CN115726043A - Calcium sulfate whisker and preparation method thereof - Google Patents
Calcium sulfate whisker and preparation method thereof Download PDFInfo
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- CN115726043A CN115726043A CN202110991996.7A CN202110991996A CN115726043A CN 115726043 A CN115726043 A CN 115726043A CN 202110991996 A CN202110991996 A CN 202110991996A CN 115726043 A CN115726043 A CN 115726043A
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Abstract
The invention relates to the technical field of materials in biological fermentation liquor, and discloses a calcium sulfate whisker and a preparation method thereof, wherein the method comprises the following steps: (1) Carrying out first extraction treatment on the first solution by using a first extraction system to obtain a first aqueous solution and a first organic solution, wherein the first extraction treatment enables at least one part of metal ions in the first solution to be extracted into the first organic solution; (2) Adding sulfuric acid into the first organic solution for reaction, and then filtering, washing and drying to obtain calcium sulfate whiskers; wherein the first solution comprises a lactic acid fermentation liquid and/or a lactic acid fermentation treatment liquid. The calcium ions are extracted from the lactic acid fermentation liquor or the lactic acid fermentation treatment liquid by using a proper extraction system, and the calcium sulfate whiskers with high purity and good quality are obtained in one step by regulating and controlling a sulfuric acid hydrolysis process on an extraction phase.
Description
Technical Field
The invention relates to the field of preparation of materials in biological fermentation broth, and in particular relates to calcium sulfate whiskers and a preparation method thereof.
Background
Lactic acid is a raw material for producing biodegradable polylactic acid, and with the increasing demand for biodegradable polymers, the lactic acid is produced industrially by a biological method at present, wherein starch, glucose, biomass and the like are used as raw materials, mold or lactic acid bacteria are inoculated, fermentation broth containing lactic acid or lactate is generated through fermentation, and then the lactic acid is obtained through separation.
During the production of lactic acid, calcium salt is usually added to neutralize lactic acid, pH is regulated to form a fermentation liquid of calcium lactate solution, and then the fermentation liquid is separated and purified by a calcium salt crystallization method, an esterification hydrolysis method, an extraction method, a membrane separation method and the like to obtain a lactic acid product. Calcium sulfate obtained by acidolysis becomes a difficult problem in the industrialization of lactic acid due to more impurities and low additional value.
CN102557077B discloses a method for producing ammonium sulfate by using calcium sulfate waste residues generated in lactic acid production, wherein calcium sulfate is converted into ammonium sulfate, so that the added value of products is improved. However, there are cases where the conversion is not complete and the crystallization of the ammonium sulfate mother liquor requires a search for a method of disposal.
CN110079864A discloses a method for preparing organic acid and calcium sulfate whisker from organic acid calcium salt by a hydrochloric acid method, wherein fermentation liquor is firstly acidified by hydrochloric acid, lactic acid is extracted and separated, and calcium chloride in a water phase is precipitated by adding sulfuric acid to obtain the calcium sulfate whisker. However, the method uses inorganic acid twice and introduces chloride ions, so that equipment is easy to corrode, and the formed waste acid is difficult to treat.
Disclosure of Invention
In order to solve the technical problems, the invention provides a calcium sulfate whisker and a preparation method thereof by combining a large number of experiments of a biological waste fermentation liquor system on the basis of summarizing the prior art.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing calcium sulfate whiskers, the method comprising:
(1) Carrying out first extraction treatment on the first solution by using a first extraction system to obtain a first aqueous solution and a first organic solution, wherein the first extraction treatment enables at least one part of metal ions in the first solution to be extracted into the first organic solution;
(2) Adding sulfuric acid into the first organic solution for reaction, and then filtering, washing and drying to obtain calcium sulfate whiskers;
wherein the first solution comprises a lactic acid fermentation liquid and/or a lactic acid fermentation treatment liquid.
The second aspect of the invention provides a calcium sulfate whisker, wherein the purity of the calcium sulfate whisker is more than 95%, and further more than 99%; the whiteness is 80-99%, and further 90-99%; the aspect ratio is 15 to 200, further 30 to 200, and further 50 to 200.
