CN101703917A - Magnetic nano hydroxyapatite adsorbent, preparation and application thereof - Google Patents

Abstract

The invention discloses a magnetic nano-hydroxyapatite adsorbent and its preparation and application. The adsorbent uses nano-hydroxyapatite Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ as a matrix, and magnetic particles are evenly dispersed in the matrix. Powder Fe ₂ O ₃ , the mass ratio of nano-hydroxyapatite to magnetic powder Fe ₂ O ₃ is (1.5-1):1, and its preparation method is to mix FeCl ₂ and FeCl with a mass ratio of (0.75-0.85):1 ₃ Dissolve in deoxygenated water, then add ammonia solution and stir evenly, then add Ca(NO ₃ ) ₂ solution and (NH ₄ ) ₂ HPO ₄ solution at the same time and stir evenly to obtain emulsion colloid, and place the emulsion colloid at 90°C Heating at ~100°C, cooling, separating, washing, drying and grinding to obtain magnetic nano-hydroxyapatite adsorbent. The adsorbent of the invention has large specific surface area, high adsorption efficiency, low cost, easy separation, and can effectively remove heavy metal ions in waste water.

Description

Magnetic nano-hydroxyapatite adsorbent and its preparation and application

technical field

The invention relates to an inorganic material adsorbent and its preparation and application, in particular to an adsorbent mainly composed of apatite and its preparation and application.

Background technique

Heavy metal pollution mainly comes from mining, metallurgy, machining, surface treatment and heavy industry. There are many ways to remove heavy metal ions in water. The traditional methods include chemical precipitation, redox, ferrite, electrolysis, evaporation and concentration, ion exchange resin, etc., but these methods have large investment, high operating cost, and The management is cumbersome, and it is easy to cause secondary pollution and other problems. At the same time, it cannot effectively realize the reuse of heavy metals and water resources. At present, the adsorption method is mostly used in practical applications. The adsorption method has been favored by people because of its cheap and easy-to-obtain materials, low cost, and good removal effect. Commonly used adsorbents for removing heavy metals mainly include activated carbon, mesoporous materials, clay, zeolite, chitosan and apatite, etc. However, these adsorbents have disadvantages such as small adsorption capacity or difficult separation after adsorption, so efforts must be made to find New promising adsorbents.

In recent years, the use of natural or synthetic inorganic materials as adsorbents has become a hot research field. The main reason is that the interaction between inorganic adsorbents and adsorbates is weak, and inorganic adsorbents have great thermal stability. This makes the regeneration of the inorganic adsorbent relatively simple. However, due to the small specific surface area of traditional inorganic adsorbents, the adsorption capacity is low.

Nanomaterials have a large specific surface area, so nanomaterials formed from inorganic substances have become one of the widely used adsorbents. Nano-hydroxyapatite (HAP for short), as a nano-material adsorbent composed of inorganic substances, has high biocompatibility and adsorption performance, and has been widely used in the removal of heavy metal ions. At present, most of the relevant reports at home and abroad focus on the study of hydroxyapatite, hydroxyapatite composites, and nano-hydroxyapatite as adsorbents. The effect still has room for further improvement and improvement.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a magnetic nano-hydroxyapatite adsorbent that combines magnetic separation technology and adsorption process with large specific surface area, high adsorption efficiency, low cost and easy separation , and also provide a preparation method and application of a low-cost and simple-to-operate magnetic nano-hydroxyapatite adsorbent matched with the adsorbent.

In order to solve the above technical problems, the technical solution proposed by the present invention is a magnetic nano-hydroxyapatite adsorbent, which is characterized in that: the adsorbent is based on nano-hydroxyapatite, and magnetic powder Fe is evenly dispersed in the matrix. ₂ O ₃ , the molecular formula of the nano-hydroxyapatite is Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , and the mass ratio of the nano-hydroxyapatite to the magnetic powder Fe ₂ O ₃ is (1.5-1 ): 1.

