Method for preparing potassium hexatitanate nanowhiskers by using waste salt

Abstract

The invention discloses a method for preparing potassium hexatitanate nanowhiskers by using waste salt, which comprises the following steps: (1) mixing the mixed waste salt of a herbicide cyhalofop-butyl synthesis byproduct with titanium dioxide, and grinding on a ball mill to obtain powder, the waste salt comprising potassium carbonate, potassium bicarbonate, potassium bromide, potassium fluoride and organic matter; the ratio of the sum of the mole number of potassium carbonate in the waste salt and the mole number of potassium in the potassium bicarbonate to the mole number of titanium dioxide is 1: (2.50-2.75); (2) heating the powder obtained in the step (1), and sintering to obtain a sintered body; (3) soaking and stirring the sintered body in clear water to obtain a slurry liquid, filtering to obtain a filter cake, and washing with water until the filtrate does not contain fluorine ions and bromine ions; drying is performed to obtain the potassium hexatitanate nano crystal whiskers; the potassium hexatitanate nanowhisker prepared by the method has high additional value and high length-diameter ratio, not only improves the use value of waste salt, but also simplifies the later separation process of potassium bromide and potassium fluoride serving as fluxing agents.

Description

Technical Field

[0001] The invention belongs to the field of waste salt resource utilization and inorganic fiber material preparation, and particularly relates to a method for preparing potassium hexatitanate nano whiskers by utilizing waste salt. Background Art

[0002] Waste salt mainly comes from the production of medicines, dyes, pesticides, flavors and the treatment of saline wastewater. These waste salts are usually a mixture of multiple salts. There are three ways to deal with waste salt: landfill, discharge into the sea and resource utilization. Among them, resource utilization is the main way to fundamentally solve the environmental pollution and resource waste caused by waste salt. At present, the resource utilization technology is to dissolve the mixed waste salt and then freeze or evaporate it to achieve separation. However, many waste salts need to be incinerated at high temperature first due to their high COD, and the organic matter in them needs to be decomposed before resource utilization. The process is complicated and energy-intensive, so the development of new technologies is the main way to solve the problem.

[0003] Potassium titanate nanowhiskers are a series of potassium titanate whisker products. They have the small size effect, quantum size effect, surface effect, macroscopic quantum tunneling effect, etc. of nanomaterials, which make nanowhiskers have more excellent physical and chemical properties and wider applications. When used as a composite material additive, the rigidity, wear resistance and optical properties of the composite material are further improved. The current main preparation process is the flux process. Since potassium titanate whiskers are sintered and prepared at high temperatures, potassium salts will be volatilized. In addition, the hardness of the sintered body obtained after sintering is relatively large, and the subsequent separation time of the whiskers and the flux is relatively long. Therefore, it is necessary to improve the preparation method.

[0004] In the process of synthesizing the herbicide cyhalofop-butyl, mixed waste salts are produced as by-products, including potassium bicarbonate, potassium carbonate, potassium bromide, potassium fluoride and organic matter (raw materials and products for the production of cyhalofop-butyl). Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing potassium hexatitanate nano whiskers using waste salt.

[0006] The technical solution of the present invention is summarized as follows:

[0007] A method for preparing potassium hexatitanate nano whiskers using waste salt comprises the following steps:

[0008] (1) Mixing a mixed waste salt produced as a byproduct of the synthetic herbicide cyhalofop-butyl with titanium dioxide, and grinding the mixture on a ball mill at a rotation speed of 300 to 400 rpm for 30 to 60 minutes to obtain a powder, wherein the waste salt comprises potassium carbonate, potassium bicarbonate, potassium bromide, potassium fluoride and organic matter; and the ratio of the sum of the molar numbers of potassium carbonate and potassium bicarbonate in the waste salt to the molar number of titanium dioxide is 1:2.50 to 2.75;

[0009] (2) heating the powder obtained in step (1) to 850-900° C. at a heating rate of 5-8° C. / min, and sintering for 3-4 hours to obtain a sintered body;

[0010] (3) soaking and stirring the sintered body obtained in step (2) in clean water to obtain a slurry, filtering to obtain a filter cake, washing the filter cake with water until the filtrate contains no fluoride ions and bromide ions; and drying at 80-100° C. to obtain potassium hexatitanate nanowhiskers.

