 ppm 4-MeI solution. For example, the alkaline earth metal silicate may have a 4-MEI adsorption capacity greater than or equal to about 800 g/g based on 25 ml of 10 ppm 4-MEI solution, greater than or equal to about 900 g/g based on 25 ml of 10 ppm 4-MEI solution, greater than or equal to about 1000 g/g based on 25 ml of 10 ppm 4-MEI solution.

[0021] According to some embodiments, the alkaline earth metal silicate may include from about 35 wt % to about 95 wt % of silica (SiO.sub.2), such as, for example, from about 35 wt % to about 80 wt % of silica, from about 35 wt % to about 65 wt % of silica, from about 55 wt % to about 75 wt % of silica, from about 35 wt % to about 50 wt % of silica, from about 50 wt % to about 65 wt % of silica, or from about 65% to about 80 wt % of silica.

[0022] According to some embodiments, the alkaline earth metal silicate may include from about 5 wt % to about 45 wt % of magnesium oxide, such as, for example, from about 10 wt % to about 30 wt % of magnesium oxide, from about 10 wt % to about 20 wt % of magnesium oxide, from about 20 wt % to about 25 wt % of magnesium oxide, from about 20 wt % to about 30 wt % of magnesium oxide, from about 15 wt % to about 25 wt % of magnesium oxide, or from about 25 wt % to about 35 wt % of magnesium oxide.

[0023] According to some embodiments, the alkaline earth metal silicate may include from about 0.1 to about 1.5 of magnesium oxide to silica molar ratios (MgO:SiO.sub.2). For example, the alkaline earth metal silicate may include from about 0.2 to about 1.0 of magnesium oxide to silica molar ratios (MgO:SiO.sub.2), from about 0.25 to about 0.55 of magnesium oxide to silica molar ratios (MgO:SiO.sub.2), from about 0.30 to about 0.50 of magnesium oxide to silica molar ratios (MgO:SiO.sub.2), from about 0.35 to about 0.45 of magnesium oxide to silica molar ratlas (MgO:SiO.sub.2), from about 0.30 to about 0.40 of magnesium oxide to silica molar atios (MgO:SiO.sub.2), from about 0.40 to about 0.50 of magnesium oxide to silica molar ratios (MgO:SiO.sub.2).

[0024] According to some embodiments, the alkaline earth metal silicate may include from about 0.1 wt % to about 60 wt % of calcium oxide, such as, for example, from about 10 wt % to about 60 wt % of calcium oxide, from about 10 wt % to about 20 wt % of calcium oxide, from about 15 wt % to about 30 wt % of calcium oxide, from about 25 wt % to about 60 wt % of calcium oxide, from about 25 wt % to about 50 wt % of calcium oxide, from about 25 wt % to about 40 wt % of calcium oxide, from about 35 wt % to about 60 wt % of calcium oxide, from about 35 wt % to about 50 wt % of calcium oxide, from about 25 wt % to about 60 wt % of calcium oxide, or from about 20 wt % to about 40 wt % of calcium oxide.

[0025] According to some embodiments, the alkaline earth metal silicate may include less than or equal to about 5 wt % of alumina, such as, for example, less than about 3 wt % of alumina.

[0026] According to some embodiments, the alkaline earth metal silicate may include less than about 2 wt % of iron oxide.

[0027] According to some embodiments, the alkaline earth metal silicate may have a particle size ranging from about 0.01 m to about 150 m, such as, for example, from about 0.01 m to about 100 m, from about 1 m to about 70 m, or from about 1 to about 50 m. According to some embodiments, the alkaline earth metal silicate may have a particle size ranging from about 1 m to about 50 m, such as, for example, from about 1 m to about 30 m, from about 1 m to about 10 m. The particle size of the alkaline earth metal silicate may be determined by a laser diffraction particle size analyzer, such as Microtrac 100X.

[0028] According to some embodiments, the alkaline earth metal silicate may form aggregates having an aggregate particle size less than or equal to about 100 m.

