Application of magnesium-based cementitious materials in the treatment of heavy metal ions in ultrastable mineralized environments

Abstract

This invention relates to the field of heavy metal contaminated water or soil remediation technology, and discloses the application of magnesium-based cementitious materials in heavy metal ion remediation in ultra-stable mineralized environments. This invention can achieve good heavy metal adsorption effects in a short time, without the release of toxic substances or secondary pollution, and is suitable for the remediation of heavy metal contaminated water or soil.

Description

Technical Field

[0001] This invention relates to the field of heavy metal contaminated water or soil remediation technology, specifically to the application of a magnesium-based cementitious material in the remediation of heavy metal ions in an ultra-stable mineralized environment. Background Technology

[0002] Currently, methods for treating heavy metal pollution in water bodies and soil include physical, biological, and chemical methods. Physical methods mainly refer to river dilution; biological methods mainly include phytoremediation, algal and microbial remediation, etc.; chemical methods mainly include adsorption, chelation, membrane separation, electroplating, etc.

[0003] Physical methods can only reduce heavy metal concentrations to a certain extent and cannot solve the problem of heavy metal pollution at its source; biological methods have the advantage of being environmentally friendly and do not produce secondary pollution, but they are costly and have a long remediation cycle; chemical methods are faster and more efficient and do not produce secondary pollution, and have provided new ideas for the treatment of heavy metal pollution in water bodies and soil in recent years.

[0004] To address the problem of heavy metal pollution and protect the ecological environment, there is an urgent need for an efficient, low-cost, and pollution-free method to adsorb heavy metal ions from polluted water and soil. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide an application of magnesium-based cementitious materials in the adsorption of heavy metal ions in water or soil.

[0006] To achieve the above objectives, the first aspect of the present invention provides the application of magnesium-based cementitious materials in the adsorption of heavy metal ions in water or soil.

[0007] A second aspect of the present invention provides a heavy metal ion adsorbent, wherein the adsorbent is a magnesium-based cementitious material.

[0008] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0009] (1) The present invention uses magnesium-based cementitious materials to adsorb heavy metal ions in water or soil, which can greatly reduce the concentration of heavy metal ions in the system and achieve the goal of adsorbing heavy metal ions.

[0010] (2) The magnesium-based cementitious material used in this invention is easy to synthesize, low in cost, and is a green and ecological magnesium-based material that is lightweight, high-strength, low-alkalinity, rich in raw materials, and energy-saving and emission-reducing.

[0011] (3) The present invention can achieve good heavy metal adsorption effect in a short time, without the release of toxic substances and without secondary pollution, and is suitable for the treatment of water bodies polluted by heavy metals. Attached Figure Description

[0012] Figure 1 The magnesium oxysulfide cementitious material prepared in Example 1 of this invention adsorbs Cd. 2+ Pb 2+ Cu 2+ Adsorption capacity diagrams.

[0013] Figure 2 The magnesium oxychloride cementitious material prepared in Example 6 of this invention adsorbs Cd. 2+ Pb 2+ Cu 2+ Adsorption capacity diagrams.

[0014] Figure 3 The magnesium phosphate cementitious material prepared in Example 11 of this invention adsorbs Cd. 2+ Pb 2+ Cu 2+ Adsorption capacity diagrams.

[0015] Figure 4 The magnesium oxysulfide cementitious material obtained in Example 1, the magnesium oxychloride cementitious material obtained in Example 6, and the magnesium phosphate cementitious material obtained in Example 11 of this invention simultaneously adsorbed Cd. 2+ Pb 2+ Cu 2+ Adsorption capacity diagrams.

[0016] Figure 5 To simultaneously adsorb Cd from three other types of cement. 2+ Pb 2+ Cu 2+ Adsorption capacity diagrams. Detailed Implementation

[0017] 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.

[0018] The first aspect of this invention provides the application of a magnesium-based cementitious material in the adsorption of heavy metal ions in water or soil.