According to the technical scheme, calcium ions are extracted from the lactic acid fermentation liquor and/or the lactic acid fermentation treatment liquor by using a proper extraction system, and the calcium sulfate whiskers with high purity and good quality are obtained in one step through a regulated sulfuric acid hydrolysis process on an extraction phase. The method provided by the invention has the advantages of recycling of the extracting agent, simplicity, mild reaction conditions, no pollution, no waste, low cost, high length-diameter ratio of the prepared calcium sulfate whisker and the like.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
As described above, in a first aspect, the present invention provides a method for preparing calcium sulfate whiskers, including:
(1) Carrying out first extraction treatment on the first solution by using a first extraction system to obtain a first aqueous solution and a first organic solution, wherein the first extraction treatment enables at least one part of metal ions in the first solution to be extracted into the first organic solution;
(2) Adding sulfuric acid into the first organic solution for reaction, and then filtering, washing and drying to obtain calcium sulfate whiskers;
wherein the first solution comprises a lactic acid fermentation liquid and/or a lactic acid fermentation treatment liquid.
In the present invention, the source of the first solution is not particularly limited, and the first solution is preferably obtained by fermenting lactic acid using agricultural and forestry waste as a raw material or by other means. The present invention is not particularly limited to the other routes, and examples thereof include those obtained by directly obtaining glucose, starch, and the like commercially, fermenting lactic acid using the obtained glucose, starch, and the like as a raw material, and those obtained by saccharifying and fermenting corn. The method for fermenting lactic acid in the present invention is not particularly limited, and a fermentation method that is conventional in the art may be used.
The source of the agricultural and forestry waste is not particularly limited, and includes, but is not limited to, one or more of straw (corn stover, wheat straw, rice straw, rape straw, barley straw, oat straw, sorghum straw, etc.), rice hull, softwood, hardwood, tree branches, livestock manure, etc.
In some embodiments of the present invention, preferably, the first solution contains lactic acid, metal ions, pigments, proteins, saccharides, and water. In the invention, the lactic acid fermentation treatment liquid is obtained by centrifuging and filtering a lactic acid fermentation liquid to remove impurities such as thalli; or adjusting pH of the lactic acid fermentation liquid to 6-10.5, centrifuging, and filtering to remove impurities such as thallus. The centrifugation and filtration method of the present invention is not particularly limited, and a separation method that is conventional in the art may be used. The lactic acid fermentation liquid or the lactic acid fermentation treatment liquid can also be concentrated and then subjected to lactic acid extraction, and the lactic acid fermentation treatment liquid or the lactic acid fermentation treatment liquid can be selected by a person skilled in the art according to actual conditions as required. In the present invention, the pH of the lactic acid fermentation broth is usually adjusted by using an alkali metal salt or hydroxide, wherein lactic acid is present in the form of a lactic acid metal salt, for example, when the pH is adjusted by using a calcium salt, lactic acid in the fermentation broth is present in the form of calcium lactate, and the extraction of lactic acid is carried out after acid hydrolysis by adding sulfuric acid.
The concentration of the metal ions in the first solution is selected from a wide range, and preferably, the concentration of the metal ions in the first solution is less than 5wt%, further less than 4wt%, and further less than 3 wt%.
The concentration of lactic acid in the first solution is selected from a wide range, and preferably, the concentration of lactic acid in the first solution is 50wt% or less, more preferably 30wt% or less, and still more preferably 5wt% or less.
In some embodiments of the present invention, preferably, the pH of the first solution is below 10.5, further between 4 and 9, further between 4.5 and 7; such as 4.5, 5.2, 5.6, 6.0, 7.0, 8.0, etc.
The present invention provides a wide selection range of the metal ions, preferably including calcium ions and optionally magnesium ions and/or iron ions.
In some embodiments of the present invention, preferably, in step (1), the volume ratio of the first extraction system to the first solution is (0.1-15): 1, further (0.2-10): 1, and further (0.25-8): 1.
In some embodiments of the present invention, preferably, the first extraction system comprises a first complexing extractant and optionally a first diluent; wherein the molar ratio of the first complexing extractant to the calcium ions in the first solution is (0.1-50): 1, further (0.5-50): 1, further (1-30): 1, further (2-20): 1; for example, 0.3.
