CN111718603A - Silica Surface Modification Method - Google Patents

Abstract

The present invention provides a method for modifying the surface of silica, comprising: cleaning the surface of a silica sample; and continuously heating the silica sample at 490° C. to 510° C. for 30 to 35 minutes. The surface of the silica sample is hydroxylated; the silica sample is placed in an electrolytic cell filled with 0.025%-0.030% calcium chloride or magnesium chloride solution, and the silica is excited by 1.5V/cm-1.7V/cm direct current. surface, to promote the Si‑O‑Si bond to break and combine with H ⁺ and ^OH‑ in water. Alkylation of silica sample; place the silica sample after hydroxylation by electro-excitation method in the preferred KH560: benzene: methanol = 1: (9-11): (0.5-0.7) new silane coupling agent reaction In the liquid, the alkylation reaction was completed to obtain a surface-modified silica sample. After the silica sample is modified by the silica surface modification method provided by the present invention, the wetting angle of deionized water on the surface of the silica sample is significantly increased, and the hydrophobicity of the surface of the silica sample is greatly improved.

Description

Silica Surface Modification Method

technical field

The invention relates to the technology of inorganic non-metallic materials, in particular to a method for modifying the surface of silica.

Background technique

Silica is the main mineral in sandstone reservoirs, and its surface wettability directly affects the occurrence and migration characteristics of oil and water in pores. In order to accurately study the effect and mechanism of different wettability, it is first necessary to realize the effective regulation of the surface wettability of the silica substrate. Ordinary silica structure contains more silanol groups, which makes the surface show strong hydrophilic properties. Combines more water molecules and polar substances. By modifying the surface of silica, the wettability of the silica surface can be changed, thereby improving the hydrophobicity of the silica, which is called the modification of the silica surface.

At present, silica surface modification methods mainly include alcohol ester modification method, polymer grafting method and silane coupling agent method, all of which are aimed at reducing the silanol groups on the surface of silica and forming an organic matrix on the surface. -The bonding layer of silane coupling agent-inorganic matrix to achieve the specific effect of hydrophobic and lipophilic. Neither the alcohol lipid modification method nor the polymer grafting method has pretreated the surface of the silica, resulting in fewer reactive sites for hydroxyl groups on the surface of silica for grafting, resulting in a very limited number of grafted functional groups, resulting in a very limited number of grafted functional groups. Silicon modification effect is poor. In addition to the problems of incomplete cleaning of the silica surface and insufficient hydroxylation of silica, the silane coupling agent method is strongly hydrolyzed, and the strong agglomeration of its hydrolyzed products leads to the failure of a large number of silane coupling agents for grafting. Functional groups cannot be combined with hydroxyl groups on the surface of silica, which also causes the problem of poor silica modification effect.

To sum up, the traditional silica surface modification technologies all have the problem of poor modification effect.

SUMMARY OF THE INVENTION

The invention provides a silica surface modification method, which is used to solve the problem of poor modification effect existing in the traditional silica surface modification technology. For the silica modified by the silica surface modification method of the present invention, the surface water-phase wetting angle is greatly increased, and the hydrophobicity is greatly improved.

In one aspect, the present invention provides a method for surface modification of silica, comprising:

The cleaned silica sample is heated to 490 ℃ ~ 510 ℃ at a high temperature and heated continuously for 30 to 35 minutes to remove the residual organic pollutants and adsorbed moisture on the surface of the silica sample to the maximum extent; The silicon oxide sample was subjected to electro-active hydroxylation treatment; the surface of silicon dioxide was electrically excited by direct current, and the Si-O-Si bond was broken and combined with H ⁺ and OH ^- in water, which effectively increased the hydroxyl groups on the surface of silicon dioxide;

After the electro-excited hydroxylation treatment is completed, the silica sample is placed in a new silane coupling agent reaction solution comprising coupling agent KH560, benzene and methanol, and the oscillating treatment and the constant temperature alkylation reaction are carried out in turn to complete the alkylation reaction. After the reaction is completed, a surface-modified silica sample is obtained.

