Ultra-stable mineralized adsorbents, methods of making and using the same

Abstract

This invention relates to the field of heavy metal contaminated water or soil remediation technology, and discloses an ultrastable mineralizing adsorbent, its preparation method, and its application. The ultrastable mineralizing adsorbent is prepared from magnesium oxide, hydrotalcite powder, a modifier, and a hydration agent as raw materials. This invention can efficiently and rapidly adsorb heavy metal ions from contaminated water or soil without causing secondary pollution, and the adsorbed ions can be separated from the water or soil, thereby completely remediating heavy metal contaminated water or soil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy metal contaminated water or soil remediation, and particularly relates to a super-stable mineralization adsorbent and a preparation method and application thereof. BACKGROUND

[0002] Common heavy metals in water and soil include cadmium, chromium, nickel, copper, zinc, arsenic, lead, mercury and the like. Among them, cadmium pollution is the most serious. Heavy metals in contaminated water and soil can seriously endanger the health and safety of human life through food chain enrichment or direct ingestion. The existence state of heavy metals in the environment can be divided into: exchangeable and free state (activated state) > carbonate or hydroxide state (passivated state) > residual state (mineralized state), and heavy metal ions in the activated state are the "culprit" of pollution.

[0003] The existing methods for treating heavy metal pollution in water and soil mainly include chemical method, biological method and physical method. The chemical method mainly includes adsorption, membrane separation, chelation and electroplating technologies, and the chemical method is rapid and efficient, but may damage the soil structure; the biological method includes plant and animal remediation method, algal and microbial remediation method and the like, and the cost is high and the remediation period is long; the physical method mainly includes river dilution method, but can only reduce the concentration of heavy metals to a certain extent and cannot fundamentally solve the pollution problem.

[0004] At present, it is urgent to develop an adsorbent capable of efficiently adsorbing heavy metal ions in water or soil. SUMMARY

[0005] The present application aims to overcome the problems in the prior art and provide a super-stable mineralization adsorbent and a preparation method and application thereof.

[0006] The super-stable mineralization adsorbent provided by the present application can not only quickly and efficiently adsorb contaminated heavy metal ions in water or soil, but also can use magnetism to completely remove the adsorbed product from the water body, avoiding the risk of secondary pollution.

[0007] In order to achieve the above-mentioned purpose, the present application provides a super-stable mineralization adsorbent composition, wherein the composition comprises the following components: magnesium oxide, hydrotalcite powder, modifier and hydrating agent.

[0008] The present application provides a super-stable mineralization adsorbent, wherein the super-stable mineralization adsorbent is prepared from the composition of the first aspect.

[0009] The third aspect of the present invention provides a method for preparing the ultrastable mineralized adsorbent described in the second aspect, wherein the method comprises: dispersing magnesium oxide, hydrotalcite powder, modifier and optional magnetic powder in a hydration agent solution to obtain a slurry, and then molding, curing, demolding and pulverizing to obtain the ultrastable mineralized adsorbent.

[0010] The fourth aspect of this invention provides the application of the ultrastable mineralized adsorbent described in the second aspect or the ultrastable mineralized adsorbent obtained by the preparation method described in the third aspect in the adsorption of heavy metal ions in water or soil.

[0011] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0012] (1) The heavy metal super-stable mineralizer provided by the present invention can greatly reduce the concentration of heavy metal ions in water or soil, and achieve the goal of adsorbing heavy metals.

[0013] (2) The present invention can achieve good heavy metal adsorption effect in a short time, and can also use magnetism to completely remove heavy metals without generating secondary pollution or releasing toxic substances. It is suitable for the treatment of water bodies or soil polluted by heavy metals.

[0014] (3) The hydrotalcite powder (e.g., CaAl-LDH) used in this invention has the advantages of large adsorption capacity, fast adsorption rate, good adsorption stability, and low overall cost in adsorbing heavy metals. Attached Figure Description

[0015] Figure 1 The image shows the XRD pattern of the ultrastable mineralized adsorbent prepared in Example 1 of this invention.

