CN1919507A - Improved nanometer nulvalent iron particle and method for making same - Google Patents
Improved nanometer nulvalent iron particle and method for making same Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 61
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- 229910052742 iron Inorganic materials 0.000 title claims description 74
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 196
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- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention discloses a modified nanometer nulvalent ferric particle and preparing method with grain size at 20-50nm and even grain size at 30-40nm and specific surface at60-70m<2>/g, which comprises the following steps: allocating soluble ferric salt solution and NaBH4 or KBH4 alcohol-water composite solution with bulk rate at 1: 1-20, adding polyvinyl pyrrolidone in the soluble ferric salt solution according to rate, stirring evenly, adding NaBH4 or KBH4 alcohol-water composite solution in the soluble ferric salt solution, stirring continually until the solution becomes black, adopting magnetic method to select nanometer nulvalent ferric particle, washing through distilled water completely, washing through acetone or alcohol then, reserving in the acetone or alcohol.
Description
One, the technical field
The invention relates to an improved nano zero-valent iron particle and a preparation method thereof, in particular to a method for preparing the nano zero-valent iron particle by using an improved liquid phase reduction method and the prepared improved nano zero-valent iron particle.
Second, background Art
The zero-valent ferroelectrics have larger negativity and stronger reducibility. It can be used to treat some trace organic pollutants in water, and can play the role of catalyst to accelerate the reaction process. Both indoor experiments and field experiments show that the zero-valent iron particles can degrade halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons, partial polychlorinated biphenyl chemical pollutants and the like, namely, when halogen atoms on the pollutants such as the halogenated hydrocarbons or the halogenated aromatic hydrocarbons obtain electrons provided by the zero-valent iron, the halogen falls off from molecules, so that the halogenated pollutants are converted into non-toxic or easily biodegradable organic matters such as ethylene and the like. The zero-valent iron particles are cheap and rich in resources, can be widely applied to repairing soil and water polluted by organic chlorine, and can simultaneously treat various pollutants such as heavy metals, dyes, substituted nitrobenzene, pesticides and the like, so the zero-valent iron particles have good application prospect. However, the degradation of chlorinated organics by applying ordinary zero-valent iron powder reduction still has some technical bottlenecks (PRB technology and prospect for polluting soil and underground water, environmental pollution treatment technology and equipment, 2001, 2 (5): 48-53): firstly, because the reactivity of common iron powder is relatively low, chlorinated organic compounds can be only partially degraded, and chlorine atoms can not be completely removed, so that the reduction reaction is incomplete, and chlorinated byproducts are generated; and the reaction rate is very slow, and the degradation reaction rate is smaller and smaller along with the reduction of the number of chlorine atoms. Researchers at home and abroad try to develop iron particles with nano scale, and the specific surface effect and small-size effect of the nano particles are utilized to improve the reaction activity and treatment efficiency of the zero-valent iron particles, so that the nano iron particles are widely applied to wastewater treatment in recent years. The reported research on the degradation of six PCB conditions by nano-iron; and a bimetal system (Fe/Pd and Mg/Pd) is adopted to degrade PCB and DDT simultaneously, so that good degradation effect is achieved. Therefore, the research on the preparation method of the nano iron particles has important significance.
The current preparation methods of the nano iron particles mainly comprise a gas phase method, a liquid phase method and a solid phase method.
The gas phase method mainly includes an inert gas condensation method (IGC), a thermal plasma method, a sputtering method, a gas phase reduction method, and a gas phase thermal decomposition method. In general, the nano iron particles prepared by the gasphase method have high purity, small particle size and uniform dispersion; however, the gas phase reduction method has high requirements on equipment, the equipment is expensive, and generally requires high temperature and high pressure, and the operation is unsafe, so the method is difficult to carry out in a laboratory and is suitable for large-scale industrial production.
The solid phase preparation method mainly comprises a high-energy ball milling method, a deep plastic deformation method and a solid phase reduction method. Generally, the solid phase preparation method has the advantages of simple process and strong operability, and is suitable for the requirement of large-scale production. However, the particle size of the particles is not easy to control in the preparation process, the problems of oxidation or impurity introduction and the like are easy to occur, and the ball mill has a complex structure and a plurality of easily-worn parts; the nano iron particles prepared by the deep plastic deformation method have low purity and the particle size range is not well controlled; the solid-phase reduction method is easy to agglomerate, the particle size distribution is not uniform and the like; therefore, the laboratory uses a simple solid phase method to prepare the nano-iron particles, which is not many, and the solid phase method is generally combined with other methods.