[0011] Advantages of the present invention:

[0012] 1) The potassium source (potassium bicarbonate and potassium carbonate), binary flux (potassium bromide and potassium fluoride) and additive (organic matter) of the present invention are all derived from the mixed waste salt by-product of the synthetic herbicide cyhalofop-butyl.

[0013] 2) In the process of preparing potassium hexatitanate nano whiskers using waste salt in the present invention, organic matter is used as an additive to generate carbon dioxide gas during the sintering process, which not only has a foaming and fluffy effect on the sintered body, but also can effectively inhibit the volatilization of potassium during the sintering process;

[0014] 3) Potassium fluoride and potassium bromide in the mixed waste salt are used as a composite flux to form a low eutectic point. Compared with a single flux, the preparation temperature of potassium hexatitanate nanowhiskers can be further reduced, thereby reducing energy consumption;

[0015] 4) COD is automatically removed from organic matter in waste salt during the sintering process, and no additional incineration is required; the separation of sodium bromide and sodium fluoride used as flux does not require COD removal, which simplifies the separation process;

[0016] 5) The potassium hexatitanate nano whiskers prepared by the present invention have high added value and a very high aspect ratio, which not only improves the use value of waste salt, but also simplifies the separation process of potassium bromide and potassium fluoride used as flux in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the microscopic morphology of potassium hexatitanate nanowhiskers prepared using waste salt as prepared in Example 1.

[0018] Figure 2 This is the microscopic morphology of potassium hexatitanate nanowhiskers prepared using waste salt as prepared in Example 2.

[0019] Figure 3 This is the microscopic morphology of potassium hexatitanate nanowhiskers prepared using waste salt as prepared in Example 3. DETAILED DESCRIPTION

[0020] The mixed waste salt produced as a byproduct during the synthesis of the herbicide cyhalofop-butyl is used as a raw material to prepare potassium hexatitanate nanowhiskers.

[0021] The waste salt used in each embodiment is the mixed waste salt by-product collected during the production of the herbicide cyhalofop-butyl. After testing, 100g of the mixed waste salt is composed of 20% potassium carbonate, 28% potassium bicarbonate, 15% potassium fluoride, 33% potassium bromide, and 4% organic matter (cyhalofop-butyl production raw materials and products); (this example is used to illustrate the present invention, but the composition of the mixed waste salt is not limited to the present invention)

[0022] The present invention will be further described below by means of specific examples.

[0023] Example 1

[0024] A method for preparing potassium hexatitanate nano whiskers using waste salt comprises the following steps:

[0025] (1) 100 g of mixed waste salt produced as a byproduct of the synthetic herbicide cyhalofop-butyl (20 g (0.14 mol, including 0.28 mol of potassium ions), 28 g (0.28 mol of potassium bicarbonate, including 0.28 mol of potassium ions), 15 g of potassium fluoride, 33 g of potassium bromide, and 4 g of organic matter (raw materials and products for cyhalofop-butyl production)) were mixed with 112 g (1.40 mol) of anatase titanium dioxide, and ground on a ball mill at a speed of 300 rpm for 60 min to obtain a powder, wherein the ratio of the sum of the molar numbers of potassium carbonate and potassium in potassium bicarbonate in the waste salt to the molar number of titanium dioxide was 1:2.50;

[0026] (2) heating the powder obtained in step (1) to 850°C at a heating rate of 5°C / min and sintering for 3 hours to obtain a sintered body; (the sintered body is the reaction product and the mixed flux of potassium fluoride and potassium bromide)

[0027] (3) placing the sintered body obtained in step (2) in clean water and immersing and stirring to obtain a slurry, filtering to obtain a filter cake, washing with water until the filtrate contains no fluoride ions and bromide ions; and drying at 80° C. to obtain potassium hexatitanate nanowhiskers.

[0028] The average diameter of potassium hexatitanate nanowhiskers is 315.32nm, the average length is 40.28μm, the average aspect ratio is 127.74, and the microscopic morphology is shown in Figure 1 .

