阅读说明：本技术 一种四氧化三铁纳米颗粒的制备方法 (Preparation method of ferroferric oxide nanoparticles ) 是由 方杰 李宏运 于 2021-11-01 设计创作，主要内容包括：本发明涉及纳米材料技术领域,具体涉及一种四氧化三铁纳米颗粒的制备方法,采用加装氨水容器的连续流反应器,将不同浓度的Fe～(2+)水溶液注入的旋转的圆盘在其表面形成一层薄膜,与挥发的氨气和薄膜内的溶解氧进行反应,仅需几秒即可在出液口处收集产物,所得的反应液用钕铁硼强磁铁进行磁分离,即得到四氧化三铁纳米颗粒。与现有技术相比,本发明不需要有机溶剂和表面活性剂等助剂,不需要加温加压和惰性气体保护等反应条件；采用空气氧化方法,反应条件温和,产物易于提纯,生产成本低廉,所得的四氧化三铁纳米颗粒平均粒径可以通过反应器参数设置进行调控,适合大规模工业生产。(The invention relates to the technical field of nano materials, in particular to a preparation method of ferroferric oxide nano particles, which adopts a continuous flow reactor additionally provided with an ammonia water container to carry out Fe with different concentrations 2+ A layer of film is formed on the surface of a rotating disc injected with the aqueous solution, the film reacts with the volatilized ammonia gas and dissolved oxygen in the film, products can be collected at a liquid outlet in a few seconds, and the obtained reaction liquid is magnetically separated by a neodymium iron boron strong magnet to obtain the ferroferric oxide nano-particles. Compared with the prior art, the invention does not need organic solvent, surfactant and other auxiliary agents, and does not need reaction conditions such as heating and pressurizing, inert gas protection and the like; the air oxidation method is adopted, the reaction condition is mild, the product is easy to purify, the production cost is low, and the average particle size of the obtained ferroferric oxide nano particles can be controlled by a reactorThe number is set for regulation and control, and the method is suitable for large-scale industrial production.)

1. A preparation method of ferroferric oxide nano particles is characterized by comprising the following steps: the method comprises the following steps:

step 1, preparing Fe²⁺An aqueous solution of Fe²⁺Adding into deionized water to obtain Fe²⁺An aqueous solution;

step 2, fixing a container filled with ammonia water on the inner wall of the continuous flow reactor;

step 3, the Fe prepared in the step 1²⁺Injecting the aqueous solution into the continuous flow reactor which is fixed by the ammonia water container in the step 2, and regulating Fe²⁺Collecting the obtained reaction product according to the injection flow rate of the aqueous solution and the disc rotating speed of the continuous flow reactor;

and 4, carrying out magnetic separation on the reaction product prepared in the step 3 by using a magnet to obtain the ferroferric oxide nano-particles.

2. The preparation method of ferroferric oxide nanoparticles according to claim 1, characterized by comprising the following steps: in said step 1, Fe²⁺Is any one of ferrous chloride, ferrous sulfate or ferrous nitrate.

3. The preparation method of ferroferric oxide nanoparticles according to claim 1, characterized by comprising the following steps: in said step 3, Fe²⁺The concentration of the aqueous solution is 1mM-200mM, the injection flow rate of the solution is 0.1ml/s-10ml/s, the rotation speed of the continuous flow reactor is 10rpm-2500rpm, and the reaction temperature is 0-80 ℃.

Technical Field

The invention relates to the technical field of nano materials, in particular to a preparation method of ferroferric oxide nano particles.

Background

The magnetic ferroferric oxide nano particles are a group of engineering and special materials with the size less than 100 nanometers, can be manipulated under the action of an external magnetic field, not only can be widely applied to magnetic recording media, gas sensing and dyes, but also can be widely applied to the fields of medical application and the like, including Magnetic Resonance Imaging (MRI), drug delivery systems, medical diagnosis, cancer treatment, microwave devices, magneto-optical devices and the like. The synthesis of magnetic nanoparticles with controlled size is very important, since the properties of these magnetic nanoparticles strongly depend on their size and the physicochemical properties characterizing the size dependence of the magnetic nanoparticles are also important, the development of low-cost and well reproducible mass production protocols is a key issue to be solved.

