CN113231007B - A kind of method and application of preparing heavy metal adsorbent by using blast furnace slag - Google Patents

Abstract

A method for preparing heavy metal adsorbent by using blast furnace slag and application thereof are disclosed, the method comprises soaking blast furnace slag in water, filtering, drying and grinding; reacting the ground product with alkali liquor, performing suction filtration, reserving filtrate and recording the filtrate as solution 1, and recording filter residue as solid 1; adjusting the pH value of the solution 1, carrying out suction filtration, and marking the filtrate as a solution 2; adding filter residue into alkali liquor 2, and reacting to obtain a clear solution 3; ultrasonically dispersing the solid 1 in water to obtain a suspension 1, adding the solution 3 into the suspension 1, ultrasonically dispersing to obtain a suspension 2, adding the solution 2, and finally centrifugally separating to obtain the adsorbent. The invention separates aluminum ions and silicate ions from the blast furnace slag, then mixes the aluminum ions and the silicate ions with the treated blast furnace slag framework, and prepares the adsorbent which has a fluffy and granular framework and is provided with a layer of raised and wrinkled aluminosilicate rough gel on the surface of the framework by controlling the dosage of the aluminum ions, the silicate ions and the curing conditions, and the adsorbent has large specific surface area and good adsorption rate on heavy metals.

Description

A kind of method and application of preparing heavy metal adsorbent by using blast furnace slag

technical field

The invention belongs to the technical field of heavy metal sewage treatment, and in particular relates to a method and application for preparing a heavy metal adsorbent by using blast furnace slag.

Background technique

my country is a big iron and steel country with the world's largest iron and steel output. Blast furnace ironmaking is the most common ironmaking method. According to incomplete statistics, in the process of blast furnace ironmaking, 350kg of blast furnace slag will be discharged for every 1 ton of iron produced, and the utilization rate of iron is 350kg. Only at 70% to 85%, the recovery rate of blast furnace slag in my country is still at a low level compared with developed countries. In order to improve the resource reuse rate of blast furnace slag, scholars have conducted in-depth research on it. According to the diversification of chemical composition and chemical properties, it is often used in machinery, construction, electronics and other fields. At present, blast furnace slag has been used in the preparation of cement, concrete, waste, gypsum, glass and other production and living materials, but the method is simple and the added value is low, and high-value utilization technology of blast furnace slag still needs to be developed.

Heavy metal pollution is one of the more common types of wastewater pollution. After heavy metal is ingested by the human body, it will cause various diseases such as kidney and liver damage. Therefore, heavy metal pollution is one of the main problems facing today's society. At this stage, the main methods for removing heavy metal ions in water include ion exchange, membrane filtration, chemical precipitation, adsorption, electrolysis, advanced oxidation and reverse osmosis. Adsorption method is a method of removing impurities in wastewater by using solid adsorbent. The advantages of this method are mainly fast reaction process, high adsorption efficiency, convenient and simple operation facilities, etc. Therefore, more and more people use this method. Carry out the removal of heavy metal impurities in wastewater.

In recent years, activated carbon, agricultural solid waste, industrial solid waste, and natural adsorbents have been widely used as solid adsorbents in the treatment of heavy metal wastewater. Among them, industrial solid waste is a hot spot as a heavy metal wastewater adsorbent. The disclosed prior art is patent CN200710175228.4 which discloses a water treatment agent prepared by utilizing blast furnace slag and its preparation method. The blast furnace slag includes: SiO ₂ : 25-30%, CaO: 40-45%, _Al2O3 : 15-20%, MgO: 10-20%, and (CaO+MgO)/( _{Al2O3 + SiO2 )} was 1.08-1.5. It is mixed with an alkaline aqueous solution with pH>11 according to a solid-liquid ratio of 1-:51, filtered and dried at 50-120°C for 24-48 hours, taken out, pulverized, and finally passed through a standard sieve of 6-80 m. Patent CN201811406908.7 discloses a modified blast furnace slag and its application. The modified blast furnace slag is prepared through the following steps: after ball milling and screening the blast furnace slag, add it to an acidic solution at a solid-liquid ratio of 0.05-0.15:1 , the modified blast furnace slag is obtained after shaking, filtering, centrifuging and drying; it is applied to the adsorption of metal ions in rare earth solution. Although the preparation method of the above-mentioned technical adsorbent is simple and the cost is low, its application effect is slightly poor, especially the adsorption rate of heavy metal ions is low, and the metal ions cannot be effectively recovered and reused. Therefore, it is necessary to further improve the blast furnace slag. The preparation method of the adsorbent is intended to improve the adsorption rate of heavy metal ions, so that the metal ions can be effectively recovered and reused, and the blast furnace slag can also be maximized in resource utilization.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the object of the present invention is to provide a method for preparing a heavy metal adsorbent by utilizing blast furnace slag. The blast furnace slag treated by the method has a fluffy and granular skeleton, and the surface of the skeleton is covered with a layer of protrusions and "folds". The aluminosilicate rough gel, the adsorbent with this structure has a large specific surface area and a good adsorption rate for heavy metals.

