Mechanical activation-based preparation method and application of sea bubble material

Abstract

The application relates to a preparation method and application of a mechanically activated sepiolite material, and comprises the following steps: S1, carrying out preliminary crushing treatment on sepiolite raw ore to obtain fine powder sepiolite; S2, acid treatment, mixing the fine powder sepiolite with 1 mol / L acid according to a mass ratio of 1:10, uniformly stirring, intermittently adding dilute hydrochloric acid under stirring until the pH value of the mixed solution is stabilized at 3, and carrying out filtration to obtain a filter cake; and S3, carrying out mechanical activation in a ball mill. The application is used for repairing soil Cd pollution, the Cd removal effect is stable, the adsorption performance is relatively high, and the utilization rate of the sepiolite is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of soil heavy metal remediation, in particular to a preparation method and application of a mechanically activated sepiolite material, and especially to a soil Cd pollution remediation technology. BACKGROUND

[0002] In-situ passivation remediation technology can be carried out under the premise of ensuring normal crop production, has little impact on the soil environment, has a wide range of applications, and shows certain advantages in the remediation of large-area Cd-contaminated soil. In-situ passivation refers to changing the physicochemical properties of soil or directly fixing heavy metals by adding safe and green passivation agents without changing the total amount of heavy metals in soil, so as to reduce the availability of heavy metals in soil to below the safety limit. Therefore, selecting appropriate passivation materials is the key to ensuring the effect of in-situ passivation remediation. Sepiolite is a natural layered chain fibrous porous magnesium silicate clay mineral. Compared with other clay minerals, sepiolite has a high specific surface area and physicochemical activity on the surface, and has the potential to fix heavy metals. At the same time, natural sepiolite contains sufficient CaCO3 and (CaMg (CO3)2), which has the potential to increase the pH value of soil, helps to increase the net negative charge of soil, promotes hydroxyl combination, and reduces the bioavailability of Cd in soil through precipitation. Therefore, sepiolite is considered to be a promising passivation agent in removing Cd.

[0003] However, natural sepiolite is currently mainly used in removing Cd, and is only crushed for use. The natural sepiolite in the prior art has low heavy metal affinity, unstable removal effect, relatively low adsorption performance, and low utilization rate of sepiolite. SUMMARY

[0004] The purpose of the present application is to provide a preparation method and application of a mechanically activated sepiolite material with stable Cd removal effect, relatively high adsorption performance, and high utilization rate of sepiolite.

[0005] The technical scheme of the present application is as follows:

[0006] A preparation method of a mechanically activated sepiolite material, comprising the following steps:

[0007] S1, carrying out preliminary crushing treatment on sepiolite raw ore to obtain fine powder sepiolite;

[0008] S2, acid treatment, mixing the fine powder sepiolite with 1 mol / L acid according to a mass ratio of 1:10, stirring uniformly, and intermittently adding dilute hydrochloric acid under stirring conditions until the pH value of the mixed solution is stable at 3, and then filtering to obtain a filter cake;

[0009] S3, mechanical activation in a ball mill.

[0010] Preferably, S1 selects sepiolite raw ore as natural sepiolite with a mass content of 41%.

[0011] Preferably, the crushing treatment of S1 is that the sepiolite raw ore is crushed and coarsely ground to obtain powdery sepiolite; and the powdery sepiolite is passed through a 100-mesh sieve to obtain fine powder sepiolite.

[0012] Preferably, the acid of S2 is hydrochloric acid, phosphoric acid or citric acid.

[0013] Preferably, the concentration of the dilute hydrochloric acid is 1 mol / L.

[0014] Preferably, in the mechanical activation process in the ball mill, the ball mill barrel is made of polytetrafluoroethylene material, the grinding balls are all made of zirconia material, the grinding balls are mixed materials of large, medium and small balls, the particle size ratio of the large, medium and small balls is about 2:2:3, the ball-to-material mass ratio is 10:1, the revolution speed of the ball mill is 320 r / min, and the rotation speed is 550 r / min; the mechanical activation is performed for 2 h to obtain the mechanically activated sepiolite.

[0015] Preferably, the diameters of the large, medium and small balls are 3 mm, 5 mm and 10 mm, respectively.

[0016] An application of a sepiolite material based on a mechanical activation technology is used for repairing Cd-polluted soil.

[0017] The beneficial technical effects brought by the present application are as follows:

[0018] (1) The present application aims at the problems of easy agglomeration, poor stability, low repair efficiency and long repair period of the existing natural sepiolite applied in heavy metal removal, and improves the affinity of the natural sepiolite to heavy metals and the high selectivity to Cd through the mechanical activation method, so that the heavy metal removal efficiency is greatly improved, and the repair period is shortened.