The liquid phase preparation method mainly comprises a liquid phase reduction method, a micro-emulsion method, a precipitation method, a sol-gel method and an electrochemical method. The principle of the liquid phase reduction method is that metallic iron salts (mainly Fe (II) and Fe (III)) in solution are in a strong reducing agent (KBH)4、NaBH4Etc.) to be reduced into simple substance metallic iron particles. The liquid phase reduction method has the advantages of simple principle and equipment, strong operability and the like, and is widely applied to the laboratory preparation of the nano iron particles. Lien et al (Nanoscale iron particles for complete reduction of chlorinated ethylene, Colloids and Surfaces A: Physi)chemical and engineering accessories, 2001, 191: 97-105.) the palladium/iron bimetallic nano-particles prepared by the method are used for degrading chlorinated hydrocarbon pollutants, the particle diameter is 30-100nm, and the specific surface area is 35m2(ii) in terms of/g. Xuxinhua et al (dechlorination of p-dichlorobenzene by metal catalytic reduction technology. environmental science, 2004, 25 (6): 101; catalysis of nano-scale Pd/Fe bimetallic system on dechlorination of 2, 4-dichlorophenol in water. catalytic report, 2004, 25 (2): 144.) the nano-iron particles prepared by liquid phase reduction method have a particle size of 30-100 nm. The principle of the microemulsion method is that a metal salt, a certain organic solvent and a surfactant are utilized to form a microemulsion, the nucleation and growth of colloidal particles are controlled in a water core (called a microreactor) micro-region, and nanoparticles are obtained after heat treatment. Zhangzhuanping et al (micro emulsion method for preparing superfine coated iron powder. applied chemistry, 2000, 3 (17): 248-. Li et al (Microemusion and solvent to nanoparticle iron production for grading of cellulose. colloids and Surfaces A: Physicochem. Eng. attributes, 2003, 223: 103-: the average particle size of the nano-iron particles prepared by the microemulsion method is smaller than that of the nano-iron particles prepared by the liquid phase reduction method. However, compared with the liquid phase reduction method, the microemulsion method has the disadvantages of high cost and relatively complex operation process. The precipitation method is to mix component atoms in a solution state, add a proper precipitator into the solution to prepare a precursor precipitate, and calcine the precipitate to obtain the nano iron particles. The sol-gel method means that metal iron salt is hydrolyzed, sol and gel are solidified, and then is subjected to special treatmentA method of forming a nano-powder by heat treatment. The nano-crystalline material prepared by the electrochemical method has high density, small porosity and little limitation on size and shape, and is a method with low cost and suitable for large-scale production of nano-metal particles. At present, domestic research is not many, Zhanzhimin (research on nano iron particles prepared by electrochemical deposition method and performance thereof. Shanxi university Proc. Nature science edition, 2003, (26): 235-237) introduces sodium Dodecyl Benzene Sulfonate (DBS) as surfactant into electrochemical deposition process for the first time to prepare the productMore uniform nano-iron particles are prepared. In summary: the liquid phase reduction method has the advantages of simple principle, simple equipment, strong operability, low production cost and the like, but also has the defects of uneven particle size distribution, easy occurrence of agglomeration and the like; the microemulsion method has small particle size, uniform distribution and easy realization of high purification, but has relatively high cost and complex process; the precipitation method has low reaction temperature, simple operation, low cost and more uniform particles; but the precipitate is in a gel state and is difficult to wash and filter; the precipitant is mixed into the powder as impurities, and the purity is low. The sol-gel method has good chemical uniformity, is not easy to introduce impurities, has low synthesis temperature and is easy to control the components; however, the raw materials are expensive, the sintering property of the dried gel particles is poor, and the shrinkage is large during drying. The electrochemical method has the advantages of simple equipment, high density, low reaction temperature, low cost and the like; but micron-sized particles are easily introduced, and the deposition isnot uniform.