[0019] Magnesium-based cementitious materials exhibit low CO2 emissions during production, and the hydration products of MgO (such as Mg(OH)2) can absorb CO2 to form carbonates, thus having a carbon fixation effect. Therefore, magnesium-based cementitious materials are a green and eco-friendly magnesium-based material with advantages such as lightweight, high strength, low alkalinity, abundant raw materials, and energy conservation and emission reduction.

[0020] The inventors of this invention were surprised to discover that when magnesium-based cementitious materials are used for the remediation of water or soil contaminated with heavy metals, they can rapidly reduce the levels of heavy metal ions (e.g., Cu) in the water or soil. 2+ Cd 2+ Pb 2+ The concentration is adjusted to achieve efficient adsorption of heavy metal ions.

[0021] In some embodiments of the present invention, the magnesium-based cementing material is selected from at least one of magnesium oxysulfate cementing material, magnesium oxychloride cementing material and magnesium phosphate cementing material, preferably magnesium oxysulfate cementing material.

[0022] In some embodiments of the present invention, the average particle size of the magnesium-based cementitious material is 2-5 mm, preferably 2-3 mm.

[0023] 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.

[0024] In some embodiments of the present invention, the magnesium-based cementitious material uses magnesium oxide, a hydrating agent, and a modifier as raw materials for preparation.

[0025] In some embodiments of the present invention, the mass ratio of magnesium oxide to hydrating agent is 7-10:2-15, preferably 8-10:2-12.

[0026] In some embodiments of the present invention, the mass ratio of magnesium oxide to modifier is 7-10:0.01-0.07, preferably 8-10:0.01-0.05.

[0027] In some embodiments of the present invention, when preparing the magnesium oxide cementitious material, the mass ratio of magnesium oxide to hydrating agent is 7-10:2-5, for example 8:3, 7:2, 10:5, 8:5, 9:3, and any value within the range of any two of the above values, preferably 8-10:2-3.

[0028] In some embodiments of the present invention, when preparing magnesium oxychloride gelling material, the mass ratio of magnesium oxide to hydrating agent is 7-10:8-15, for example 8:10, 7:8, 10:15, 8:12, 9:10, and any value within the range of any two of the above values, preferably 8-10:10-12.

[0029] In some embodiments of the present invention, when preparing magnesium phosphate cementitious materials, the mass ratio of magnesium oxide to hydrating agent is 7-10:5-10, for example 8:6, 7:5, 10:10, 9:6, 10:6, and any value within the range of any two of the above values, preferably 8-10:6-8.

[0030] 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.

[0031] 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.

[0032] In some embodiments of the present invention, the preparation method of the magnesium-based cementitious material includes: dispersing magnesium oxide and a modifier in a hydrating agent solution to obtain a slurry, followed by molding, curing, demolding, and pulverizing to obtain the magnesium-based cementitious material. The hydrating agent solution can be obtained by dissolving the corresponding hydrating agent in deionized water.

[0033] According to a particularly preferred embodiment of the present invention, the preparation method of the magnesium-based cementitious material includes the following steps:

[0034] (1) Mix magnesium oxide with the modifier in the first step;

[0035] (2) Pour the hydration agent solution into the mixture of magnesium oxide and modifier for a second mixing;

[0036] (3) Pour the slurry obtained in step (2) into a mold for molding, curing, demolding and crushing to obtain the magnesium-based cementitious material.

[0037] 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.

[0038] In some embodiments of the present invention, the amount of magnesium-based cementitious material used in the application is 0.5-3 g / L of the water to be treated, preferably 1 g / L of the water to be treated.

[0039] In some embodiments of the present invention, the application is performed by stirring at a speed of 100-800 rpm, preferably 500 rpm.

[0040] A second aspect of the present invention provides a heavy metal ion adsorbent, wherein the adsorbent is a magnesium-based cementitious material.

[0041] Magnesium-based cementitious materials, as heavy metal ion adsorbents, adsorb heavy metal ions in water or soil, and have the advantages of low cost, simple operation, fast and efficient operation, environmental friendliness, and no secondary pollution.

[0042] In some embodiments of the present invention, the magnesium-based cementing material is selected from at least one of magnesium oxysulfate cementing material, magnesium oxychloride cementing material and magnesium phosphate cementing material, preferably magnesium oxysulfate cementing material.