For realizing the above object, the concrete technical scheme that the present invention takes is as follows:

A method for preparing a heavy metal adsorbent using blast furnace slag, comprising the following steps:

S1: soak the blast furnace slag in water, filter, dry, take it out and put it in a ball mill, grind it, and use it for later use;

S2: the ground product obtained in step S1 is mixed with lye 1, heated and heated, then kept constant temperature stirring reaction, finally cooled, suction filtered, reserved filtrate is recorded as solution 1, the filter residue is washed with water to constant weight, dried for standby and recorded as solid 1;

S3: Add acid solution to solution 1 to adjust pH, then suction filtration, and reserve the filtrate as solution 2 for standby; wash the filter residue with water, then gradually add alkali solution 2, adjust pH, and ultrasonically treat to obtain clear solution 3, which is for later use.

S4: add the solid 1 to water, carry out ultrasonic dispersion for the first time to obtain the suspension 1, add the solution 3 to the suspension 1 and mix evenly, then ultrasonically disperse again to obtain the suspension 2, continue to add the solution 2 to the suspension 2, Finally, the temperature is raised and kept at a constant temperature for solidification, and the above heavy metal adsorbent is obtained through centrifugal separation and sediment drying.

The weight ratio of blast furnace slag and water described in step S1 is 1:1.2-2.0, the soaking time is 10-20min, and this step can remove soluble substances in the blast furnace slag; the grinding is to grind to a particle size of 50-200 mesh , preferably 100-180 mesh.

The lye 1 described in step S2 is not particularly limited, and can be commonly used in this field, including but not limited to at least one of sodium hydroxide solution or potassium hydroxide solution, and the concentration of the lye 1 is 5-10mol/L , the weight ratio of the lye solution 1 to the blast furnace slag is 3-6:1; the heating is heating to 40-80° C., the reaction time is 0.5-1.5 h, and the cooling is cooling to room temperature. In this step, the amorphous silicon, aluminum, sodium silicate, sodium chlorate and other substances on the blast furnace slag are dissolved by using alkaline solution, so as to obtain a solution 1 containing silicon, aluminum and sodium and a blast furnace slag skeleton.

The acid solution described in step S3 is not particularly limited, and can be commonly used in the art, including but not limited to at least one of sulfuric acid or hydrochloric acid solution, the concentration of the acid solution is 2-4mol/L, and the pH is adjusted to 7.5-8.5 , the washing times are 1-3 times, the lye 2 is not particularly limited, and can be commonly used in this field, including but not limited to at least one of sodium hydroxide solution or potassium hydroxide solution, the lye solution The concentration of 2 is 0.5-2mol/L, and the weight ratio of the lye 2 to the filter residue is 5-10:1, and the pH is adjusted to 8.5-10.5; the ultrasonic processing power is 1-3kW, and the ultrasonic processing frequency is 60-80kHz, ultrasonic treatment time is 1-3h. In this step, by adjusting the pH of solution 1 to neutral or slightly alkaline, silicon and aluminum are separated, silicon is present in the silicic acid filter residue, and aluminum is present in solution 2 in the form of sodium aluminate; and the filter residue is added to the lye solution 2 In , the pH is controlled within the range of 8.5-10.5, and the silicic acid can be dissolved to obtain a stable sodium silicate solution 3.