The liquid phase reduction method has the advantages of simple principle, simple equipment, strong operability and the like, and is widely applied in laboratories. However, the liquid phase reduction method has the greatest disadvantage of uneven particle size distribution and easy agglomeration, so that the defect must be overcome by adding a certain dispersant. Meanwhile, because iron particles are easily oxidized in the air to generate iron oxide, all the operation processes in the searched documents are to carry out NaBH in a nitrogen protective atmosphere4Or KBH4Dropwise addition to Fe2+Or Fe3+In a metal salt solution of (a). Through experiments, we find that: in the preparation process, nitrogen protection is difficult to control, the operation process of dropwise adding prolongs the reaction time, so that iron particles generated in the process are easy to oxidize, and the final experimental result fails.
Polyvinylpyrrolidone (PVP, wherein the molecular weight of PVP K-30 is 40000-. In addition, the optical fiber is also widely applied to the emerging high-tech fields such as separation membranes, medical polymer materials, photocurable resins, photocurable coatings, optical fibers, laser video discs and the like.
A process for preparing nano-iron powder (CN200410064751.6) and a process for preparing nano-iron (CN200410084285.8) are disclosed, but the former method uses iron salt dissolved in alcohol, water or the mixture of alcohol and water, NaOH and hydrazine hydrate solution are added, and the nano-iron powder is obtained by heating, and the size of iron powder is controlled by changing reaction solvent and regulating alkali concentration. The latter adopts a radiation chemical method to prepare the nano material.
The results of the literature search showed: before the invention is completed,reports that the nanometer zero-valent iron particles are prepared by simultaneously adding the high molecular dispersant polyvinylpyrrolidone (PVP K-30) and ethanol and the improved nanometer zero-valent iron particles are not found.
Third, the invention
1. The purpose of the invention is as follows:
aiming at the problems of uneven particle distribution, easy agglomeration and the like in the process of preparing the nano zero-valent iron particles by a liquid phase reduction method. The invention provides an improved nano zero-valent iron particle and a preparation method thereof, aiming at improving the defects of uneven particle distribution, easy agglomeration and the like and obtaining the improved nano iron particle with even distribution, small average particle size and large specific surface area.
2. The technical scheme is as follows:
the principle of the invention is that the metal iron salts (mainly sulfate and chloride salts of Fe (II) and Fe (III)) in the solution are in a strong reducing agent (KBH)4、NaBH4) Reducing the iron particles into simple substance metal iron particles.
For fe (ii):
for fe (iii):
the technical scheme of the invention is as follows:
a method for preparing nanometer zero-valent iron particles by an improved liquid phase reduction method mainly comprises the following steps:
(A) preparing a soluble ferric salt ethanol-water mixed solution with the concentration of 0.01-0.1M, and preparing NaBH with the concentration 2-4 times that of the soluble ferric salt solution4Or KBH4An ethanol-water mixed solution;
wherein the volume ratio of the ethanol to the water is 1: 1-20.
(B) Adding polyvinylpyrrolidone (PVP K-30) into the ethanol-water mixed solution of the soluble ferric salt according to the proportion of 5-20 g/L, and stirring to fully and uniformly mix the mixture;
(C) under mechanical stirring, NaBH is added4Or KBH4The ethanol-water mixed solution is rapidly added into the ethanol-water solution of the soluble ferric salt to lead Fe2+/Fe3+∶BH4 -The molar ratio of (A) to (B) is: 1: 2-4, and continuously stirring until the solution turns black;
(D) selecting out nanometer zero-valent iron particles by a magnetic separation method, fully washing with distilled water, fully washing with acetone or ethanol, and storing in acetone or ethanol.
An improved nanometer zero-valent iron particle, the particle size distribution range of the nanometer iron particle is 20-50nm, the average particle size is 30-40 nm, and the specific surface area is 60-70 m2/g。
The ethanol-water solution of the soluble ferric salt in the step (A) is FeSO4、FeCl2、Fe2(SO4)3Or FeCl3And (3) solution. And (B) adding polyvinylpyrrolidone in the proportion of 15-20 g/L in the step (B), so that the obtained effect is good, and experiments show that when the adding amount is more than 20g/L, the obtained effect is almost not different from 20g/L, so that the control in 20g/L is recommended from the economic perspective. In step (C), NaBH is added4Or KBH4The ethanol-water solution is added to the above-mentioned ethanol-water solution of the soluble ironsalt at a speed as fast as possible to minimize the influence of other factors.