[0029] According to some embodiments, the alkaline earth metal silicate may have a BET surface area greater than or equal to about 50 m.sup.2/g, such as, for example, greater than or equal to about 75 m.sup.2/g, greater than or equal to about 100 m.sup.21g, greater than or equal to about 150 m.sup.2/g, greater than or equal to about 200 m.sup.2/g, greater than or equal to about 250 m.sup.2/g, greater than or equal to about 300 m.sup.2/g, greater than or equal to about 350 m.sup.2/g, greater than or equal to about 400 m.sup.2/g, or greater than or equal to about 500 m.sup.2/g. According to some embodiments, the alkaline earth metal silicate may have a BET surface area ranging from about 50 m.sup.2/g to about 500 m.sup.2/g, such as, for example, ranging from about 50 m.sup.2/g to about 150 m.sup.2/g, ranging from about 100 m.sup.2/g to about 300 m.sup.2/g, ranging from about 150 m.sup.2/g to about 250 m.sup.2/g, or ranging from about 300 m.sup.2/g to about 500 m.sup.2/g.

[0030] According to some embodiments, magnesium silicate has a BET surface area greater than or equal to about 75 m.sup.2/g, such as, for example, greater than or equal to about 100 m.sup.2/g, greater than or equal to about 150 m.sup.2/g, greater than or equal to about 200 m.sup.2/g, greater than or equal to about 250 m.sup.2/g, greater than or equal to about 300 m.sup.2/g, greater than or equal to about 350 m.sup.2/g, or greater than or equal to about 400 m.sup.2/g.

[0031] According to some embodiments, calcium silicate has a BET surface area greater than or equal to about 50 m.sup.2/g, such as, for example, greater than or equal to about 75 m.sup.2/g, greater than or equal to about 100 m.sup.2/g, greater than or equal to about 150 m.sup.2/g, greater than or equal to about 200 m.sup.2/g, greater than or equal to about 250 m.sup.2/g, greater than or equal to about 300 m.sup.2/g, greater than or equal to about 350 m.sup.2/g, or greater than or equal to about 400 m.sup.2/g.

[0032] According to some embodiments, a method for removing 4-methylimidazole (4-MEI) from solution may include contacting an adsorbent clay material with a solution containing 4-MEI and adsorbing at least some of the 4-MEI using the adsorbent clay material. The method may further include removing at least some of the adsorbent clay material having the adsorbed 4-MEI from the solution.

[0033] According to some embodiments, the adsorbent clay material may include smectite or bentonite.

[0034] According to some embodiments, the adsorbent clay material may include an activated adsorbent clay material. According to some embodiments, the adsorbent clay material may be an activated or un-activated American Oil Chemists' Society (AOCS) clay, such as, for example, an un-activated AOCS bleaching clay, an activated AOCS bleaching clay, an un-activated AOCS bleach earth material, or an activated AOCS bleach earth material.

[0035] According to some embodiments, the absorbent clay material may have a BET surface area greater than or equal to about 20 m.sup.2/g, such as, for example, greater than or equal to about 30 m.sup.2/g, greater than or equal to about 50 m.sup.2/g, greater than or equal to about 75 m.sup.2/g, greater than or equal to about 100 m.sup.2/g, greater than or equal to about 150 m.sup.2/g, greater than or equal to about 200 m.sup.2/g, greater than or equal to about 250 m.sup.2/g, or greater than or equal to about 300 m.sup.2/g. According to some embodiments, the absorbent clay material may have a BET surface area ranging from about 20 m.sup.2/g to about 400 m.sup.2/g, such as, for example, ranging from about 30 m.sup.2/g to about 300 m.sup.2/g, ranging from 50 m.sup.2/g to about 250 m.sup.2/g, ranging from about 30 m.sup.2/g to about 150 m.sup.2/g, or ranging from about 150 m.sup.2/g to about 300 m.sup.2/g.

[0036] According to some embodiments, the adsorbent clay material may have a 4-MeI adsorption capacity greater than or equal to about 2000 g/g based on 25 ml of 50 ppm 4-MeI solution, such as, for example, greater than or equal to about 3000 g/g based on 25 ml of 50 ppm 4-MeI solution, greater than or equal to about 3500 g/g based on 25 ml of 50 ppm 4-MeI solution, or greater than or equal to about 4000 g/g based on 25 ml of 50 ppm 4-MeI solution.