[0043] In some embodiments of the present invention, the average particle size of the magnesium-based cementitious material is 2-5 mm, preferably 2-3 mm.

[0044] 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.

[0045] In some embodiments of the present invention, the magnesium-based cementitious material uses magnesium oxide, a hydrating agent, and a modifier as raw materials for preparation.

[0046] In some embodiments of the present invention, the mass ratio of magnesium oxide to hydrating agent is 7-10:2-15, preferably 8-10:2-12.

[0047] In some embodiments of the present invention, the mass ratio of magnesium oxide to modifier is 7-10:0.01-0.07, preferably 8-10:0.01-0.05.

[0048] In some embodiments of the present invention, when preparing the magnesium oxide cementitious material, the mass ratio of magnesium oxide to hydrating agent is 7-10:2-5, preferably 8-10:2-3.

[0049] In some embodiments of the present invention, when preparing magnesium oxychloride cementitious materials, the mass ratio of magnesium oxide to hydrating agent is 7-10:8-15, preferably 8-10:10-12.

[0050] In some embodiments of the present invention, when preparing magnesium phosphate cementitious materials, the mass ratio of magnesium oxide to hydrating agent is 7-10:5-10, preferably 8-10:6-8.

[0051] 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.

[0052] 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.

[0053] The present invention will be described in detail below through embodiments.

[0054] 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.

[0055] Preparation Example 1

[0056] This preparation example illustrates the preparation of magnesium oxysulfate cementitious material as a heavy metal ion adsorbent.

[0057] (1) Weigh 8g MgO and 0.03g citric acid (CA), add them to a 500mL beaker, and mix them evenly using mechanical stirring; the mass ratio of MgO to CA is 8:0.03.

[0058] (2) Weigh 3g of MgSO4·7H2O into a 100mL beaker, add 10mL of deionized water, and ultrasonically disperse until MgSO4·7H2O is completely dissolved to obtain a solution; wherein the mass ratio of MgO to MgSO4·7H2O is 8:3;

[0059] (3) Quickly pour the MgSO4·7H2O solution into a 500mL beaker containing MgO and CA, and mechanically stir at 500rpm for 30min;

[0060] (4) After stirring, pour the mixture into a 50*50*50mm steel cementitious material mold, let it stand at room temperature for 12 hours, spray 10mL of water to moisten it, let it stand for another 12 hours, and repeat the curing process for 4 days.

[0061] (5) Use an ergometer to crush the cured cementitious material to a particle size of 2-3 mm to obtain magnesium oxysulfate cementitious material.

[0062] Preparation Example 2

[0063] The magnesium oxysulfate cementitious material used as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 1, except that the mass ratio of MgO to MgSO4·7H2O was 7:2.

[0064] Preparation Example 3

[0065] The magnesium oxysulfate cementitious material used as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 1, except that the mass ratio of MgO to MgSO4·7H2O was 10:5.

[0066] Preparation Example 4

[0067] The magnesium oxysulfate cementitious material used as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 1, except that the mass ratio of MgO to MgSO4·7H2O was 8:5.

[0068] Preparation Example 5

[0069] The magnesium oxysulfate cementitious material used as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 1, except that the mass ratio of MgO to MgSO4·7H2O was 9:3.

[0070] Preparation Example 6

[0071] This preparation example illustrates the preparation of magnesium oxychloride gelling material as a heavy metal ion adsorbent.

[0072] (1) Weigh 8g of MgO and 0.03g of H3PO4 and add them to a 500mL beaker. Mix them thoroughly with mechanical stirring. The mass ratio of MgO to H3PO4 is 8:0.03.

[0073] (2) Weigh 10g of MgCl2·6H2O into a 100mL beaker, add 10mL of deionized water, and ultrasonically disperse until MgCl2·6H2O is completely dissolved to obtain a solution; wherein the mass ratio of MgO to MgCl2·6H2O is 8:10;

[0074] (3) Quickly pour the MgCl2·6H2O solution into a 500mL beaker containing MgO and H3PO4, and mechanically stir at 1000rpm for 30min;

[0075] (4) After stirring, pour the mixture into a 50*50*50mm steel cementitious material mold, let it stand at room temperature for 12 hours, spray 10mL of water to moisten it, let it stand for another 12 hours, and repeat the curing process for 4 days.