[0016] Figure 2 The images show SEM images of the ultrastable mineralized adsorbent and CaAl-LDH prepared in Example 1 of this invention.

[0017] Figure 3 The ultrastable mineralizing adsorbent prepared in Example 1 of this invention adsorbs Cu. 2+ Cd 2+ and Pb 2+ The adsorption capacity and removal rate are shown in the following figures.

[0018] Figure 4 The ultrastable mineralizing adsorbent prepared in Example 1 of this invention co-adsorbs Cu 2+ Cd 2+ and Pb 2+ The adsorption capacity and removal rate are shown in the following figures.

[0019] Figure 5 This is a schematic diagram showing the magnetic properties of the ultrastable mineralized adsorbent prepared in Example 1 of the present invention. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] The first aspect of the present invention provides an ultrastable mineralized adsorbent composition, wherein the composition comprises the following components: magnesium oxide, hydrotalcite powder, modifier and hydrating agent.

[0022] The ultrastable mineralizing adsorbent composition provided by this invention can be used to prepare ultrastable mineralizing adsorbents. When this ultrastable mineralizing adsorbent is applied to water or soil contaminated with heavy metals, it can rapidly reduce the concentration of heavy metal ions (e.g., Cu) in the water or soil. 2+ Cd 2+ Pb 2+ This enables the efficient adsorption of heavy metal ions.

[0023] In some embodiments of the present invention, the hydrotalcite powder is selected from at least one of calcium aluminum hydrotalcite powder, magnesium aluminum hydrotalcite powder, calcium iron hydrotalcite powder and magnesium iron hydrotalcite powder, preferably calcium aluminum hydrotalcite powder.

[0024] In some embodiments of the present invention, the modifier is selected from at least one of citric acid, phosphoric acid, boric acid, salicylic acid and ethylenediaminetetraacetic acid.

[0025] In some embodiments of the present invention, the hydrating agent is selected from at least one of magnesium sulfate, magnesium chloride, potassium dihydrogen phosphate, sodium dihydrogen phosphate, and ammonium dihydrogen phosphate.

[0026] In some embodiments of the present invention, the mass ratio of magnesium oxide to hydrotalcite powder is 2-8:5-10, preferably 4-7:6-10.

[0027] In some embodiments of the present invention, the mass ratio of magnesium oxide, hydrotalcite powder, modifier and hydrating agent is 2-8:5-10:0.01-0.05:1-3, preferably 4-7:6-10:0.03-0.05:2-3.

[0028] In some embodiments of the present invention, the composition further includes magnetic powder.

[0029] Existing methods for treating heavy metal pollution in water or soil share a common drawback: they cannot completely remove the heavy metals, leading to the risk of secondary pollution such as desorption. This invention, by adding magnetic powder, can completely remove the adsorbent after adsorption. The process is simple, easy to recover and separate, and can be reused.

[0030] In some embodiments of the present invention, the magnetic powder is selected from at least one of Fe3O4 magnetic powder and rubidium iron boron magnetic powder, preferably Fe3O4 magnetic powder.

[0031] In some embodiments of the present invention, the mass ratio of the magnetic powder to magnesium oxide is 1-5:3-10, preferably 2-4:4-7.

[0032] A second aspect of the present invention provides an ultrastable mineralizing adsorbent, wherein the ultrastable mineralizing adsorbent is prepared from the composition described in the first aspect.

[0033] In some embodiments of the present invention, the average particle size of the ultrastable mineralized adsorbent is 2-5 mm, preferably 2-3 mm.

[0034] In some embodiments of the present invention, the ultrastable mineralized adsorbent includes magnesium-based cement, hydrotalcite, and optionally magnetic powder.

[0035] In some embodiments of the present invention, the magnesium-based cement is selected from at least one of magnesium oxysulfate cement, magnesium oxychloride cement, and magnesium phosphate cement. The magnesium-based cement used in the present invention is simple to synthesize, low in cost, lightweight, high-strength, and low-alkalinity, making it a green and eco-friendly magnesium-based material.

