Rare earth phosphate for selectively adsorbing lead, titanium and iron, and preparation method and application thereof

Abstract

The application provides a rare earth phosphate for selectively adsorbing lead, titanium and iron, and a preparation method and application thereof, and the preparation method comprises the following steps: mixing rare earth salt, phosphate and water to obtain a solution, and performing a hydrothermal reaction after adjusting the pH of the solution. The rare earth phosphate provided by the application has a large specific surface area and good adsorption effect, can realize selective adsorption of lead, titanium and iron under the condition that multiple metals coexist, the preparation method prepares the rare earth phosphate compound through a one-step hydrothermal reaction method, the process is simple, green and environment-friendly, has potential for large-scale industrial production and application, and can be widely applied to efficient selective adsorption separation of lead, titanium and iron, wastewater treatment and resource recycling.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and relates to a selective adsorption material, in particular to a rare earth phosphate for selectively adsorbing lead, titanium and iron as well as a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of industry, a large amount of toxic and harmful substances are discharged into water bodies, among which the pollution problem of heavy metals is becoming more and more serious. Heavy metal ions such as lead, cadmium and chromium in water bodies have significant persistent toxic effects on human beings, animals, plants and microorganisms. These heavy metals not only cannot be degraded by microorganisms, but also can be enriched in the body, especially in the human body, to produce more serious toxic effects. When accumulated to a certain content, the human body will appear a series of symptoms such as dizziness, nausea, joint pain, forgetfulness and so on, which is extremely harmful to the human body. For example, lead mainly enters the human body through ingestion and inhalation, and is toxic to almost all organs. Acute and chronic lead exposure can cause hemolytic anemia, high blood pressure and cardiovascular diseases. Although titanium and iron have little toxicity to humans and animals, when the human body ingests water with excessive titanium content, it is easy to cause the human body to lack active peptides, thereby causing decreased immunity, slowed metabolic rate and endocrine disorders, and causing various diseases; and when the concentration of iron compounds in water is high, it will affect the sensory properties such as color, smell and taste of water.

[0003] In recent years, people have developed a series of treatment technologies such as chemical precipitation method, electrochemical method, coagulation / flocculation, adsorption method, biochemical method, membrane filtration method and ion exchange method to remove heavy metals in wastewater. Among them, the adsorption method is one of the most studied methods for treating heavy metal wastewater, and it is an economical and effective method for treating heavy metal wastewater to use an adsorbent with simple preparation process, low cost and wide source to adsorb and remove heavy metal ions.

[0004] CN115193421A discloses a preparation method of a sewage treatment adsorbent. First, a styrene-based modified mesoporous silica is prepared, then a novel mercapto hyperbranched polyester is synthesized, and the mercapto hyperbranched polyester is grafted to the surface of the silica through a photo-click reaction to obtain the sewage treatment adsorbent. The grafted mercapto hyperbranched polyester contains functional groups such as mercapto, amide groups and carboxyl groups, and has strong coordination chelation and adsorption performance for metal ions such as lead, copper and cadmium. However, the preparation of the adsorbent requires a large amount of organic compounds, and the preparation process is not environmentally friendly; and the grafting rate of the organic groups is not high.

[0005] CN114700047A discloses a kind of red soil mineral and tolerance bacterial complex for the adsorption of heavy metals, the invention utilizes mineral and bacteria to form complex, utilize mineral to provide barrier for bacteria, make bacteria reduce degree of persecution by heavy metal, make it can utilize bacteria surface to adsorb, also can give full play to its intracellular enrichment effect, relative to the adsorption of heavy metals by mineral, adsorption effect is better.But the thermal stability of the red soil mineral and tolerance bacterial complex is poor, it is difficult to be applied to high-temperature adsorption environment.

[0006] CN113336522A discloses a kind of blast furnace titanium ore slag-based porous phosphate material and its application, the porous phosphate material has the advantages of high specific surface area, abundant adsorption active sites, low density, etc., can be applied to adsorb heavy metals or dyeing agents in wastewater, and has good adsorption performance, but the material does not have high selectivity for the adsorption of heavy metals or dyeing agents.

[0007] Therefore, it is necessary to provide an adsorption material for selectively adsorbing lead, titanium and iron ions, which has a simple preparation method and an environmentally friendly process. SUMMARY

[0008] The present application provides a rare earth phosphate for selectively adsorbing lead, titanium and iron, and a preparation method and application thereof, which can effectively and selectively adsorb lead, titanium and iron, and can be used for wastewater treatment containing heavy metal ions and resource recycling of metals.