[0076] (5) Use an jaw crusher to crush the solidified cementitious material to a particle size of 2-3 mm.

[0077] Preparation Example 7

[0078] Magnesium oxychloride gelling material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 6, except that the mass ratio of MgO to MgCl2·6H2O was 7:8.

[0079] Preparation Example 8

[0080] Magnesium oxychloride gelling material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 6, except that the mass ratio of MgO to MgCl2·6H2O was 10:15.

[0081] Preparation Example 9

[0082] Magnesium oxychloride gelling material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 6, except that the mass ratio of MgO to MgCl2·6H2O was 8:12.

[0083] Preparation Example 10

[0084] Magnesium oxychloride gelling material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 6, except that the mass ratio of MgO to MgCl2·6H2O was 9:10.

[0085] Preparation Example 11

[0086] This preparation example illustrates the preparation of magnesium phosphate cementitious material as a heavy metal ion adsorbent.

[0087] (1) Weigh 8g of MgO and 0.01g of H3BO3, add them to a 500mL beaker, and mix them evenly with mechanical stirring; the mass ratio of MgO to H3BO3 is 8:0.01.

[0088] (2) Weigh 6g of KH2PO4 into a 100mL beaker, add 10mL of deionized water, and sonicate until KH2PO4 is completely dissolved; the mass ratio of MgO to KH2PO4 is 8:6.

[0089] (3) Quickly pour the KH2PO4 solution into a 500mL beaker containing MgO and H3BO3, and mechanically stir at 1000rpm for 30min;

[0090] (4) After stirring, pour the mixture into a 50*50*50mm steel cementitious material mold, let it stand at room temperature for 12 hours, spray 10mL of water to moisten it, let it stand for another 12 hours, and repeat the curing process for 4 days.

[0091] (5) Use an jaw crusher to crush the solidified cementitious material to a particle size of 2-3 mm.

[0092] Preparation Example 12

[0093] Magnesium phosphate cementitious material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 11, except that the mass ratio of MgO to KH2PO4 was 7:5.

[0094] Preparation Example 13

[0095] Magnesium phosphate cementitious material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 11, except that the mass ratio of MgO to KH2PO4 was 10:10.

[0096] Preparation Example 14

[0097] Magnesium phosphate cementitious material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 11, except that the mass ratio of MgO to KH2PO4 was 9:6.

[0098] Preparation Example 15

[0099] Magnesium phosphate cementitious material as a heavy metal ion adsorbent was prepared according to the method of Preparation Example 11, except that the mass ratio of MgO to KH2PO4 was 10:6.

[0100] Comparative Preparation Example 1

[0101] (1) Add commercially available sulfoaluminate cement to a 50*50*50mm steel cement mold, add an appropriate amount of water and mix evenly. Let it stand at room temperature for 12 hours, spray 10mL of water to moisten it, let it stand for another 12 hours, and repeat the curing process for 4 days.

[0102] (2) Use an jaw crusher to crush the solidified cement to a particle size of 2-3 mm to obtain sulfoaluminate cement particles.

[0103] Comparative Preparation Example 2

[0104] The material was prepared according to the method of Comparative Preparation Example 1, except that commercially available sulfoaluminate cement was replaced with commercially available pozzolanic silicate cement to obtain pozzolanic silicate cement particles.

[0105] Comparative preparation example 3

[0106] The material was prepared according to the method of Comparative Preparation Example 1, except that commercially available sulfoaluminate cement was replaced with commercially available steel slag silicate cement to obtain steel slag silicate cement particles.

[0107] Example 1

[0108] This embodiment illustrates the use of magnesium oxysulfate gelling material for adsorbing heavy metal ions in water.

[0109] Experimental methods:

[0110] First, prepare a simulated heavy metal ion contamination solution. Prepare separate solutions with Cu concentrations of 500 ppm each. 2+ Cd 2+ Pb 2+ The solution and each of Cu 100 ppm 2+ Cd 2+ Pb 2+ Coexisting solutions.