[0037] According to some embodiments, the adsorbent clay material may have a 4-MEI adsorption capacity greater than or equal to about 500 g/g based on 25 ml of 10 ppm 4-MEI solution, such as, for example, greater than or equal to about 800 g/g based on 25 ml of 10 ppm 4-MEI solution, greater than or equal to about 900 g/g based on 25 ml of 10 ppm 4-MEI solution, or greater than or equal to about 1000 g/g based on 25 ml of 10 ppm 4-MEI solution.

[0038] According to some embodiments, the alkaline earth metal silicate or the adsorbent clay material may be mixed with the solution containing 4-MEI. The mixing may include, for example, blending, stirring, shaking, and the like, as may be carried out with the aid of any mechanical means, including but not limited to, paddles, propellers, blades, shakers,rollers, and the like.

EXAMPLE 1

[0039] A solution of 10 ppm 4-MEI solution was prepared by dilution with DI water with a stock solution containing 1000 ppm 4-MEI in diluted sulfuric acid solution (0.1N H.sub.2SO.sub.4). 1.0 ml of diazotised sulphanilic acid and 2.0 ml of Na.sub.2CO.sub.3 (5%) solution was added to each of a series of 25 ml volumetric flasks containing 0.0, 1.0, 2.0, 3.0, and 5.0 of working standard solution. The absorbance at 505 nm was measured using a spectrophotometric method and plotted as a standard graph.

[0040] Samples A-E were obtained for testing from various sources. Sample A includes a synthetic magnesium silicate, commercially available as CELKATE T-21 from World Minerals Inc. Sample B includes synthetic, hydrous, amorphous magnesium silicate, commercially available as DALSORB or Magnesol-series from the Dallas Group of America, Inc. Sample C includes an activated AOCS bleach earth clay, such as commercially available from BASF. Sample D includes an un-activated AOCS bleaching clay, such as commercially available from BASF. Sample E includes a natural diatomaceous earth material containing a clay material, commercially available as CELITE S from World Minerals Inc.

[0041] Exemplary chemical compositions for samples A, B, D, and E are shown below in Table 1.

TABLE-US-00001 TABLE 1 Exemplary Compositions Sample D (Un- activated Sample A Sample B AOCS (Celkate (Dalsorb Bleaching Sample E Compound T21) F) Clay) (Celite S) NA.sub.2O 0.21 1.87 1.22 0.17 MgO 21.2 19.8 2.54 0.37 Al.sub.2O.sub.3 3.3 0.1 17.8 5.56 SiO.sub.2 72.7 77.3 71.6 91.03 P.sub.2O.sub.5 0.13 0.01 0.04 K.sub.2O 0.43 0.01 0.24 CaO 0.35 0.21 1.75 0.61 MnO 0.03 0 0.01 TiO.sub.2 0.16 0.01 0.21 Fe.sub.2O.sub.3 1.1 0.02 2.87 1.64 Cl 0.04 0.02 0.01 SO.sub.3 0.9 0 not detected total 100.55 99.35 97.78 99.89 CaO:SiO.sub.2 0.01 0.00 0.03 0.01 Molar ratio MgO:SiO.sub.2 0.43 0.38 0.05 0.01 Molar ratio

[0042] Table 2 shows exemplary BET surface areas for samples A, B, D and E.

TABLE-US-00002 TABLE 2 Exemplary BET Surface Areas Sample ID Silica Source BET Surface Area (m.sup.2/g) Sample A (Celkate T21) Lompoc DE 200.0 Sample B (Dalsorb F) Synthetic Silica 463.0 Sample D (Un-activated Clays 128.2 AOCS Bleaching Clay) Sample E (Celite S) Mexican DE 45

[0043] Samples A-E were added separately to a 50-ml Fisherbrand polypropylene centrifuge tube in varying loading amounts, as shown in Table 3. 25 ml of the 10 ppm 4-MEI solution was added to the centrifuge, mixed separately with each of Samples A-E at the different loading amounts, and allowed to stand for 30 minutes. The solutions of 4-MEI and Samples A-E were then centrifuged at 2500 rpm for 10 minutes. 1 ml of the supernatant was removed via pipette for measurement. The concentrations of 4-MEI in the solution were calculated both before and after the adsorbent was added to the solution.