[0009] To achieve the object of the present application, the following technical solutions are adopted:

[0010] In a first aspect, the present application provides a preparation method of a rare earth phosphate, which comprises the following steps:

[0011] The rare earth salt, phosphate and water are mixed to obtain a solution, and the solution is adjusted in pH and then subjected to hydrothermal reaction.

[0012] The preparation method provided by the present application can prepare a rare earth phosphate compound by one-step hydrothermal reaction, which has a simple process, is environmentally friendly, has potential for large-scale industrial production and application, and can be widely used in efficient and selective adsorption and separation of lead, titanium and iron, wastewater treatment and resource recycling.

[0013] Preferably, the rare earth salt includes any one or a combination of at least two of rare earth chloride, rare earth bromide, rare earth nitrate or rare earth sulfate, and typical but non-limiting combinations include a combination of rare earth chloride and rare earth bromide, a combination of rare earth bromide and rare earth nitrate, a combination of rare earth nitrate and rare earth sulfate, a combination of rare earth chloride, rare earth bromide and rare earth nitrate, or a combination of rare earth chloride, rare earth bromide, rare earth nitrate and rare earth sulfate.

[0014] Exemplary, the rare earth chloride includes cerium chloride and / or yttrium chloride hexahydrate.

[0015] Exemplary, the rare earth bromide includes cerium bromide and / or gadolinium bromide hexahydrate.

[0016] Exemplary, the rare earth nitrate includes yttrium nitrate hexahydrate and / or cerium nitrate hexahydrate.

[0017] Exemplary, the rare earth sulfate includes cerium sulfate and / or neodymium sulfate.

[0018] Preferably, the rare earth element in the rare earth salt includes any one or a combination of at least two of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium, typical but non-limiting combinations include a combination of scandium and yttrium, a combination of praseodymium and neodymium, a combination of europium and gadolinium, a combination of yttrium, lanthanum and cerium, or, a combination of gadolinium, terbium and dysprosium.

[0019] Preferably, the phosphate salt includes any one or a combination of at least two of sodium phosphate, potassium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate or dipotassium hydrogen phosphate, typical but non-limiting combinations include a combination of sodium phosphate and potassium phosphate, a combination of sodium dihydrogen phosphate and potassium dihydrogen phosphate, a combination of sodium phosphate and potassium dihydrogen phosphate, a combination of potassium phosphate and sodium dihydrogen phosphate, a combination of sodium phosphate, sodium dihydrogen phosphate and disodium hydrogen phosphate, or, a combination of potassium phosphate, potassium dihydrogen phosphate and disodium hydrogen phosphate.

[0020] Preferably, the molar ratio of the rare earth salt to the phosphate salt is 1:(0.5-4), for example, it can be 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4, but is not limited to the listed values, other values not listed within the value range are also applicable.

[0021] Preferably, the temperature of the mixing is 15-40℃, for example, it can be 15℃, 20℃, 25℃, 30℃, 35℃ or 40℃, but is not limited to the listed values, other values not listed within the value range are also applicable.

[0022] Preferably, the time of the mixing is 0.5-4h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h, but is not limited to the listed values, other values not listed within the value range are also applicable.

[0023] Preferably, the method of the mixing includes stirring.

[0024] Preferably, the rotation speed of the stirring is 100-500 rpm, for example, it can be 100 rpm, 200 rpm, 300 rpm, 400 rpm or 500 rpm, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0025] Preferably, the concentration of phosphate in the solution is 0.05-0.4 mol / L, for example, it can be 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L or 0.4 mol / L, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0026] Preferably, the end point pH value of the pH adjustment is 8-12, for example, it can be 8, 9, 10, 11 or 12, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0027] Preferably, the temperature of the hydrothermal reaction is 100-180℃, for example, it can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0028] Preferably, the time of the hydrothermal reaction is 8-20 h, for example, it can be 8 h, 10 h, 12 h, 14 h, 15 h, 16 h, 18 h or 20 h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0029] Preferably, the hydrothermal reaction is followed by solid-liquid separation and drying in sequence.

