CN1413945A - Preparation method of water-base acid Co ferrite CoFe2O4 magnetic solution - Google Patents

Abstract

An acidic water-based cobalt ferrite CoFe2O4 as magnetic liquid is prepared through preparing aqueous solutions of FeCl3, Co(NO3)2 and NaOH, proportional mixing, reaction to obtain cobalt ferrite microparticles, washing and synthesizing to obtain stable magnetic liquid. Its advantages are simple process, low cost and high purity.

Description

A kind of water-base acid vectolite CoFe 2O 4The preparation method of magnetic liquid

Technical field

The present invention relates to a kind of water-base acid vectolite CoFe ₂O ₄The preparation method of magnetic liquid.

Technical background

Magnetic liquid is called magnetic fluid again, the unit for uniform suspension body of being made up of ferromagnetism particulate and base fluid (also claiming carrier fluid) with magnetic and liquid fluidity.As new-type functional material, have the advantages that optical property, rheological property, magnetic property etc. can be subjected to the foreign field regulation and control, have a wide range of applications in many fields such as engineering, medical science, biologies.

Under the normal temperature, the density of magnetic particle under action of gravity, occurs the isolating precipitation of particulate and base fluid generally greater than liquid easily.In order to obtain the magnetic liquid of particulate stable suspersion, magnetic particle is necessary for nanometer scale.Like this, when microparticulate is in base fluid, because random pedesis greater than the gravity settling effect, just may guarantee stable being suspended in the base fluid of magnetic particle.But nanoparticle has the trend that spontaneous gathering forms big particulate because surface energy is big.Along with particulate increases, random pedesis weakens, the gravitational effect grow, thus cause random pedesis less than action of gravity, particulate precipitates thereupon.Also have magnetostatic interaction between the ferromagnetism nanoparticle, this also can aggravate to assemble the big particulate of formation.Therefore, mainly comprise the prevention with agglomeration of producing of ferromagnetism nanoparticle among the preparation method of magnetic liquid.Known magnetic liquid causes settled different mechanisms can be divided into two classes according to overcoming owing to assembling: a class is that the tensio-active agent of one deck long-chain is wrapped up to overcome the agglomeration between the particulate in the magnetic particle surface; Another kind of is magnetic particle surface adsorption hydrogen ion (H ⁺) or hydroxide ion (OH ^-), be used for overcoming agglomeration between particulate by Coulomb repulsion.The preparation of this two classes magnetic liquid all needs after producing magnetic nanometer particles, to carry out special processing to particulate, ability synthesizing magnetic liquid, its preparation process is more complicated all, cost is higher, and the objectionable constituent of waste (mainly being acid or alkali) concentration is higher, amount is bigger.

Summary of the invention

The objective of the invention is to propose a kind of new water-base acid vectolite CoFe ₂O ₄The preparation method of magnetic liquid, at the pilot process that does not have complicated particulate special processing to the acquisition of magnetic liquid of producing of magnetic nanometer particles, so the preparation method is simple, and with low cost, waste is less and objectionable constituent concentration is lower.

Concrete preparation method of the present invention is as follows:

I step configuration FeCl ₃The aqueous solution (solution 1), Co (NO ₃) ₂The aqueous solution (solution 2), and by every liter of Co (NO ₃) ₂The ratio that adds 2-8 mole HCl adds HCl, disposes the NaOH aqueous solution (solution 3) in addition.

II step is to choose an amount of solution 1 and solution 2 at 2: 1 according to Fe, Co mol ratio earlier, with solution 1 pour into obtain in the solution 2 solution 2 '.Again according to solution 2 ' with the volume ratio of solution 3 be 1: 5-15 chooses an amount of solution 3, under agitation solution 2 ' pour into is fast obtained in the solution 3 solution 3 '.

The III step is heated solution 3 ' extremely boiling at first under agitation.Keep boiling 0.5-1.5 minute, stop heating then, naturally cool to room temperature.In the process of cooling, the bottom has black precipitate to separate out gradually.After 1 hour, top solution becomes limpid liquid, and the bottom is black CoFe ₂O ₄Particulate deposits.

The IV step is outwelled clear liquid, stays throw out, adds the 0.01M HNO of about 5 times of volumes ₃In throw out, to stir 0.5-2.0 minute, upper clear supernate is gone in centrifugation then (1000-1200 rev/min).This process is repeatedly carried out, pH=7～8 of the upper clear supernate after centrifugal.

The V step is according to the particulate volume ratio φ of required configuration magnetic liquid _V, the HNO of adding respective concentration C ₃In the particulate of the aqueous solution after cleaning, fully mix, just can obtain magnetic liquid.φ _VSee formula (2) with the relation of C.

In this kind water-base magnetic liquid, CoFe ₂O ₄Nanoparticle is because acid etching forms the charged viscous layer of surface porosity.This top layer has stoped the reunion between the particulate, thereby makes particulate form stable magnetic liquid at pedesis effect low suspension in base fluid.

