Disclosure of Invention
In order to overcome the technical problems, the invention provides a method for preparing rare earth phosphate based on a hydrothermal synthesis method.
The technical problems to be solved by the invention are as follows:
(1) high-temperature roasting treatment is needed in the traditional preparation process of the rare earth phosphate powder, the powder formed in the process is hard to agglomerate, so that the rare earth phosphate powder has low purity and poor dispersibility, and phosphate radical ions and hydrogen ions in water are combined to generate hydrogen phosphate radicals and dihydrogen phosphate radicals, so that the hydrogen ion concentration in the water is reduced, the hydroxide radical concentration is increased, and the solution is changed into alkalinity;
(2) the existing surfactant acting on the surface of the rare earth phosphate leaves the rare earth phosphate after being roasted at high temperature, but is not easy to degrade and can cause pollution to the environment.
The purpose of the invention can be realized by the following technical scheme:
a method for preparing rare earth phosphate based on a hydrothermal synthesis method comprises the following steps:
firstly, weighing the following raw materials in parts by weight: 20-35 parts of rare earth element sulfate, 150-200 parts of deionized water, 3-10 parts of tri-n-butylamine, 10-15 parts of absolute ethyl alcohol, 15-25 parts of 5mol/L phosphoric acid solution and 1-5 parts of hydrogen peroxide;
secondly, adding rare earth element sulfate into deionized water, magnetically stirring for 15min at the rotating speed of 120r/min, then adding tri-n-butylamine and absolute ethyl alcohol, continuously stirring for 30min, transferring to a three-port reactor, heating in a water bath at 45 ℃, dropwise adding 5mol/L phosphoric acid solution, and stirring for 1.5h at the rotating speed of 180r/min to obtain a gel precursor;
thirdly, transferring the prepared gel precursor into a reaction kettle, adding hydrogen peroxide, stirring at a constant speed for 5min, then dropwise adding 10% ammonia water, adjusting the pH =9, heating to 150 ℃, carrying out hydrothermal crystallization for 4h at the temperature, cooling, centrifuging, washing with deionized water until sulfate ions do not exist, then replacing with anhydrous ethanol for three times, centrifuging after replacement is finished, and then transferring into a 120 ℃ drying box for drying for 5h to prepare rare earth phosphate powder;
and step four, mixing the environment-friendly surfactant with acetone, stirring at a constant speed for 15min, adding the rare earth phosphate powder prepared in the step three, stirring at a constant speed for 1h, adding 10% dilute hydrochloric acid, continuing stirring until sol is formed, standing until the acetone is completely volatilized, and then transferring to a muffle furnace at 350 ℃ for roasting for 5 h.
In the second step, a rare earth element sulfate solution is prepared firstly, then tri-n-butylamine is added under the stirring condition, the nitrogen atoms in the tri-n-butylamine have non-bonded arc pair electrons and have strong electronegativity, so that the tri-n-butylamine can be endowed with strong nucleophilic ability and can be preferentially combined with the rare earth elements, therefore, the tri-n-butylamine is firstly combined with the rare earth elements, then a phosphoric acid solution is added, the phosphoric acid group needs to overcome the steric hindrance effect of the tri-n-butylamine per se and forms crystal nuclei with the rare earth ions, and the reaction liquid can be subjected to convective homogenization by stirring at the rotating speed of 180r/min for 1.5h, so that the excessive agglomeration of small particles in the system is avoided; performing hydrothermal crystallization on the prepared precursor at 150 ℃ for 4h to prepare the rare earth phosphate, wherein the method does not need high-temperature roasting treatment in the process of preparing the rare earth phosphate powder, so that hard agglomeration of the powder formed in the process is avoided, and the rare earth phosphate powder has low purity and poor dispersibility; dispersing the environment-friendly surfactant in acetone, adding rare earth phosphate powder to form sol, roasting to prepare mesoporous rare earth phosphate, adding 10% dilute hydrochloric acid in the preparation process, wherein phosphate ions and hydrogen ions in water are combined to generate hydrogen phosphate radicals and dihydrogen phosphate radicals, so that the hydrogen ion concentration in water is reduced, the hydroxide radical concentration is increased, the solution becomes alkaline, the 10% dilute hydrochloric acid is added to ensure that the system is acidic, and roasting at 350 ℃ for 5 hours to remove the environment-friendly surfactant to prepare the finally prepared mesoporous rare earth phosphate.
