CN114891273A

CN114891273A - Modified overhaul slag based on tannic acid and preparation method and application thereof

Info

Publication number: CN114891273A
Application number: CN202210660443.8A
Authority: CN
Inventors: 李晶; 涂皓; 任登辉; 陈有潮; 李鑫禹
Original assignee: Guangxi University
Current assignee: Guangxi University
Priority date: 2022-06-13
Filing date: 2022-06-13
Publication date: 2022-08-12
Anticipated expiration: 2042-06-13
Also published as: CN114891273B

Abstract

The invention discloses modified overhaul slag based on tannic acid, a preparation method and application thereof, and belongs to the field of green resource recycling of solid wastes. Forming a tannin polymer coating layer on the surface of the overhaul slag powder through self-polymerization reaction of tannin, and grafting a functional group with a hydrophobic function on the surface of the coating layer through a chemical grafting method to form a hydrophobic protective layer, wherein the obtained product is the composite modified overhaul slag based on the tannin; wherein the substance having a hydrophobic functional group is octadecylamine or hexamethyldisilazane. The process reduces the concentration of pollutants in the sewage through process characteristics, and greatly reduces the wastewater treatment cost. Meanwhile, the problem that the long-term stability of the product obtained after the resource treatment of the existing overhaul slag and other pollutants with poor long-term stability is insufficient is solved. The composite film layer achieves the purposes of protecting pollutants from leakage and modifying the surface, and provides a new method for recycling hazardous wastes.

Description

Modified overhaul slag based on tannic acid and preparation method and application thereof

Technical Field

The invention belongs to the technical field of green resource recycling of solid wastes, and particularly relates to modified overhaul residues based on tannic acid, and a preparation method and application thereof.

Background

Various wastes are inevitably generated in the production process of the aluminum electrolysis production industry, and Overhauled Slag (OWRs) is one of the various wastes with larger yield. In recent years, overhaul residues are classified as dangerous wastes by the nation due to the characteristics of high toxicity, high content and the like of pollution components carried by the overhaul residues, and the cost of the aluminum industry production industry can be greatly increased by carrying out harmless treatment on the overhaul residues according to the national dangerous waste standard. Therefore, in order to reduce the treatment cost of the overhaul slag to relieve the pressure of the increase of the industrial cost of the aluminum electrolysis production on the industrial development, the research on the recycling approach of the overhaul slag becomes a hotspot in the research fields of the current environment, chemical industry and the like. The resource recycling process of the overhaul residues is less, and particularly in the category of wet process, inorganic salt is directly generated in the early stage so as to achieve the purpose of making the overhaul residues harmless and further recycling. The resource overhaul slag obtained by the method is an inorganic salt material, and fluorine elements in fluoride exist in an ion form, so that the fluoride is easy to dissolve out quickly under the condition of aqueous solution erosion, and the stability is poor. Therefore, the research on a new fluoride recycling process needs to optimize the overhaul slag recycling process to enhance the long-term stability of the solidified fluoride, and the process not only exerts the good mechanical property of the overhaul slag inorganic salt in the using process, but also ensures that the overhaul slag product can not be directly contacted with the environment, and finally achieves the purpose of long-term stable and effective utilization of the recycling overhaul slag.

The early method of the wet recycling treatment process of the overhaul residue in the aluminum industry mainly uses various inorganic fluoride ion curing agents, such as calcium fluoride, calcium chloride, calcium oxide and other calcium agents, and precipitates are generated through ion reaction to cure free fluoride ions. Although the purpose of recycling the overhaul slag can be achieved by the mode, the method has the following problems in the actual use process:

(1) cured fluoride has poor stability. In the actual use of inorganic precipitated fluoride in a short time, the solidified fluorine ions are dissolved out into the natural environment due to the erosion of the natural environment such as air and rainwater.

(2) Fluoride recovery costs are high. The content of fluorine ions in the overhaul residue waste liquid treated by the wet method can not directly reach the national wastewater discharge standard, and the wastewater after fluoride sedimentation still needs other processes for defluorination.

(3) The reuse way is less. The overhaul slag obtained by the prior recycling process has low activity and poor performance in practical use.

