Method for preparing nano-scale alpha-type calcium sulfate hemihydrate whiskers from phosphogypsum in reverse microemulsion system

An inverse microemulsion, calcium sulfate hemihydrate technology, applied in chemical instruments and methods, single crystal growth, crystal growth and other directions, can solve the problem that phosphogypsum has not seen relevant reports, and promote the utilization of high value-added resources. , the process is simple, the effect of low energy consumption

Active Publication Date: 2020-02-25
KUNMING UNIV OF SCI & TECH
8 Cites 10 Cited by

AI-Extracted Technical Summary

Problems solved by technology

However, using unpretreated raw phosphogypsum as a raw material, using fatty primary alcohol-surfactant-water to construct an inverse microemulsion as a reaction system, the main component of phosphogypsum, calcium sulfate dihydrate, is dissolved in the nano-scale in the emulsion. Recrystallization and precipitation in water droplets to prepare nanoscale α-type calcium sulfate hem...
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Method used

(2) the preparation of calcium sulfate hemihydrate whisker of α type: 100 parts of inverse microemulsions and 15 parts of original state phosphogypsum are added there-necked flask, mix in pH adjuster magnesium hydroxide, adjust emulsion pH value to 6.8 ~ Within the scope of 7.2, add 0.56 parts of crystal accelerator calcium chloride according to 0.08% of the water consumption, then place it on a temperature-controllable magnetic heating stirrer and heat it at 105°C for 4 hours, and connect an external condensing device to avoid water evaporation to ensure three-port The liquid phase in the flask equilibrated.
(2) the preparation of calcium sulfate hemihydrate whisker of α type: 100 parts of inverse microemulsions and 20 parts of original state phosphogypsums are added to there-necked flask, mix into pH regulator sodium hydroxide, adjust emulsion pH value to 6.8 ~ Within the scope of 7.2, add 0.9 parts of crystal accelerator potassium chloride according to 0.15% of the water consumption, and then place it on a temperature-controllable magnetic heating stirrer to heat at 100°C for 3.5 hours, and connect an external condensation device to avoid water evaporation to ensure The liquid phase in the three-necked flask was equilibrated.
(2) the preparation of calcium sulfate hemihydrate whisker of α type: 100 parts of inverse microemulsions and 22.5 parts of original state phosphogypsum are added there-necked flask, mix into pH regulator magnesium hydroxide, adjust emulsion pH value to 6.8 ~ Within the scope of 7.2, add 0.575 parts of crystal a...
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Abstract

The invention relates to a method for preparing nano-scale alpha-type calcium sulfate hemihydrate whiskers in a reverse microemulsion system under normal pressure by using raw phosphogypsum as a raw material, and belongs to the technical field of preparation of inorganic functional materials. A fatty primary alcohol, a surfactant, and water are adopted to construct the reverse microemulsion reaction system, the raw phosphogypsum is added in a proportion, after uniform stirring, a PH regulator is added to control the PH value, and a crystal accelerator is added in a proportion; the reverse microemulsion reaction system is heated to a control temperature, and alpha-type calcium sulfate hemihydrate whiskers are formed by crystallization in nano-scale water droplets; and after filtering, washing and drying, the nano-scale alpha-type calcium sulfate hemihydrate whiskers having a high added value and having a diameter range of 200 nm to 500 nm are formed. The method has the advantages of simple process, high operability, short preparation time, low energy consumption, high yield, multiple times of use of the reverse microemulsion and washing water, high product added value, and the like,and is of great significance to ecological environment protection, natural gypsum resource saving, promotion of high value-added resource utilization of the phosphogypsum.

Application Domain

Polycrystalline material growthFrom normal temperature solutions +1

Technology Topic

Active agentCalcium Sulfate Hemihydrate +9

Image

  • Method for preparing nano-scale alpha-type calcium sulfate hemihydrate whiskers from phosphogypsum in reverse microemulsion system
  • Method for preparing nano-scale alpha-type calcium sulfate hemihydrate whiskers from phosphogypsum in reverse microemulsion system
  • Method for preparing nano-scale alpha-type calcium sulfate hemihydrate whiskers from phosphogypsum in reverse microemulsion system

Examples

  • Experimental program(5)