[0036] The third aspect of the present invention provides a method for preparing the ultrastable mineralized adsorbent described in the second aspect, wherein the method comprises: dispersing magnesium oxide, hydrotalcite powder, modifier and optional magnetic powder in a hydration agent solution to obtain a slurry, and then molding, curing, demolding and pulverizing to obtain the ultrastable mineralized adsorbent.

[0037] In some embodiments of the present invention, the dispersion conditions include: first mechanical stirring at 100-300 rpm for 1 min, and then mechanical stirring at 800-1000 rpm for 5 min.

[0038] According to a particularly preferred embodiment of the present invention, the preparation method of the ultrastable mineralizing adsorbent includes the following steps:

[0039] (1) The magnesium oxide, hydrotalcite powder, modifier and optional magnetic powder are mixed for the first time;

[0040] (2) Pour the hydration agent solution into the mixture obtained from the first mixing and perform a second mixing;

[0041] (3) Pour the slurry obtained in step (2) into a mold for molding, curing, demolding and crushing to obtain the ultra-stable mineralized adsorbent.

[0042] The fourth aspect of this invention provides the application of the ultrastable mineralized adsorbent described in the second aspect or the ultrastable mineralized adsorbent obtained by the preparation method described in the third aspect in the adsorption of heavy metal ions in water or soil.

[0043] In some embodiments of the present invention, the heavy metal ions are selected from Cd. 2+ Pb 2+ and Cu 2+ At least one of them.

[0044] In some embodiments of the present invention, the concentration of heavy metal ions in the water or soil is 50-1000 ppm, preferably 100-500 ppm.

[0045] In some embodiments of the present invention, the amount of the ultrastable mineralizing adsorbent is 0.5-3 g / L of the water to be treated, preferably 1 g / L of the water to be treated.

[0046] The present invention will be described in detail below through embodiments.

[0047] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0048] Example 1

[0049] This example illustrates the preparation of an ultrastable mineralized adsorbent.

[0050] (1) Weigh 6g MgO, 6g CaAl-LDH, 0.03g citric acid (CA) and 2g Fe3O4 magnetic powder, add them to a 500mL beaker, and mix the powders evenly using mechanical stirring;

[0051] (2) Weigh 2g of MgSO4·7H2O into a 100mL beaker, add 10mL of deionized water, and ultrasonically disperse until MgSO4·7H2O is completely dissolved;

[0052] (3) Quickly pour the MgSO4·7H2O solution into a 500mL beaker containing a uniformly mixed powder, and mechanically stir at 300rpm for 1min and at 1000rpm for 5min.

[0053] (4) After mixing, pour into a 50*50*50mm steel cement mold, let it stand at room temperature for 12 hours, spray 10mL of water to moisten, let it stand for another 12 hours, and repeat the curing process for 4 days.

[0054] (5) Use an ergometer to crush the solidified block adsorbent to a particle size of 2-3 mm to obtain ultra-stable mineralized adsorbent particles.

[0055] Example 2

[0056] The ultrastable mineralized adsorbent particles were prepared according to the method in Example 1, except that citric acid was replaced with H3PO4 and 2g MgSO4·7H2O was replaced with 10g MgCl2·6H2O.

[0057] Example 3

[0058] The ultrastable mineralized adsorbent particles were prepared according to the method in Example 1, except that citric acid was replaced with H3BO3 and 2g MgSO4·7H2O was replaced with 6g KH2PO4.

[0059] Example 4

[0060] The ultrastable mineralized adsorbent was prepared according to the method in Example 1, except that the mass of MgO was adjusted to 2g and the mass of CaAl-LDH was adjusted to 5g.

[0061] Example 5

[0062] The ultrastable mineralized adsorbent was prepared according to the method in Example 1, except that the mass of MgO was adjusted to 8g and the mass of CaAl-LDH was adjusted to 10g.

[0063] Example 6

[0064] The ultrastable mineralized adsorbent was prepared according to the method in Example 1, except that the mass of MgO was adjusted to 4g and the mass of CaAl-LDH was adjusted to 6g.