The existing wet chemical method for synthesizing the ferroferric oxide nano particles mainly comprises a coprecipitation method and a thermal decomposition method, wherein the ferroferric oxide nano particle method prepared by the coprecipitation method needs to perform precipitation reaction on a mixed solution of a ferrous salt and a ferric salt and sodium hydroxide or ammonia water, the prepared simple product particles have wide size distribution, and the thermal decomposition can prepare high-quality nano particles, but the production rarely complies with green chemical rules, and inert gas atmosphere, organic solvent, expensive and toxic reagents and long-time high reaction temperature are used; and the synthesis is mainly carried out in a laboratory, a small scale and a batch amount.

Disclosure of Invention

Aiming at the problems, the invention provides the preparation method which has mild reaction conditions, low cost and green synthesis mode and can continuously produce and prepare reproducible ferroferric oxide nano-particles with different sizes and specifications.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of ferroferric oxide nanoparticles comprises the following steps:

step 1, preparing Fe²⁺An aqueous solution of Fe²⁺Adding into deionized water to obtain Fe²⁺An aqueous solution;

step 2, fixing a container filled with ammonia water on the inner wall of the continuous flow reactor;

step 3, the Fe prepared in the step 1²⁺Injecting the aqueous solution into the continuous flow reactor which is fixed by the ammonia water container in the step 2, and regulating Fe²⁺Collecting the obtained reaction product according to the injection flow rate of the aqueous solution and the disc rotating speed of the continuous flow reactor;

and 4, carrying out magnetic separation on the reaction product prepared in the step 3 by using a magnet to obtain the ferroferric oxide nano-particles.

Preferably, in step 1, Fe²⁺Can beSoluble ferrous salt solution of any one of ferrous chloride, ferrous sulfate, ferrous nitrate, etc.

Preferably, in step 3, Fe²⁺The concentration of the aqueous solution is 1mM-200mM, the injection flow rate of the solution is 0.1ml/s-10ml/s, the rotation speed of the continuous flow reactor is 10rpm-2500rpm, and the reaction temperature is 0-80 ℃.

By adopting the technical scheme, Fe with different concentrations is prepared²⁺And (2) setting different injection speeds for injecting the solution into the surface of a disc of the continuous flow reactor with the ammonia water container to form a layer of film, adjusting the content of dissolved oxygen in the film and the mixing reaction degree of ammonia gas and dissolved oxygen volatilized from the ammonia water by adjusting the rotating speed of the disc, and performing magnetic separation on the obtained product by using a magnet to obtain the ferroferric oxide nano-particles.

The present invention does not require an inert atmosphere and the developed continuous flow process allows the preparation of uniform magnetite nanoparticles of different sizes. Compared with other batch synthesis methods, the method disclosed by the invention has the advantages that the ferroferric oxide nanoparticles with narrow size distribution are continuously prepared by using specific concentration, flow rate and rotating speed, the operation is simpler, only the single ferrous salt solution and ammonia water are used, and the raw material cost and the post-treatment cost are greatly reduced. The method has the advantages of continuous production, high production efficiency, small occupied area, high purity of the obtained ferroferric oxide nano particles and narrow particle size distribution.

The invention has the beneficial effects that:

1. the invention uses only Fe²⁺The air oxidation is used for synthesizing the ferroferric oxide, the needed raw materials are very cheap, and the reaction cost is extremely low.

2. The invention can be prepared in large scale by continuous production by means of ferroferric oxide nano particles synthesized by a continuous flow reactor.

3. The invention is based on a continuous flow reactor and can control Fe²⁺Uniformly dispersed ferroferric oxide nano particles are prepared according to the concentration, the injection flow rate and the rotating speed, and the size distribution of the prepared ferroferric oxide nano particles is narrow.

4. According to the invention, a micro-film is formed on a rotating disc by using a divalent molten iron solution, ammonia gas volatilized from oxygen and ammonia water in air is adsorbed, rapid reaction and crystallization are carried out to prepare the ferroferric oxide nano-particles, and the average particle size of the obtained ferroferric oxide nano-particles can be regulated and controlled through reactor parameter setting.

