CN113332965B - Magnetic fly ash @ PDMS sponge material for oil-water separation and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of resource utilization of solid waste, and discloses a magnetic fly ash@PDMS sponge material used for oil-water separation and a preparation method thereof. In the present invention, the magnetic fly ash material is first prepared from fly ash as a raw material, and then the obtained magnetic fly ash material, PDMS prepolymer and curing agent are poured into a beaker, after fully stirring, anhydrous ethanol is added to mix evenly, and then slowly drip Add water, fully stir and emulsify, pour into a mold to form, and then dry and solidify to obtain dark brown spongy magnetic fly ash @PDMS. The material obtained in the present invention has completely different wettability to oil and water, which can effectively avoid the limitation of the prior art and realize efficient oil-water separation (that is, water droplets form spherical shapes on the surface, while oil droplets will penetrate into the material). Simultaneously, the present invention explores a new way of resource utilization of solid waste fly ash, which allows fly ash to "turn waste into treasure" with low cost and achieves the purpose of treating waste with waste and being green and environmentally friendly.

Description

A magnetic fly ash@PDMS sponge material for oil-water separation and its preparation method

technical field

The invention relates to the technical field of resource utilization of solid waste, in particular to a magnetic fly ash@PDMS sponge material used for oil-water separation and a preparation method thereof.

Background technique

Fly ash is fine solid particles in the flue gas ash produced by fuel combustion, mainly containing silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and iron oxide (Fe ₂ O ₃ ). According to the coal consumption situation in our country, about 250-300kg of fly ash is produced by burning 1 ton of coal. If a large amount of fly ash is not controlled or treated, it will cause air pollution, and if it enters the water, it will silt up the river course, and certain chemical substances in it will cause harm to organisms and humans. Since the 1920s, many countries have studied the processing and utilization of fly ash, and achieved certain results. Fly ash has been widely used in the preparation of cement and various lightweight building materials. In addition, fly ash can also be used as floating beads and fertilizers.

Oil spills and organic wastes have caused serious damage to water resources. However, their treatment methods, such as flotation, combustion, and oil-absorbing felts, have disadvantages such as poor selectivity and low efficiency. In the article "Modification of fly ash and its application in the treatment of oily wastewater", Yang Zili et al. used power plant waste fly ash as raw material, and carried out surface modification on it to achieve the purpose of expanding the pore size of fly ash. Polymer quaternary ammonium salt groups were grafted on the surface of coal ash to overcome the problem of reduced dirt-holding capacity of the filter material due to bio-fixation growth. At the same time, the application of modified fly ash in oily wastewater was investigated. Under the optimal process conditions, that is, the temperature is 30°C, the mass concentration of the adsorbent is 33g/L, and the pH is 10, the removal rate of oil by the modified fly ash is above 90%. However, this method also has disadvantages such as poor selectivity and low efficiency, and the modification method is complicated.

Contents of the invention

The object of the present invention is to overcome the deficiency of the above-mentioned background technology, and provide a magnetic fly ash@PDMS sponge material and its preparation method for oil-water separation. The present invention prepares a superhydrophobic material with bionic function by imitating lotus leaves and using fly ash as a raw material. The obtained material has a completely different wettability to oil and water, which can effectively avoid the limitations of the prior art and realize efficient oil-water separation (that is, water droplets in its The surface forms a ball, and the oil droplets penetrate into the material). At the same time, a new way of resource utilization of solid waste fly ash has been explored, so that fly ash can "turn waste into treasure" with low cost, and achieve the purpose of treating waste with waste and being green and environmentally friendly.

In order to achieve the purpose of the present invention, the present invention utilizes the natural porous structure of solid waste fly ash to construct a PDMS framework to roughen it, and improve the oil-water separation efficiency. In addition, remote control through an external magnetic field will greatly facilitate the separation, recovery and transportation of oil pollution. Therefore, the present invention introduces magnetic components into PDMS to endow it with magnetic responsiveness, so that it moves to the oil-contaminated area under the manipulation of an external magnetic field to separate and recover the oil.