Therefore, an economical and simple modification process needs to be researched to solve the problem of low chemical activity of waste water and products in the process of recycling overhaul residues, and the modified overhaul residues are used as engineering material modifiers to increase the service performance of building materials.

Disclosure of Invention

In order to solve the technical problems, the invention provides modified overhaul residues based on tannic acid and a preparation method and application thereof. The product is used as a modifier applied to asphalt pavements, and can achieve the effects of improving the viscoelasticity and the deformation resistance of modified asphalt.

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

the first technical scheme is as follows: a modified overhaul slag based on tannic acid forms a tannic acid polymer coating layer on the surface of overhaul slag powder through self-polymerization of tannic acid, and then functional groups with a hydrophobic function are grafted on the surface of the coating layer through a chemical grafting method to form a hydrophobic protective layer, so that the obtained product is the modified overhaul slag based on tannic acid; wherein the substance having a hydrophobic functional group is octadecylamine or hexamethyldisilazane.

The second technical scheme is as follows: a preparation method of modified overhaul residues based on tannic acid comprises the following steps:

1) performing fluorine precipitation treatment on the overhaul slag powder, filtering, drying and grinding to obtain fluorine precipitation overhaul slag powder;

2) mixing the fluorine-deposited overhaul residue powder with a buffer solution to obtain an overhaul residue solution;

3) adding tannic acid into the overhaul residue solution, performing ultrasonic treatment, heating and stirring, filtering, washing, drying, re-grinding, directly soaking the obtained product in octadecylamine or hexamethyldisilane amine, performing hot-mixing treatment, standing, cleaning, drying and grinding the obtained product to obtain the modified overhaul residue based on the tannic acid.

In the operation process, the grain diameter of each grinding is the same as that of the overhaul slag powder.

Further, in the step 1), the particle size of the fluorine precipitation overhaul slag powder is 100-200 meshes.

Further, in the step 2), the pH value of the buffer solution is 8-9, and the solid-to-liquid ratio of the fluorine precipitation overhaul residue powder to the buffer solution is 1 g: (3-10) mL.

Further, in the step 3), the mass ratio of the tannic acid to the fluorine precipitation overhaul residue powder is (0.5-1.0): 5.

the fluorine precipitation treatment is a fluorine precipitation method for precipitating soluble fluoride in the overhaul slag into insoluble fluoride, and mainly uses inorganic and organic matters which can have a precipitation reaction with fluorine ions as a precipitating agent, so that the obtained fluorine precipitation overhaul slag has the properties of stability and hardness; the settling agent can be anhydrous calcium chloride, which can provide Ca ²⁺ The settling reaction direction in the reaction process is changed, and meanwhile, the polymerization rate of the tannic acid is accelerated by means of the chelation reaction with the tannic acid.

Further, in the step 3), the ultrasonic treatment time is 15-30min, the heating temperature is 25-60 ℃, the stirring time is 12-24h, and the rotation speed is 350-450 rpm.

Further, in the step 3), the dosage ratio of the octadecylamine or hexamethyldisilane amine to the fluorine precipitation overhaul residue powder is (5-7) mL:5 g.

Further, in the step 3), the hot-mixing treatment temperature is 60 ℃, the hot-mixing treatment time is 1-2 hours, the standing temperature is 25-60 ℃, and the standing time is 12-18 hours.

The third technical scheme is as follows: a composite modified asphalt is prepared through modifying asphalt by the modifying agent based on tannic acid and SBS (styrene-butadiene-styrene block copolymer) to obtain composite modified asphalt (OWRs/SBS). When the modified overhaul slag is doped into the asphalt, the temperature is kept constant at 200 ℃ in 150-class and the modified overhaul slag is dispersed at the rotating speed of 450rpm in 350-class, so that the overhaul slag powder is uniformly dispersed in the asphalt.

The mixing amount of the modified overhaul slag is 1.0-2.0% of the total mass of the asphalt, and the mixing amount of the SBS is 5% of the total mass of the asphalt.