The weight ratio of the solid 1 to water in step S4 is 1:3-6, preferably 1:4-5, the first ultrasonic dispersion power is 0.5kW-1.5kW, the dispersion frequency is 40-60kHz, and the dispersion time is 1 -3h, the weight ratio of the suspension 1 and the solution 3 is 1:1-3, the power of the ultrasonic dispersion again is 0.5kW-1.5kW, the dispersion frequency is 60-80kHz, and the dispersion time is 30-90min. The weight ratio of the suspension 2 and the solution 2 is 1:0.5-4, preferably 1:2-4, the heating temperature is 50-100°C, preferably 50-80°C, and the constant temperature curing time is 5- 10d. This step is to disperse the blast furnace slag skeleton into a uniform suspension 1. By adjusting the amount of blast furnace slag particles in the suspension 1 and the mixing ratio with solution 2 and solution 3, a continuous special with a certain thickness is formed on the surface of the blast furnace slag skeleton. The raised and "wrinkled" aluminosilicate rough gel structure has a large specific surface area of blast furnace slag and has good adsorption performance for heavy metals.

The invention also provides an application of the above heavy metal adsorbent. The adsorbent and the sewage with the divalent heavy metal ion concentration of 1.0-1.2g/L are uniformly mixed in a ratio of (0.1-1) g:100ml, and the oscillation speed is Vibration for 20-50min on a 50-100r/min oscillator, the adsorption rate of divalent heavy metal ions in sewage is ≥65%.

Compared with the prior art, the beneficial effects of the present invention are:

In the present invention, aluminum ions and silicate ions are separated from blast furnace slag, then the two are mixed with the treated blast furnace slag skeleton, and the dosage and curing conditions of the three are controlled to prepare a fluffy, granular skeleton, At the same time, the surface of the skeleton is covered with a raised and "wrinkled" aluminosilicate rough gel adsorbent. The adsorbent with this structure has a large specific surface area and a good adsorption rate for heavy metal ions.

The preparation method of the invention is safe and simple, does not require strict equipment and process conditions, has cheap raw materials and low cost, and is suitable for scale-up production.

Description of drawings

Fig. 1 is the SEM image of the heavy metal adsorbent prepared in Preparation Example 1 at a magnification of 3000 times.

FIG. 2 is a 1000 times magnified SEM image of the heavy metal adsorbent prepared in Preparation Example 1.

3 is the EDS spectrum of the heavy metal adsorbent prepared in Preparation Example 1.

Fig. 4 is the technological process of preparing heavy metal adsorbent of the present invention.

Detailed ways

The present invention is further described below in conjunction with specific embodiments, but is not limited to the contents in the description. Unless otherwise specified, the "parts" in the examples are all parts by weight.

The blast furnace slag used in the embodiment of the present invention comes from Shanxi Huaxing Aluminum Co., Ltd. The content of the main chemical components of blast furnace slag was analyzed by X-ray fluorescence spectroscopy (instrument model: XRF-1800), and the results are shown in Table 1:

Table 1

Preparation Example 1

S1: Immerse 100 parts of blast furnace slag in 200 parts of water for 20 minutes, filter, dry, take out and place in a ball mill, grind to a particle size of 120 mesh, for use;

S2: Mix the ground product obtained in step S1 with a sodium hydroxide solution with a concentration of 10 mol/L at a weight ratio of 1:6, heat up to 60° C., then keep the constant temperature stirring for 1.5 hours, and finally cool and filter with suction to retain the filtrate. Denoted as solution 1, the filter residue was washed with water 4 times to a constant weight, dried for use and denoted as solid 1; this step is to separate aluminum and silicon from blast furnace slag with alkaline solution.

S3: adding the hydrochloric acid solution with a concentration of 4mol/L in solution 1 to adjust pH to 8, then suction filtration, and retaining the filtrate as solution 2 for subsequent use; washing the filter residue with water 3 times, then adding to the sodium hydroxide solution of 1mol/L, The pH was adjusted to 10, and the solution was ultrasonically treated with a power of 2kW and a frequency of 60kHz for 1.5h to obtain a clear solution 3, which was used for later use.

