Hydroxyapatite as well as preparation method and application thereof

Abstract

The invention discloses hydroxyapatite as well as a preparation method and application thereof. The preparation method specifically comprises the following steps: (1) dissolving phosphate tailings in an acid solution, heating, stirring, filtering and collecting filtrate; and (2) adjusting the pH value of the filtrate to 10 by using stronger ammonia water, stirring, and carrying out microwave reaction. Or adjusting the pH value of the filtrate to 10 by using stronger ammonia water, heating, stirring, filtering, collecting filter residues, washing, drying and roasting to obtain the catalyst. The raw materials are low in cost and easy to obtain, the preparation method is simple, preparation instruments are easy and convenient to operate, and the prepared hydroxyapatite has good adsorption performance on metal ions.

Description

Technical Field

[0001] The invention relates to the technical field of tailings utilization, and more particularly to hydroxyapatite and a preparation method and application thereof. Background Art

[0002] Phosphate tailings are solid wastes generated after the selection of phosphate ore, and are mostly stored in tailings ponds. According to statistics, 0.44 tons of phosphate tailings are generated for every ton of phosphate concentrate produced. Although phosphate tailings are a solid waste, they are rich in minerals such as carbon fluoroapatite, dolomite, calcite, muscovite, and valuable elements such as Fe and Al, and have recycling value.

[0003] At present, phosphorus tailings are mainly reused in the fields of construction, agriculture, ceramics and flame retardants, but their comprehensive utilization has problems such as complex decomposition and impurity removal process (not fully utilized), low product added value and low utilization rate, which not only causes serious waste of strategic resources such as phosphorus, calcium and magnesium, but also brings environmental risks such as land occupation and water pollution. Therefore, it is urgent to explore an innovative and promising way to utilize phosphorus tailings to achieve full and high-value utilization of phosphorus tailings.

[0004] The construction of high value-added chemicals from phosphate tailings is an important way to utilize them as resources, among which the preparation of hydroxyapatite has attracted much attention. 10 (PO4)6(OH)2, HAP) is a hexagonal crystal system, and its structure is PO4 3- Tightly bound tetrahedral groups, Ca 2+ PO4 3- Surrounded by tetrahedrons, Ca(I) and Ca(II) occupy two independent positions in the unit cell, forming two channels with different diameters and no connection with each other. This unique pore structure allows HAP to undergo substitution reactions with a variety of anions and cations. 2+ ) and P position (PO4 3- ) Two different types of acid-base binding sites, the C site preferentially adsorbs acid molecules, and the P site is more likely to bind alkaline molecules, thus showing better acid-base regulation. In addition, the particularity of the HAP structure is that under the condition of charge balance, all anions, cations, and groups can be replaced, but the crystal structure remains unchanged, with the characteristics of both stability and flexibility. HAP has a unique chemical composition and crystal structure, as well as surface acid-base adjustability and strong ion exchangeability, making it a popular material in the fields of biology, environment, and chemical industry.

[0005] Therefore, how to utilize phosphate tailings to efficiently produce high-quality hydroxyapatite is a problem that technicians in this field urgently need to solve. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a hydroxyapatite and a preparation method and application thereof to solve the deficiencies in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for preparing hydroxyapatite, comprising the following steps:

[0009] (1) dissolving the phosphate tailings in an acid solution, heating and stirring, filtering, and collecting the filtrate;

[0010] (2) Microwave method: adjust the pH of the filtrate to 10 with concentrated ammonia water, stir, and microwave to obtain hydroxyapatite;

[0011] Or, precipitation method: adjust the pH of the filtrate to 10 with concentrated ammonia water, heat up and stir, filter, collect the filter residue, wash, dry and calcine to obtain hydroxyapatite.

[0012] Furthermore, in the above step (1), the phosphate tailings include the following raw materials in terms of mass percentage: Ca71.37%, P14.94%, Fe3.413%, Si7.775%, Al0.727%, K0.552%, Cr0.033% and Mn0.228%, with the remainder being impurities.

[0013] Furthermore, in the above step (1), the phosphate tailings include the following raw materials in terms of mass percentage: Ca 65.31%, P 13.56%, Fe 10.55%, Si 7.85%, Al 0.753%, K 0.529%, Cr 0.386% and Mn 0.365%, with the remainder being impurities.

[0014] Furthermore, in the above step (1), the usage ratio of phosphate tailings and acid solution is 5g:(50-75)mL.