[0065] Example 7

[0066] The ultrastable mineralized adsorbent was prepared according to the method in Example 1, except that the mass of MgO was adjusted to 7g and the mass of CaAl-LDH was adjusted to 10g.

[0067] Comparative Example 1

[0068] (1) Weigh 8g of commercially available sulfoaluminate cement powder, 6g of CaAl-LDH and 2g of Fe3O4 magnetic powder, add them to a 500mL beaker, and mix the powders evenly using mechanical stirring.

[0069] (2) Quickly pour 30 mL of deionized water into a 500 mL beaker containing a uniformly mixed powder, and mechanically stir at 300 rpm for 1 min and at 1000 rpm for 5 min.

[0070] (3) After mixing, pour into a 50*50*50mm steel cement mold, let it stand at room temperature for 12 hours, spray 10mL of water to moisten, let it stand for another 12 hours, and repeat the curing process for 4 days.

[0071] (4) Use an ergometer to crush the solidified block adsorbent to a particle size of 2-3 mm to obtain ultra-stable mineralized adsorbent particles.

[0072] Test Example 1

[0073] Figure 1 The image shows the XRD pattern of the ultrastable mineralized adsorbent prepared in Example 1. It can be seen that the adsorbent simultaneously exhibits characteristic peaks of both CaAl-LDH and magnesium oxysulfate cement, demonstrating that the structures of CaAl-LDH and magnesium oxysulfate cement were well preserved during the synthesis process, and that CaAl-LDH and magnesium oxysulfate cement coexist in the adsorbent.

[0074] Figure 2 The images show SEM images of the ultrastable mineralized adsorbent and CaAl-LDH prepared in Example 1. CaAl-LDH exhibits a layered structure. The magnesium oxysulfate cement in the adsorbent has a cross-linking and curing effect, which binds the layered structure of CaAl-LDH together with other components.

[0075] Test Example 2

[0076] Experimental method: First, prepare a solution simulating heavy metal ion contamination. Prepare solutions with 500 ppm Cu. 2+ Cd 2+ Pb 2+ The solution and each of Cu 100 ppm 2+ Cd 2+ Pb 2+ Coexisting solutions.

[0077] (1) Weigh 1.901 g of Cu(NO3)2·3H2O, dissolve it in a small amount of deionized water, and dilute to 1000 mL in a volumetric flask to obtain 500 ppm of Cu. 2+ Solution.

[0078] (2) Weigh 1.372 g of Cd(NO3)2·4H2O, dissolve it in a small amount of deionized water, and dilute to 1000 mL in a volumetric flask to obtain 500 ppm of Cd. 2+ Solution.

[0079] (3) Weigh 0.799 g of Pb(NO3)2 and dissolve it in a small amount of deionized water, then dilute to 1000 mL in a volumetric flask to obtain 500 ppm of Pb. 2+ Solution.

[0080] (4) Weigh out 0.3802g Cu(NO3)2·3H2O, 0.2744g Cd(NO3)2·4H2O, and 0.1598g Pb(NO3)2 respectively, dissolve them in a small amount of deionized water, and make up to 1000mL in a volumetric flask to obtain Cu(NO3)2 at 100ppm each. 2+ Cd 2+ Pb 2+ Coexisting solutions.

[0081] 100 mg of ultrastable mineralizing adsorbent was added to 100 mL of the above solution, and stirred at 500 rpm at room temperature. Samples were taken at different times according to the reaction time. The concentration of heavy metal ions in the solution before and after adsorption was tested by ICP-OES to determine the adsorption capacity.

[0082] Based on the ICP-OES determination results, the adsorption capacity q is calculated according to the following formula. t and removal rate R. q t Plot a graph of adsorption capacity and removal rate with R (%) on the ordinate and time t on the abscissa.

[0083]

[0084] Where C0 (mg / L) is the initial concentration of heavy metal ions in the solution, C t (mg / L) represents the concentration of heavy metal ions at time t, V(L) represents the solution volume, and m(g) represents the amount of adsorbent used.