Further, the environment-friendly surfactant in the fourth step is prepared from the following raw materials in parts by weight: 10-20 parts of alkyl glycol, 2-8 parts of carbon tetrachloride, 20-45 parts of fatty acyl chloride, 20-30 parts of chlorosulfonic acid and 70-100 parts of mixed solvent.
Further, the environment-friendly surfactant is prepared by the following method:
(1) adding alkyl diol and carbon tetrachloride into a three-neck flask, magnetically stirring for 15min, adding fatty acyl chloride, heating in a water bath at 75 ℃, reacting at the temperature for 8-10h, washing with 10% sodium bicarbonate solution after the reaction is finished until the pH is =7, performing suction filtration, and transferring to a drying oven at 50 ℃ for drying for 10h to obtain a mixture;
(2) adding the mixture prepared in the step (1) into a reactor, taking absolute ethyl alcohol as a reflux solvent, stirring at the rotating speed of 120r/min, dropwise adding chlorosulfonic acid at the temperature of 45 ℃, heating to 60 ℃, reacting at the temperature for 10-12h, heating to 90 ℃, aging for 2-3 h, then adding hydrogen peroxide for bleaching for 10min, dropwise adding 10% potassium hydroxide solution to adjust the pH =7, finally recrystallizing for 3 times by using a mixed solvent, performing suction filtration, and performing vacuum drying at the temperature of 40 ℃ for 4h to prepare the environment-friendly surfactant.
In the step (1), a mixture is prepared by raw materials such as alkyl diol, carbon tetrachloride, fatty acyl chloride and the like, the mixture is actually fatty acid alkyl diester, the fatty acid alkyl diester is prepared by esterification in the step (1), then the fatty acid alkyl diester and chlorosulfonic acid are mixed for sulfonation in the step (2), then the pH is adjusted by 10 percent potassium hydroxide solution, on one hand, the acid-base property of the system is controlled, on the other hand, the environment-friendly surfactant is prepared by combining potassium ions in the system, the activator is actually fatty acid alkyl diester potassium disulfonate, ester bonds in the activator are easy to degrade, so that the activator is endowed with excellent degradation performance and cannot pollute the environment, when the activator is mixed with the rare earth phosphate, the diester bond can act on the rare earth phosphate to form uniform pore diameters on the rare earth phosphate.
Further, the mixed solvent is formed by mixing chloroform and hexyl ether according to the weight ratio of 1: 5.
Further, in the fourth step, the weight ratio of the environment-friendly surfactant, the acetone, the rare earth phosphate powder and the 10% diluted hydrochloric acid is controlled to be 1: 150-200: 5-8.
Further, the rare earth element is one or both of cerium and europium.