[0015] Furthermore, the acid solution is a hydrochloric acid solution or a nitric acid solution, the mass concentration of the hydrochloric acid solution is 5%-20%, and the molar concentration of the nitric acid solution is 1-4 mol / L.

[0016] The above further beneficial effect is that the phosphate tailings can be dissolved in a hydrochloric acid solution or a nitric acid solution to extract the Ca in the phosphate tailings. 2+ and PO4 3- .

[0017] Furthermore, in the above step (1), the device for heating and stirring is a water bath, the temperature is 60° C., and the time is 2 h.

[0018] Furthermore, in the above step (2), the stirring time is 10 min.

[0019] Furthermore, in the above step (2), the microwave reaction is carried out in a microwave oven with a power of 560 W and a reaction time of 10 min.

[0020] The above further beneficial effect is that the filtrate is subjected to microwave reaction in a 560W microwave oven for 10 min, which can remove the Ca in the phosphate tailings. 2+ and PO4 3- Synthetic hydroxyapatite.

[0021] Furthermore, in the above step (2), the equipment for heating and stirring is a water bath, the temperature is 80° C., and the time is 3 hours.

[0022] The above method has the further beneficial effect that the filtrate is stirred in a water bath at 80°C for 3 h to make Ca 2+ and PO4 3- The reaction is complete to generate hydroxyapatite.

[0023] Furthermore, in the above step (2), the calcination equipment is a muffle furnace, the temperature is 800° C., and the calcination time is 2 h.

[0024] A further beneficial effect of the above method is that calcining hydroxyapatite at 800° C. for 2 h in a muffle furnace can improve its crystallinity.

[0025] The present invention also claims protection for hydroxyapatite obtained by the above preparation method.

[0026] The present invention also claims to protect the use of hydroxyapatite prepared by the above preparation method in adsorbing metal ions.

[0027] Furthermore, the metal ion is Pb 2+ and / or Cu 2+ .

[0028] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The raw materials of the invention are cheap and easily available, the preparation method is simple, and the preparation instrument is easy to operate. The hydroxyapatite prepared thereby has good adsorption performance for metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The hydroxyapatite prepared in Example 1-4 is 2+ Adsorption capacity and removal efficiency;

[0031] Figure 2 The hydroxyapatite prepared in Example 5-8 is 2+ Adsorption capacity and removal efficiency;

[0032] Figure 3The hydroxyapatite prepared in Examples 9-12 is 2+ Adsorption capacity and removal efficiency;

[0033] Figure 4 The hydroxyapatite prepared in Examples 13-16 has a Pb 2+ Adsorption capacity and removal efficiency;

[0034] Figure 5 is the XRD characterization result of hydroxyapatite;

[0035] Figure 6 This is the SEM characterization result of a commercially available hydroxyapatite;

[0036] Figure 7 The SEM characterization results of the hydroxyapatite prepared in Example 1;

[0037] Figure 8 This is the SEM characterization result of the hydroxyapatite prepared in Example 5;

[0038] Fig. 9 The XRD characterization results of the phosphate tailings in Examples 1-8 and Examples 9-16;

[0039] Fig.10 The hydroxyapatite prepared in Example 1, Example 5, Example 10 and Example 13 has a Cu 2+ The adsorption amount;

[0040] Fig.11 The hydroxyapatite prepared in Example 1, Example 5, Example 10 and Example 13 has a Cu 2+ removal efficiency. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the following Examples 1-8, the phosphate tailings include the following raw materials, by mass percentage: Ca 71.37%, P14.94%, Fe 3.413%, Si 7.775%, Al 0.727%, K 0.552%, Cr 0.033% and Mn 0.228%, with the remainder being impurities.

[0043] In the following Examples 9-16, the phosphate tailings include the following raw materials, by mass percentage: Ca 65.31%, P13.56%, Fe 10.55%, Si 7.85%, Al 0.753%, K0.529%, Cr 0.386% and Mn 0.365%, with the remainder being impurities.