S4: add the solid 1 to water at a weight ratio of 1:5, and perform ultrasonic dispersion for the first time, the ultrasonic dispersion power is 1.2kW, the dispersion frequency is 50kHz, and the dispersion time is 2.0h to obtain suspension 1; The weight ratio of solution 1 and solution 3 is 1:1, add solution 3 and mix evenly, then ultrasonically disperse again, the power of ultrasonic dispersion is 1.5kW, the dispersion frequency is 60kHz, and the dispersion time is 60min to obtain suspension 2; continue to the suspension In 2, the weight ratio of the solution 2 to the solution 2 was 1:2, and the solution 2 was added, and finally the temperature was raised to 80° C., and kept at a constant temperature for curing for 8 d. After centrifugation and sediment drying, the above-mentioned heavy metal adsorbent was obtained.

Fig. 1 is the SEM image of the heavy metal adsorbent prepared in Preparation Example 1 at a magnification of 3000 times. FIG. 2 is a 1000 times magnified SEM image of the heavy metal adsorbent prepared in Preparation Example 1. 3 is the EDS spectrum of the heavy metal adsorbent prepared in Preparation Example 1. Table 2 is the chemical composition analysis table of the surface micro-region of the EDS spectrum

Table 2

Preparation Example 2

The rest are the same as in Preparation Example 1, except that in Step S4, the suspension 1 is prepared from the solid 1 and the water in a weight ratio of 1:4.

Preparation Example 3

The rest are the same as in Preparation Example 1, except that in step S4, suspension 2 is prepared by suspension 1 and solution 3 in a weight ratio of 1:3.

Preparation Example 4

The rest are the same as in Preparation Example 1, except that in step S4, the weight ratio of suspension 2 to solution 2 is 1:0.5.

Preparation Example 5

The rest are the same as in Preparation Example 1, except that in step S4, the suspension 1 is prepared by the solid 1 and the water in a weight ratio of 1:3.

Preparation Example 6

The rest are the same as in Preparation Example 1, except that in step S4, the suspension 1 is prepared by the solid 1 and the water in a weight ratio of 1:6.

Preparation Example 7

The rest are the same as in Preparation Example 1, except that in step S4, the weight ratio of suspension 2 to solution 2 is 1:4.

Preparation Example 8

The rest are the same as in Preparation Example 1, except that in step S4, the temperature is finally raised to 50° C., and the temperature is maintained for 8 d.

Preparation Example 9

The rest is the same as that of Preparation Example 1, except that in step S4, the temperature is finally raised to 100° C., and the temperature is maintained for 8 d.

Examples 1-9

Mix the adsorbent and sewage with a Pb ²⁺ concentration of 1.0g/L at a rate of 1g:100ml, shake for 50min on a shaker with a shaking speed of 80r/min, filter to obtain the equilibrium solution after adsorption, and use the ICP-AES method The Pb ²⁺ concentration in the equilibrium solution was determined and the recovery was calculated. ICP-AES, equipment: ICP emission spectrometer SPS 1200AR model; atomic absorption spectrophotometer: AA8200 model. The two-point standard curve method of 0 mg/L and 1.0 mg/L was used for the determination.

In the formula: R is the recovery rate;

C ₀ is the initial concentration of Pb ²⁺ in the solution (g/L);

C _e is the equilibrium concentration of Pb ²⁺ in the solution (g/L);

m is the mass of the adsorbent (g);

V is the volume (L) of the adsorption solution.

The adsorbents prepared in Preparation Examples 1-9 were successively subjected to the experimental tests in the Examples, corresponding to Examples 1-9 respectively.

Replace the sewage containing Pb ²⁺ with the sewage containing Cu ²⁺ , Mn ²⁺ sewage, Mn ⁴⁺ sewage, Ni ²⁺ sewage, Cd ²⁺ sewage, and Co ³⁺ sewage with the same concentration. Repeat the experimental test in the above embodiment. The results are shown in Table 3 below.

table 3

It can be seen from Figures 1 and 2 that the adsorbent prepared by the present invention has a fluffy and granular framework, and the surface of the framework is also covered with a layer of convex and "wrinkled" aluminosilicate rough gel adsorbent. The specific surface area of the agent is large, which is very helpful for the adsorption of heavy metal ions.

From Figures 3 and 4, it can be seen that the surface of the fluffy and granular skeleton is tightly wrapped by convex and wrinkled gelatinous substances. The elemental composition of the gelatinous substances in the red box is studied by EDS, and it is found that it is mainly composed of silicon and aluminum. The composition of calcium oxide and sodium elements (the carbon element is caused by carbon spraying on the surface of the sample when preparing the sample) proves that the gel is a special structure of aluminosilicate material.