[0030] Preferably, the temperature of the drying is 60-100℃, for example, it can be 60℃, 70℃, 80℃, 90℃ or 100℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0031] Preferably, the time of the drying is 6-12 h, for example, it can be 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0032] As a preferred technical solution of the preparation method provided by the present application, the preparation method comprises the following steps:

[0033] (1) mixing the rare earth salt and the phosphate salt according to a molar ratio of 1:(0.5-4) with water to form a solution, the concentration of phosphate in the solution is 0.05-0.4 mol / L, stirring the solution at a speed of 100-500 rpm for 0.5-4 h at 15-40℃, then adjusting the pH of the solution to 8-12 to obtain a uniform solution;

[0034] (2) reacting the obtained uniform solution in a reaction kettle at 100-180℃ for 8-20 h, after the reaction is completed, solid-liquid separation is performed, and the obtained solid is dried at 60-100℃ for 6-12 h to obtain the rare earth phosphate material.

[0035] In a second aspect, the present application provides a rare earth phosphate, which is prepared by the preparation method in the first aspect.

[0036] The rare earth phosphate provided by the present application has a block structure of particle accumulation, a nanometer-sized particle size, a large specific surface area, and a good adsorption effect, and can realize selective adsorption of lead, titanium and iron under the condition that multiple metals coexist.

[0037] In a third aspect, the present application provides an application of the rare earth phosphate in the second aspect, and the rare earth phosphate is applied to adsorb any one or a combination of at least two of lead, titanium or iron.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] The rare earth phosphate provided by the present application has a large specific surface area and a good adsorption effect, and can realize selective adsorption of lead, titanium and iron under the condition that multiple metals coexist, the preparation method prepares a rare earth phosphate compound by a one-step hydrothermal reaction method, the process is simple and green, has a large-scale industrial production and application potential, and can be widely applied to efficient selective adsorption and separation of lead, titanium and iron, wastewater treatment and resource recycling. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 FIG. 1 is a scanning electron microscope image of the rare earth phosphate prepared in Example 1.

[0041] Figure 2 FIG. 4 is an N2 adsorption-desorption curve of the rare earth phosphate prepared in Example 1.

[0042] Figure 3 FIG. 5 is a pore size distribution curve of the rare earth phosphate prepared in Example 1.

[0043] Figure 4 FIG. 6 is a curve of the adsorption concentration of lead ions of the rare earth phosphate prepared in Example 1 changing with time.

[0044] Figure 5is a N2 adsorption-desorption curve of the rare earth phosphate provided by Comparative Example 1.

[0045] Figure 6 is a pore size distribution curve of the rare earth phosphate provided by Comparative Example 1. DETAILED DESCRIPTION

[0046] The technical solutions of the present application are further illustrated below by means of specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0047] Example 1

[0048] The present embodiment provides a preparation method of a rare earth phosphate, which comprises the following steps:

[0049] (1) cerium chloride and sodium phosphate are mixed with water to form a solution according to a molar ratio of 1:1, the concentration of phosphate in the solution is 0.1 mol / L, the solution is stirred at a speed of 300 rpm at 25℃ for 2h, and then the pH of the solution is adjusted to 10 by sodium hydroxide to obtain a uniform solution;

[0050] (2) after the obtained uniform solution is hydrothermally reacted at 140℃ for 12h, solid-liquid separation is performed, and the obtained solid is dried at 80℃ for 9h to obtain a rare earth phosphate.

[0051] Example 2

[0052] The present embodiment provides a preparation method of a rare earth phosphate, which comprises the following steps:

[0053] (1) cerium chloride and sodium phosphate are mixed with water to form a solution according to a molar ratio of 1:0.5, the concentration of phosphate in the solution is 0.05 mol / L, the solution is stirred at a speed of 100 rpm at 40℃ for 0.5h, and then the pH of the solution is adjusted to 10 by sodium hydroxide to obtain a uniform solution;

[0054] (2) after the obtained uniform solution is hydrothermally reacted at 140℃ for 12h, solid-liquid separation is performed, and the obtained solid is dried at 60℃ for 12h to obtain a rare earth phosphate.

[0055] Example 3

[0056] The present embodiment provides a preparation method of a rare earth phosphate, which comprises the following steps:

[0057] (1) cerium chloride and sodium phosphate are mixed with water to form a solution according to a molar ratio of 1:4, the concentration of phosphate in the solution is 0.4 mol / L, the solution is stirred at a speed of 500 rpm at 15℃ for 4h, and then the pH of the solution is adjusted to 10 by sodium hydroxide to obtain a uniform solution;

[0058] (2) After the obtained homogeneous solution is hydrothermally reacted at 140℃ for 12h, solid-liquid separation is performed, and the obtained solid is dried at 100℃ for 6h to obtain the rare earth phosphate.