The magnetic separation method in step (D) has been described in "liquid phase preparation of metallic iron nanoparticles, surface modification and structural characterization thereof" (Proc. physico-chemical, 1999 Vol. 12, No. 6).
Measurement using TEM (transmission electron microscope), XRD (X-ray diffraction), BET (nitrogen adsorption specific surface analyzer) the results of the nano-iron particles obtained in the present invention were respectively as follows:
(1) test results of TEM
The TEM test results show that: the particles are uniformly dispersed for about 20-50nm, and the average particle size is 35-40 nm; the particles are spherical and distributed in a dendritic form, and the magnetic nanoparticles are subjected to a geomagnetic force, a magnetostatic force between small particles, a surface tension, and the like. See figure 1 of the specification.
(2) Test results of XRD
The test result of XRD shows that: when the scanning diffraction angle (2 theta) is 30-100 degrees, the corresponding 2 theta is 44-46 degrees, 64-66 degrees and 81-83 degrees when the diffraction peak appears, and the diffraction peaks are found to correspond to the corresponding 110-plane diffraction (44.6732 degrees), 200-plane diffraction (65.0211 degrees) and 211-plane diffraction (82.3326 degrees) compared with the standard PDF card of iron, so that the particles are simple substance iron and no iron oxide substance appears. See figure 2 of the specification.
(3) Test results for BET:
the measurement results by using the nitrogen adsorption specific surface analyzer show that: the specific surface area of the iron particles synthesized by the method is 60-70 m2/g。
3. Advantageous effects
The invention provides improved nano zero-valent iron particles and a preparation method thereof, the nano iron particles prepared by the method are uniformly distributed (20-50 nm), the average particle size is about 30-40 nm, the dispersibility is greatly improved, and the specific surface area is 60-70 m2The product has high purity, and no ferric oxide impurity is generated.
Description of the drawings
FIG. 1 is a diagram showing the TEM test result of the nano-iron particles obtained by the present invention;
FIG. 2 is a diagram of the XRD test result of the nano-iron particles obtained by the present invention;
fifth, example
The invention is further illustrated by the following examples
Example 1: (comparative experiment)
0.13g of FeSO was weighed4.7H2O, dissolved in 50ml ethanol-water mixture (ethanol: water 1: 9) to make 0.01M FeSO4.7H2And (3) mixing the O ethanol-water mixed solution, and stirring the mixture by electromagnetic stirring to fully and uniformly mix the mixture. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in 50ml of mixed solution of ethanol and water (ethanol: water: 1: 9) to obtain 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirringthe O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 40-100nm, and the average particle size is about 80 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.30 degrees, 64.85 degrees and 81.99 degrees respectively, and the standard PDF card of the reference iron shows that the particles just correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which indicates that the particles are simple substance iron and do not have iron oxide substances.
The BET test results show that: the specific surface area of the particles was 45.62m2/g
Example 2:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.1g polyvinylpyrrolidone (PVP K-30) is added, and the mixture is stirred electromagnetically to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placedOn a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (3) continuously stirring the O ethanol-water mixed solution for 5 to 15 seconds, and stopping stirring when the solution becomes black. Selecting bymagnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 31-96nm, and the average particle size is about 80 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.65 degrees, 65.02 degrees and 82.35 degrees respectively, and the standard PDF card of the reference iron shows that the particles just correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which indicates that the particles are simple substance iron and do not have iron oxide substances.
The BET test results show that: the specific surface area of the particles was 61.3m2/g
Example 3:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.2g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 30-60nm, and the average particle size is about 50 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.83 degrees, 65.24 degrees and 82.51 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particles are simple substance iron without the occurrence of iron oxide substances.
The BET test results show that: the specific surface area of the particles was 60.8m2/g
Example 4:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.3g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that:the particle size range is 25-50nm, and the average particle size is about 40 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.50 degrees, 64.98 degrees and 82.05 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particle is simple substance iron, and no iron oxide substance occurs.