[0085] Experimental results:

[0086] Figure 3 The ultrastable mineralizing adsorbent prepared in Example 1 adsorbed Cu at an initial concentration of 500 ppm. 2+ Cd 2+ Pb 2 + The adsorption capacity and removal rate of the adsorbent are shown in the group of graphs. The adsorbent can remove the three heavy metal ions in a short time with a removal rate of nearly 100%, and the removal effect is good.

[0087] Figure 4 The ultrastable mineralizing adsorbent prepared in Example 1 co-adsorbs Cu with an initial concentration of 100 ppm. 2+ Cd 2+ Pb 2+ The adsorption capacity and removal rate of the adsorbent are shown in the group of graphs. The adsorbent can remove three heavy metal ions at the same time in a short period of time, with a removal rate of nearly 100%, and the removal effect is good.

[0088] Table 1. Heavy metal ion adsorption capacity of different ultrastable mineralized adsorbent particles (adsorption amounts, respectively)

[0089]

[0090] Test Example 4

[0091] Figure 5 This is a schematic diagram illustrating the magnetic properties of the ultrastable mineralized adsorbent prepared in Example 1. It can be seen that the adsorbent can be easily attracted by a magnet, thus enabling complete removal from water or soil.

[0092] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an ultrastable mineralizing adsorbent, characterized in that, The method includes: dispersing magnesium oxide, hydrotalcite powder, modifier and magnetic powder in a hydration agent solution to obtain a slurry, and then molding, curing, demolding and crushing to obtain the ultra-stable mineralized adsorbent; The modifier is selected from at least one of citric acid and boric acid; The hydrating agent is selected from at least one of magnesium sulfate and magnesium chloride; The mass ratio of magnesium oxide, hydrotalcite powder, modifier and hydrating agent is 4-7:6-10:0.03-0.05:2-3.

2. The method according to claim 1, wherein, The hydrotalcite powder is selected from at least one of calcium aluminum hydrotalcite powder, magnesium aluminum hydrotalcite powder, calcium iron hydrotalcite powder, and magnesium iron hydrotalcite powder.

3. The method according to claim 1, wherein, The hydrotalcite powder is calcium aluminum hydrotalcite powder.

4. The method according to any one of claims 1-3, wherein, The dispersion conditions include: first mechanical stirring at 100-300 rpm for 1 min, and then mechanical stirring at 800-1000 rpm for 5 min.

5. The method according to claim 1, wherein, The magnetic powder is selected from at least one of Fe3O4 magnetic powder and neodymium iron boron magnetic powder; And / or, the mass ratio of the magnetic powder to magnesium oxide is 1-5:3-10.

6. The method according to claim 1, wherein, The magnetic powder is Fe3O4 magnetic powder; And / or, the mass ratio of the magnetic powder to magnesium oxide is 2-4:4-7.

7. A superstable mineralizing adsorbent, characterized in that, The ultrastable mineralized adsorbent is prepared by the method according to any one of claims 1-6.

8. The ultrastable mineralizing adsorbent according to claim 7, characterized in that, The average particle size of the ultrastable mineralized adsorbent is 2-5 mm.

9. The ultrastable mineralizing adsorbent according to claim 8, characterized in that, The average particle size of the ultrastable mineralized adsorbent is 2-3 mm.

10. The application of the ultrastable mineralizing adsorbent according to any one of claims 7-9 in the adsorption of heavy metal ions in water or soil.

11. The application according to claim 10, wherein, The heavy metal ions are selected from Cd. 2+ Pb 2+ and Cu 2+ At least one of them; And / or, the concentration of heavy metal ions in the water body is 50-1000 ppm; And / or, the amount of the ultrastable mineralizing adsorbent is 0.5-3 g / L of the water to be treated.

12. The application according to claim 10, wherein, The concentration of heavy metal ions in the water body is 100-500 ppm; And / or, the amount of the ultrastable mineralizing adsorbent is 1 g / L of the water to be treated.

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