CN107916452B

CN107916452B - Preparation method of calcium carbonate whiskers with continuously controllable morphology

Info

Publication number: CN107916452B
Application number: CN201711122887.1A
Authority: CN
Inventors: 王宗荣; 李庆蕾; 刘剑; 王珊; 田薇; 杜丕一
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2017-11-14
Filing date: 2017-11-14
Publication date: 2020-03-03
Anticipated expiration: 2037-11-14
Also published as: CN107916452A

Abstract

The invention discloses a preparation method of calcium carbonate whiskers with continuously controllable morphology, which comprises the following steps: adding calcium oxide into deionized water, digesting at a certain temperature, adding a crystal form control agent, uniformly stirring, introducing carbon dioxide gas at a certain flow rate by using a double-tube ventilation device to perform carbonation reaction, and finally performing suction filtration, washing and drying on the obtained suspension to obtain a sample. The invention is characterized in that the prepared multi-arm whisker is a calcium carbonate whisker with a new appearance, and the number of the whisker branches can be controlled by reaction conditions. The crystal whisker is used as a filling material of a composite material, and has great advantages in the aspects of improving the chemical property, the mechanical property and the like of the composite material.

Description

Preparation method of calcium carbonate whiskers with continuously controllable morphology

Technical Field

The invention relates to the technical field of inorganic material preparation, in particular to a preparation method of calcium carbonate whiskers with continuously controllable morphology.

Background

The inorganic whisker has a complete structure and few defects, the strength and the modulus of the inorganic whisker are close to theoretical values of a complete crystal, and the flame retardant property of the inorganic whisker is better than that of the organic whisker, so that the inorganic whisker becomes an ideal reinforcing and toughening material of a composite material, such as ZnO, SiC, potassium titanate, mullite, aluminum borate and the like, which has already realized industrial production but obstructs large-scale application due to high cost, and the calcium carbonate whisker has wide raw material sources and low production cost, can be prepared even by using industrial waste residues, and is expected to become the most important inorganic whisker material.

At present, scholars at home and abroad make a great deal of research on the preparation of aragonite calcium carbonate whiskers, and five preparation methods are mainly adopted: (1) a double decomposition method; (2) ca (HCO)₃)₂A thermal decomposition method; (3) urea waterA solution method; (4) sol-gel method; (5) carbonation method. The carbonation method is the most and mature method studied at home and abroad, and is expected to realize the industrialization of calcium carbonate at the earliest because of simple preparation process and low cost.

The research on the shape control technology of calcium carbonate products at home and abroad is rapidly advanced, researchers have synthesized calcium carbonate in various crystal forms, such as spindle-shaped, cubic-shaped, chain-shaped, sheet-shaped, spherical, needle-shaped and the like, but multi-arm whiskers are rare. Through the analysis of the structure, the multi-arm whisker has greater advantages in the aspects of improving the chemical property, the mechanical property and the like, and because the multi-arm whisker has more functional groups than a single whisker and has stronger 'pinning' effect when used as a filler, the multi-arm whisker has more excellent chemical property and mechanical property than a rod-shaped whisker. Therefore, the research aim of the inventor is to find a preparation method of the multi-arm calcium carbonate whisker, and in consideration of increasing the position of continuous crystallization on the whisker to enable the whisker to grow into a multi-arm structure, the inventor tries to carry out an experiment by using a double-pipe ventilation device to prepare the multi-arm calcium carbonate whisker based on a carbonation method. The whisker prepared by the method is proved to be a multi-arm structure, and the number of arms of the whisker can be controlled according to reaction conditions.

Disclosure of Invention

The invention aims to provide a preparation method of calcium carbonate whiskers with continuously controllable morphology, which is characterized in that a carbonation method is adopted, a double-tube ventilation device is adopted, and multi-arm calcium carbonate whiskers are synthesized, so that the number of arms of the whiskers is 2-16. The concrete implementation is as follows:

step 1, weighing a certain amount of calcium oxide, adding the calcium oxide into deionized water to obtain Ca (OH) with the concentration of 0.1-0.3mol/L₂Heating the suspension to digest it;

step 2, weighing magnesium chloride as a crystal form control agent, adding water for dissolving, and adding a magnesium chloride solution into digested Ca (OH)₂Stirring the suspension liquid to be uniform;

and 3, introducing carbon dioxide gas to the bottom of the reaction device by using a double-pipe ventilation device, carrying out carbonation reaction, carrying out suction filtration, washing and drying on the obtained precipitate after the reaction is finished, and thus obtaining the sample.

In the technical scheme, the temperature of heating digestion in the step 1 is 70-100 ℃.

The adding amount of the magnesium chloride in the step 2 is such that the molar ratio of magnesium to calcium is 1: 1-2.5: 1.

The flux of the carbon dioxide gas in the step 3 is usually 60-150 ml/min.

The double tube aeration device in the step 3 can adopt a three-mouth round-bottom flask, and carbon dioxide enters the round-bottom flask from openings on two sides of the round-bottom flask simultaneously.