In consideration of the viscosity and the layering effect of the first complexing extraction agent, the invention improves the physical and chemical properties of the first extraction system by adding the first diluent so as to better improve the extraction effect. The proportion relationship between the first complexing extractant and the first diluent is not particularly limited in the present invention, as long as the metal can be extracted, and the proportion relationship can be selected by a person skilled in the art according to actual conditions.
In some embodiments of the present invention, preferably, the first complex extractant is an acidic phosphorus-oxygen type extractant having the general formula XYP (O) OH; wherein, X and Y are respectively independent alkoxy and alkyl with a straight chain or branched chain structure with 2-10 carbon atoms; more preferably an alkoxy group or an alkyl group having a linear or branched structure and having 5 to 10 carbon atoms. The acidic phosphorus-oxygen type extracting agent of the invention includes but is not limited to 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (P507), di (2-ethylhexyl) phosphoric acid (P204) and the like.
In some embodiments of the present invention, preferably, the first diluent is at least one selected from the group consisting of ether compounds, ester compounds, linear, branched or cyclic alcohol compounds, alkanes, alkyl halides and aromatic compounds; further comprises at least one selected from the group consisting of ether compounds having 4 to 10 carbon atoms, ester compounds having 2 to 10 carbon atoms, linear, branched or cyclic alcohol compounds having at least four carbon atoms, linear or cyclic alkane compounds having five carbon atoms and mixtures thereof, alkyl halides having 1 to 3 carbon atoms and aromatic compounds.
In a specific embodiment of the present invention, the ether compound having 4 to 10 carbon atoms includes, but is not limited to, isopropyl ether, ethyl ether, n-butyl ether, and the like.
In a specific embodiment of the present invention, the ester compound having 2 to 10 carbon atoms is ethyl acetate and/or butyl acetate.
In a specific embodiment of the present invention, the linear, branched or cyclic alcohol compound having at least four carbon atoms is at least one selected from the group consisting of n-octanol, isooctanol, heptanol, cyclohexanol, isobutanol and decanol.
In a specific embodiment of the present invention, the linear or cyclic alkane compound having five carbon atoms and the mixture thereof includes, but is not limited to, one, two or more of kerosene, n-pentane, n-hexane, cyclohexane, n-dodecane, and n-tridecane.
In a specific embodiment of the present invention, the alkyl halide having 1 to 3 carbon atoms may be alkyl chloride and/or alkyl bromide, and may also be alkyl monohalide, alkyl dihalide, alkyl trihalide, alkyl tetrahalide, including but not limited to carbon tetrachloride, chloroform, dichloromethane, 1, 2-dichloroethane, etc.
In a particular embodiment of the present invention, the aromatic compound includes, but is not limited to, benzene, toluene, ethylbenzene, chlorobenzene, xylene, and the like.
According to a preferred embodiment of the present invention, the first diluent is selected from at least one of dichloromethane, carbon tetrachloride, xylene, ethyl acetate, butyl acetate, isopropyl ether, n-octanol, isooctanol, heptanol, cyclohexanol, isobutanol, and decanol.
In some embodiments of the present invention, preferably, in step (1), the difference Δ pH between the pH of the first aqueous solution and the pH of the first solution is > 0.5, further > 1, further > 2; for example, 0.5,1,1.5,2,3 or more. The higher the absolute value of Δ pH, the more metal ions are extracted and less lactic acid is extracted.
In some embodiments of the invention, preferably, the pH of the first solution is greater than the pH of the first aqueous solution.
In some embodiments of the present invention, preferably, the first extraction treatment is performed so that the extraction rate of the metal ions is 30% or more, further 50% or more, further 85% or more, and further 90% or more. In the present invention, the extraction rate of the metal ions refers to the percentage of the metal ions entering the first organic solution to the metal ions in the first solution.
In the present invention, the temperature of the first extraction treatment is not particularly limited, and preferably, the temperature of the first extraction treatment is 10 to 95 ℃, further 20 to 60 ℃, and further 20 to 40 ℃, for example, 10 ℃, 22 ℃, 25 ℃, 28 ℃, 30 ℃, 32 ℃, 35 ℃, 38 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or the like.
In some embodiments of the present invention, preferably, the number of extraction stages of the first extraction treatment is 1 to 30, more preferably 1 to 20, and even more preferably 1 to 10, and the first extraction may be performed by a multi-stage counter-current or multi-stage cross-flow extraction method. The present invention may be subjected to a concentration step between any two stages of extraction treatment.