The BET test results show that: the specific surface area of the particles was 65.41m2/g
Example 5:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.4g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 25-50nm, and the average particle size is about 40 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 45.38 degrees, 65.63 degrees and 82.76 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particles are simple substance iron without the occurrence of iron oxide substances.
The BET test results show that: the specific surface area of the particles was 60.78m2/g
Example 6:
0.139 g of FeSO are weighed out4.7H2Dissolving O in ethanol-water mixed solution (ethanol: water: 1: 9) to obtain 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.5g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2Continuously stirring the O ethanol-water mixed solution for 5 to 15 seconds until the solution is changed intoThe stirring was stopped at black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 22-50nm, and the average particle size is about 38 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.01 degrees, 64.86 degrees and 81.97 degrees, and the standard PDF card of the control iron is found to correspond to 110 surfaces, 200 surfaces and 211 surfaces, which indicate that the particles are simple substance iron and no iron oxide substance occurs.
The BET test results show that: the specific surface area of the particles was 68.23m2/g
Example 7:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.6g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol. The TEM test results show that: the particle size range is 20-80nm, and the average particle size is 60 nm.
The TEM test results show that: the particle size is 22-59nm, and the average particle size is about 33 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.62 degrees, 65.01 degrees and 82.30 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particles are simple substance iron without the occurrence of iron oxide substances.
The BET test results show that: the specific surface area of the particles was 62.49m2/g
Example 8:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.7g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 25-40nm, and the average particle size is about 30 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.32 degrees, 64.91 degrees and 82.01 degrees, and the standard PDF card of the control iron is found to correspond to 110 surfaces, 200 surfaces and 211 surfaces, which indicate that the particles are simple substance iron and no iron oxide substance occurs.
The BET test results show that: the specific surface area of the particles was 63.77m2/g
Example 9:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.8g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed in the machineOn a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 21-50nm, and the average particle size is about 36 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.66 degrees, 65.01 degrees and 82.32 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particles are simple substance iron without the occurrence of iron oxide substances.
The BET test results show that: the specific surface area of the particles was 66.4m2/g
Example 10:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 0.9g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 22-50nm, and the average particle size is about 36 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.72 degrees, 65.07 degrees and 82.38 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particles are simple substance iron without the occurrence of iron oxide substances.
The BET test results show that: the specific surface area of the particles was 67.43m2/g
Example 11:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 1.0g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 23-48nm, and the average particle size is about 35 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.30 degrees, 64.85 degrees and 81.99 degrees respectively, and the standard PDF card of the reference iron shows that the particles just correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which indicates that the particles are simple substance iron and do not have iron oxide substances.
The BET test results show that: the specific surface area of the particles was 68.42m2/g
Example 12:
0.139 g of FeSO are weighed out4.7H2O, dissolved in an ethanol-water mixed solution (ethanol: water)1:9) to 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 1g polyvinylpyrrolidone (PVP) is added, and the mixture is stirred by electromagnetism to be mixed evenly. The solution was added to a 500ml three-necked, round-bottomed flask, placed on a mechanical stirrer and purged with nitrogen for several minutes to remove oxygen from the solution. Weighing 0.0567g NaBH4Dissolving in mixed solution of alcohol and water (alcohol and water ratio 1: 9) to obtain NaBH 50M 0.03M4The solution was mixed ethanol-water and then added to a separatory funnel and placed on a mechanical stirrer. Under the conditions of mechanical stirring and nitrogen protection, NaBH is added by using a separating funnel4The ethanol-water mixed solution was added dropwise to FeSO4.7H2And (3) continuously stirring the O ethanol-water mixed solution for a plurality of minutes to ensure that the reaction is fully carried out. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 24-50nm, and the average particle size is about 39 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.93 degrees, 64.38 degrees and 81.72 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particle is simple substance iron, and no iron oxide substance occurs.
The BET test results show that: the specific surface area of the particles was 65.71m2/g
By comparison of example 13 with the previous examples it was found that: the non-dropwise addition process has no influence on the properties of the generated iron particles, so that the non-dropwise addition process is simpler and faster to operate, and generates a large amount of iron particles in a short time, thereby preventing oxidation caused by long time of dropwise addition. Therefore, we adopt a large-amount added operation process.