The invention has the beneficial effects that:
(1) the invention relates to a method for preparing rare earth phosphate based on a hydrothermal synthesis method, wherein a rare earth element sulfate solution is prepared in the second step in the preparation process, then tri-n-butylamine is added under the stirring condition, and nitrogen atoms in the tri-n-butylamine have non-bonded arc pair electrons and have strong electronegativity, so that the tri-n-butylamine can be endowed with strong nucleophilic ability and can be preferentially combined with rare earth elements, so that the tri-n-butylamine is firstly combined with the rare earth elements, then a phosphoric acid solution is added, phosphate groups need to overcome the steric hindrance effect of the tri-n-butylamine and form crystal nuclei with the rare earth ions, and the stirring is carried out at the rotating speed of 180r/min for 1.5h, so that the convective homogenization of reaction liquid can be realized, and the excessive agglomeration of small particles in; performing hydrothermal crystallization on the prepared precursor at 150 ℃ for 4h to prepare the rare earth phosphate, wherein the method does not need high-temperature roasting treatment in the process of preparing the rare earth phosphate powder, so that hard agglomeration of the powder formed in the process is avoided, and the rare earth phosphate powder has low purity and poor dispersibility; dispersing an environment-friendly surfactant in acetone, adding rare earth phosphate powder to form sol, roasting to prepare mesoporous rare earth phosphate, adding 10% dilute hydrochloric acid in the preparation process, wherein phosphate ions are combined with hydrogen ions in water to generate hydrogen phosphate radicals and dihydrogen phosphate radicals, so that the hydrogen ion concentration in water is reduced, the hydroxide radical concentration is increased, the solution is changed into alkalinity, the 10% dilute hydrochloric acid is added to ensure that the system is acidic, roasting at 350 ℃ for 5 hours to remove the environment-friendly surfactant to prepare the final mesoporous rare earth phosphate, the problem that high-temperature roasting treatment is needed in the traditional preparation process of rare earth phosphate powder is solved, powder hard agglomeration can be formed in the process, the rare earth phosphate powder is low in purity and poor in dispersity, and the phosphate ions are combined with the hydrogen ions in water to generate hydrogen phosphate radicals and dihydrogen phosphate radicals, thus, the concentration of hydrogen ions in water is reduced, and the concentration of hydroxyl is increased, so that the technical problem that the solution is changed into alkaline is solved;
(2) the invention prepares an environment-friendly surfactant, in the preparation process, a mixture is prepared by raw materials such as alkyl diol, carbon tetrachloride, fatty acyl chloride and the like in the step (1), the mixture is actually fatty acid alkyl diester, the step (1) prepares the fatty acid alkyl diester through esterification reaction, then the step (2) mixes the fatty acid alkyl diester and chlorosulfonic acid for sulfonation reaction, then the pH is adjusted by 10 percent potassium hydroxide solution, on one hand, the acid-base property of the system is controlled, on the other hand, potassium ions in the system are combined to prepare the environment-friendly surfactant, the surfactant is actually fatty acid alkyl diester potassium disulfonate, ester bonds in the surfactant are easy to degrade, so that the surfactant has excellent degradation performance and cannot pollute the environment, and when the surfactant is mixed with rare earth phosphate, diester bonds can act on the rare earth phosphate, the uniform pore size is formed on the rare earth phosphate, so that the technical problem that the existing surfactant acting on the surface of the rare earth phosphate leaves the rare earth phosphate after being roasted at high temperature, but is not easy to degrade and can cause environmental pollution is solved.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A method for preparing rare earth phosphate based on a hydrothermal synthesis method comprises the following steps:
firstly, weighing the following raw materials in parts by weight: 20 parts of cerium sulfate, 150 parts of deionized water, 3 parts of tri-n-butylamine, 10 parts of absolute ethyl alcohol, 15 parts of 5mol/L phosphoric acid solution and 1 part of hydrogen peroxide;
secondly, adding rare earth element sulfate into deionized water, magnetically stirring for 15min at the rotating speed of 120r/min, then adding tri-n-butylamine and absolute ethyl alcohol, continuously stirring for 30min, transferring to a three-port reactor, heating in a water bath at 45 ℃, dropwise adding 5mol/L phosphoric acid solution, and stirring for 1.5h at the rotating speed of 180r/min to obtain a gel precursor;
thirdly, transferring the prepared gel precursor into a reaction kettle, adding hydrogen peroxide, stirring at a constant speed for 5min, then dropwise adding 10% ammonia water, adjusting the pH =9, heating to 150 ℃, carrying out hydrothermal crystallization for 4h at the temperature, cooling, centrifuging, washing with deionized water until sulfate ions do not exist, then replacing with anhydrous ethanol for three times, centrifuging after replacement is finished, and then transferring into a 120 ℃ drying box for drying for 5h to prepare cerium phosphate powder;
and fourthly, mixing the environment-friendly surfactant with acetone, stirring at a constant speed for 15min, adding the cerium phosphate powder prepared in the third step, stirring at a constant speed for 1h, adding 10% dilute hydrochloric acid, continuing stirring until sol is formed, standing until the acetone is completely volatilized, transferring to a 350 ℃ muffle furnace, and roasting for 5h, wherein the weight ratio of the environment-friendly surfactant to the acetone to the 10% dilute hydrochloric acid is controlled to be 1: 150: 5.