The manner of contacting the first extraction system with the first solution to perform the first extraction treatment is not particularly limited in the present invention, and the extraction can be performed by a manner conventional in the art, for example, when the first extraction system only contains the first complex extractant, the first complex extractant is mixed with the first solution to achieve the contact between the first solution and the first complex extractant; when the first extraction system contains the first complexing extraction agent and the first diluent at the same time, the first complexing extraction agent is mixed with the first diluent and then mixed with the first solution, so that the first solution is contacted with the first complexing extraction agent and the first diluent to extract.
In the invention, the metal ions in the first solution are subjected to complexing extraction by adopting the first extraction system, and the metal ions are transferred from the water phase to the organic phase, so that the metal ions are separated from lactic acid and the like in the fermentation liquor, at least most of the lactic acid is reserved in the first aqueous solution, the effect of separating and purifying the lactic acid is achieved, and the process efficiency is improved.
In some embodiments of the present invention, calcium sulfate whiskers with high purity and good quality can be obtained by adding a proper amount of sulfuric acid to react with calcium ions for crystallization, and preferably, in step (2), the molar concentration ratio of the added amount of sulfuric acid to calcium ions in the first organic solution is 0.95-10, and further 1.02-5;
the concentration of the sulfuric acid is selected in a wide range, preferably, the concentration of the sulfuric acid is 30-98wt%, and further 50-98wt%.
The adding mode of the sulfuric acid is not particularly limited, and the sulfuric acid can be added at one time or in batches, and can be selected by a person skilled in the art according to actual conditions as required.
In some embodiments of the present invention, preferably, in step (2), the reaction conditions include: the temperature is 70-100 ℃, and further 80-100 ℃; the total reaction time is 1-72h, further 1-48h, wherein the feeding time is 0.5-48h, further 0.5-24h. The reaction according to the invention can be carried out with stirring.
The filtration method in step (2) is not particularly limited in the present invention, and examples thereof include, but are not limited to, separation of calcium sulfate by filtration or centrifugation. The apparatus used for filtration or centrifugation is not particularly limited in the present invention, as long as the purpose of separation can be achieved, and examples thereof include, but are not limited to, separation by using an apparatus such as a centrifuge, a filter press, drum filtration, or belt filtration.
In the invention, the calcium sulfate is washed by adopting a detergent, and the dosage of the detergent is 0.3-5 times, further 0.5-5 times and further 1-3 times of the mass of the calcium sulfate on a dry basis. The detergent of the present invention is preferably an organic solvent or water. The organic solvent is selected in a wide range, and preferably, the alcohol compound which is the same as the first diluent is used as a detergent to wash the calcium sulfate.
In the present invention, the separated calcium sulfate may be subjected to size mixing and elutriation in hot water and then separated again to further remove the residual solvent.
In some embodiments of the invention, preferably the temperature of the drying is 40-120 ℃, further 50-110 ℃. In the present invention, the drying method in step (2) is not particularly limited, and examples thereof include, but are not limited to, vacuum drying, atmospheric drying, and the like.
In some embodiments of the present invention, preferably, in step (2), before adding sulfuric acid to the first organic solution for reaction, the method further comprises: adding a proper amount of water into the first organic solution, and then adding sulfuric acid for reaction.
Preferably, the amount of water added is 0.1 to 10 times, further 0.5 to 5 times, and further 1 to 3 times the volume of the first organic solution.
According to a preferred embodiment of the present invention, the step (2) relates to a specific method comprising: adding a proper amount of water into the first organic solution obtained in the step (1), heating the system, stirring, adding sulfuric acid to react while maintaining the temperature, filtering and separating to obtain a filtrate and a filter cake after the reaction is finished, and washing the filter cake to obtain a calcium sulfate whisker product; the filtrate is the mixture of extractant, diluent, lactic acid and water.
In a second aspect, the invention provides a calcium sulfate whisker prepared by the method of the first aspect, wherein the purity of the calcium sulfate whisker is up to 95% or more, and further up to 99% or more; the whiteness is 80-99%, and further 90-99%; the aspect ratio is 15 to 200, further 30 to 200, and further 50 to 200. The calcium sulfate whisker provided by the invention has the advantages of high purity, good quality, high length-diameter ratio and the like.