[0044] Example 1

[0045] The preparation method of hydroxyapatite specifically comprises the following steps:

[0046] (1) Dissolve 5 g of phosphate tailings in 50 mL of 5% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0047] (2) The filtrate pH was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0048] Example 2

[0049] The preparation method of hydroxyapatite specifically comprises the following steps:

[0050] (1) Dissolve 5 g of phosphate tailings in 50 mL of 10% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0051] (2) The pH of the filtrate was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0052] Example 3

[0053] The preparation method of hydroxyapatite specifically comprises the following steps:

[0054] (1) Dissolve 5 g of phosphate tailings in 50 mL of 15% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0055] (2) The filtrate pH was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0056] Example 4

[0057] The preparation method of hydroxyapatite specifically comprises the following steps:

[0058] (1) Dissolve 5 g of phosphate tailings in 50 mL of 20% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0059] (2) The filtrate pH was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0060] Example 5

[0061] The preparation method of hydroxyapatite specifically comprises the following steps:

[0062] (1) Dissolve 5 g of phosphate tailings in 50 mL of 5% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0063] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0064] Example 6

[0065] The preparation method of hydroxyapatite specifically comprises the following steps:

[0066] (1) Dissolve 5 g of phosphate tailings in 50 mL of 10% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0067] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0068] Example 7

[0069] The preparation method of hydroxyapatite specifically comprises the following steps:

[0070] (1) Dissolve 5 g of phosphate tailings in 50 mL of 15% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0071] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0072] Example 8

[0073] The preparation method of hydroxyapatite specifically comprises the following steps:

[0074] (1) Dissolve 5 g of phosphate tailings in 50 mL of 20% hydrochloric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0075] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0076] Example 9

[0077] The preparation method of hydroxyapatite specifically comprises the following steps:

[0078] (1) Dissolve 5 g of phosphate tailings in 75 mL of 1 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0079] (2) The filtrate pH was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0080] Example 10

[0081] The preparation method of hydroxyapatite specifically comprises the following steps:

[0082] (1) Dissolve 5 g of phosphate tailings in 75 mL of 2 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0083] (2) The filtrate pH was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0084] Embodiment 11

[0085] The preparation method of hydroxyapatite specifically comprises the following steps:

[0086] (1) Dissolve 5 g of phosphate tailings in 75 mL of 3 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0087] (2) The filtrate pH was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0088] Example 12

[0089] The preparation method of hydroxyapatite specifically comprises the following steps:

[0090] (1) Dissolve 5 g of phosphate tailings in 75 mL of 4 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0091] (2) The pH of the filtrate was adjusted to 10 with concentrated ammonia water, stirred for 10 min, and placed in a microwave oven to react at 560 W for 10 min to obtain hydroxyapatite.

[0092] Example 13

[0093] The preparation method of hydroxyapatite specifically comprises the following steps:

[0094] (1) Dissolve 5 g of phosphate tailings in 75 mL of 1 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0095] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0096] Embodiment 14

[0097] The preparation method of hydroxyapatite specifically comprises the following steps:

[0098] (1) Dissolve 5 g of phosphate tailings in 75 mL of 2 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0099] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0100] Embodiment 15

[0101] The preparation method of hydroxyapatite specifically comprises the following steps:

[0102] (1) Dissolve 5 g of phosphate tailings in 75 mL of 3 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0103] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0104] Example 16

[0105] The preparation method of hydroxyapatite specifically comprises the following steps:

[0106] (1) Dissolve 5 g of phosphate tailings in 75 mL of 4 mol / L nitric acid solution, place in a water bath and vigorously stir at 60° C. for 2 h, filter, and collect the filtrate;

[0107] (2) The pH value of the filtrate is adjusted to 10 with concentrated ammonia water, and the filtrate is placed in a water bath and stirred at 80°C for 3 hours. The filtrate is filtered, the filtrate residue is collected, washed, dried, and placed in a muffle furnace and calcined at 800°C for 2 hours to obtain hydroxyapatite.

[0108] Performance Testing

[0109] 1. Pb in hydroxyapatite 2+ Adsorption test

[0110] 0.125 g of hydroxyapatite (HAP) prepared in Examples 1-16 was added to 250 mL of 800 mg / L Pb 2+ In the solution, a 1 mol / L HCl solution was used to adjust the pH to 3. The conical flask containing the mixed solution was then placed in a constant temperature oscillator and oscillated at 25°C with a speed set to 200 rpm. 2 mL of supernatant was taken at 0, 15, 30, 60, 90, 120, 180, 240, 360, 720 and 1440 min, respectively, and filtered through a 0.45 μm hydrophilic nylon filter. Atomic absorption spectrophotometer (AAS) was used to detect Pb in the solution. 2+ The residual concentration was calculated and the adsorption amount and removal efficiency were calculated respectively.

[0111] Among them, the adsorption amount q e =(C0-C t )×V / m;

[0112] Removal efficiency R (%) = (C0-C t ) / C0×100%;

[0113] Where C0 is Pb 2+ The initial concentration of the solution, C t Pb at time t 2+ The concentration of the solution, V is Pb 2+ is the volume of the solution and m is the mass of hydroxyapatite.