The environment-friendly surfactant is prepared from the following raw materials in parts by weight: 10 parts of alkyl diol, 2 parts of carbon tetrachloride, 20 parts of fatty acyl chloride, 20 parts of chlorosulfonic acid and 70 parts of mixed solvent.
The environment-friendly surfactant is prepared by the following steps:
(1) adding alkyl diol and carbon tetrachloride into a three-neck flask, magnetically stirring for 15min, adding fatty acyl chloride, heating in a water bath at 75 ℃, reacting for 8h at the temperature, washing with a 10% sodium bicarbonate solution until the pH is =7 after the reaction is finished, performing suction filtration, and transferring to a drying oven at 50 ℃ for drying for 10h to obtain a mixture;
(2) adding the mixture prepared in the step (1) into a reactor, taking absolute ethyl alcohol as a reflux solvent, stirring at the rotating speed of 120r/min, dropwise adding chlorosulfonic acid at the temperature of 45 ℃, heating to 60 ℃, reacting at the temperature for 10 hours, heating to 90 ℃, aging for 2 hours, then adding hydrogen peroxide for bleaching for 10 minutes, dropwise adding 10% potassium hydroxide solution to adjust the pH =7, finally recrystallizing for 3 times by using the mixed solvent, filtering, and vacuum drying for 4 hours at the temperature of 40 ℃ to prepare the environment-friendly surfactant.
The mixed solvent is formed by mixing chloroform and hexyl ether according to the weight ratio of 1: 5.
Example 2
A method for preparing rare earth phosphate based on a hydrothermal synthesis method comprises the following steps:
firstly, weighing the following raw materials in parts by weight: 25 parts of cerium sulfate, 160 parts of deionized water, 5 parts of tri-n-butylamine, 12 parts of absolute ethyl alcohol, 18 parts of a 5mol/L phosphoric acid solution and 3 parts of hydrogen peroxide;
secondly, adding rare earth element sulfate into deionized water, magnetically stirring for 15min at the rotating speed of 120r/min, then adding tri-n-butylamine and absolute ethyl alcohol, continuously stirring for 30min, transferring to a three-port reactor, heating in a water bath at 45 ℃, dropwise adding 5mol/L phosphoric acid solution, and stirring for 1.5h at the rotating speed of 180r/min to obtain a gel precursor;
thirdly, transferring the prepared gel precursor into a reaction kettle, adding hydrogen peroxide, stirring at a constant speed for 5min, then dropwise adding 10% ammonia water, adjusting the pH =9, heating to 150 ℃, carrying out hydrothermal crystallization for 4h at the temperature, cooling, centrifuging, washing with deionized water until sulfate ions do not exist, then replacing with anhydrous ethanol for three times, centrifuging after replacement is finished, and then transferring into a 120 ℃ drying box for drying for 5h to prepare cerium phosphate powder;
and fourthly, mixing the environment-friendly surfactant with acetone, stirring at a constant speed for 15min, adding the cerium phosphate powder prepared in the third step, stirring at a constant speed for 1h, adding 10% dilute hydrochloric acid, continuing stirring until sol is formed, standing until the acetone is completely volatilized, transferring to a 350 ℃ muffle furnace, and roasting for 5h, wherein the weight ratio of the environment-friendly surfactant to the acetone to the 10% dilute hydrochloric acid is controlled to be 1: 160: 5: 6.
The rest is the same as example 1.