The present invention will be described in detail below by way of examples. In the following examples, various raw materials used are commercially available without specific description; the physical parameters related to the raw materials or the performance parameters of the product are obtained by measuring the physical parameters, the performance parameters and the like by adopting a conventional method in the field.
Preparation of the first solution
Preparing a first solution with reference to the method disclosed in CN11294117A, specifically comprising:
putting pretreated solid particle form corn straws with solid content of 30 (w/w)% into a fermentation tank as a raw material, adding cellulase with 5mg of protein per gram of straw (dry basis), and performing pre-saccharification for 6.5h at 48 ℃ and 200 rpm; after the pre-saccharification is finished, inoculating pediococcus acidilactici seed liquid into a fermentation tank according to the inoculation amount of 5% (v/v), simultaneously adding nutrient salts (10 g/L peptone, 10g/L yeast extract, 2g/L diammonium hydrogen citrate and 0.25g/L manganese sulfate monohydrate), adjusting and maintaining the pH value of fermentation liquor to be 5.4 by using calcium carbonate as a neutralizer in the fermentation process, fermenting for 96 hours at 42 ℃ and 200rpm, and then filtering to separate the fermentation liquor from the corn straw residues to obtain a first solution for later use, wherein the concentration of lactic acid in the first solution is 9wt%, and the concentration of calcium ions is 2wt%.
Preparation of calcium sulfate whisker
Example 1
(1) Carrying out first extraction treatment on the first solution at the temperature of 24 ℃ by using a first extraction system (comprising P204 and n-octanol), wherein the extraction order is 8, so as to obtain a first aqueous solution (the pH value is 2.4) and a first organic solution, the volume ratio of the first extraction system to the first solution is 1.3, the molar ratio of a first complexing extraction agent to calcium ions in the first solution is 4;
(2) Adding a proper amount of water into the first organic solution (the adding amount of the water is 1 time of the volume of the first organic solution), then adding sulfuric acid with the concentration of 98wt% into the first organic solution, wherein the molar concentration ratio of the adding amount of the sulfuric acid to calcium ions in the first organic solution is 1.
The purity of the calcium sulfate crystal whisker is over 99 percent, the whiteness is 92 percent, and the length-diameter ratio is 150.
Other examples were carried out by the same procedure as in example 1, and specific reaction conditions and physical properties of the product are shown in Table 1.
TABLE 1
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A preparation method of calcium sulfate whiskers is characterized by comprising the following steps:
(1) Carrying out first extraction treatment on the first solution by adopting a first extraction system to obtain a first aqueous solution and a first organic solution, wherein the first extraction treatment enables at least one part of metal ions in the first solution to be extracted into the first organic solution;
(2) Adding sulfuric acid into the first organic solution for reaction, and then filtering, washing and drying to obtain calcium sulfate whiskers;
wherein the first solution comprises a lactic acid fermentation liquid and/or a lactic acid fermentation treatment liquid.
2. The method according to claim 1, wherein the first solution is obtained by fermentation of lactic acid from agricultural and forestry waste or by other means;
further, the agricultural and forestry waste is selected from at least one of straw, rice hull, softwood, hardwood, tree branches and livestock manure.
3. The method of claim 1, wherein the first solution comprises lactic acid, metal ions, pigments, proteins, sugars, and water;
wherein the concentration of metal ions in the first solution is below 5wt%, further below 4wt%, further below 3 wt%; and/or
The concentration of lactic acid in the first solution is 50wt% or less, further 30wt% or less, further 5wt% or less; and/or
The pH of the first solution is below 10.5, further 4-9, further 4.5-7; and/or
The metal ions include calcium ions and optionally magnesium ions and/or iron ions.
4. The method according to any one of claims 1 to 3, wherein in step (1), the volume ratio of the first extraction system to the first solution is (0.1-15: 1), further (0.2-10: 1, further (0.25-8: 1; and/or
The first extraction system comprises a first complex extractant and optionally a first diluent; wherein the molar ratio of the first complexing extraction agent to the calcium ions in the first solution is (0.1-50): 1, further (0.5-50): 1, further (1-30): 1, and further (2-20): 1.