In the method provided by the present invention, in the cleaning stage of the silica sample, the silica sample is placed in a muffle furnace, and heated to 490°C to 510°C at a high temperature for 30 to 35 minutes, so as to completely remove the adsorbed particles on the surface of the sample. Water molecules and pollutants, impurities, etc.

After the surface of the silicon dioxide sample is cleaned at high temperature, the silicon dioxide sample is electro-excited to be hydroxylated. As shown in Figure 1, the silicon dioxide sample is placed in a reaction vessel containing an electrolyte solution, and the silicon dioxide sample is Connect the DC power supply on both sides. In the electro-active hydroxylation treatment, an inorganic salt solution can be used as an electrolytic medium. The inventors found that when the electro-active hydroxylation treated electrolyte is a magnesium chloride solution with a mass fraction of 0.025% to 0.030% or a calcium chloride solution with a mass fraction of 0.025% to 0.030% and the voltage on a silicon dioxide sample per unit length When the range is 1.2V～1.7V, the wetting angle has a more significant improvement. Preferably, the voltage of the electro-active hydroxylation treatment is 1.6 V/cm, and the corresponding electrolyte is a calcium chloride solution with a mass fraction of 0.025%.

After the electro-active hydroxylation treatment is completed, a new coupling agent reaction solution comprising coupling agent KH560, benzene and methanol is prepared, and the new coupling agent reaction solution is shaken. The coupling agent KH560, benzene and methanol are added into the beaker, and after mixing, they are subjected to shaking treatment for 3 to 5 minutes, and the shaking treatment is ultrasonic shaking treatment. During the preparation of the new coupling agent reaction solution, the vibration is conducive to the full dispersion of methanol in the coupling agent, inhibiting the hydrolysis of the coupling agent KH560 and the condensation reaction of the hydrolyzed product, and enhancing the dispersion stability of the reaction solution.

The silica sample after electro-excited hydroxylation treatment was then placed in a new coupling agent reaction solution comprising coupling agent KH560, benzene and methanol, and subjected to shaking treatment and isothermal alkylation reaction in sequence, and the shaking treatment was ultrasonic wave. Shake, and the time of ultrasonic shaking is 3 to 5 minutes. In the process of ultrasonic vibration, methanol can effectively inhibit the hydrolysis of the coupling agent KH560 and the condensation reaction of the hydrolyzed products, enhance the dispersion stability of the solution, and promote the effective alkylation of the coupling agent KH560 with the hydroxyl groups on the surface of the silica sample. Increase the hydrophobicity of the silica sample surface. The isothermal alkylation reaction is to place the silica sample in the novel coupling agent reaction solution to carry out the alkylation reaction, the temperature of the alkylation reaction can be 90°C, and the time of the alkylation reaction can be 6 ~8 hours.

In the method provided by the present invention, before placing the silica sample in the novel coupling agent reaction solution, the novel coupling agent reaction solution needs to be prepared first. In the new coupling agent reaction solution, the coupling agent KH560, benzene and methanol must be included. Among them, the coupling agent KH560 is used for the alkylation of the surface of the silica sample, and the methanol is used to inhibit the hydrolysis of the coupling agent KH560. And to inhibit the condensation reaction of the hydrolysis product of the coupling agent KH560, benzene is used as a reagent to disperse the coupling agent KH560 and methanol. When selecting the reagents of the new coupling agent reaction solution, the use of benzene dispersion coupling agent KH560 and methanol can effectively improve the hydrophobicity of the surface of the silica sample.

In the experiment of selecting the reagents of the new coupling agent reaction solution, the selected reagents were ethanol, n-hexane and benzene respectively. After the silica samples, it was found that the wetting angle of deionized water on the surface of the silica samples could be further improved when the reagent was benzene, and the surface of the silica samples was more hydrophobic.

In one of the embodiments, in the novel coupling agent reaction solution, the volume ratio of coupling agent KH560, benzene and methanol is 1:(9-11):(0.5-0.7).

Preferably, when the coupling agent KH560 is used, the volume ratio of benzene and methanol is 1:10:0.6, and the corresponding electro-active hydroxylation treatment voltage is 1.6V/cm, and the electrolyte is a calcium chloride solution with a mass fraction of 0.025% , the hydroxylation effect of silica samples is better.