Example 3
A method for preparing rare earth phosphate based on a hydrothermal synthesis method comprises the following steps:
firstly, weighing the following raw materials in parts by weight: 30 parts of cerium sulfate, 180 parts of deionized water, 8 parts of tri-n-butylamine, 14 parts of absolute ethyl alcohol, 22 parts of 5mol/L phosphoric acid solution and 4 parts of hydrogen peroxide;
secondly, adding rare earth element sulfate into deionized water, magnetically stirring for 15min at the rotating speed of 120r/min, then adding tri-n-butylamine and absolute ethyl alcohol, continuously stirring for 30min, transferring to a three-port reactor, heating in a water bath at 45 ℃, dropwise adding 5mol/L phosphoric acid solution, and stirring for 1.5h at the rotating speed of 180r/min to obtain a gel precursor;
thirdly, transferring the prepared gel precursor into a reaction kettle, adding hydrogen peroxide, stirring at a constant speed for 5min, then dropwise adding 10% ammonia water, adjusting the pH =9, heating to 150 ℃, carrying out hydrothermal crystallization for 4h at the temperature, cooling, centrifuging, washing with deionized water until sulfate ions do not exist, then replacing with anhydrous ethanol for three times, centrifuging after replacement is finished, and then transferring into a 120 ℃ drying box for drying for 5h to prepare cerium phosphate powder;
and fourthly, mixing the environment-friendly surfactant with acetone, stirring at a constant speed for 15min, adding the rare earth phosphate powder prepared in the third step, stirring at a constant speed for 1h, adding 10% dilute hydrochloric acid, continuing stirring until sol is formed, standing until the acetone is completely volatilized, transferring to a 350 ℃ muffle furnace, and roasting for 5h, wherein the weight ratio of the environment-friendly surfactant to the acetone to the 10% dilute hydrochloric acid is controlled to be 1: 180: 5: 7.
The rest is the same as example 1.
Example 4
A method for preparing rare earth phosphate based on a hydrothermal synthesis method comprises the following steps:
firstly, weighing the following raw materials in parts by weight: 35 parts of cerium sulfate, 200 parts of deionized water, 10 parts of tri-n-butylamine, 15 parts of absolute ethyl alcohol, 25 parts of 5mol/L phosphoric acid solution and 5 parts of hydrogen peroxide;
secondly, adding rare earth element sulfate into deionized water, magnetically stirring for 15min at the rotating speed of 120r/min, then adding tri-n-butylamine and absolute ethyl alcohol, continuously stirring for 30min, transferring to a three-port reactor, heating in a water bath at 45 ℃, dropwise adding 5mol/L phosphoric acid solution, and stirring for 1.5h at the rotating speed of 180r/min to obtain a gel precursor;
thirdly, transferring the prepared gel precursor into a reaction kettle, adding hydrogen peroxide, stirring at a constant speed for 5min, then dropwise adding 10% ammonia water, adjusting the pH =9, heating to 150 ℃, carrying out hydrothermal crystallization for 4h at the temperature, cooling, centrifuging, washing with deionized water until sulfate ions do not exist, then replacing with anhydrous ethanol for three times, centrifuging after replacement is finished, and then transferring into a 120 ℃ drying box for drying for 5h to prepare cerium phosphate powder;
and fourthly, mixing the environment-friendly surfactant with acetone, stirring at a constant speed for 15min, adding the rare earth phosphate powder prepared in the third step, stirring at a constant speed for 1h, adding 10% dilute hydrochloric acid, continuing stirring until sol is formed, standing until the acetone is completely volatilized, transferring to a 350 ℃ muffle furnace, and roasting for 5h, wherein the weight ratio of the environment-friendly surfactant to the acetone to the 10% dilute hydrochloric acid is controlled to be 1: 200: 5: 8.
The rest is the same as example 1.
Comparative example 1
In this comparative example, compared to example 1, the preparation method without mixing the environmentally friendly surfactant with the cerium phosphate powder is as follows:
firstly, weighing the following raw materials in parts by weight: 20 parts of cerium sulfate, 150 parts of deionized water, 3 parts of tri-n-butylamine, 10 parts of absolute ethyl alcohol, 15 parts of 5mol/L phosphoric acid solution and 1 part of hydrogen peroxide;
secondly, adding cerium phosphate powder into deionized water, magnetically stirring for 15min at the rotating speed of 120r/min, then adding tri-n-butylamine and absolute ethyl alcohol, continuously stirring for 30min, transferring to a three-port reactor, heating in a water bath at 45 ℃, dropwise adding 5mol/L phosphoric acid solution, and stirring for 1.5h at the rotating speed of 180r/min to obtain a gel precursor;
and thirdly, transferring the prepared gel precursor into a reaction kettle, adding hydrogen peroxide, stirring at a constant speed for 5min, then dropwise adding 10% ammonia water, adjusting the pH =9, heating to 150 ℃, carrying out hydrothermal crystallization for 4h at the temperature, cooling, centrifuging, washing with deionized water until sulfate ions do not exist, then replacing with anhydrous ethanol for three times, centrifuging after replacement is finished, and then transferring into a 120 ℃ drying box for drying for 5h to obtain cerium phosphate powder.