Key problem in technology of the present invention: 1. the I～III step stirs and must fully be beneficial to the formation of ferrite particulate.2. the selection of the acid concentration of base fluid is suitable when synthetic.Acid concentration is too high, can make CoFe ₂O ₄Particulate seriously decomposes, so that can not form magnetic liquid; The concentration of acid is low excessively, can not produce effective powered surfaces viscous layer to overcome the reunion between particulate, and particulate will be because of the reunion sedimentation.The acid concentration of base fluid selects to pass through H ⁺Determine with the mol ratio of atoms metal (Co, Fe): $Q=\frac{\left[H^{+}\right]}{[\mathrm{Fe}\left(\mathrm{III}\right)+\mathrm{Co}\left(\mathrm{II}\right)]}---\left(1\right)$ Acid concentration C is chosen as:

φ in the formula _VBe the particulate volume fraction in the magnetic liquid: (2) formula shows, according to the different particulate volume fractions of desiring synthesizing magnetic liquid, should select the HNO of different base fluids ₃Concentration.If the particulate volume is V, then prepare certain φ _VThe volume required V ' of magnetic liquid be: $V^{\′}=\frac{1-{\mathrm{\φ}}_V}{{\mathrm{\φ}}_V}V---\left(4\right)$ In the present invention, (2) formula and two relational expressions of (4) formula have illustrated: if particulate volume V is certain, can design synthetic different φ _VMagnetic liquid.Because the Q value is a constant in this preparation method, so the pH value of magnetic liquid also is a constant.Experiment shows that the pH perseverance is 2.7.

The advantage that the present invention had is:

1, this law is at the pilot process that does not have complicated particulate special processing to the acquisition of magnetic liquid of producing of magnetic nanometer particles, so the preparation method is simple, is easy to streamline operration, and is with low cost.

The basic parameter φ of magnetic liquid in 2 this laws _VOnly relevant with the acid concentration C of base fluid, can produce different φ easily _VMagnetic liquid.

The factor of performance that influences the magnetic liquid product in 3 this laws is few, and susceptibility is low, is easy to keep the consistence of product characteristics.

4 this laws are purchased in the process of magnetic liquid, and waste is few, and acid, alkali concn are low, and environment is not almost had influence.

The magnetic liquid that 5 this laws are purchased produces using value in may and rebuilding traditional industry in biological, medicine, engineering field.

Description of drawings

Fig. 1 is water-base acid vectolite CoFe of the present invention ₂O ₄The preparation flow figure of magnetic liquid.

Embodiment

The present invention will be further described below in conjunction with preparation flow figure and example.

Embodiment 1:(I) dosing

Solution 1 is used FeCl ₃6H ₂The FeCl of O (purity 98.06%) configuration 1M concentration ₃The aqueous solution.

Solution 2 usefulness Co (NO ₃) ₂H ₂Co (the NO of O (purity 97.00%) configuration 2M concentration ₃) ₂The aqueous solution, and by [5M HCl/1 rises Co (NO ₃) ₂The aqueous solution] an amount of HCl of ratio adding.

The NaOH aqueous solution of solution 3 usefulness NaOH (purity 96.00%) configuration 0.7M concentration.(II) mix

By the mol ratio of Fe and Co is that 2: 1 ratio is chosen solution 1 and solution 2, and solution 1 is poured in the solution 2, obtain solution 2 '.

By solution 2 ' with the volume ratio of solution 3 be that 1: 11 ratio is chosen solution 3.Under the agitation condition solution 2 ' quick (being no more than 10 seconds) poured in the solution 3.Continue to stir after 10 minutes solution 3 '.(III) reaction

Under agitation condition,, keep boiling 1 minute with solution 3 ' be warming up to boiling.Stop heating and stirring subsequently, naturally cool to room temperature, engender black CoFe in the process of cooling ₂O ₄Particulate deposits.After 1 hour, precipitate complete layering: top is clear liquid, and the bottom is a black precipitate.(IV) clean

Outwell the upper clear supernate in the reaction product, retain throw out.Add 5 times of volumes to sedimentary 0.01M HNO ₃The aqueous solution stirred 0.5 minute.Centrifugation (rotating speed is 1000～1200 rev/mins) was outwelled upper clear supernate after 3 minutes.Repeatedly for several times, pH=7～8 of the upper clear supernate after centrifugal.(V) synthetic

Magnetic liquid φ according to required configuration _V, and the volume of acquired particulate is determined the concentration C of base fluid by (2) formula, is selected the amount V ' of base fluid by (4) formula.Then base fluid is added in the particulate after the cleaning, fully mixes, just obtain stable magnetic liquid.

Claims (1)

1, a kind of water-base acid vectolite CoFe ₂O ₄The preparation method of magnetic liquid:

I step configuration FeCl ₃The aqueous solution 1, Co (NO ₃) ₂The aqueous solution 2, and by every liter of Co (NO ₃) ₂The ratio that adds 2-8 mole HCl adds HCl, disposes the NaOH aqueous solution 3 in addition;

II step is to choose solution 1 and solution 2 at 2: 1 according to Fe, Co mol ratio earlier, with solution 1 pour into obtain in the solution 2 solution 2 '; Be 1: 5～15 to choose solution 3 according to solution 2 ' again with the volume ratio of solution 3, under agitation solution 2 ' pour into is fast obtained in the solution 3 solution 3 ';

The III step is heated solution 3 ' extremely boiling at first under agitation; Keep boiling 0.5～1.5 minute, stop heating then, naturally cool to room temperature; After 1 hour, top solution becomes limpid liquid, and the bottom is black CoFe ₂O ₄Particulate deposits;

The IV step is outwelled clear liquid, stays throw out, adds the 0.01M HNO of about 5 times of volumes ₃In throw out, to stir 0.5～2 minute, upper clear supernate is gone in centrifugation then (1000-1200 rev/min); This process is repeatedly carried out, pH=7～8 of the upper clear supernate after centrifugal;

The V step is according to the particulate volume ratio φ of required configuration magnetic liquid _V, the HNO of adding respective concentration C ₃In the particulate of the aqueous solution after cleaning, fully mix, just can obtain magnetic liquid.φ _VSee formula with the relation of C:

Wherein Q is the ratio of hydrogen ion and ferro-cobalt atom, is the quality factor that this law is purchased magnetic liquid.