As a general technical idea, the present invention also provides a preparation method of magnetic nano-hydroxyapatite adsorbent, the operation steps are as follows: at room temperature and under the protection of inert gas, the mass ratio is (0.75～0.85): 1 FeCl ₂ and FeCl ₃ (also crystalline hydrates of ferrous chloride and ferric chloride, such as FeCl ₂ 4H ₂ O, FeCl ₃ 6H ₂ O, etc.) are dissolved in deoxygenated water, and then added to the solution Ammonia solution (the concentration of the ammonia solution is preferably 25% to 28% within the known range) and stirred evenly to obtain a precipitate, and then the Ca(NO ₃ ) ₂ solution and (NH ₄ ) ₂ HPO ₄ The solution is added to the precipitation solution at the same time, wherein the molar ratio of Ca(NO ₃ ) ₂ to FeCl ₂ satisfies (18-18.5):1, and the molar ratio of (NH ₄ ) ₂ HPO ₄ to FeCl ₂ satisfies (10-11 ): 1, after stirring evenly to obtain emulsion colloid, heat the emulsion colloid at a temperature of 90°C to 100°C (heating time is preferably 2h to 3h in a known range), then cool to room temperature and age, and finally age the obtained The precipitate was separated, washed with deionized water until neutral, dried and ground to obtain a magnetic nano-hydroxyapatite adsorbent.

In the above preparation method, the pH values of the Ca(NO ₃ ) ₂ solution and the (NH ₄ ) ₂ HPO ₄ solution after pH adjustment are preferably controlled at 10-11.

As a general technical conception, the present invention also provides the application of a magnetic nano-hydroxyapatite adsorbent, characterized in that: the adsorbent is used to remove heavy metal ions in wastewater, and the heavy metals include copper, lead, zinc, One or more of cobalt, nickel, manganese, cadmium, mercury, tungsten, and molybdenum, and the amount of the adsorbent used in the waste water is 0.1g/L-0.2g/L.

In the above application, the pH value of the adsorbent is preferably controlled at 5-8 when the adsorption treatment is carried out in the wastewater, and the time of the adsorption treatment is preferably controlled at 12h-24h.

Compared with the prior art, the present invention has the advantages that: the magnetic nano-hydroxyapatite adsorbent provided by the present invention is a new adsorbent that combines magnetic separation technology with the adsorption process, and not only has a large specific surface area of nanoparticles, Surface atoms are easy to combine with other atoms and ions, and because the synthesized nanoparticles are magnetic, they can be easily separated from the solution to be treated. Compared with adsorbents such as activated carbon, zeolite, clay, and chitosan, the magnetic nano-hydroxyapatite in the present invention not only has a larger specific surface area and higher adsorption efficiency, but also has simple preparation, low cost, and is easy to separate from the solution. and recycle. Compatible with the magnetic nano-hydroxyapatite adsorbent of the present invention, the present invention also provides a corresponding preparation method and use method of the magnetic nano-hydroxyapatite adsorbent. The method is not only simple in operation and low in cost, but also can effectively realize The industrial production of the magnetic nano-hydroxyapatite adsorbent realizes its effective adsorption and treatment of heavy metal ions in wastewater, and the removal rate of heavy metals in wastewater by using the magnetic nano-hydroxyapatite adsorbent of the present invention is basically stable at 75%. The above, up to 95%, is obviously better than the existing nano-hydroxyapatite adsorbent, which provides a new way for the treatment of heavy metal pollution in wastewater in the future.

Description of drawings

Fig. 1 is the scanning electron micrograph of magnetic nano-hydroxyapatite adsorbent in Example 1 of the present invention;

Fig. 2 is the X-ray energy dispersion analysis diagram of magnetic nano-hydroxyapatite adsorbent in Example 1 of the present invention;

Fig. 3 is a graph of the magnetization curve of the magnetic nano-hydroxyapatite adsorbent in Example 1 of the present invention.

Detailed ways

Example 1:

A magnetic nano-hydroxyapatite adsorbent. The adsorbent is based on nano-hydroxyapatite, and magnetic powder Fe ₂ O ₃ is evenly dispersed in the matrix. The molecular formula of nano-hydroxyapatite is Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , the mass ratio of nano-hydroxyapatite to magnetic powder Fe ₂ O ₃ is about 1.36, that is, the mass fraction of magnetic powder Fe ₂ O ₃ in the adsorbent is about 42.4%.