The reaction principle of the invention is as follows:

calcium agents or other metal ions are used to react with the fluorine ions to form hard precipitates based on the self properties of the fluorine ions, then tannin coating layers are adhered to the surfaces of the fluorine-precipitating overhaul residue powder through the self-polymerization reaction of tannin, and in the process, the existing fluoride precipitation powder is also coated, so that the amount of sediments in direct contact with the solution in the solution is reduced, and the continuous precipitation of the fluorine ions in the solution is promoted. And finally, carrying out Michael addition and Schiff base reaction on a large number of hydroxyl groups on the surface of the overhaul residue coated by the tannic acid and amino groups of the modifier, and grafting oleophilic hydrophobic groups on the surface of the overhaul residue powder.

The invention adopts tannic acid as a coating layer to protect the inner core of the overhaul slag, and ensures that the overhaul slag cannot directly contact with the environment in the use process: the tannic acid coating layer is used as an organic polymer and has good stability and coating property. In the modification process, the overhaul slag powder can be used as a core to form a nucleocapsid structure, and simultaneously, a chemical grafting method is used for grafting hydrophobic groups outside the tannin coating layer to further form a hydrophobic protective layer, so that the excellent mechanical property of the overhaul slag as an inorganic salt is reserved, and the long-term stability of the recycled overhaul slag is greatly improved.

The invention utilizes tannic acid autopolymerization reaction, wraps the settled fluoride in the settling process, changes the amount of the sediment in the solution in the settling reaction process, promotes the further settling of free fluoride ions in the wastewater, and has less total process steps, thus having lower cost: in the process of recycling the overhaul residues, the tannic acid is polymerized by itself to form a coating layer to wrap solid powder in the solution, and the coating layer is isolated from the solution. The ion sedimentation reaction is used as a reversible reaction, and the concentration of the fluorine ions in the final solution is controlled by the solubility product in the reaction environment. The amount of the precipitate in the solution can be reduced by coating the tannic acid, so that the fluoride ions in the solution are further precipitated with calcium ions, the limit capability of directly precipitating the fluoride ions by using an inorganic calcium agent in the conventional process is broken through, the content of the fluoride ions in the wastewater generated by the process can reach the concentration of direct discharge, and the resource cost is greatly reduced.

Chemically grafting the surface of the overhaul slag to make the overhaul slag suitable for being used as a modifier in asphalt: the compatibility of the asphalt with the inorganic salt powder is poor, and the metal cations in the inorganic salt powder can reduce the service life of the asphalt. Therefore, the hydrophobic group is grafted on the tannin coating layer, the compatibility of the resource overhaul slag and the asphalt is improved, and the phenomenon that the water is directly contacted with the resource overhaul slag powder to cause ionization of metal cations to damage the service life of the asphalt is further prevented. Meanwhile, the asphalt serving as an oily organic matter can well protect the resource overhaul residues and further enhance the stability of the asphalt.

Compared with the prior art, the invention has the beneficial effects that:

1. in the reaction process, the tannic acid is added, is adhered to the surface of the overhaul slag powder, and is rapidly deposited and gathered on the surface of the overhaul slag powder to form a poly-tannic acid coating layer, the coating layer has lasting stability, and can be used as a link to increase the binding force between the inorganic overhaul slag powder and the asphalt; and the deposited poly-tannic acid layer also has functional groups such as hydroxyl, imino and the like, provides a large amount of active groups for further functionalization, is easy to react with amino groups in substances such as octadecylamine, hexamethyldisilane amine and the like to generate Schiff base and the like, and further promotes the hydrophobic functional groups to be efficiently grafted on the surface of the overhaul residue powder.

2. The invention well improves the low compatibility of the overhaul slag powder as an inorganic material with the asphalt, and helps the overhaul slag powder to be better and more uniformly dispersed in the asphalt, thereby providing a three-dimensional mechanical support and enhancing the elasticity of the asphalt. Meanwhile, the hydrophobic functional group obtained by secondary modification of the overhaul slag powder can improve the hydrophobic property of the asphalt so as to improve the water loss resistance of the asphalt, and the overhaul slag can also well ensure that the fluoride precipitate cannot be directly contacted with water, so that the fluoride is ionized to generate fluoride ions and flows into the environment.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 shows the complex shear modulus G of the overhaul slag/SBS composite modified asphalt of the application example 4 and the comparative example 1 ^* (10Hz) vs. temperature;

