阅读说明：本技术 一种以几丁质为晶型控制剂制备纳米碳酸钙的方法 (Method for preparing nano calcium carbonate by using chitin as crystal form control agent ) 是由 谢晓兰 高平章 孙丽丹 雷键 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种以几丁质为晶型控制剂制备纳米碳酸钙的方法。该方法包括如下步骤：(1)用无水氯化钙配制浓度为0.9-1.1mol/L、pH为11.5-12.5的CaCl<Sub>2</Sub>溶液；(2)在上述CaCl<Sub>2</Sub>溶液中加入几丁质溶液,然后在反应体系中通入CO<Sub>2</Sub>气体,在磁力搅拌条件下进行反应,控制反应温度为25-35℃,反应时间为5-6min；(3)收集反应产物,将反应产物充分洗涤后用恒温鼓风干燥箱干燥至恒重,获得纳米碳酸钙。本发明采用几丁质作为晶型控制剂使纳米碳酸钙的颗粒更小,更加均匀,本发明的生产工艺操作简单,绿色环保,具有很好的推广应用前景。(The invention discloses a method for preparing nano calcium carbonate by using chitin as a crystal form control agent. The method comprises the following steps: (1) using anhydrous calcium chloride to prepare CaCl with the concentration of 0.9-1.1mol/L, pH of 11.5-12.5 2 A solution; (2) in the above-mentioned CaCl 2 Adding chitin solution into the solution, and introducing CO into the reaction system 2 Gas reacts under the condition of magnetic stirring, the reaction temperature is controlled to be 25-35 ℃, and the reaction time is 5-6 min; (3) and collecting a reaction product, fully washing the reaction product, and drying the reaction product to constant weight by using a constant-temperature air-blast drying oven to obtain the nano calcium carbonate. The invention adopts chitin as the crystal form control agent to ensure that the particles of the nano calcium carbonate are smaller and more uniform, and the production process has simple operation, is green and environment-friendly, and has good popularization and application prospects。)

1. A method for preparing nano calcium carbonate by using chitin as a crystal form control agent is characterized by comprising the following steps: which comprises the following steps:

(1) using anhydrous calcium chloride to prepare CaCl with the concentration of 0.9-1.1mol/L, pH of 11.5-12.5₂A solution;

(2) in the above-mentioned CaCl₂Adding chitin solution into the solution, and introducing CO into the reaction system₂Gas reacts under the condition of magnetic stirring, the reaction temperature is controlled to be 25-35 ℃, and the reaction time is 5-6 min;

(3) and collecting a reaction product, fully washing the reaction product, and drying the reaction product to constant weight by using a constant-temperature air-blast drying oven to obtain the nano calcium carbonate.

2. The method for preparing nano calcium carbonate by using chitin as a crystal form control agent according to claim 1, wherein the crystal form control agent comprises the following steps: the CaCl is₂The concentration of the solution was 1.0mol/L, pH of 12.5.

3. The method for preparing nano calcium carbonate by using chitin as a crystal form control agent according to claim 1, wherein the crystal form control agent comprises the following steps: the mass concentration of the chitin solution is 1-5 percent, and CaCl is added₂The volume ratio of the solution to the chitin solution is 30mL: 10-30 mL.

4. The method for preparing nano calcium carbonate by using chitin as a crystal form control agent according to claim 1, wherein the crystal form control agent comprises the following steps: the reaction temperature is 35 ℃ and the reaction time is 6 min.

5. The method for preparing nano calcium carbonate by using chitin as a crystal form control agent according to claim 1, wherein the crystal form control agent comprises the following steps: introducing CO₂The gas velocity was 1L/min.

Technical Field

The invention relates to the technical field of preparation of nano calcium carbonate, in particular to a method for preparing nano calcium carbonate by using chitin as a crystal form control agent.

Background

The nano calcium carbonate is a novel material developed in the last thirty years, and has the scientific name of ultrafine calcium carbonate with the particle size of 1-100 nm. Due to the ultra-fining of the nano calcium carbonate, the crystal structure and the surface electronic structure of the nano calcium carbonate are changed, so that the quantum size effect, the small size effect, the surface effect and the macroscopic quantum effect which are not possessed by the common calcium carbonate are generated, and the nano calcium carbonate has unique properties, so that the nano calcium carbonate is widely applied to the industries of rubber, plastics, paper making, food and the like. The nano calcium carbonate is added into the production process of rubber materials and plastics, so that the surface smoothness of rubber products is improved, and the mechanical and thermal properties of the rubber materials and the plastic products, such as toughness, tearing resistance, tensile strength, tensile property, heat resistance, stability and the like, can be improved. If the nano calcium carbonate is added into the production process of high-grade ink and paint, the performance of the ink and paint can be effectively improved, so that the ink and paint can meet the requirements of the current industry on products.