[0114] The results are as follows Figure 1-4 shown.

[0115] Depend on Figure 1 It can be seen that Example 1 (microwave-5% HCl-HAP) has an effect on Pb 2+ The adsorption performance is the best, the maximum adsorption capacity is 1237.6 mg / g, and the maximum removal efficiency is 74.82%.

[0116] Depend on Figure 2 It can be seen that Example 5 (precipitation-5% HCl-HAP) has an effect on Pb 2+The adsorption performance is the best, the maximum adsorption capacity is 1237.4 mg / g, and the maximum removal efficiency is 99.21%.

[0117] Depend on Figure 3 It can be seen that Example 10 (microwave-2 mol / L HNO3-HAP) has an effect on Pb 2+ The adsorption performance is the best, with the maximum adsorption capacity of 1272.2 mg / g and the maximum removal efficiency of 86.4%.

[0118] Depend on Figure 4 It can be seen that Example 13 (precipitation-1 mol / L HNO3-HAP) has an effect on Pb 2+ The adsorption performance is the best, with the maximum adsorption capacity of 1415.32 mg / g and the maximum removal efficiency of 96.12%.

[0119] 2. XRD characterization of hydroxyapatite

[0120] The hydroxyapatite (microwave-HAP-5% HCl) prepared in Example 1 and the hydroxyapatite (precipitation-HAP-5% HCl) prepared in Example 5 were taken, and a commercially available hydroxyapatite (commercial-HAP) was used as a comparison, and XRD characterization was performed respectively. The results are as follows: Figure 5 shown.

[0121] Depend on Figure 5 It can be seen that the characteristic peaks of commercial-HAP, microwave-HAP-5% HCl and precipitation-HAP-5% HCl are similar to Ca 10 The characteristic peaks of (PO4)6(OH)2 (PDF#74-0565) have good correspondence, indicating that Example 1 and Example 5 successfully prepared hydroxyapatite.

[0122] 3. SEM characterization of hydroxyapatite

[0123] The hydroxyapatite (microwave-HAP-5% HCl) prepared in Example 1 and the hydroxyapatite (precipitation-HAP-5% HCl) prepared in Example 5 were respectively characterized by SEM using a commercially available hydroxyapatite (commercial-HAP) as a comparison. Figure 6-8 shown.

[0124] Depend on Figure 6-8 It can be seen that in the SEM image of commercial-HAP, the crystals are formed by agglomerated particles into nanorod morphology, microwave-HAP-5% HCl presents an ellipsoidal particle porous structure, and precipitation-HAP-5% HCl material presents a coral-type nanorod structure.

[0125] 4. XRD characterization of phosphate tailings

[0126] The phosphate tailings (phosphate tailings-1-5) in Examples 1-8 and the phosphate tailings (phosphate tailings-1-6) in Examples 9-16 were respectively subjected to XRD characterization. The results are shown in FIG. Fig. 9 shown.

[0127] Depend on Fig. 9 It can be seen that phosphate tailings-1-5 and phosphate tailings-1-6 are mainly composed of CaO, MgO, SiO2 and P2O5, and the main minerals are dolomite and fluorapatite.

[0128] 5. XRF characterization of phosphate tailings

[0129] The phosphate tailings in Example 1-8 (phosphate tailings-1-5) and the phosphate tailings in Example 9-16 (phosphate tailings-1-6) were respectively subjected to XRF characterization. The results are shown in Table 1-2.

[0130] Table 1 XRF characterization results of Example 1-8 Phosphate tailings (Phosphate tailings-1-5)

[0131] Ca P Fe Si Al K Cr Mn 71.37 14.94 3.413 7.775 0.727 0.552 0.033 0.228

[0132] Table 2 XRF characterization results of examples 9-16 phosphate tailings (phosphate tailings-1-6)

[0133] Ca P Fe Si Al K Cr Mn 65.31 13.56 10.55 7.85 0.753 0.529 0.386 0.365

[0134] It can be seen from Table 1 that, in terms of mass percentage, the phosphate tailings of Example 1-8 (phosphate tailings-1-5) include the following raw materials: Ca71.37%, P 14.94%, Fe 3.413%, Si 7.775%, Al 0.727%, K 0.552%, Cr 0.033% and Mn0.228%, and the remainder is impurities.