FIG. 2 shows the complex shear modulus G of the overhaul slag/SBS composite modified asphalt of the application example 5 and the comparative example 2 ^* (10Hz) vs. temperature;

FIG. 3 shows the complex shear modulus G of the overhaul slag/SBS composite modified asphalt of the application example 6 and the comparative example 3 of the present invention ^* (10Hz) vs. temperature;

FIG. 4 is a graph showing the effect of the amount of tannic acid added on the fluoride ion concentration in the overhaul residues;

FIG. 5 is a toxicity soaking experiment before and after overhaul slag modification.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

In the test process, the concentration of fluorine ions in each batch of overhaul residues is different, and the treatment sample needs to be tested to obtain the theoretical amount of fluorine deposition. The overhaul slag used in the invention is tested by a standard soaking process, and the solid-to-liquid ratio is 10 g: under the condition of 100mL, the fluorine ion concentration in the leaching solution is 2523.75 mg/L. The theoretical addition amount of the anhydrous calcium chloride is 7.38g/L through mole number calculation, and the actual addition amount of the anhydrous calcium chloride in the process flow is 5 times of the theoretical value, namely 36.9 g/L.

Preparation of Tris-HCl buffer: 0.6057g of Tris (Tris hydroxymethyl aminomethane) was dissolved in 100mL of water and titrated to pH with 1mol of HCl solution.

Example 1

(1) Weighing 5g of overhaul residues sieved to 100 meshes, dissolving the overhaul residues in 50mL of aqueous solution in a magnetic stirrer heated at a constant temperature of 50 ℃ for 30min, adding anhydrous calcium chloride with the total amount of 36.9g/L in two times, precipitating fluorine for 10min after adding the anhydrous calcium chloride each time, and performing vacuum filtration to obtain a product, and putting the product in an oven at a temperature of 60 ℃ for 8h for later use;

(2) grinding the fluorine-deposited overhaul residues obtained in the step (1) to 100 meshes again, and then removing water in an oven at 60 ℃ for 2 hours to obtain overhaul residue powder;

(3) placing 5g of the overhaul residue powder obtained in the step (2) into 50ml of Tris-HCl buffer solution with the pH value of 8.5, adding 0.5g of tannic acid, performing ultrasound in an ultrasonic cell disruption instrument for 15min, controlling the ultrasound temperature below 60 ℃ in a suspension ultrasound or physical heat dissipation mode, and stirring at the rotating speed of 350rpm for 12h at the temperature of 35 ℃;

(4) filtering the product after the reaction is finished, repeatedly washing the product for 3 times by using absolute ethyl alcohol and water, drying the product in a 60 ℃ drying oven for 12 hours to obtain a product, grinding the product to 100 meshes again, directly soaking the product in 5mL of ODA or HMDS solution, carrying out hot mixing for 1 hour at the hot mixing temperature of 60 ℃, then standing the product at a constant temperature of 45 ℃ for 12 hours, repeatedly washing the final product for 3 times by using the absolute ethyl alcohol and the water, drying and grinding the product to 100 meshes to obtain modified overhaul residues, namely octadecylamine/tannic acid composite modified overhaul residues (ODA/T-OWRs) or hexamethyldisilazane/tannic acid composite modified overhaul residues (HMDS/T-OWRs).

Example 2

(1) Weighing 5g of overhaul residues sieved to 150 meshes in 50mL of aqueous solution, dissolving out the overhaul residues in a magnetic stirrer heated at the constant temperature of 55 ℃ for 30min, adding anhydrous calcium chloride with the total amount of 36.9g/L in two times, precipitating fluorine for 10min after adding the anhydrous calcium chloride each time, and performing vacuum filtration to obtain a product, and putting the product in an oven at the temperature of 60 ℃ for 8h for later use;

(2) grinding the fluorine-deposited overhaul residues obtained in the step (1) to 150 meshes again, and then removing water in an oven at 60 ℃ for 2 hours to obtain overhaul residue powder;