[0059] Example 4

[0060] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (1), the pH is adjusted to 12, and the rest is the same as Example 1.

[0061] Example 5

[0062] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (1), the pH is adjusted to 8, and the rest is the same as Example 1.

[0063] Example 6

[0064] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (1), the pH is adjusted to 13, and the rest is the same as Example 1.

[0065] Example 7

[0066] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (1), the pH is adjusted to 7, and the rest is the same as Example 1.

[0067] Example 8

[0068] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (2), the hydrothermal reaction temperature is 180℃, and the rest is the same as Example 1.

[0069] Example 9

[0070] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (2), the hydrothermal reaction temperature is 100℃, and the rest is the same as Example 1.

[0071] Example 10

[0072] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (2), the hydrothermal reaction temperature is 200℃, and the rest is the same as Example 1.

[0073] Example 11

[0074] This example provides a preparation method of a rare earth phosphate. Compared with Example 1, in step (2), the hydrothermal reaction temperature is 80℃, and the rest is the same as Example 1.

[0075] Example 12

[0076] The present example provides a method for preparing a rare earth phosphate salt. Compared with Example 1, the time for the hydrothermal reaction in step (2) is 20 h, and the rest is the same as Example 1.

[0077] Example 13

[0078] The present example provides a method for preparing a rare earth phosphate salt. Compared with Example 1, the time for the hydrothermal reaction in step (2) is 8 h, and the rest is the same as Example 1.

[0079] Example 14

[0080] The present example provides a method for preparing a rare earth phosphate salt. Compared with Example 1, the time for the hydrothermal reaction in step (2) is 22 h, and the rest is the same as Example 1.

[0081] Example 15

[0082] The present example provides a method for preparing a rare earth phosphate salt. Compared with Example 1, the time for the hydrothermal reaction in step (2) is 6 h, and the rest is the same as Example 1.

[0083] Comparative Example 1

[0084] The present comparative example provides a rare earth phosphate salt, which is a commercially purchased cerium phosphate (CAS: 13454-71-2).

[0085] The rare earth phosphate salts provided by the examples and comparative examples are subjected to experiments of adsorbing lead, titanium and iron ions, and the experimental method is as follows:

[0086] 200 mg of the rare earth phosphate salt is weighed and placed in a conical flask, 50 mL of a solution containing Pb, Ti, Fe, Mn, Cr, Ni, Cu, Zn, Ga, Cd, Ba, Tl, Mg, Be, Al and Co metal ions (the concentration of each metal ion is 5 mg / L) is added to the conical flask, ultrasonic cleaning machine is used for ultrasonic treatment for 10 min, and then constant temperature shaking table is used for oscillation shaking at a shaking rate of 200 rpm for 24 h. The solution in the conical flask is sampled and filtered, and ICP instrument is used to detect the residual metal ion concentration in the solution, so as to calculate the removal rate of lead, titanium and iron and the adsorption rate of other elements of the rare earth phosphate salt material. The results are shown in Tables 1 and 2.

[0087] Table 1

[0088]

[0089]

[0090] Table 2

[0091]

[0092]

[0093] By Figures 1-6 It can be seen that the cerium phosphate prepared in Example 1 is an irregular block structure of particle accumulation, the particle size is in nanometer size, the specific surface area is 172.99 m 2 / g, compared with the commercial cerium phosphate provided in Comparative Example 1 (the specific surface area is 21.28 m 2 / g), the specific surface area is multiplied, and the adsorption effect on lead ions is very good, reaching 94% of the adsorption removal rate in 1 minute, and reaching adsorption equilibrium within 1 hour.

[0094] As can be seen from Table 1 and Table 2, the rare earth phosphate prepared in the present application can selectively adsorb lead, titanium and iron ions in the presence of 16 kinds of metal ions, and the adsorption removal rate can reach more than 82%.