5. The ferroferric oxide nano particles prepared by ferrous iron oxidation continuous flow production have controllable particle size (3nm to 30nm) and highest saturation magnetization of 89emu/g, and are suitable for large-scale industrial production.

6. The synthesis device is simple and easy to operate, mild in reaction condition, green and pollution-free in experimental process, short in consumed time and high in industrial application prospect.

Drawings

FIG. 1 is an XRD pattern of ferroferric oxide nanoparticles prepared in examples 1-3 of the present invention.

FIG. 2 is an SEM image of the ferroferric oxide nanoparticles prepared in examples 1-3 of the present invention.

FIG. 3 is a DLS diagram of ferroferric oxide nanoparticles prepared in examples 1-3 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, and thus the scope of the present invention is more clearly defined. The embodiments described herein are only a few embodiments of the present invention, rather than all embodiments, and all other embodiments that can be derived by one of ordinary skill in the art without inventive faculty based on the embodiments described herein are intended to fall within the scope of the present invention.

All the raw materials used in the invention are commercially available analytically pure.

Example 1

A method for continuously producing ferroferric oxide nano particles through oxidation precipitation specifically comprises the following steps:

a container containing 10ml of ammonia water was fixed to the side wall of the continuous flow reactor, and 0.3976g of Fe was added²⁺Salt was added to 50ml of deionized water by setting Fe²⁺The concentration of the aqueous solution is 1mM, the solutionInjecting the solution at the flow rate of 1ml/s, adjusting the disc rotation speed of the continuous flow reactor to 1000rpm, adjusting the reaction temperature to 20 ℃, and performing magnetic separation on the obtained product by using a magnet to obtain the ferroferric oxide nanoparticles. Wherein, the above-mentioned Fe²⁺Is ferrous chloride.

Example 2

A container containing 10ml of ammonia water was fixed to the side wall of the continuous flow reactor, and 1.988g of Fe was added²⁺Salt was added to 50ml of deionized water by setting Fe²⁺The concentration of the aqueous solution is 100mM, the injection flow rate of the solution is 0.3ml/s, then the disc rotation speed of the continuous flow reactor is adjusted to 2000rpm, the reaction temperature is 50 ℃, and the obtained product is magnetically separated by a magnet, so that the ferroferric oxide nano-particles are obtained. Wherein, the above-mentioned Fe²⁺Is ferrous chloride.

Example 3

A container containing 10ml of ammonia water was fixed to the side wall of the continuous flow reactor, and 0.7952g of Fe was added²⁺Salt was added to 50ml of deionized water by setting Fe²⁺The concentration of the aqueous solution is 200mM, the injection flow rate of the solution is 4ml/s, then the disc rotation speed of the continuous flow reactor is adjusted to 1250rpm, the reaction temperature is 80 ℃, and the obtained product is magnetically separated by a magnet, so that the ferroferric oxide nano-particles are obtained. Wherein, the above-mentioned Fe²⁺Is ferrous chloride.

Finally, an X-ray diffractometer is used for measuring the ferroferric oxide nanoparticles prepared in the above examples 1-3, the XRD pattern of the obtained product is shown in figure 1, and the obtained product is pure-phase ferroferric oxide nanoparticles as can be obtained from figure 1.

The scanning electron microscope is used for measuring the ferroferric oxide nanoparticles prepared in the embodiments 1-3, the SEM image of the obtained product is shown in figure 2, and the SEM image can be obtained from figure 2, and the obtained product has uniform size distribution, the diameter of the product is less than 15nm, and the product has superparamagnetism.

When the ferroferric oxide nanoparticles prepared in the above examples 1 to 3 were measured by a nanometer particle size analyzer, the DLS diagram of the obtained product is shown in fig. 3, and it can be obtained from fig. 3 that the size distribution range of the obtained product is narrow.

In addition, it should be noted that the continuous flow reactor related to the above-mentioned invention is the prior art disclosed in patent CN111495291A, and therefore, the structure, operation principle, using method, etc. of the continuous flow reactor are not described in detail herein.

The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.