[0135] It can be seen from Table 2 that, in terms of mass percentage, the phosphate tailings of Examples 9-16 (phosphate tailings-1-6) include the following raw materials: Ca 65.31%, P 13.56%, Fe 10.55%, Si 7.85%, Al 0.753%, K 0.529%, Cr 0.386% and Mn 0.365%, and the remainder is impurities.

[0136] 6. Cu in hydroxyapatite 2+ Adsorption test

[0137] 0.125 g of each of the hydroxyapatite prepared in Example 1 (microwave-5% HCl-HAP), the hydroxyapatite prepared in Example 5 (precipitation-5% HCl-HAP), the hydroxyapatite prepared in Example 10 (microwave-2M HNO3-HAP), and the hydroxyapatite prepared in Example 13 (precipitation-1M HNO3-HAP) were added to 250 mL of 100 mg / L Cu2+ In the solution, a 1 mol / L HCl solution was used to adjust the pH to 4. The conical flask containing the mixed solution was then placed in a constant temperature oscillator and oscillated at 25°C with a speed set to 200 rpm. 2 mL of supernatant was taken at 0, 15, 30, 60, 90, 120, 180, 240, 360, 480 and 1440 min, respectively, and filtered through a 0.45 μm hydrophilic nylon filter. The Cu in the solution was detected by atomic absorption spectrophotometer (AAS). 2+ The residual concentration was calculated and the adsorption amount and removal efficiency were calculated respectively.

[0138] Among them, the adsorption amount q e =(C0-C t )×V / m;

[0139] Removal efficiency R (%) = (C0-C t ) / C0×100%;

[0140] Where C0 is Cu 2+ The initial concentration of the solution, C t Cu at time t 2+ The concentration of the solution, V is Cu 2+ is the volume of the solution and m is the mass of hydroxyapatite.

[0141] The results are as follows Figure 10-11 shown.

[0142] Depend on Figure 10-11 It can be seen that microwave-5%-HCl-HAP, precipitation-5%-HCl-HAP, microwave-2M-HNO3-HAP, precipitation-1M-HNO3-HAP have a significant effect on Cu 2+ The maximum adsorption capacities were 116.78 mg / g, 100.78 mg / g, 114.88 mg / g, and 112.28 mg / g, respectively, and the maximum removal rates were 53.7%, 46.34%, 52.82%, and 51.63%, respectively, indicating that these four HAPs can effectively adsorb Cu 2+ .

[0143] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing hydroxyapatite, characterized in that: The specific steps include: (1) dissolving the phosphate tailings in an acid solution, heating and stirring, filtering, and collecting the filtrate; (2) adjusting the pH value of the filtrate to 10 with concentrated ammonia water, stirring, and subjecting the mixture to microwave reaction to obtain the hydroxyapatite; Alternatively, the pH value of the filtrate is adjusted to 10 with concentrated ammonia water, the temperature is raised and stirred, filtered, the filter residue is collected, washed, dried, and calcined to obtain the hydroxyapatite.

2. The method for preparing hydroxyapatite according to claim 1, characterized in that: In step (1), the usage ratio of the phosphate tailings and the acid solution is 5g:(50-75)mL.

3. The method for preparing hydroxyapatite according to claim 2, characterized in that: The acid solution is a hydrochloric acid solution or a nitric acid solution. The mass concentration of the hydrochloric acid solution is 5%-20%, and the molar concentration of the nitric acid solution is 1-4 mol / L.

4. The method for preparing hydroxyapatite according to claim 1, characterized in that: In step (1), the heating and stirring device is a water bath, the temperature is 60° C., and the time is 2 h.

5. The method for preparing hydroxyapatite according to claim 1, characterized in that: In step (2), the stirring time is 10 min.

6. The method for preparing hydroxyapatite according to claim 1, characterized in that: In step (2), the microwave reaction is carried out in a microwave oven with a power of 560 W and a reaction time of 10 min.

7. The method for preparing hydroxyapatite according to claim 1, characterized in that: In step (2), the heating and stirring device is a water bath, the temperature is 80° C., and the time is 3 hours.

8. The method for preparing hydroxyapatite according to claim 1, characterized in that: In step (2), the calcination equipment is a muffle furnace, the temperature is 800° C., and the calcination time is 2 h.

9. Hydroxyapatite obtained by the preparation method according to any one of claims 1 to 8.

10. Use of hydroxyapatite obtained by the preparation method according to any one of claims 1 to 8 in adsorbing metal ions.

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