[0019] (2) The present application strengthens the Cd removal capacity of the natural sepiolite, and the preparation process is simple, the operation condition is mild, and no strong acid needs to be added in the preparation process, so that the present application is easier to realize.

[0020] (3) The present application has stable Cd removal effect, relatively high adsorption performance, and high utilization rate of sepiolite, and the mechanically activated sepiolite can be directly applied to the heavy metal-polluted soil, so that the repair efficiency and repair effect are better than those of the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a scanning electron microscope (SEM) image of natural sepiolite.

[0022] Figure 2 It is an adsorption kinetics curve of sepiolite ore treated by three kinds of acids to Cd(II).

[0023] Figure 3 SEM image of mechanically activated sepiolite;

[0024] Figure 4 Adsorption isotherm plot of sepiolite without mechanical activation on Cd(II);

[0025] Figure 5 Adsorption isotherm plot of mechanically activated 2h sepiolite on Cd(II);

[0026] Figure 6 Adsorption kinetics plot of sepiolite without mechanical activation on Cd(II);

[0027] Figure 7 Adsorption kinetics plot of mechanically activated 2h sepiolite on Cd(II). DETAILED DESCRIPTION

[0028] (I) Acid treatment of sepiolite

[0029] 11, The bulk sepiolite ore is preliminarily crushed by a crusher, and after the preliminary crushing, sepiolite ore of a proper size is selected and its components are analyzed, and the detection results show that the content of natural sepiolite clay minerals is respectively: montmorillonite (43%), illite (16%) and sepiolite (41%). Figure 1 SEM image of natural sepiolite.

[0030] 12, The natural sepiolite with a sepiolite content of 41% is selected in the application, is crushed and coarsely ground into sepiolite powder with a larger particle size; the sepiolite powder is passed through a 100-mesh screen to obtain fine powder sepiolite; the fine powder sepiolite is mixed with 1 mol / L dilute hydrochloric acid (HCl), phosphoric acid (H3PO4) and citric acid (C6H8O7) respectively according to a mass ratio (sepiolite: acid = 1:10), is uniformly stirred at room temperature by using a magnetic stirrer, and is intermittently supplemented with dilute hydrochloric acid under stirring conditions until the pH value of the mixed solution is stabilized at about 3. A circulating water type multi-purpose vacuum pump and a Buchner funnel are used for filtration to obtain a filter cake.

[0031] 13, 0.01 g of sepiolite treated by the three kinds of acids respectively, 20 mg·L -1Cd(II) solution 20 mL (the solid-liquid ratio of the material is 0.5 g / L), adjust the pH of the solution system to 7.0, the background electrolyte is 0.01 mol / L NaNO3, under the condition of 25°C and 200r / min continuous shaking. At the adsorption time of 0, 1, 5, 30, 150, 300 min, the supernatant is taken to determine the concentration difference of Cd solution before and after the adsorption of the material, and the material after the reaction is reserved to determine the adsorption capacity change of the material to Cd(II). Three repeated experiments are set. At the same time, a blank control without adding material is set. The adsorption kinetics of the experimental structure is analyzed. The analysis results are shown in Figure 2 It can be seen from Figure 2 that the adsorption capacity of the citric acid treated sepiolite to Cd is the largest, and the adsorption performance is the best.

[0032] (II) Mechanical activation treatment of sepiolite

[0033] 21. The fine powder sepiolite treated by citric acid is placed in a FOCUCY Fritsch planetary ball mill for mechanical activation. The ball mill barrel is made of polytetrafluoroethylene material, and the grinding balls are made of zirconia material. The grinding balls are mixed with large, medium and small balls with diameters of 3 mm, 5 mm and 10 mm respectively, and the ratio of different particle sizes of grinding balls is about 2:2:3. The ball-to-material ratio is set to 10:1, and the revolution speed of the ball mill is set to 320r / min and the rotation speed is set to 550r / min. The fine powder sepiolite is mechanically activated in the ball mill for 2h to obtain the mechanically activated sepiolite.

[0034] 22. As shown in the scanning electron microscope (SEM) image of the mechanically activated sepiolite in Figure 3 It can be seen that the minimum particle size of the mechanically activated sepiolite can be reduced to below 200 nm, and the material is in a state of agglomeration, and the particle size is uneven.

[0035] 23. As shown in Table 1, after 2h of mechanical activation, the average pore size of the natural sepiolite is increased from 21.604 nm to 26.241 nm of the mechanically activated sepiolite, the pore volume is increased from 0.010 cm 3 ·g -1 to 0.043 cm 3 ·g -1 , the specific surface area is increased from 1.816 m 2 ·g -1 to 6.585 m 2 ·g -1 .