(3) placing 5g of the overhaul residue powder obtained in the step (2) into 50ml of Tris-HCl buffer solution with the pH value of 8.0, adding 0.75g of tannic acid, performing ultrasound in an ultrasonic cell disruption instrument for 20min, controlling the ultrasound temperature below 60 ℃ in a suspension ultrasound or physical heat dissipation mode, and stirring at the rotating speed of 400rpm for 18h at the temperature of 40 ℃;

(4) filtering the product after the reaction is finished, repeatedly washing the product for 3 times by using absolute ethyl alcohol and water, drying the product in a 60 ℃ drying oven for 12 hours to obtain a product, grinding the product to 150 meshes again, directly soaking the product in 6.5mL of ODA or HMDS solution, carrying out hot mixing for 1.5 hours at the hot mixing temperature of 60 ℃, standing the product at the constant temperature of 50 ℃ for 13 hours, repeatedly washing the final product for 3 times by using the absolute ethyl alcohol and the water, drying and grinding the product to 150 meshes to obtain modified overhaul residues, namely octadecylamine/tannin composite modified overhaul residues (ODA/T-OWRs) or hexamethyldisilazane/tannin composite modified overhaul residues (HMDS/T-OWRs).

Example 3

(1) Weighing 5g of overhaul residues sieved to 200 meshes, dissolving the overhaul residues in 50mL of aqueous solution in a magnetic stirrer heated at the constant temperature of 55 ℃ for 30min, adding anhydrous calcium chloride with the total amount of 36.9g/L in two times, precipitating fluorine for 10min after adding the anhydrous calcium chloride each time, and performing vacuum filtration to obtain a product, and putting the product in an oven at the temperature of 60 ℃ for 8h for later use;

(2) grinding the fluorine-deposited overhaul residues obtained in the step (1) to 200 meshes again, and then removing water in an oven at 60 ℃ for 2 hours to obtain overhaul residue powder;

(3) placing 5g of the overhaul residue powder obtained in the step (2) into 50ml of Tris-HCl buffer solution with the pH value of 8.5, adding 1.0g of tannic acid, performing ultrasound in an ultrasonic cell disruption instrument for 30min, controlling the ultrasound temperature below 60 ℃ in a suspension ultrasound or physical heat dissipation mode, and stirring at the rotation speed of 450rpm for 12h at the temperature of 45 ℃;

(4) filtering the product after the reaction is finished, repeatedly washing the product for 3 times by using absolute ethyl alcohol and water, drying the product in a 60 ℃ drying oven for 12 hours to obtain a product, grinding the product to 200 meshes again, directly soaking the product in 5mL of ODA or HMDS solution, carrying out hot mixing for 1 hour at the hot mixing temperature of 60 ℃, then standing the product at a constant temperature of 45 ℃ for 14 hours, repeatedly washing the final product for 3 times by using the absolute ethyl alcohol and the water, drying and grinding the product to 200 meshes to obtain modified overhaul residues, namely octadecylamine/tannic acid composite modified overhaul residues (ODA/T-OWRs) or hexamethyldisilazane/tannic acid composite modified overhaul residues (HMDS/T-OWRs).

Application example 4

Weighing 150g of SK-70A asphalt, drying in a 135 ℃ oven for 2h to remove redundant moisture, adding the HMDS/T-OWRs or ODA/T-OWRs obtained in the embodiment 1 and SBS into the asphalt, keeping the temperature constant at 150 ℃, shearing for 2h under a 5000rpm high-speed shearing machine, and dispersing for 2h under a 400rpm high-speed shearing machine to obtain HMDS/T-OWRs/SBS or ODA/T-OWRs/SBS composite modified asphalt; the content of HMDS/T-OWRs or ODA/T-OWRs is 1% of the total mass of the asphalt, and the content of SBS is 5% of the total mass of the asphalt.

Application example 5

Weighing 150g of SK-70A asphalt, drying in a 135 ℃ oven for 2h to remove redundant moisture, adding the HMDS/T-OWRs or ODA/T-OWRs obtained in the embodiment 2 and SBS into the asphalt, keeping the temperature of 165 ℃ constant, shearing for 2h under a 5000rpm high-speed shearing machine, and dispersing for 2h under a 450rpm high-speed shearing machine to obtain HMDS/T-OWRs/SBS or ODA/T-OWRs/SBS composite modified asphalt; the content of HMDS/T-OWRs or ODA/T-OWRs is 1.5% of the total mass of the asphalt, and the content of SBS is 5% of the total mass of the asphalt.