In one of the embodiments, the time for the electro-active hydroxylation treatment is 1-1.5 hours.

The hydroxylation effect is reduced if the time of the electro-active hydroxylation is too short, and the electro-active hydroxylation treatment time of 1-1.5 hours can effectively increase the active reaction sites of silanols available for grafting on the surface of the silica sample.

In one of the embodiments, the electro-active hydroxylation treatment is performed after heating the cleaned silica sample at a high temperature to 500° C. and continuously heating for 30 minutes.

The cleaned silica samples were heated to 490°C, 500°C, 510°C, 520°C, and 530°C, respectively, for 30 min. Cool to normal temperature in a vacuum drying oven, and then measure the wetting angle of deionized water on the surface of the silica sample, that is, the surface of the quartz glass slide corresponds to: 38.01°, 36.244°, 37.481°, 39.657°, 40.314°. The experimental results show that the minimum wetting angle can be achieved at 500 °C, the surface cleaning is the most thorough, and the pretreatment is the most sufficient. Therefore, 500°C is the optimum heating temperature.

In one of the embodiments, the temperature of the isothermal alkylation reaction is 90° C. and the time is 6-8 hours.

It should be noted that the time of the constant temperature alkylation reaction is 6-8 hours, and if the time is too short, the efficiency of grafting the silane coupling agent on the surface of the silica is not high. When the temperature of the isothermal alkylation reaction is 90°C and the reaction time is 6 to 8 hours, the coupling agent KH560 and the silanols available for grafting on the surface of the silica sample undergo an alkylation reaction, and then Increase the hydrophobicity of the silica sample surface.

In one of the embodiments, the time of the shaking treatment is 3-5 minutes.

It can be understood that, the time of the shaking treatment can be selected by the experimenter according to actual needs. The oscillating treatment time of 3 to 5 minutes is favorable for methanol to be fully dispersed in the coupling agent, which can help methanol effectively inhibit the hydrolysis of the coupling agent KH560 and the condensation between the hydrolyzed products.

In one of the embodiments, ultrasonic cleaning is performed on the silica sample sequentially using acetone and deionized water to obtain the cleaned silica sample.

The number of times of the ultrasonic cleaning is 3 times, and each cleaning time is 3-5 minutes. It can be understood that proper cleaning is beneficial to completely remove impurities on the surface of silica and reduce the influence on the experimental results.

In one embodiment, after the constant temperature alkylation reaction, it further includes:

The silica sample after the constant temperature alkylation reaction is washed with ethanol, and after drying, the surface-modified silica sample is obtained.

The present invention provides a method for surface modification of silica, which comprises heating the cleaned silica sample at a high temperature to 490° C. to 510° C. for 30 minutes to 35 minutes, and then electrifying the silica sample. Excitation hydroxylation treatment; after the electric excitation hydroxylation treatment is completed, the silica sample is placed in a new coupling agent reaction solution including coupling agent KH560, benzene and methanol to perform vibration treatment and constant temperature alkylation reaction in sequence, Surface-modified silica samples were obtained. The silica surface modification method provided by the present invention can greatly increase the wetting angle of deionized water on the surface of the silica sample, thereby greatly improving the hydrophobicity of the surface of the silica sample. It has good application effects for micro-etching models made of ordinary silica substrates in oil and gas industries, regulation of surface wettability of microfluidic chips, and internal modification of silica capillaries.

Description of drawings

Figure 1 is a schematic diagram of electro-active hydroxylation treatment.

Figure 2 is a test chart of the silica sample before modification.

Figure 3 is a test chart of the modified silica sample.

The foregoing drawings have shown clear embodiments of the present disclosure, and will be described in greater detail hereinafter. The drawings and written description are not intended to limit the scope of the disclosed concepts in any way, but rather to illustrate the disclosed concepts to those skilled in the art by referring to specific embodiments.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the implementation of the present invention. examples, but not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

The silica surface modification method of this embodiment is carried out according to the following method:

1. Use acetone and deionized water to ultrasonically clean the silica samples in sequence, the cleaning times are 3 times, and each cleaning time is 5 minutes to obtain the cleaned silica samples.