[0036] Table 1 Comparison of basic properties of sepiolite mechanically activated for 2h and sepiolite without mechanical activation

[0037]

[0038] (III) Heavy metal removal performance

[0039] 31. Cd(II) solutions of different concentrations were prepared using chemically pure Cd(NO3)2·4H2O.

[0040] 32. 0.01 g of sepiolite not subjected to mechanical activation and 0.01 g of mechanically activated sepiolite subjected to mechanical activation for 2 h were taken, and 20 mL of Cd(II) solution with a concentration gradient of 0, 0.2, 1, 20, 50, 100, 500, and 1000 mg·L -1 was added to each (the solid-to-liquid ratio of the material was 0.5 g / L), the pH of the solution system was adjusted to 7.0, the background electrolyte was 0.01 mol / L NaNO3, and the system was continuously shaken at 25°C and 200 r / min for 20 h. After centrifugal filtration, the concentration difference of the Cd solution before and after the adsorption of the material was determined, and the material after the reaction was reserved to determine the adsorption capacity change of the material for Cd(II). Three repeated experiments were set, and a blank control without the material was also set. The experimental structure was subjected to isothermal adsorption analysis. The results are shown in Figure 4 and Figure 5 The adsorption isotherm of the material for Cd(II) is shown in Table 2. As shown in Table 2, the adsorption capacity of the mechanically activated sepiolite for Cd can reach 58.82 mg·g -1 , which is 5.47 times that of the sepiolite not subjected to mechanical activation and higher than that of the conventional sepiolite clay mineral.

[0041] Table 2. Adsorption isotherm data of sepiolite not subjected to mechanical activation and mechanically activated sepiolite for Cd(II)

[0042]

[0043] 33. 0.01 g of sepiolite not subjected to mechanical activation and 0.01 g of mechanically activated sepiolite subjected to mechanical activation for 2 h were taken, and 20 mL of Cd(II) solution with an initial concentration gradient of 20 mg·L -1 was added to each (the solid-to-liquid ratio of the material was 0.5 g / L), the pH of the solution system was adjusted to 7.0, the background electrolyte was 0.01 mol / L NaNO3, and the system was continuously shaken at 25°C and 200 r / min. At 0, 1, 5, 30, 150, and 300 min of the adsorption time, the concentration difference of the Cd solution before and after the adsorption of the material was determined, and the material after the reaction was reserved to determine the adsorption capacity change of the material for Cd(II). Three repeated experiments were set, and a blank control without the material was also set. The experimental structure was subjected to adsorption kinetics analysis. The results are shown in Figure 6 and Figure 7The adsorption kinetics data of the materials to Cd(II) are shown in Table 3. From Table 3, the adsorption capacity of the mechanically activated sepiolite to Cd can reach 36.10 mg·g -1 , which is 1.31 times of that of the sepiolite without mechanical activation.

[0044] Table 3 Adsorption isotherm data of the sepiolite without mechanical activation and the mechanically activated sepiolite for 2h to Cd(II)

[0045] .

[0046] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments, which are made according to the technical essence of the present application, still belong to the scope of the technical solution of the present application.

Claims

1. A method for preparing a mechanically activated sea spongin material, characterized by, Comprising the following steps: S1, a preliminary crushing treatment is performed on the raw sepiolite to obtain fine powder sepiolite; the raw sepiolite selected in S1 is natural sepiolite with a mass content of 41%; the crushing treatment in S1 is: the raw sepiolite is crushed and coarsely ground to obtain powder sepiolite; the powder sepiolite is passed through a 100-mesh sieve to obtain fine powder sepiolite; S2, acid treatment: the fine powder sepiolite is mixed with 1 mol / L citric acid at a mass ratio of 1:10, stirred uniformly, and intermittently supplemented with dilute hydrochloric acid under stirring until the pH value of the mixture is stabilized at 3, and then filtered to obtain a filter cake; S3, mechanical activation treatment in a ball mill; the material of the ball mill barrel is polytetrafluoroethylene, the material of the grinding balls is zirconia, the grinding balls are a mixture of large, medium and small balls, the particle size ratio of the large, medium and small balls is 2:2:3, the ball-to-material mass ratio is 10:1, the revolution speed of the ball mill is 320 r / min, and the rotation speed is 550 r / min; the mechanical activation is performed for 2 h to obtain mechanically activated sepiolite.

2. The method according to claim 1, wherein The concentration of the dilute hydrochloric acid is 1 mol / L.

3. The method for preparing sepiolite material based on mechanical activation according to claim 1, characterized in that, The diameters of the large, medium and small balls are 3 mm, 5 mm and 10 mm, respectively.

4. Use of a sea sponge material prepared according to the method of any one of claims 1 to 3, characterized in that, For remediation of soil Cd pollution.

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