The preparation method of the above-mentioned magnetic nano-hydroxyapatite adsorbent in this embodiment is as follows:

Dissolve 1.85mmoL of FeCl ₂ 4H ₂ O and 3.7mmoL of FeCl ₃ 6H ₂ O in 30mL of deoxygenated water at room temperature under a nitrogen atmosphere, and then add 10mL of 25% ammonia solution to the solution And carry out mechanical stirring for 15min, after stirring evenly, to obtain the precipitated liquid, then adjust the pH value to 11 respectively 50mL of Ca(NO ₃ ) ₂ (containing 33.67mmol of solute) and 50mL of (NH ₄ ) ₂ HPO ₄ (containing 20mmol of solute ) solution was added dropwise to the precipitation solution and mechanically stirred. After stirring evenly, a dark brown emulsion colloid was obtained. The emulsion was heated at 90°C for 2h, then cooled to room temperature and aged for 12h to 24h, and finally aged The obtained precipitate was separated with a magnet, and then washed with deionized water until it was neutral. The washed product was dried in an oven at 90° C. for 4 hours, cooled, ground and pulverized to obtain the finished product. From the physical properties of the finished product and the basic principle of the chemical reaction, it can be preliminarily judged that the finished product is a magnetic nano-hydroxyapatite adsorbent.

Place the above-mentioned finished product under a scanning electron microscope of 10,000 times to observe the surface morphology and structure of the finished product. The scanning electron microscope picture is shown in Figure 1. From Figure 1, it can be seen that the surface of the finished product is loose and porous, and has a huge specific surface area. . This finished product is analyzed by X-ray energy dispersion again, and its analysis result is as shown in Figure 2, can find out that mainly contains Ca, P, Fe and O four kinds of elements in this finished product by Fig. 2 (because the content of hydrogen element is less, so The intensity of the absorption peak is weak, so it is not marked), and the Ca element in it can also ion-exchange with heavy metal ions. These properties and characteristics further prove that the finished product belongs to a nano-hydroxyapatite adsorbent, making the adsorption It is possible for the agent to adsorb heavy metal ions. Carry out magnetization test to this finished product again, as can be seen from the magnetization curve figure (as shown in Figure 3) after the test, this nano-hydroxyapatite adsorbent has stronger magnetism, and appearance is tan, and this shows that in this Magnetic powder Fe ₂ O ₃ is dispersed in the nano-hydroxyapatite adsorbent, which belongs to the magnetic nano-hydroxyapatite adsorbent of the present invention, so it can be easily separated from the solution by a magnet.

Example 2:

The magnetic nano-hydroxyapatite adsorbent of the present invention prepared in Example 1 was added to 20 mL of Cd2 ⁺ and Zn2 ⁺ -containing wastewater respectively (the initial concentration of heavy metal ions in each wastewater is shown in Table 1. Shown), the amount of the adsorbent in each kind of wastewater is 0.1g/L, adjust the pH value to 5.0±0.1, use a water bath constant temperature oscillator to carry out oscillation adsorption at room temperature, and use a magnet to remove the adsorbent from the above wastewater after 24h The content of unadsorbed Cd ²⁺ and Zn ²⁺ in the wastewater was determined by flame atomic absorption spectrophotometry. The results are shown in Table 1 below.

Table 1: Contents of heavy metal ions in wastewater before and after treatment

Heavy metal ions in wastewater Initial concentration (mg/L) Residual concentration (mg/L) removal rate Cd ²⁺ 220.93 17.02 92.3% Zn ²⁺ 126.75 12.67 90.0%

Example 3:

The magnetic nano-hydroxyapatite adsorbent of the present invention that is made in embodiment 1 is added to 20mL containing Cd ²⁺ and Zn ²⁺ in the wastewater of two kinds of heavy metal ions (the initial concentration of each heavy metal ion in the wastewater is shown in Table 2 Shown), the amount of adsorbent is 0.1g/L, adjust the pH value to 5.0±0.1, use a water bath constant temperature oscillator to carry out vibration adsorption at room temperature, use a magnet to separate the adsorbent from the above wastewater after 24h, and use a flame Determination of unadsorbed Cd ²⁺ and Zn ²⁺ contents in wastewater by atomic absorption spectrophotometry. Table 2 lists the removal effect of using magnetic nano-hydroxyapatite adsorbent to simultaneously treat wastewater containing Cd ²⁺ and Zn ²⁺ .

Table 2: Contents of heavy metal ions in wastewater before and after treatment

Heavy metal ions in wastewater Initial concentration (mg/L) Residual concentration (mg/L) removal rate Cd ²⁺ 223.75 37.1 83.4% Zn ²⁺ 128 23.56 81.6%

Example 4:

The magnetic nano-hydroxyapatite adsorbent of the present invention prepared in Example 1 was added to 20mL of waste water containing Cd2 ⁺ and Zn2 ⁺ respectively (the initial concentration of heavy metal ions in each kind of waste water is shown in Table 3. Shown), the amount of adsorbent is 0.1g/L, adjust the pH value to 8.0±0.1, use a water bath constant temperature oscillator to carry out oscillation adsorption at room temperature, use a magnet to separate the adsorbent from the above wastewater after 24h, and use a flame Determination of unadsorbed Cd ²⁺ and Zn ²⁺ contents in wastewater by atomic absorption spectrophotometry. Table 3 lists the removal effect when using magnetic nano-hydroxyapatite adsorbent to treat Cd ²⁺ and Zn ²⁺ wastewater at pH=8.