2. Use a muffle furnace to heat the cleaned silica sample at a high temperature, so that the silica sample is continuously heated at 490° C. for 30 minutes. The cleaned silica sample was heated for 30 minutes at a high temperature, and the temperature of the high temperature heat treatment was 490° C. to obtain a cleaned silica sample. The high temperature heat treatment was performed in a muffle furnace.

3. After cleaning the surface of the silicon dioxide sample after the high temperature heat treatment, the silicon dioxide sample is placed in an electrolytic cell for electro-active hydroxylation treatment. The electrolyte is a calcium chloride solution with a mass fraction of 0.030%, and the voltage is 1.6 V/cm. After 1 h, a silicon dioxide sample after electro-active hydroxylation treatment is obtained.

4. Mix the coupling agent KH560, benzene and methanol according to the volume ratio of 1:9:0.5, and shake for 5 minutes to obtain the novel coupling agent reaction solution of this embodiment.

The silica sample after electro-hydroxylation treatment was placed in the fully dispersed new coupling agent reaction solution, and vibrated for 5 minutes. At this time, methanol can effectively inhibit the hydrolysis of coupling agent KH560 and the condensation reaction of hydrolyzed products. The novel coupling agent reaction solution and the silica sample placed in the novel coupling agent reaction solution are put into the reaction kettle, and then the reaction kettle is placed in a vacuum drying box to carry out the constant temperature alkylation reaction. The isothermal alkylation was modified at a temperature of 90°C for 6 hours.

5. Take out the silica sample in the vacuum drying box, wash with ethanol, and dry to complete the modification of the silica sample.

Product determination:

The wetting angle was measured by the sessile drop method. The specific steps were: washing the quartz glass slide with deionized water, drying it in vacuum, and then placing the quartz glass slide on the sample platform; adjusting the platform to keep it level, turning on the light source, and adjusting the sample The quartz glass slide on the platform appears in the center of the screen. Deionized water was titrated on the surface of the quartz glass slide with a needle, and the shape of the oil droplets was recorded by a CCD camera in real time, and the wetting angle was determined. Measure 3 times, and the average value of the wetting angle calculated is the wetting angle determined by the product. The wetting angle of deionized water on the surface of the modified silica sample in this example was measured to be 119.79°. The larger the wetting angle of the water droplet on the silica sample, the better the hydrophobicity of the silica sample.

Example 2

The silica surface modification method of this embodiment is carried out according to the following method:

1. Use acetone and deionized water to ultrasonically clean the silica samples in sequence, the cleaning times are 3 times, and each cleaning time is 5 minutes to obtain the cleaned silica samples.

2. Use a muffle furnace to heat the cleaned silica sample at a high temperature, so that the silica sample is continuously heated at 500° C. for 30 min. The cleaned silica sample was heated for 30 minutes at a high temperature, and the temperature of the high temperature heat treatment was 500° C. to obtain a cleaned silica sample. The high temperature heat treatment was performed in a muffle furnace.

3. After cleaning the surface of the silicon dioxide sample after the high temperature heat treatment, the silicon dioxide sample is placed in an electrolytic cell for electro-active hydroxylation treatment. The electrolyte is a magnesium chloride solution with a mass fraction of 0.025%, and the voltage is 1.2 V/cm. After 1 h, a silicon dioxide sample after electro-active hydroxylation treatment is obtained.

4. Mix the coupling agent KH560, benzene and methanol according to the volume ratio of 1:10:0.6, and shake for 5 minutes to obtain the novel coupling agent reaction solution of this embodiment.

The silica sample after electro-hydroxylation treatment was placed in the fully dispersed new coupling agent reaction solution, and vibrated for 5 minutes. At this time, methanol can effectively inhibit the hydrolysis of coupling agent KH560 and the condensation reaction of hydrolyzed products. The novel coupling agent reaction solution and the silica sample placed in the novel coupling agent reaction solution are put into the reaction kettle, and then the reaction kettle is placed in a vacuum drying box to carry out the constant temperature alkylation reaction. The isothermal alkylation was modified at a temperature of 90°C for 6 hours.