The preparation method of the magnetic fly ash@PDMS sponge material used for oil-water separation in the present invention comprises the following steps:

(1) Preparation of magnetic fly ash: Pour FeCl ₂ 4H ₂ O and FeCl ₃ 6H ₂ O into a three-necked flask, add distilled water, stir, then add ammonia water drop by drop until the pH is 9.5-10.5, drop In the process of adding ammonia water, black substances can be seen to form. After the solution turns black, continue to react. Add sodium citrate solution to the system, heat up and age for stability, add fly ash, continue to stir and react, and then separate solid from liquid. Wash the solid with distilled water repeatedly to Neutral, mechanically pulverized after drying to obtain magnetic fly ash material (CFA@Fe ₃ O ₄ );

(2) Preparation of magnetic fly ash@PDMS biomimetic material: Take the magnetic fly ash material obtained in step (1), PDMS prepolymer and curing agent and pour them into a beaker. After fully stirring, add absolute ethanol to mix evenly, and then slowly drop Add water, fully stir and emulsify, pour into a mold for molding, and then dry and solidify to obtain dark brown spongy magnetic fly ash @PDMS (CFA@Fe ₃ O ₄ @PDMS).

Further, in some embodiments of the present invention, the mass ratio of FeCl ₂ .4H ₂ O, FeCl ₃ .6H ₂ O to fly ash in the step (1) is 1:1-4:2-8.

Further, in some embodiments of the present invention, the stirring in the step (1) is at 75-85° C., and the stirring time may be 5-15 minutes.

Preferably, in some embodiments of the present invention, the reaction is continued for 25-35 minutes after the solution in step (1) turns black.

Further, in some embodiments of the present invention, in the step (1), 0.25-0.35M sodium citrate solution is added to the system, and the amount added can be 15-25mL.

Further, in some embodiments of the present invention, in the step (1), the temperature is raised to 85-95° C. for aging and stabilization, and the aging stabilization time may be 25-35 minutes.

Further, in some embodiments of the present invention, the drying in the step (1) is at 75-85° C., and the drying time may be 10-14 hours.

Further, in some embodiments of the present invention, in the step (2), the curing agent is selected from one or more of Dow Corning 184 curing agent, hydrogen-containing silicone oil and platinum catalyst; preferably, in some of the present invention In an embodiment, the curing agent in the step (2) is Dow Corning 184 curing agent.

Further, in some embodiments of the present invention, the mass ratio of the magnetic fly ash material, the PDMS prepolymer and the curing agent in the step (2) is 0.4-0.6:9-11:1.

Further, in some embodiments of the present invention, the mass ratio of magnetic fly ash material, absolute ethanol and water in the step (2) is 1:8-12:16-24.

Further, in some embodiments of the present invention, the drying and curing in the step (2) is performed in a drying oven at 110-130° C. for 1-2 hours.

Further, in some embodiments of the present invention, the time for stirring and emulsifying in the step (2) is 10-20 minutes.

On the other hand, the present invention also provides a magnetic fly ash@PDMS sponge material for oil-water separation, the magnetic fly ash@PDMS sponge material is prepared by the aforementioned method.

The invention uses modified fly ash as a raw material to prepare magnetic fly ash@PDMS, which not only improves the oil-water separation effect of PDMS, but also improves its flexibility, and can remotely process/separate and recycle oil pollution under the control of an external magnetic field and transportation to solve the thorny problems of cleaning up floating oil on the water surface and oil spills causing negative impacts on the environment and organisms. Moreover, the oil absorbed inside the material obtained in the present invention can be recovered by simple extrusion, and can be restored to its original state after extrusion for recycling.

Description of drawings

Fig. 1 is a schematic diagram of the hydrophobic performance/oil-water separation performance characterization of the sponge bionic material obtained in Example 1 of the present invention;

Fig. 2 is a schematic diagram of the flexible deformation of the sponge biomimetic material obtained in Example 2 of the present invention during the oil absorption-extrusion-drying process;

Fig. 3 is a comparison chart of adsorption multiples of pure PDMS, fly ash@PDMS, Fe ₃ O ₄ @PDMS and the sponge biomimetic material obtained in Example 3.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is only used to explain the present invention, not to limit the present invention.

As used herein, the terms "comprises," "including," "has," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or device comprising listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to such composition, step, method, article, or device. element.

When amounts, concentrations, or other values or parameters are expressed in terms of ranges, preferred ranges, or ranges bounded by a series of upper preferred values and lower preferred values, it is to be understood that any range upper or preferred value combined with any lower range limit is specifically disclosed. All ranges formed by any pairing of values or preferred values, whether or not such ranges are individually disclosed. For example, when the range "1 to 5" is disclosed, the recited range should be construed to include the ranges "1 to 4," "1 to 3," "1 to 2," "1 to 2, and 4 to 5" , "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, that range is intended to include its endpoints and all integers and fractions within the range.