[0111] (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.

[0112] (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.

[0113] (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.

[0114] (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.

[0115] 100 mg of magnesium oxysulfate gelling material (preparation examples 1-5) was added to 100 mL of the above solution, stirred at 500 rpm at room temperature, and samples were taken at 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.

[0116] Based on the ICP-OES determination results, the adsorption capacity q is calculated according to the following formula. t . with q t Plot the adsorption capacity curve with t as the vertical axis and time as the horizontal axis.

[0117]

[0118] 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.

[0119] Experimental results:

[0120] Figure 1 To prepare the magnesium oxysulfide cementitious material obtained in Example 1, 500 ppm of Cd was adsorbed. 2+ Pb 2+ and Cu 2+ A series of graphs showing the adsorption capacity of solutions, and the adsorption of Cu by magnesium oxysulfate cementitious materials. 2+ Its ability to adsorb Cd is slightly weaker. 2+ and Pb 2+ The magnesium oxysulfate cementitious material achieved its Cd-resistance effect at 100, 300, and 400 min, respectively. 2+ Pb 2+ and Cu 2+ The maximum adsorption value and the adsorption rate, which are initially fast and then slow down, both indicate good adsorption effects for Cd. 2+ Pb 2+ and Cu 2+ The final adsorption capacities were 523.25 mg / g, 475.17 mg / g, and 498.59 mg / g, respectively.

[0121] Table 1. Heavy metal ion adsorption capacity of different magnesium oxysulfate cementitious materials (adsorption amounts, respectively).

[0122]

[0123]

[0124] Example 2

[0125] This example illustrates the use of magnesium oxychloride gelling material for adsorbing heavy metal ions in water.

[0126] The experimental method was the same as in Example 1, except that the magnesium oxychloride cementitious material particles prepared in Examples 6-10 were used instead of the magnesium oxysulfide cementitious material particles.

[0127] Experimental results:

[0128] Figure 2 To prepare the magnesium oxychloride cementitious material obtained in Example 6, 500 ppm of Cd was adsorbed. 2+ Pb 2+ and Cu 2+ A series of graphs showing the adsorption capacity of solutions, illustrating the adsorption of Pb by magnesium oxychloride cementitious materials. 2+ Its ability to adsorb Cd is superior. 2+ and Cu 2+ Magnesium oxychloride cementitious materials achieved Pb saturation at 200, 500, and 1440 min, respectively. 2+ Cd 2+ and Cu 2+ Adsorption maximum value for Pb 2+ and Cd 2+ The adsorption rate is initially fast and then slows down for Cu. 2+ The adsorption rate remains almost constant, and good adsorption effects can be achieved for Cd. 2+ Pb 2+ and Cu 2+ The final adsorption capacities were 459.36 mg / g, 471.81 mg / g, and 467.48 mg / g, respectively.

[0129] Table 2. Heavy metal ion adsorption capacity of different magnesium oxychloride cementitious materials (adsorption amounts, respectively).

[0130]

[0131]

[0132] Example 3

[0133] This embodiment illustrates the use of magnesium phosphate gelling materials for adsorbing heavy metal ions in water.

[0134] The experimental method was the same as in Example 1, except that the magnesium phosphate cementitious material particles prepared in Examples 11-15 were used instead of the magnesium oxysulfate cementitious material particles.

[0135] Experimental results:

[0136] Figure 3 To prepare the magnesium phosphate cementitious material obtained in Example 11, 500 ppm of Cd were adsorbed. 2+ Pb 2+ and Cu 2+ A series of graphs showing the adsorption capacity of the solution. Magnesium phosphate cementitious material achieved its adsorption capacity for Cd at 400, 300, and 800 min, respectively. 2+ Pb 2+ and Cu 2+ The maximum adsorption value and the adsorption rate, which are initially fast and then slow down, both indicate good adsorption effects for Cd. 2+ Pb 2+ and Cu 2+ The final adsorption capacities were 464.91 mg / g, 464.24 mg / g, and 497.57 mg / g, respectively.