Application example 6

Weighing 150g of SK-70A asphalt, drying in a 135 ℃ oven for 2h to remove redundant moisture, adding the HMDS/T-OWRs or ODA/T-OWRs obtained in the embodiment 3 and SBS into the asphalt, keeping the temperature of 175 ℃ constant, shearing for 2h under a 5000rpm high-speed shearing machine, and dispersing for 2h under a 450rpm high-speed shearing machine to obtain HMDS/T-OWRs/SBS or ODA/T-OWRs/SBS composite modified asphalt; the content of HMDS/T-OWRs or ODA/T-OWRs is 2.0% of the total mass of the asphalt, and the content of SBS is 5% of the total mass of the asphalt.

Comparative example 1

The difference from application example 4 is that HMDS/T-OWRs or ODA/T-OWRs in example 1 are replaced by OWRs which are only fluorine-precipitation treated, and OWRs/SBS composite modified asphalt is obtained.

Comparative example 2

The difference from application example 5 is that HMDS/T-OWRs or ODA/T-OWRs in example 1 are replaced by OWRs which are only fluorine-precipitation treated, and OWRs/SBS composite modified asphalt is obtained.

Comparative example 3

The difference from application example 6 is that HMDS/T-OWRs or ODA/T-OWRs in example 1 are replaced by OWRs which are only fluorine-precipitation treated, and OWRs/SBS composite modified asphalt is obtained.

Test example 1

DSR tests were carried out on application examples 4 to 6, comparative examples 1 to 3, and a control group (modified asphalt to which only SBS was added, and the SBS incorporation was 5% of the total mass of the asphalt) by pouring 1.0g of asphalt into the center of a test plate having a diameter of 25mm, moving the test plate to press the asphalt between the two test plates, heating the test piece dresser, correcting the excess asphalt at the periphery, and then adjusting the gap to a test gap of 1 mm. When the temperature is balanced, the device will automatically perform the test at a frequency of 10rad/s and the selected stress target value, and the recording and calculation are completed by the data acquisition system (for illustration, the HMDS-TA-OWRs and ODA-TA-OWRs/SBS in the attached figures 1-3 are HMDS/T-OWRs and ODA/T-OWRs/SBS in the embodiment).

FIG. 1 is a graph comparing the storage modulus of tests on the products obtained in comparative example 1 using example 4. As can be seen from fig. 1, the complex shear modulus G of the HMDS/T-OWRs or ODA/T-OWRs/SBS composite modified asphalt in application example 4 is greater than the complex shear modulus G of the fluorine precipitation-only OWRs/SBS modified asphalt in comparative example 1 at the same temperature, and it is demonstrated that the overhaul residues modified by tannic acid, hexamethyldisilane amine and octadecylamine, when added into the asphalt, can harden the asphalt, thereby improving the deformation resistance.

FIG. 2 is a graph comparing the storage modulus of the test using the product obtained in example 5 and comparative example 2. As can be seen from FIG. 2, when the storage moduli G ' of the HMDS/T-OWRs or the ODA/T-OWRs/SBS composite modified asphalt are at the same temperature, the storage moduli G ' of the HMDS/T-OWRs or the ODA/T-OWRs/SBS composite modified asphalt are greater than the storage moduli G ' of the fluorine precipitation-only treated OWRs/SBS modified asphalt, which indicates that the elastic properties of the HMDS/T-OWRs or the ODA/T-OWRs modified asphalt are enhanced.

FIG. 3 is a graph comparing the storage modulus of tests using the products obtained in example 6 and comparative example 3. As can be seen from FIG. 3, the loss modulus G' of the HMDS/T-OWRs or ODA/T-OWRs/SBS composite modified asphalt at the same temperature is greater than that of the fluorine precipitation-only OWRs/SBS modified asphalt, which indicates that the viscosity performance of the HMDS/T-OWRs or ODA/T-OWRs modified asphalt is enhanced.