In addition, descriptions of terms such as "one embodiment", "some embodiments", "example", "specific examples", or "some examples" described below mean specific features, structures described in conjunction with the embodiments or examples , material or feature is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not constitute conflicts with each other.

Example 1

① Preparation of magnetic fly ash: Pour FeCl ₂ 4H ₂ O (1.72g) and FeCl ₃ 6H ₂ O (4.72g) into a three-necked flask, add 80mL of distilled water, stir at 80°C for 10min, then drop by drop Add ammonia water until the pH is 10; black substances can be seen during the dropping process, and continue to react for 30 minutes after the solution turns black. 8.00g of fly ash was stirred and reacted for 2 hours, separated from solid and liquid, washed repeatedly with distilled water until neutral, dried at 80°C for 12 hours, and crushed mechanically to obtain magnetic fly ash material (CFA@Fe ₃ O ₄ ).

②Preparation of magnetic fly ash@PDMS biomimetic material: Weigh 0.20g and 4.00g of self-made magnetic fly ash and PDMS prepolymer 0.40g and pour them into a beaker, stir well, add 2.00g of absolute ethanol and mix evenly. Then slowly add 4.0g of water dropwise, fully stir and emulsify for 15 minutes, pour it into a funnel mold with a sand core to form it, and then put it in a 120°C drying oven to cure for 1.5 hours to obtain a dark brown spongy magnetic fly ash @PDMS (CFA@Fe ₃ O ₄ @PDMS), hereinafter referred to as sponge biomimetic material, its sponge morphology is shown in Figure 1.

Example 2

①Preparation of magnetic fly ash: FeCl ₂ 4H ₂ O (2.70g) and FeCl ₃ 6H ₂ O (2.70g) were poured into a three-necked flask with a mass ratio of 1:1, and 80mL of distilled water was added. Stir at ℃ for 10 minutes, then add ammonia water drop by drop until the pH is 10; black substances can be seen during the dropping process, and continue to react for 30 minutes after the solution turns black, add 20mL of 0.3M sodium citrate solution to the system, and heat up Stable at 90°C for 30 minutes, add 8.00 g of fly ash, continue to stir for 2 hours, separate solid and liquid, wash repeatedly with distilled water until neutral, dry at 80°C for 12 hours, and mechanically pulverize to obtain magnetic fly ash material (CFA@Fe ₃ O ₄ ).

②Preparation of magnetic fly ash@PDMS biomimetic material: Weigh 0.20g and 3.60g of self-made magnetic fly ash and PDMS prepolymer 0.40g respectively and pour them into a beaker. After fully stirring, add 2.00g of absolute ethanol and mix evenly. Then slowly add 4.0g of water dropwise, fully stir and emulsify for 15 minutes, pour it into a funnel mold with a sand core to form it, and then put it in a 120°C drying oven to cure for 1.5 hours to obtain a dark brown spongy magnetic fly ash @PDMS (CFA@Fe ₃ O ₄ @PDMS).

Example 3

① Preparation of magnetic fly ash: FeCl ₂ 4H ₂ O (1.10g) and FeCl ₃ 6H ₂ O (4.40g) were poured into a three-necked flask with a mass ratio of 1:4, and 80mL of distilled water was added. Stir at ℃ for 10 minutes, then add ammonia water drop by drop until the pH is 10; black substances can be seen during the dropping process, and continue to react for 30 minutes after the solution turns black, add 20mL of 0.3M sodium citrate solution to the system, and heat up Stable at 90°C for 30 minutes, add 8.00 g of fly ash, continue to stir for 2 hours, separate solid and liquid, wash repeatedly with distilled water until neutral, dry at 80°C for 12 hours, and mechanically pulverize to obtain magnetic fly ash material (CFA@Fe ₃ O ₄ ).

② Weigh 0.20g and 4.40g of self-made magnetic fly ash and 0.40g of curing agent into a beaker respectively, after stirring fully, add 2.00g of absolute ethanol and mix evenly, then slowly add 4.0g of water dropwise, fully stir and emulsify After 15 minutes, it was poured into a sand core funnel mold for molding, and then put into a 120°C drying oven to cure for 1.5 hours to obtain a dark brown spongy magnetic fly ash @PDMS (CFA@Fe ₃ O ₄ @PDMS).

performance testing

Oil-water separation performance

The deionized water (water phase) dyed with blue ink and the n-hexane (oil phase) dyed with oil-soluble black dye were respectively dropped on the surface of the sponge bionic material obtained in Example 1, and the experimental results are shown in Figure 1.