5. Take out the silica sample in the vacuum drying box, wash with ethanol, and dry to complete the modification of the silica sample.

Product determination:

The wetting angle was measured by the sessile drop method. The specific steps were: washing the quartz glass slide with deionized water, drying it in vacuum, and then placing the quartz glass slide on the sample platform; adjusting the platform to keep it level, turning on the light source, and adjusting the sample The quartz glass slide on the platform appears in the center of the screen. Deionized water was titrated on the surface of the quartz glass slide with a needle, and the shape of the oil droplets was recorded by a CCD camera in real time, and the wetting angle was determined. Measure 3 times, and the average value of the wetting angle calculated is the wetting angle determined by the product. The wetting angle of deionized water on the surface of the modified silica sample in this example was measured to be 119.077°. The larger the wetting angle of the water droplet on the silica sample, the better the hydrophobicity of the silica sample.

Example 3

The silica surface modification method of this embodiment is carried out according to the following method:

1. Use acetone and deionized water to ultrasonically clean the silica samples in sequence, the cleaning times are 3 times, and each cleaning time is 5 minutes to obtain the cleaned silica samples.

2. Use a muffle furnace to heat the cleaned silica sample at a high temperature, so that the silica sample is continuously heated at 490° C. for 30 minutes. The cleaned silica sample was heated for 30 minutes at a high temperature, and the temperature of the high temperature heat treatment was 490° C. to obtain a cleaned silica sample. The high temperature heat treatment was performed in a muffle furnace.

3. After cleaning the surface of the silicon dioxide sample after the high temperature heat treatment, the silicon dioxide sample is placed in an electrolytic cell for electro-active hydroxylation treatment. Wherein, the electrolyte is a magnesium chloride solution with a mass fraction of 0.030%, the voltage is 1.4 V/cm, and after 1 h, a silicon dioxide sample after electro-active hydroxylation treatment is obtained.

4. Mix the coupling agent KH560, benzene and methanol according to the volume ratio of 1:9:0.5, and shake for 5 minutes to obtain the novel coupling agent reaction solution of this embodiment.

The silica sample after electro-hydroxylation treatment was placed in the fully dispersed new coupling agent reaction solution, and vibrated for 5 minutes. At this time, methanol can effectively inhibit the hydrolysis of coupling agent KH560 and the condensation reaction of hydrolyzed products. The novel coupling agent reaction solution and the silica sample placed in the novel coupling agent reaction solution are put into the reaction kettle, and then the reaction kettle is placed in a vacuum drying box to carry out the constant temperature alkylation reaction. The isothermal alkylation was modified at a temperature of 90°C for 6 hours.

5. Take out the silica sample in the vacuum drying box, wash with ethanol, and dry to complete the modification of the silica sample.

Product determination:

The wetting angle was measured by the sessile drop method. The specific steps were: washing the quartz glass slide with deionized water, drying it in vacuum, and then placing the quartz glass slide on the sample platform; adjusting the platform to keep it level, turning on the light source, and adjusting the sample The quartz glass slide on the platform appears in the center of the screen. Deionized water was titrated on the surface of the quartz glass slide with a needle, and the shape of the oil droplets was recorded by a CCD camera in real time, and the wetting angle was determined. Measure 3 times, and the average value of the wetting angle calculated is the wetting angle determined by the product. The wetting angle of deionized water on the surface of the modified silica sample in this example was measured to be 119.912°. The larger the wetting angle of the water droplet on the silica sample, the better the hydrophobicity of the silica sample.

Example 4

The silica surface modification method of this embodiment is carried out according to the following method:

1. Use acetone and deionized water to ultrasonically clean the silica samples in sequence, the cleaning times are 3 times, and each cleaning time is 5 minutes to obtain the cleaned silica samples.

2. Use a muffle furnace to heat the cleaned silica sample at a high temperature, so that the silica sample is continuously heated at 500° C. for 30 min. The cleaned silica sample was heated for 30 minutes at a high temperature, and the temperature of the high temperature heat treatment was 500° C. to obtain a cleaned silica sample. The high temperature heat treatment was performed in a muffle furnace.