Example Embodiment

[0029] Example 1
[0030] (1) Preparation of inverse microemulsion: Take 63 parts of n-hexanol, 30 parts of surfactant cetyltrimethylammonium bromide, and 7 parts of water into a beaker, stir with a constant speed stirrer until the emulsion is clear, and get 100 parts reverse phase microemulsion.
[0031] (2) Preparation of α-type calcium sulfate hemihydrate whiskers: Add 100 parts of inverse microemulsion and 15 parts of original phosphogypsum into a three-neck flask, add pH regulator magnesium hydroxide, and adjust the pH value of the emulsion to 6.8~7.2 , and then mixed with 0.56 parts of crystal accelerator calcium chloride according to 0.08% of the water consumption, and then placed on a temperature-controllable magnetic heating stirrer and heated at 105 ° C for 4 hours, and an external condensation device was used to avoid water evaporation to ensure the three-necked flask. Liquid phase equilibrium.
[0032] (3) After the reaction, take out the three-necked flask, pour the emulsion into a sand core filter for filtration, and take the filtered emulsion as the reverse microemulsion for next cycle; take the remaining solid phase with hot water at a temperature not lower than 90°C For washing, the water consumption is 1.0 times the mass of the original phosphogypsum. After washing, the hydration reaction is terminated with absolute ethanol, and the solid phase is dried in an oven at 50°C to obtain the finished product of nano-scale α-type calcium sulfate hemihydrate whiskers; Take the solid-phase washing liquid and let it stand for 10 minutes to remove the organic impurities floating on the liquid surface and then use it as washing water for recycling.
[0033] like figure 2 As shown in the electron microscope picture, the obtained crystals are nanoscale prismatic crystals with a length of 2440nm, a width of 354nm, and an aspect ratio of about 6.89.

Example Embodiment

[0034] Example 2:
[0035] (1) Preparation of inverse microemulsion: Take 69 parts of n-hexanol, 26 parts of surfactant cetyltrimethylammonium bromide, and 5 parts of water into a beaker, stir with a constant speed stirrer until the emulsion is clear, and get 100 parts reverse phase microemulsion.
[0036] (2) Preparation of α-type calcium sulfate hemihydrate whiskers: Add 100 parts of inverse microemulsion and 22.5 parts of original phosphogypsum into a three-necked flask, add pH regulator magnesium hydroxide, and adjust the pH value of the emulsion to 6.8~7.2 , and then mixed with 0.575 parts of crystal accelerator magnesium chloride according to 0.115% of the water consumption, and then placed on a temperature-controllable magnetic heating stirrer and heated at 95 ° C for 3 hours, and an external condensation device was used to avoid water evaporation, so as to ensure the liquid phase in the three-necked flask balance.
[0037] (3) After the reaction, take out the three-necked flask, pour the emulsion into a sand core filter for filtration, and take the filtered emulsion as the reverse microemulsion for next cycle; take the remaining solid phase with hot water at a temperature not lower than 90°C For washing, the water consumption is 2.0 times the mass of the original phosphogypsum. After washing, the hydration reaction is terminated with absolute ethanol, and the solid phase is dried in an oven at 62.5°C to obtain the finished product of nano-scale α-type calcium sulfate hemihydrate whiskers; Take the solid-phase washing liquid and let it stand for 10 minutes to remove the organic impurities floating on the liquid surface and then use it as washing water for recycling.
[0038] like image 3 As shown in the electron microscope picture, the obtained crystals are nano-scale prismatic crystals, the length is in the range of 5000-15000nm, the width is 300-800nm, and the aspect ratio is in the range of 16.67-18.75.

Example Embodiment

[0039] Example 3:
[0040] (1) Preparation of reverse-phase microemulsion: Take 72 parts of n-amyl alcohol, 25 parts of surfactant polyethylene glycol, and 3 parts of water into a beaker, stir with a constant speed stirrer until the emulsion is clear, and obtain 100 parts of reverse-phase microemulsion. lotion.
[0041] (2) Preparation of α-type calcium sulfate hemihydrate whiskers: Add 100 parts of inverse microemulsion and 30 parts of original phosphogypsum into a three-necked flask, add pH regulator sodium hydroxide, and adjust the pH value of the emulsion to 6.8~7.2 , and then mixed with 0.45 parts of crystal accelerator magnesium chloride according to 0.15% of the water consumption, and then placed on a temperature-controllable magnetic heating stirrer and heated at 85 ° C for 2 hours, and an external condensation device was used to avoid water evaporation, so as to ensure the liquid phase in the three-necked flask balance.
[0042] (3) After the reaction, take out the three-necked flask, pour the emulsion into a sand core filter for filtration, and take the filtered emulsion as the reverse microemulsion for next cycle; take the remaining solid phase with hot water at a temperature not lower than 90°C For washing, the water consumption is 3.0 times the mass of the original phosphogypsum. After washing, the hydration reaction is terminated with absolute ethanol, and the solid phase is dried in an oven at 75°C to obtain the finished product of nano-scale α-type calcium sulfate hemihydrate whiskers; Take the solid-phase washing liquid and let it stand for 10 minutes to remove the organic impurities floating on the liquid surface and then use it as washing water for recycling.
[0043] like Figure 4 As shown in the electron microscope picture, the obtained crystals are nanoscale prismatic crystals with a length of 12100nm, a width of 320nm, and an aspect ratio of about 37.81.
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PUM

PropertyMeasurementUnit
Aspect ratio6.89 ~ 2440.0
Aspect ratio16.67 ~ 15000.0
Aspect ratio37.81 ~ 12100.0
tensileMPa
Particle sizePa
strength10

Description & Claims & Application Information

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