As can be seen from FIGS. 1 to 3, the complex shear modulus G, storage modulus G 'and loss modulus G' of the HMDS/T-OWRs or ODA/T-OWRs/SBS composite modified asphalt are all larger than those of the fluorine precipitation-only OWRs/SBS modified asphalt. This indicates that while the tack is improved, the elasticity is also improved somewhat. The modified overhaul slag powder is proved to be capable of effectively improving the viscoelastic property and the deformation resistance of the asphalt after being added into the asphalt.

Test example 2

The same as example 3 except that the amounts of tannic acid added were 0g, 0.25g, 0.5g, 0.75g, 1.0g and 1.25g, respectively, and the results are shown in FIG. 4.

As can be seen from FIG. 4, as the amount of tannic acid added increases, the fluoride ion concentration gradually decreases, reaching the lowest at 1.0g, but increasing slightly as the amount of tannic acid is increased, which demonstrates that at 0.75g, tannic acid has completely wrapped the overhaul residue, and 0.75g is the lowest addition point for reaching the performance standard.

Test example 3

The hexamethyldisilazane/tannic acid composite modified overhaul residue obtained in example 3 and the overhaul residue before modification were subjected to a toxicity soaking experiment, and the results are shown in fig. 5.

As can be seen from fig. 5, the modified overhaul slag shows an obvious fluoride sequestration capacity in a long-time toxicity soaking experiment, and although a certain leaching condition occurs in the early stage, it can be seen that the stable fluoride ion concentration has good stability, and the fluoride ion concentration is almost unchanged in the soaking process of more than 50 days.

After the modified overhaul slag obtained in the example 3 is used as the modifier and added into the asphalt, the asphalt can form a protective layer on the surface of the modifier, the modified modifier is uniformly distributed in the asphalt, the surface interfacial force is strong, and the asphalt can uniformly and strictly coat the surface of the modifier, so that a better protection effect can be shown in the actual use process.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included therein.

Claims

1. The modified overhaul slag based on the tannic acid is characterized in that a tannic acid polymer coating layer is formed on the surface of overhaul slag powder through self-polymerization of the tannic acid, and then a functional group with a hydrophobic function is grafted to the surface of the coating layer through a chemical grafting method to form a hydrophobic protective layer, so that the obtained product is the modified overhaul slag based on the tannic acid; wherein the substance having a hydrophobic functional group is octadecylamine or hexamethyldisilazane.

2. The method for preparing the modified tannin based overhaul slag as claimed in claim 1, which is characterized by comprising the following steps of:

3. The method as claimed in claim 2, wherein in step 1), the particle size of the fluorine precipitating overhaul residue powder is 100-200 mesh.

4. The preparation method according to claim 2, wherein in the step 2), the pH of the buffer solution is 8-9, and the solid-to-liquid ratio of the fluorine precipitation overhaul residue powder to the buffer solution is 1 g: (3-10) mL.

5. The preparation method according to claim 2, wherein in the step 3), the mass ratio of the tannic acid to the fluorine precipitation overhaul slag powder is (0.5-1.0): 5.

6. the preparation method as claimed in claim 2, wherein in the step 3), the ultrasonic treatment time is 15-30min, the heating temperature is 25-60 ℃, the stirring time is 12-24h, and the rotation speed is 350-450 rpm.

7. The preparation method according to claim 2, wherein in the step 3), the ratio of the octadecyl amine or hexamethyldisilane amine to the fluorine precipitating overhaul residue powder is (5-7) mL:5 g.

8. The preparation method of claim 2, wherein in the step 3), the hot-mixing treatment temperature is 60 ℃, the hot-mixing treatment time is 1-2h, the standing temperature is 25-60 ℃, and the standing time is 12-18 h.

9. A modified asphalt, which is characterized in that the tannin-based modified slag modifier disclosed by claim 1 is used together with SBS to modify asphalt to obtain composite modified asphalt.

10. The composite modified asphalt of claim 9, wherein the modified overhaul slag is incorporated in an amount of 1.0 to 2.0% of the total mass of the asphalt.