[0137] Table 3. Heavy metal ion adsorption capacity of different magnesium phosphate cementitious materials (adsorption amounts, respectively).

[0138]

[0139] pass Figure 1 , Figure 2 and Figure 3 In comparison, the magnesium oxysulfate cementitious materials adsorbed 500 ppm of Cd. 2+ Pb 2+ and Cu 2+ Its overall adsorption capacity is slightly better than that of magnesium oxychloride cementitious materials and magnesium phosphate cementitious materials.

[0140] Figure 4 To prepare magnesium oxysulfate cementitious material obtained in Example 1, magnesium oxychloride cementitious material obtained in Example 6, and magnesium phosphate cementitious material obtained in Example 11, 100 ppm of Cd was simultaneously adsorbed. 2+ Pb 2+ and Cu 2+ A series of graphs showing the adsorption capacity of the coexisting solutions. All three can reach their maximum adsorption capacity in a relatively short time, indicating good adsorption performance. Compared to the other two, the magnesium oxysulfate cementitious material exhibits superior adsorption performance, with a higher adsorption capacity and a faster adsorption rate.

[0141] Comparative Example

[0142] The experimental method was the same as in Example 1, except that the cement particles prepared in Comparative Preparation Examples 1-3 were used instead of the magnesium oxysulfate cementitious material.

[0143] Figure 5Simultaneous adsorption of 100 ppm Cd by sulfoaluminate cement particles, pozzolanic silicate cement particles, and steel slag silicate cement particles. 2+ Pb 2+ and Cu 2+ A series of graphs showing the adsorption capacity of coexisting solutions. Compared to the three magnesium-based cementitious materials, sulfoaluminate cement, pozzolanic silicate cement, and steel slag silicate cement have weaker adsorption capacity and lower adsorption amounts than magnesium-based cementitious materials.

[0144] 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. Application of magnesium-based cementitious materials as a single component in the adsorption of heavy metal ions in water or soil; in, The magnesium-based cementitious material is a magnesium oxysulfate cementitious material.

2. The application according to claim 1, wherein, The average particle size of the magnesium-based cementitious material is 2-5 mm. And / or, the heavy metal ions are selected from Cd. 2+ Pb 2+ and Cu 2+ At least one of them.

3. The application according to claim 2, wherein, The average particle size of the magnesium-based cementitious material is 2-3 mm.

4. The application according to claim 1, wherein, The magnesium-based cementitious material is prepared using magnesium oxide, hydration agent, and modifier as raw materials.

5. The application according to claim 4, wherein, The mass ratio of magnesium oxide to modifier is 7-10:0.01-0.

07.

6. The application according to claim 4, wherein, The mass ratio of magnesium oxide to modifier is 8-10:0.01-0.

05.

7. The application according to any one of claims 1-4, wherein, The mass ratio of magnesium oxide to hydrating agent is 7-10:2-5; And / or, the hydrating agent is magnesium sulfate; And / or, the modifier is selected from at least one of citric acid, phosphoric acid, boric acid, salicylic acid and ethylenediaminetetraacetic acid.

8. The application according to claim 7, wherein, The mass ratio of magnesium oxide to hydrating agent is 8-10:2-3.

9. The application according to any one of claims 1-3, wherein, The preparation method of the magnesium-based cementitious material includes: adding magnesium oxide and a modifier to a hydrating agent solution for dispersion to obtain a slurry, and then molding, curing, demolding, and crushing to obtain the magnesium-based cementitious material.

10. The application according to any one of claims 1-3, wherein, The concentration of heavy metal ions in the water body is 50-1000 ppm; And / or, in the application, the amount of magnesium-based cementitious material used is 0.5-3 g / L of the water to be treated; And / or, the application is performed by stirring at a speed of 100-800 rpm.

11. The application according to claim 10, wherein, The concentration of heavy metal ions in the water body is 100-500 ppm; And / or, in the application, the amount of magnesium-based cementitious material used is 1 g / L of the water to be treated; And / or, the stirring rate is 500 rpm.

Images