Preferably, in the step 3, the carbonation reaction time is 2 to 3 hours, the number of arms of the obtained calcium carbonate whisker is 2 to 16, and the number of arms of the whisker is different depending on the reaction time, for example, when the carbonation reaction time is 2 hours, the obtained product is mainly a whisker containing 4 arms, when the carbonation reaction time is 2.5 hours, the obtained product is mainly a whisker containing 5 to 7 arms, when the carbonation reaction time is 3 hours, the obtained product is mainly a whisker containing more than 10 arms, and the number of arms of the calcium carbonate whisker can be regulated and controlled by regulating and controlling the carbonation reaction time length.

Compared with the prior art for preparing calcium carbonate crystal whisker, the invention has the outstanding characteristics and remarkable progress that:

1. introducing CO by adopting a double-pipe ventilation device₂The gas is beneficial to increasing the position of continuous crystallization on the whisker and increasing the growth points, so that the whisker grows into a multi-arm structure;

2. the prepared whisker is multi-armed, the number of the arms of the whisker can be continuously controlled, and the whisker functional groups of the multi-armed structure are more than those of single whisker, so that the whisker has stronger 'pinning' effect when used as a filler and has better chemical property and mechanical property.

Drawings

FIG. 1 is a scanning electron micrograph of a whisker in example 1;

FIG. 2 is a scanning electron micrograph of a whisker in example 2;

FIG. 3 is a scanning electron micrograph of a whisker in example 3;

figure 4 is a schematic view of a dual tube aerator useful in the present invention.

Detailed Description

Example 1

Step 1: calcium oxide was added to deionized water to give Ca (OH) at a concentration of 0.1mol/L₂Heating the suspension to 70 ℃ simultaneously, and digesting for 2 h;

step 2: weighing magnesium chloride as crystal form control agent, adjusting magnesium-calcium ratio to 1:1, dissolving in water, and adding magnesium chloride solution to digested Ca (OH)₂Stirring for 0.5h in the suspension liquid to be uniform; and step 3: introducing CO from two side openings with a flux of 150ml/min by using a three-neck round-bottom flask₂The gas enters the bottom of the reaction device to carry out carbonation reaction;

and 4, step 4: and finishing the carbonization reaction after 2 hours, and performing suction filtration, washing and drying on the obtained precipitate to obtain a sample.

The number of the arms of the prepared calcium carbonate whisker is mainly 4, and an SEM image of the calcium carbonate whisker is shown in figure 1.

Example 2

Step 1: calcium oxide was added to deionized water to give Ca (OH) at a concentration of 0.2mol/L₂Heating the suspension to 80 ℃ simultaneously, and digesting for 2 h;

step 2: weighing magnesium chloride as crystal form control agent, adjusting magnesium-calcium ratio to 2:1, dissolving in water, and adding magnesium chloride solution to digested Ca (OH)₂Stirring for 0.5h in the suspension liquid to be uniform; and step 3: introducing CO from two side openings with a throughput of 100ml/min by using a three-neck round-bottom flask₂The gas enters the bottom of the reaction device to carry out carbonation reaction;

and 4, step 4: and finishing the carbonization reaction after 2.5h, and performing suction filtration, washing and drying on the obtained precipitate to obtain a sample.

The number of arms of the prepared calcium carbonate whisker is mainly about 7, and an SEM image is shown in figure 2.

Example 3

Step 1: calcium oxide was added to deionized water to give Ca (OH) at a concentration of 0.3mol/L₂Heating the suspension to 100 ℃ simultaneously, and digesting for 2 h;

step 2: weighing magnesium chloride as crystal form control agent with magnesium-calcium ratio of 2.5:1, dissolving in water, and dissolving magnesium chlorideAdding the solution to the digested Ca (OH)₂Stirring for 0.5h in the suspension liquid to be uniform;

and step 3: introducing CO from two side openings with a flux of 60ml/min by using a three-neck round-bottom flask₂The gas enters the bottom of the reaction device to carry out carbonation reaction;

and 4, step 4: and finishing the carbonization reaction after 3 hours, and performing suction filtration, washing and drying on the obtained precipitate to obtain a sample.

The number of arms of the prepared calcium carbonate whisker can reach as high as 16, and an SEM image is shown in figure 3.

Claims

1. A preparation method of calcium carbonate whiskers with continuously controllable morphology comprises the following specific steps:

3, introducing carbon dioxide gas to the bottom of the reaction device by using a double-pipe ventilation device, carrying out carbonation reaction, and carrying out suction filtration, washing and drying on the obtained precipitate after the reaction is finished to obtain a sample; the double-tube ventilating device is a three-mouth round-bottom flask, carbon dioxide enters the round-bottom flask from openings on two sides of the round-bottom flask simultaneously, and carbonation reaction is carried out for 3 hours; wherein the flux of carbon dioxide gas is 60-150 ml/min;

the obtained sample mainly contains calcium carbonate whiskers containing more than 10 branch arms.

2. The method for preparing calcium carbonate whiskers with continuously controllable morphology according to claim 1, characterized in that: the temperature of heating digestion in the step 1 is 70-100 ℃.

3. The method for preparing calcium carbonate whiskers with continuously controllable morphology according to claim 1, characterized in that: the adding amount of the magnesium chloride in the step 2 is such that the molar ratio of magnesium to calcium is 1: 1-2.5: 1.