Comparative example 2
In comparison with example 1, the comparative example uses a betaine surfactant instead of the eco-surfactant, and the preparation method is as follows:
firstly, weighing the following raw materials in parts by weight: 20 parts of cerium sulfate, 150 parts of deionized water, 3 parts of tri-n-butylamine, 10 parts of absolute ethyl alcohol, 15 parts of 5mol/L phosphoric acid solution and 1 part of hydrogen peroxide;
secondly, adding rare earth element sulfate into deionized water, magnetically stirring for 15min at the rotating speed of 120r/min, then adding tri-n-butylamine and absolute ethyl alcohol, continuously stirring for 30min, transferring to a three-port reactor, heating in a water bath at 45 ℃, dropwise adding 5mol/L phosphoric acid solution, and stirring for 1.5h at the rotating speed of 180r/min to obtain a gel precursor;
thirdly, transferring the prepared gel precursor into a reaction kettle, adding hydrogen peroxide, stirring at a constant speed for 5min, then dropwise adding 10% ammonia water, adjusting the pH =9, heating to 150 ℃, carrying out hydrothermal crystallization for 4h at the temperature, cooling, centrifuging, washing with deionized water until sulfate ions do not exist, then replacing with anhydrous ethanol for three times, centrifuging after replacement is finished, and then transferring into a 120 ℃ drying box for drying for 5h to prepare cerium phosphate powder;
and step four, mixing the betaine type surfactant with acetone, stirring at a constant speed for 15min, adding the rare earth phosphate powder prepared in the step three, stirring at a constant speed for 1h, adding 10% diluted hydrochloric acid, continuing stirring until sol is formed, standing until the acetone is completely volatilized, transferring to a 350 ℃ muffle furnace, roasting for 5h, and controlling the weight ratio of the betaine type surfactant, the acetone, the cerium phosphate powder and the 10% diluted hydrochloric acid to be 1: 150: 5.
Comparative example 3
This comparative example is a cerium phosphate prepared according to the prior art.
The pore diameters of the cerium phosphates of examples 1 to 4 and comparative examples 1 to 3 were measured, and the results are shown in table 1 below;
TABLE 1
The degradation performance of the environment-friendly surfactant prepared by the invention is tested, and the result is shown in the following table 2;
TABLE 2
|
Example 1
|
Comparative example 1
|
Comparative example 2
|
Degradation Rate (%)
|
97
|
95
|
37 |
From the above tables 1-2, it can be seen that the pore volume of examples 1-4 is 0.28-0.33cm3The degradation rate of example 1 is 97%; comparative examples 1 to 3 had pore volumes of 0.08 to 0.20cm3In g, the degradation rate of comparative example 1 was 95%, and the degradation rate of comparative example 2 was 37%. Therefore, 10% of dilute hydrochloric acid is added in the preparation process, hydrogen phosphate radicals and dihydrogen phosphate radicals are generated by combining phosphate radical ions with hydrogen ions in water, the concentration of the hydrogen ions in the water is reduced, the concentration of hydroxyl is increased, the solution is changed into alkaline, the 10% of dilute hydrochloric acid is added to ensure that the system is acidic, then the system is roasted at 350 ℃ for 5 hours to remove the environment-friendly surfactant, and the final mesoporous rare earth phosphate is preparedAcid hydrogen radical and dihydrogen phosphate radical, so that the hydrogen ion concentration in water is reduced, and the hydroxide radical concentration is increased, resulting in the technical problem that the solution becomes alkaline.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.