It can be seen from the above table that the adsorbent prepared from blast furnace slag has a good adsorption effect on heavy metals, especially Pb ²⁺ , Cu ²⁺ , Mn ²⁺ , Ni ²⁺ , Cd ²⁺ divalent heavy metal ions, adsorption The adsorption rate is all above 80%, but also has certain selectivity, especially when the heavy metal ions are Mn ⁴⁺ , Co ³⁺ non-divalent heavy metal ions, the highest adsorption rate is only 78.77%.

The above detailed description is a specific description of one of the feasible embodiments of the present invention, and this embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not depart from the present invention shall be included in the present invention. within the scope of the technical solution.

Claims (9)

1. A method for preparing a heavy metal adsorbent by using blast furnace slag comprises the following steps:

s1: soaking blast furnace slag in water, filtering, drying, taking out, putting into a ball mill, and grinding for later use;

s2: mixing the ground product obtained in the step S1 with alkali liquor 1, heating, raising the temperature, keeping constant temperature, stirring for reaction, cooling, performing suction filtration, keeping the filtrate as solution 1, washing the filter residue with water to constant weight, and drying for later use as solid 1; in the step S2, the alkali liquor 1 is at least one of sodium hydroxide solution or potassium hydroxide solution, the concentration of the alkali liquor 1 is 5-10mol/L, and the weight ratio of the alkali liquor 1 to the blast furnace slag is 3-6: 1;

s3: adding acid liquor into the solution 1 to adjust the pH value, then carrying out suction filtration, and keeping the filtrate as a solution 2 for later use; washing the filter residue with water, then gradually adding an alkali liquor 2, adjusting the pH, and performing ultrasonic treatment to obtain a clear solution 3 for later use;

s4: adding a solid 1 into water, wherein the weight ratio of the solid 1 to the water is 1:3-6, performing primary ultrasonic dispersion to obtain a suspension 1, adding a solution 3 into the suspension 1, uniformly mixing, wherein the weight ratio of the suspension 1 to the solution 3 is 1:1-3, performing secondary ultrasonic dispersion to obtain a suspension 2, continuously adding a solution 2 into the suspension 2, wherein the weight ratio of the suspension 2 to the solution 2 is 1:0.5-4, finally heating and maintaining constant-temperature curing, wherein the heating temperature is 50-100 ℃, the constant-temperature curing time is 5-10 days, performing centrifugal separation, and drying precipitates to obtain the heavy metal adsorbent.

2. The method according to claim 1, wherein the weight ratio of the blast furnace slag to the water in step S1 is 1:1.2-2.0, and the soaking time is 10-20 min.

3. The method of claim 1, wherein the heating to raise the temperature to 40-80 ℃ in step S2, the reaction time is 0.5-1.5h, and the cooling is to cool to room temperature.

4. The method according to claim 1, wherein the acid solution in step S3 is at least one selected from sulfuric acid and hydrochloric acid, the acid solution has a concentration of 2 to 4mol/L, the pH is adjusted to 7.5 to 8.5, and the number of washing is 1 to 3.

5. The preparation method according to claim 1, wherein the concentration of the lye 2 in step S3 is 0.5-2mol/L, the weight ratio of the lye 2 to the filter residue is 5-10:1, and the pH is adjusted to 8.5-10.5; the ultrasonic treatment power is 1-3kW, the ultrasonic treatment frequency is 60-80kHz, and the ultrasonic treatment time is 1-3 h.

6. The method according to claim 1, wherein the weight ratio of the solid 1 to the water in the step S4 is 1:4-5, the primary ultrasonic dispersion power is 0.5kW-1.5kW, the dispersion frequency is 40 kHz-60 kHz, and the dispersion time is 1 h-3 h.

7. The method of claim 1, wherein the re-ultrasonic dispersion is carried out at a power of 0.5kW to 1.5kW, a dispersion frequency of 60kHz to 80kHz, and a dispersion time of 30 min to 90 min.

8. The method of claim 1, wherein the elevated temperature in step S4 is 50-80 ℃.

9. Use of the adsorbent obtained by the preparation method according to any one of claims 1 to 8 for adsorbing heavy metal ions in sewage.

Images