Table 3: Contents of heavy metal ions in wastewater before and after treatment

Heavy metal ions in wastewater Initial concentration (mg/L) Residual concentration (mg/L) removal rate Cd ²⁺ 223.75 12.53 94.4% Zn ²⁺ 128 11.14 91.3%

Example 5:

The magnetic nano-hydroxyapatite adsorbent of the present invention prepared in Example 1 was added to 20mL of Cd2 ⁺ and Zn2 ⁺ -containing wastewater respectively (see Table 4 for the initial concentration of heavy metal ions in each wastewater) Shown), the amount of adsorbent is 0.2g/L, adjust the pH value to 5.0±0.1, use a water bath constant temperature oscillator to carry out oscillation adsorption at room temperature, use a magnet to separate the adsorbent from the above wastewater after 24h, and use a flame Determination of unadsorbed Cd ²⁺ and Zn ²⁺ contents in wastewater by atomic absorption spectrophotometry. Table 4 lists the removal effect when using magnetic nano-hydroxyapatite adsorbent to treat wastewater containing Cd ²⁺ and Zn ²⁺ when the amount of adsorbent is 0.2g/L.

Table 4: Contents of heavy metal ions in wastewater before and after treatment

Heavy metal ions in wastewater Initial concentration (mg/L) Residual concentration (mg/L) removal rate Cd ²⁺ 220.93 8.33 96.2% Zn ²⁺ 126.75 8.12 93.6%

Claims (7)

1. magnetic nano hydroxyapatite adsorbent is characterized in that: described adsorbent is to be matrix with the nanometer hydroxyapatite, evenly is dispersed with Magnaglo Fe in the matrix ₂O ₃, the molecular formula of described nanometer hydroxyapatite is Ca ₁₀(PO ₄) ₆(OH) ₂, described nanometer hydroxyapatite and described Magnaglo Fe ₂O ₃Mass ratio be (1.5～1): 1.

2. the preparation method of a magnetic nano hydroxyapatite adsorbent, its operating procedure is as follows: under room temperature and inert gas shielding, be (0.75～0.85) with mass ratio: 1 FeCl ₂And FeCl ₃Be dissolved in the deoxidized water, in this solution, add ammonia spirit then and stir and obtain precipitated liquid, will distinguish the Ca (NO behind the adjust pH again ₃) ₂Solution and (NH ₄) ₂HPO ₄Solution joins in the described precipitated liquid simultaneously, wherein Ca (NO ₃) ₂With FeCl ₂Mol ratio satisfy (18～18.5): 1, (NH ₄) ₂HPO ₄With FeCl ₂Mol ratio satisfy (10～11): 1, get liliquoid after stirring, this liliquoid is heated under 90 ℃～100 ℃ temperature, cool to room temperature is also aging then, the sediment of gained of will wearing out at last separates, spend deionised water to neutral, obtain magnetic nano hydroxyapatite adsorbent after drying, the grinding.

3. preparation method according to claim 2 is characterized in that: the concentration of described ammonia spirit is 25%～28%.

4. according to claim 2 or 3 described preparation methods, it is characterized in that: the Ca (NO behind the described adjust pH ₃) ₂Solution, (NH ₄) ₂HPO ₄The pH value of solution is 10～11.

5. according to claim 2 or 3 described preparation methods, it is characterized in that: the time of described liliquoid heating is 2h～3h.

6. the application of a magnetic nano hydroxyapatite adsorbent, it is characterized in that: with the heavy metal ion in the described adsorbent removal waste water, described heavy metal comprises one or more in copper, lead, zinc, cobalt, nickel, manganese, cadmium, mercury, tungsten, the molybdenum, and described adsorbent consumption in waste water is 0.1g/L～0.2g/L.

7. application according to claim 6 is characterized in that: the pH value when described adsorbent carries out adsorption treatment in waste water is controlled at 5～8, and the time of adsorption treatment is controlled at 12h～24h.

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