The preparation process of the nano calcium carbonate can be divided into a physical preparation method and a chemical preparation method according to whether chemical change occurs or not, and the carbonization method in the chemical method is generally adopted in industry to prepare the nano calcium carbonate. The carbonization method is to obtain calcium oxide by calcining limestone at high temperature, obtain calcium hydroxide slurry by a series of subsequent treatments on the calcium oxide, add a certain crystal form control agent in the preparation process, then introduce carbon dioxide gas, control the reaction end point to obtain calcium carbonate slurry, and obtain the nano calcium carbonate by filtering, washing, drying and surface treatment on the slurry.

The main existing forms of calcium carbonate include spindle-shaped, cubic-shaped, needle-shaped, flake-shaped, rod-shaped, and the like, and the properties thereof are different due to the difference in form, and thus the calcium carbonate is applied to different fields. The crystal form control agent has the main functions of promoting the rapid nucleation of product particles at the initial stage of reaction, and selectively adsorbing or retarding the growth of certain crystal faces on different crystal faces of the crystal at the later stage of reaction, so that the growth speed of each crystal face is changed, and the size and the crystal form of the crystal are controlled, therefore, the appearance of the calcium carbonate can be controlled by adding the crystal form control agent.

Chitin, also known as chitin, is a polysaccharide formed by polymerizing N-acetylglucosamine monomers through beta linkage, and is degradable into low molecular weight, soluble or insoluble oligosaccharides. Chitin is widely found in the shells of crustaceans, the carapace of insects, and the cell walls of fungi, as well as in some green algae. Chitin has many important functions in the health care aspect of human body: activating immune function, preventing cancer cell metastasis, inhibiting cancer, improving acidic constitution, removing bacteria, improving diabetes, increasing intestinal beneficial bacteria, relieving pain, stopping bleeding, inhibiting hypertension, and strengthening liver function.

A method for preparing nano calcium carbonate by using chitin as a crystal form control agent is not available at home and abroad.

Disclosure of Invention

The invention aims to provide a method for preparing nano calcium carbonate by using chitin as a crystal form control agent.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing nano calcium carbonate by using chitin as a crystal form control agent comprises the following steps:

(1) using anhydrous calcium chloride to prepare CaCl with the concentration of 0.9-1.1mol/L, pH of 11.5-12.5₂A solution;

(2) in the above-mentioned CaCl₂Adding chitin solution into the solution, and introducing CO into the reaction system₂Gas reacts under the condition of magnetic stirring, the reaction temperature is controlled to be 25-35 ℃, and the reaction time is 5-6 min;

(3) and collecting a reaction product, fully washing the reaction product, and drying the reaction product to constant weight by using a constant-temperature air-blast drying oven to obtain the nano calcium carbonate.

Preferably, the CaCl is₂The concentration of the solution was 1.0mol/L, pH of 12.5.

Preferably, the mass concentration of the chitin solution is 1-5%, and CaCl is added₂The volume ratio of the solution to the chitin solution is 30mL: 10-30 mL.

Preferably, the reaction temperature is 35 ℃ and the reaction time is 6 min.

Further, CO is introduced in the reaction process₂The gas velocity was 1L/min.

According to the technical scheme, the chitin is used as the crystal form control agent to prepare the nano calcium carbonate, and the added chitin can reduce the particle size of the nano calcium carbonate and is more uniform. The nano calcium carbonate prepared by the method can be used as a food additive to be added into the production process of calcium supplement products, and the nano calcium carbonate with small and uniform particle size can be absorbed by human bodies more easily, so that more calcium supplement products can be selected for people. The production process disclosed by the invention is simple to operate, green and environment-friendly, and has a good popularization and application prospect.

Drawings

FIG. 1 shows Ca at various temperatures²⁺Conversion rate;

FIG. 2 shows Ca at various reactant concentrations²⁺Conversion rate;

FIG. 3 is the calcium ion conversion at various pH;

FIG. 4 shows the calcium ion conversion for each reaction time;

FIG. 5 is an SEM image of calcium carbonate without added chitin;

FIG. 6 is a SEM image of calcium carbonate with 10mL of 1% chitin added;

FIG. 7 is a SEM image of calcium carbonate with 30mL of 1% chitin added;

FIG. 8 is a SEM image of calcium carbonate with 30mL of 5% chitin added.

Detailed Description

The substance and advantageous effects of the present invention will be described in further detail with reference to examples, which are provided only for illustrating the present invention and not for limiting the present invention. In addition, after reading the teaching of the present invention, those skilled in the art can make various changes or modifications to the invention, and these equivalents also fall within the scope of the claims appended to the present application.