5. The process of claim 4, wherein the first complex extractant is an acidic phosphorus-oxygen type extractant having the general formula XYP (O) OH; wherein, X and Y are respectively independent alkoxy and alkyl with a straight chain or branched chain structure with 2-10 carbon atoms; preferably alkoxy or alkyl with a linear or branched structure having 5 to 10 carbon atoms; further, the acidic phosphorus-oxygen type extractant is selected from 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester and/or di (2-ethylhexyl) phosphoric acid; and/or
The first diluent is at least one selected from ether compounds, ester compounds, straight-chain, branched-chain or cyclic alcohol compounds, alkanes, alkyl halides and aromatic compounds; further selected from at least one of ether compounds with 4-10 carbon atoms, ester compounds with 2-10 carbon atoms, linear, branched or cyclic alcohol compounds with at least four carbon atoms, linear or cyclic alkane compounds with five carbon atoms and mixtures thereof, alkyl halides with 1-3 carbon atoms and aromatic compounds; further, the ether compound having 4 to 10 carbon atoms is at least one selected from isopropyl ether, ethyl ether and n-butyl ether; the ester compound with the carbon atom number of 2-10 is ethyl acetate and/or butyl acetate; the straight chain, branched chain or cyclic alcohol compound containing at least four carbon atoms is selected from at least one of n-octanol, isooctanol, heptanol, cyclohexanol, isobutanol and decanol; the straight chain or cyclic alkane compound containing five carbon atoms and the mixture thereof are selected from one, two or more of kerosene, n-pentane, n-hexane, cyclohexane, n-dodecane and n-tridecane; the alkyl halide with 1-3 carbon atoms is chloroalkane and/or bromoalkane, preferably at least one of carbon tetrachloride, trichloromethane, dichloromethane and 1, 2-dichloroethane; the aromatic compound is at least one selected from benzene, toluene, ethylbenzene, chlorobenzene and xylene.
6. The method according to any one of claims 1 to 5, wherein in step (1) the difference between the pH of the first aqueous solution and the pH of the first solution, Δ pH, is > 0.5, further > 1, further > 2; and/or
The pH value of the first solution is greater than that of the first aqueous solution; and/or
The first extraction treatment is performed so that the extraction rate of metal ions is 30% or more, further 50% or more, further 85% or more, and further 90% or more; and/or
The temperature of the first extraction treatment is 10-95 ℃, further 20-60 ℃, and further 20-40 ℃; and/or
The extraction stage number of the first extraction treatment is 1-30 stages, preferably 1-20 stages, and further preferably 1-10 stages, and the first extraction adopts a multi-stage countercurrent or multi-stage cross-flow extraction mode.
7. The method according to any one of claims 1 to 6, wherein in step (2), the ratio of the addition amount of sulfuric acid to the molar concentration of calcium ions in the first organic solution is from 0.95 to 10, and further from 1.02 to 5; and/or
The concentration of sulfuric acid is 30 to 98wt%, further 50 to 98wt%.
8. The method according to any one of claims 1 to 7, wherein in step (2), the reaction conditions comprise: the temperature is 70-100 ℃, and further 80-100 ℃; the total reaction time is 1-72h, further 1-48h, wherein the feeding time is 0.5-48h, further 0.5-24h; and/or
Washing calcium sulfate by using a detergent, wherein the dosage of the detergent is 0.3-5 times, further 0.5-5 times and further 1-3 times of the mass of the calcium sulfate on a dry basis; the detergent is organic solvent or water, and/or
The drying temperature is 40-120 deg.C, and further 50-110 deg.C.
9. The method according to any one of claims 1 to 8, wherein in step (2), before adding sulfuric acid to the first organic solution for reaction, the method further comprises: adding water into the first organic solution, and then adding sulfuric acid for reaction;
further, the amount of water added is 0.1 to 10 times, further 0.5 to 5 times, and further 1 to 3 times the volume of the first organic solution.
10. Calcium sulfate whiskers produced by the method of any one of claims 1-9, wherein the calcium sulfate whiskers have a purity of 95% or more, further 99% or more; the whiteness is 80-99%, and further 90-99%; the aspect ratio is 15 to 200, further 30 to 200, and further 50 to 200.
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