It can be seen from Figure 1 that the blue ink deionized water presents a typical spherical shape on the surface of the material, while the black n-hexane penetrates into the material, indicating that the material has good superhydrophobicity.

Reusable performance

For the characterization of the reusable performance of the sponge bionic material obtained in Example 2, an experiment as shown in Figure 2 was designed. The sponge material was put into n-hexane dyed with Sudan Red II. In only 10 minutes, the thickness of the material could be observed by Swell from 0.6cm to 1.2cm (the middle picture in Figure 2); take it out and weigh it to calculate the adsorption multiple of the sponge bionic material (adsorption multiple = the weight of the material after absorbing n-hexane / the weight of the material), and the material can absorb 6 times its own weight of n-hexane; simple compression can extrude its internal oil phase, and the material will recover to its original state within 30 minutes after extrusion (the rightmost picture in Figure 2); after 5 adsorption-extrusion-drying reuse tests, the results show that its oil absorption capacity It remained stable without significant decline, showing good reusability.

Comparison of Adsorption Properties

According to the experimental process of the reusable performance test, the adsorption times of pure PDMS, fly ash@PDMS, Fe ₃ O ₄ @PDMS and the sponge biomimetic material obtained in Example 3 to absorb n-hexane were tested, and the results are shown in Figure 3. It can be seen from Figure 3 that the magnetic fly ash@PDMS sponge biomimetic material has the highest adsorption multiple, reaching 6 times its own weight, indicating that the addition of magnetic fly ash significantly improves the oil-water separation effect of the hydrophobic biomimetic material PDMS.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (12)

1. A preparation method of a magnetic fly ash @ PDMS sponge material for oil-water separation is characterized by comprising the following steps:

(1) FeCl is added ₂ ·4H ₂ O and FeCl ₃ ·6H ₂ Pouring O into a three-neck flask, adding distilled water, stirring, dropwise adding ammonia water until the pH is 9.5-10.5, wherein a black substance is generated in the process of dropwise adding the ammonia water, continuing to react after the solution becomes black, adding a sodium citrate solution into the system, heating, ageing and stabilizing, adding fly ash, continuously stirring for reaction, carrying out solid-liquid separation, repeatedly washing the solid with distilled water to be neutral, drying, and mechanically crushing to obtain a magnetic fly ash material; wherein the FeCl ₂ ·4H ₂ O、FeCl ₃ ·6H ₂ The mass ratio of the O to the fly ash is 1-4;

(2) Pouring the magnetic fly ash material obtained in the step (1), a PDMS prepolymer and a curing agent into a beaker, fully stirring, adding absolute ethyl alcohol, uniformly mixing, slowly dripping water, fully stirring and emulsifying for 10-20min, pouring into a mold for molding, and then putting into a drying oven at 110-130 ℃ for drying and curing for 1-2h to obtain dark brown spongy magnetic fly ash @ PDMS; wherein the mass ratio of the magnetic fly ash material, the PDMS prepolymer and the curing agent is (0.4-0.6); the curing agent is selected from one or more of Dow Corning 184 curing agent, hydrogen-containing silicone oil and platinum catalyst.

2. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation according to claim 1, wherein the stirring in the step (1) is performed at 75-85 ℃.

3. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation according to claim 2, wherein the stirring time is 5-15min.

4. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation according to claim 3, wherein the reaction is continued for 25-35min after the solution turns black in step (1).

5. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation as claimed in claim 1, wherein in the step (1), 0.25-0.35M sodium citrate solution is added into the system.

6. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation as claimed in claim 5, wherein the amount of the added sodium citrate solution is 15-25mL.

7. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation according to claim 1, wherein the temperature in step (1) is raised to 85-95 ℃ for aging and stabilization.

8. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation as claimed in claim 7, wherein the aging stabilization time is 25-35min.

9. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation according to claim 1, wherein the drying in the step (1) is drying at 75-85 ℃.

10. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation according to claim 9, wherein the drying time is 10-14h.

11. The preparation method of the magnetic fly ash @ PDMS sponge material for oil-water separation according to claim 1, wherein the mass ratio of the magnetic fly ash material to the absolute ethyl alcohol to the water in the step (2) is 1.

12. The magnetic fly ash @ PDMS sponge material for oil-water separation is characterized by being prepared by the preparation method of any one of claims 1-11.

Images