[0029] Example 2

[0030] A method for preparing potassium hexatitanate nano whiskers using waste salt comprises the following steps:

[0031] (1) 100 g of mixed waste salt produced as a byproduct of the synthetic herbicide cyhalofop-butyl (20 g (0.14 mol, including 0.28 mol of potassium ions), 28 g (0.28 mol of potassium bicarbonate, including 0.28 mol of potassium ions), 15 g of potassium fluoride, 33 g of potassium bromide, and 4 g of organic matter (raw materials and products for cyhalofop-butyl production)) were mixed with 117 g (1.46 mol) of anatase titanium dioxide, and ground on a ball mill at a speed of 350 rpm for 45 min to obtain a powder, wherein the ratio of the sum of the molar numbers of potassium carbonate and potassium bicarbonate in the waste salt to the molar number of titanium dioxide was 1:2.61;

[0032] (2) heating the powder obtained in step (1) to 870°C at a heating rate of 7°C / min and sintering for 4 hours to obtain a sintered body; (the sintered body is the reaction product and the mixed flux of potassium fluoride and potassium bromide)

[0033] (3) placing the sintered body obtained in step (2) in clean water and immersing and stirring to obtain a slurry, filtering to obtain a filter cake, washing with water until the filtrate contains no fluoride ions and bromide ions; and drying at 90° C. to obtain potassium hexatitanate nanowhiskers.

[0034] The average diameter of potassium hexatitanate nanowhiskers is 236.94nm, the average length is 71.25μm, the average aspect ratio is 300.71, and the microscopic morphology is shown in Figure 2 .

[0035] Example 3

[0036] A method for preparing potassium hexatitanate nano whiskers using waste salt comprises the following steps:

[0037] (1) 100 g of mixed waste salt produced as a byproduct of the synthetic herbicide cyhalofop-butyl (20 g (0.14 mol, including 0.28 mol of potassium ions), 28 g (0.28 mol of potassium bicarbonate, including 0.28 mol of potassium ions), 15 g of potassium fluoride, 33 g of potassium bromide, and 4 g of organic matter (raw materials and products for cyhalofop-butyl production)) were mixed with 123 g (1.54 mol) of anatase titanium dioxide, and ground on a ball mill at a speed of 400 rpm for 30 min to obtain a powder, wherein the ratio of the sum of the molar numbers of potassium carbonate and potassium in potassium bicarbonate in the waste salt to the molar number of titanium dioxide was 1:2.75;

[0038] (2) heating the powder obtained in step (1) to 900°C at a heating rate of 8°C / min and sintering for 3 hours to obtain a sintered body; (the sintered body is the reaction product and the mixed flux of potassium fluoride and potassium bromide)

[0039] (3) The sintered body obtained in step (2) is placed in clean water and immersed and stirred to obtain a slurry, filtered to obtain a filter cake, and washed with water until the filtrate contains no fluoride ions and bromide ions; dried at 100°C to obtain potassium hexatitanate nanowhiskers. The average diameter of the potassium hexatitanate nanowhiskers is 190.15 nm, the average length is 101.25 μm, the average aspect ratio is 532.47, and the microscopic morphology is shown in FIG. Figure 3 .

Claims

1. A method for preparing potassium hexatitanate nanowhiskers using waste salt, characterized in that: The following steps are involved: (1) Mixing a mixed waste salt produced as a byproduct of the synthetic herbicide cyhalofop-butyl with titanium dioxide, and grinding the mixture on a ball mill at a rotation speed of 300 to 400 rpm for 30 to 60 minutes to obtain a powder, wherein the waste salt comprises potassium carbonate, potassium bicarbonate, potassium bromide, potassium fluoride and organic matter; and the ratio of the sum of the molar numbers of potassium carbonate and potassium bicarbonate in the waste salt to the molar number of titanium dioxide is 1:2.50 to 2.75; (2) heating the powder obtained in step (1) to 850-900° C. at a heating rate of 5-8° C. / min, and sintering for 3-4 hours to obtain a sintered body; (3) soaking and stirring the sintered body obtained in step (2) in clean water to obtain a slurry, filtering to obtain a filter cake, washing the filter cake with water until the filtrate contains no fluoride ions and bromide ions; and drying at 80-100° C. to obtain potassium hexatitanate nanowhiskers.

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