Example 14:
0.139 g of FeSO are weighed out4.7H2O, dissolved in ethanol-water mixture (ethanol: water: 1: 19) to make 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 1.0g polyvinylpyrrolidone (PVP k-30) is added, and the mixture is stirred electromagnetically to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio 1: 19) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 21-48nm, and the average particle size is about 36 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.01 degrees, 63.79 degrees and 81.83 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows thatthe particles are simple substance iron without the occurrence of iron oxide substances.
The BET test results show that: the specific surface area of the particles was 64.93m2/g
Example 15:
0.139 g of FeSO are weighed out4.7H2Dissolving O in ethanol-water mixed solution (ethanol: water: 1: 4) to obtain 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 1.0g polyvinylpyrrolidone (PVP K-30) is added, and the mixture is stirred electromagnetically to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 4) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2O ethanol-water mixed solution, and continuously stirring5-15 seconds, and stopping stirring when the solution turns black. Magnetic separation method is used for separationFully washing the mixture with distilled water for three times, fully washing the mixture with acetone or ethanol for three times, and storing the mixture in the acetone or the ethanol.
The TEM test results show that: the particle size is 20-49nm, and the average particle size is about 37 nm.
The test result of XRD shows that: at a scanning angle (2 theta) of 30-100 degrees, the diffraction peaks appear at 29 of 44.69 degrees, 65.06 degrees and 82.37 degrees, respectively, and the standard PDF card of the control iron shows that the particles just correspond to 110 surfaces, 200 surfaces and 211 surfaces, respectively, which indicates that the particles are simple substance iron and do not have iron oxide substances.
The BET test results show that: the specific surface area of the particles was 68.97m2/g
Example 16:
0.139 g of FeSO are weighed out4.7H2Dissolving O in ethanol-water mixed solution (ethanol: water: 1) to obtain 50ml of 0.01M FeSO4.7H2O ethanol-water mixed solution, then 1.0g polyvinylpyrrolidone (PVP K-30) is added, and the mixture is stirred electromagnetically to be mixed evenly. The solution was then added to a 200ml Erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 1) to obtain 50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4The ethanol-water mixed solution is rapidly added to FeSO4.7H2And (4) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 20-50nm, and the average particle size is about 38 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.33 degrees, 64.68 degrees and 82.05 degrees respectively, and the standard PDF card of the reference iron shows that the diffraction peak just corresponds to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which indicates that the particles are simple substance iron and do not have iron oxide substances.
The test result of BET shows that: the specific surface area of the particles was 67.45m2/g
Example 17:
0.099 g FeCl was weighed2.4H2O, dissolved in an ethanol-water mixture (ethanol: water: 1: 9) to make 50ml of 0.01M FeCl2.4H2O ethanol-water mixed solution, then 1.0g polyvinylpyrrolidone (PVP K-30) is added, and the mixture is stirred electromagnetically to be mixed evenly. The solution was then added to the erlenmeyer flask and placed on a mechanical stirrer. 0.0378g of NaBH was weighed4Dissolving in mixed solution of ethanol and water (ethanol: water: 1: 9) to obtain 50ml of 0.02M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4Ethanol-water mixed solution was added rapidly to FeCl2.4H2And (4) continuously stirring the O ethanol-water mixed solution for 5 to 15 seconds, and stopping stirring when the solution becomes black. Magnetic separation is carried out by fully using distilled waterWashing three times, then fully washing three times with acetone or ethanol, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 21-46nm, and the average particle size is about 35 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.93 degrees, 64.38 degrees and 81.72 degrees, and the standard PDF card of the reference iron is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces, which shows that the particle is simple substance iron, and no iron oxide substance occurs.