[0044] The 4-MEI measurements were carried out in aqueous solution using a spectrophotometric method. Color was developed using a sulphanilic acid solution in alkaline medium as described above. The color was measured using a 505 nm wavelength and the amount of 4-methyl imidazole present was calculated from the standard calibration curve.

[0045] FIG. 1 shows the adsorption of Samples A-E at loading values in grams per 25 ml of 10 ppm 4-MEI solution. Table 3 shows the adsorption of Sample A-E of the 10 ppm 4-MEI in solution.

TABLE-US-00003 TABLE 3 Concentration of 4-MEI in 25 ml 4-MEI or 10 ppm Solution after Adsorption Sample D Sample C (Un- (Activated activated Loading Sample A Sample B AOCS AOCS Sample E (g/25 (Celkate (Dalsorb Bleach Bleaching (Celite ml) T21) F) Earth) Clay) S) 0 9.1 9.1 9.1 9.1 9.1 0.05 4.1 4.9 3.6 4.0 7.1 0.1 1.6 3.5 3.1 2.1 6.0 0.2 0.4 1.7 2.0 1.2 4.6 0.4 0.0 0.8 1.1 0.6 3.2 Capac- 1085 928 889 984 564 ity* (g/g) *The adsorption capacity is calculated based on 0.2 g loading.

EXAMPLE 2

[0046] A solution of 50 ppm 4-MEI solution was prepared from a stock solution containing 1000 ppm 4-MEI in diluted sulfuric acid (0.1N H.sub.2SO.sub.4). Samples A-C and E were respectively added to 25 ml of the 50 ppm 4-MEI solution, and the adsorbent properties of the samples were measured, as described in Example 1.

[0047] FIG. 2 shows the amount of 4-MEI in solution after adsorption of Samples A-C and E at various loading values in grams per 25 ml of 50 ppm 4-MEI solution. Table 4 shows the adsorption of Sample A-C and E of the 50 ppm 4-MEI in solution.

TABLE-US-00004 TABLE 4 Concentration of 4-MEI in 25 ml of 50 ppm 4-MEI Solution after Adsorption Sample A Sample B Sample C Loading (Celkate (Dalsorb (Activated AOCS Sample E (g/25 ml) T21) F) Bleach Earth) (Celite S) 0 48 48 48 48 0.05 38 40 32 42 0.1 28 32 24 36 0.2 20 22 15 32 0.4 9 13 8 24 0.8 2 6 5 18 Capacity* 3560 3241 4161 2044 (g/g) *The adsorption capacity is calculated based on 0.2 g loading

[0048] As shown in FIGS. 1 and 2 and Tables 3 and 4. Samples A-E have relatively high adsorption values for 4-MEI in solution. Without wishing to be bound to a particular theory, it is believed that the adsorbent materials adsorb 4-MEI through surface bonding effects. For example, the 4-MEI may form surface compounds with surface metals in the adsorbent materials.

[0049] FIGS. 3 and 4 show exemplary adsorptions of 4-MEI from an exemplary soft drink (PEPSI). In particular, a series of sorbent material was analyzed for its efficacy to remove 4-MEI from PEPSI. PEPSI was spiked to a final concentration of 500 ppb, and thereafter, 50 mL of this solution was mixed with 0, 0.1, 0.2, 0.4, 0.8, and 1.6 grams of sorbent, Celkate T21, Celite S, Dalsorb F, activated AOCS, and activated carbon. After agitation for thirty minutes, each of the samples were filtered, and the filtrate was analyzed by LC-MS for 4-MEI. The results are shown in FIG. 3.

[0050] In an additional study with the results shown in FIG. 4, Celkate T21 was analyzed for its efficacy as an adsorbent for 4-MEI removal from PEPSI. A spiked PEPSI solution containing 221 ppb 4-MEI was agitated with T21 at a loading of 1 g/50 mL PEPSI. Analysis by LC/MS/MS determined that 4-MEI was below the limit of detection of the instrument (50 ppb), indicating that T21 is a candidate for 4-MEI removal from complex media such as PEPSI.

[0051] Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the exemplary embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.