[0095] Compared with Example 1, in Examples 6-7, the control of solution pH plays an important role in the physical properties of rare earth phosphate crystal structure, morphology and particle size, when pH < 8, the increase of H + concentration, the ionization of H n PO4 (3-n)- causes the decrease of free PO4 3- in the solution, which causes the decrease of material adsorption active sites, in addition, the rare earth phosphate crystal shows anisotropic growth habit during the formation and growth process of the crystal, which leads to the formation of nanorod-shaped morphology of rare earth phosphate and the decrease of specific surface area; when pH > 12, the large concentration of OH - in the solution causes the decrease of phosphoric acid functional group adsorption active sites on the surface of the material, which is not conducive to the selective adsorption of lead, titanium and iron ions; in Examples 10-11, the hydrothermal temperature will affect the generation of rare earth phosphate material, the crystal structure of the material is affected by the reaction temperature, when the hydrothermal temperature is lower than 100℃, the rare earth phosphate crystal structure cannot be effectively generated, when the hydrothermal temperature is higher than 180℃, it will cause the formation rate of nanoparticles to be too fast, excessive growth and uneven distribution, and the dissolution-recrystallization reaction is easy to occur, which makes the crystal grow too large; in Examples 14-15, the hydrothermal time will affect the performance of rare earth phosphate material, when the hydrothermal reaction time is too long, it will cause the continuous growth of nanocrystals, the specific surface area and surface adsorption active sites decrease, when the hydrothermal reaction time is too short, the rare earth phosphate crystal cannot be effectively generated, which leads to the decrease of adsorption removal rate; therefore, the rare earth phosphate prepared under the preferred preparation conditions of the present application can achieve the best adsorption removal effect of lead, titanium and iron.

[0096] Compared with Example 1, the adsorption removal rate of lead, titanium and iron ions of the commercial cerium phosphate provided in Comparative Example 1 is lower.

[0097] In summary, the rare earth phosphate provided by the present application has a large specific surface area and good adsorption effect, can realize selective adsorption of lead, titanium and iron under the condition of coexistence of multiple metals, the preparation method is a one-step hydrothermal reaction method for preparing a rare earth phosphate compound, the process is simple, green and environment-friendly, has potential for large-scale industrial production and application, and can be widely applied to efficient selective adsorption separation of lead, titanium and iron, wastewater treatment and resource recycling.

[0098] The applicant declares that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the present application, which can be easily thought of by any person skilled in the art, falls within the protection scope and disclosure scope of the present application.

Claims

1. An application of a rare earth phosphate in the selective adsorption of lead, titanium, and iron, characterized in that, The preparation method of the rare earth phosphate includes the following steps: A solution is prepared by mixing rare earth salts, phosphates, and water. The pH of the solution is adjusted before a hydrothermal reaction is carried out. The final pH value of the pH adjustment is 9-12. The temperature of the hydrothermal reaction is 100-180℃. The time of the hydrothermal reaction is 8-20h.

2. The application according to claim 1, characterized in that, The rare earth salts include any one or a combination of at least two of rare earth chlorides, rare earth bromides, rare earth nitrates, or rare earth sulfates.

3. The application according to claim 1, characterized in that, The rare earth elements in the rare earth salt include any one or a combination of at least two of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium.

4. The application according to claim 1, characterized in that, The phosphate includes any one or a combination of at least two of sodium phosphate, potassium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, or dipotassium hydrogen phosphate.

5. The application according to claim 1, characterized in that, The molar ratio of the rare earth salt to the phosphate is 1:(0.5-4).

6. The application according to claim 1, characterized in that, The mixing temperature is 15-40℃.

7. The application according to claim 1, characterized in that, The mixing time is 0.5-4 hours.

8. The application according to claim 1, characterized in that, The mixing method includes stirring.

9. The application according to claim 8, characterized in that, The stirring speed is 100-500 rpm.

10. The application according to claim 1, characterized in that, The concentration of phosphate in the solution is 0.05-0.4 mol / L.

11. The application according to claim 1, characterized in that, The hydrothermal reaction is followed by solid-liquid separation and drying.

12. The application according to claim 11, characterized in that, The drying temperature is 60-100℃.

13. The application according to claim 11, characterized in that, The drying time is 6-12 hours.

14. The application according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix rare earth salt and phosphate with water at a molar ratio of 1:(0.5-4) to form a solution with a phosphate concentration of 0.05-0.4 mol / L. Stir at 100-500 rpm for 0.5-4 h at 15-40℃. Then adjust the pH of the solution to 9-12 to obtain a homogeneous solution. (2) The obtained homogeneous solution is kept at 100-180℃ for 8-20h in a reaction vessel. After the reaction is completed, the solid and liquid are separated. The obtained solid is dried at 60-100℃ for 6-12h to obtain rare earth phosphate material.

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