The BET test results show that: the specific surface area of the particles was 65.71m2/g
Example 18:
0.135 g FeCl was weighed3.6H2O, dissolved in an ethanol-water mixture (ethanol: water: 1: 4) to make 50ml of 0.01M FeCl3.6H2O ethanol-water mixed solution, then 1.0g polyvinylpyrrolidone (PVP K-30) is added, and the mixture is stirred electromagnetically to be mixed evenly. The solution was then added to the erlenmeyer flask and placed on a mechanical stirrer. 0.0567g of NaBH was weighed out4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9), and mixing50ml of 0.03M NaBH4Ethanol-water mixed solution. Under the condition of mechanical stirring, NaBH is added4Ethanol-water mixed solution was added rapidly to FeCl3.6H2And (3) continuously stirring the O ethanol-water mixed solution for 5-15 seconds, and stopping stirring when the solution becomes black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 20-50nm, and the average particle size is about 39 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees, the corresponding 2 theta when the diffraction peak occurs is 44.77 degrees, 65.23 degrees and 82.34 degrees respectively, and the particles are just corresponding to the corresponding 110 surfaces, 200 surfaces and 211 surfaces as found by comparison with the standard PDF card of iron, so that the particles are simple substance iron, and no iron oxide substance occurs.
The BET test results show that: the specific surface area of the particles was 69.50m2/g
Example 19
1.0g of Fe are weighed out2(SO4)3Dissolving in ethanol-water mixed solution (ethanol: water ratio of1: 4) to obtain 50ml of 0.05M Fe2(SO4)3The ethanol-water mixed solution was added with 1.0g of polyvinylpyrrolidone (PVPK-30) and stirred magnetically to mix well. The solution was poured into an erlenmeyer flask and placed on a mechanical stirrer. Weighing 0.591g NaBH4Dissolving in mixed solution of ethanol and water (ethanol: water ratio of 1: 9) to obtain 50ml of 0.2M NaBH4An aqueous solution. Under the condition of mechanical stirring, 50ml of NaBH is added4Rapid pouring of the aqueous solution into FeCl3.6H2The stirring of the aqueous solution was continued for several seconds, and the stirring was stopped when the solution became black. Selecting by magnetic separation, washing with distilled water for three times, washing with acetone or ethanol for three times, and storing in acetone or ethanol.
The TEM test results show that: the particle size range is 23-50nm, and the average particle size is about 38 nm.
The test result of XRD shows that: when the scanning angle (2 theta) is 30-100 degrees,when diffraction peaks appear, the corresponding 2 theta are 44.77 degrees, 65.23 degrees and 82.34 degrees respectively, and the 2 theta is found to correspond to the corresponding 110 surfaces, 200 surfaces and 211 surfaces by comparing with the standard PDF card of iron, so that the particles are simple substance iron without the occurrence of iron oxide substances. The BET test results show that: the specific surface area of the particles was 67.6m2/g。
Claims (5)
1. A preparation method of improved nano zero-valent iron particles mainly comprises the following steps:
(A) preparing a soluble ferric salt ethanol-water mixed solution with the concentration of 0.01-0.1M, and preparing NaBH with the concentration 2-4 times that of the soluble ferric salt solution4Or KBH4An ethanol-water mixed solution; wherein the volume ratio of the ethanol to the water is 1: 1-20.
(B) Adding polyvinylpyrrolidone into the ethanol-water mixed solution of the soluble ferric salt according to the proportion of 5-20 g/L, and stirring to fully and uniformly mix;
(C) under mechanical stirring, NaBH is added4Or KBH4The ethanol-water mixed solution is rapidly added into the ethanol-water solution of the soluble ferric salt to lead Fe2+/Fe3+∶BH4 -The molar ratio of (A) to (B) is: 1: 2-4, and continuously stirring until the solution turns black;
(D) selecting out nanometer zero-valent iron particles by a magnetic separation method, fully washing with distilled water, fully washing with acetone or ethanol, and storing in acetone or ethanol.
2. The method as claimed in claim 1, wherein the soluble ferric salt solution in step (A) is FeSO4、FeCl2、Fe2(SO4)3Or FeCl3And (3) solution.
3. The preparation method of the improved nanometer zero-valent iron particles as claimed in claim 2, wherein polyvinylpyrrolidone is added in the step (B) according to a ratio of 15-20 g/L.
4. The method for preparing improved nano zero-valent iron particles as claimed in claim 3, wherein in step (C), NaBH is added4Or KBH4The aqueous solution is added to the above-mentioned ethanol-water solution of the soluble iron salt at as high a rate as possible.
5. An improved nano zero-valent iron particle is characterized in that the particle size distribution range of the nano iron particle is 20-50nm, the average particle size is 30-40 nm, and the specific surface area is 60-70 m2/g。
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