3. After cleaning the surface of the silicon dioxide sample after the high temperature heat treatment, the silicon dioxide sample is placed in an electrolytic cell for electro-active hydroxylation treatment. The electrolyte is a magnesium chloride solution with a mass fraction of 0.025%, and the voltage is 1.6 V/cm. After 1 h, a silicon dioxide sample after electro-active hydroxylation treatment is obtained.

4. Mix the coupling agent KH560, benzene and methanol according to the volume ratio of 1:10:0.6, and shake for 5 minutes to obtain the novel coupling agent reaction solution of this embodiment.

The silica sample after electro-hydroxylation treatment was placed in the fully dispersed new coupling agent reaction solution, and vibrated for 5 minutes. At this time, methanol can effectively inhibit the hydrolysis of coupling agent KH560 and the condensation reaction of hydrolyzed products. The novel coupling agent reaction solution and the silica sample placed in the novel coupling agent reaction solution are put into the reaction kettle, and then the reaction kettle is placed in a vacuum drying box to carry out the constant temperature alkylation reaction. The isothermal alkylation was modified at a temperature of 90°C for 6 hours.

5. Take out the silica sample in the vacuum drying box, wash with ethanol, and dry to complete the modification of the silica sample.

Product determination:

The wetting angle was measured by the sessile drop method. The specific steps were: washing the quartz glass slide with deionized water, drying it in vacuum, and then placing the quartz glass slide on the sample platform; adjusting the platform to keep it level, turning on the light source, and adjusting the sample The quartz glass slide on the platform appears in the center of the screen. Deionized water was titrated on the surface of the quartz glass slide with a needle, and the shape of the oil droplets was recorded by a CCD camera in real time, and the wetting angle was determined. Measure 3 times, and the average value of the wetting angle calculated is the wetting angle determined by the product. Please refer to Figure 2 and Figure 3, Figure 2 is the wetting angle measured by water droplets on the surface of the unmodified silica sample, Figure 3 is the silica sample modified by the water droplets by the method provided in this example The wetting angle measured on the surface is 122.152°. The larger the wetting angle of the water droplet on the silica sample, the better the hydrophobicity of the silica sample.

Example 5

The silica surface modification method of this embodiment is carried out according to the following method:

1. Use acetone and deionized water to ultrasonically clean the silica samples in sequence, the cleaning times are 3 times, and each cleaning time is 5 minutes to obtain the cleaned silica samples.

2. Use a muffle furnace to heat the cleaned silica sample at a high temperature, so that the silica sample is continuously heated at 500° C. for 30 min. The cleaned silica sample was heated for 30 minutes at a high temperature, and the temperature of the high temperature heat treatment was 500° C. to obtain a cleaned silica sample. The high temperature heat treatment was performed in a muffle furnace.

3. After cleaning the surface of the silicon dioxide sample after the high temperature heat treatment, the silicon dioxide sample is placed in an electrolytic cell for electro-active hydroxylation treatment. The electrolyte is a calcium chloride solution with a mass fraction of 0.030%, and the voltage is 1.8 V/cm. After 1 h, a silicon dioxide sample after electro-active hydroxylation treatment is obtained.

4. Mix the coupling agent KH560, benzene and methanol according to the volume ratio of 1:9:0.5, and shake for 5 minutes to obtain the novel coupling agent reaction solution of this embodiment.

The silica sample after electro-hydroxylation treatment was placed in the fully dispersed new coupling agent reaction solution, and vibrated for 5 minutes. At this time, methanol can effectively inhibit the hydrolysis of coupling agent KH560 and the condensation reaction of hydrolyzed products. The novel coupling agent reaction solution and the silica sample placed in the novel coupling agent reaction solution are put into the reaction kettle, and then the reaction kettle is placed in a vacuum drying box to carry out the constant temperature alkylation reaction. The isothermal alkylation was modified at a temperature of 90°C for 6 hours.

5. Take out the silica sample in the vacuum drying box, wash with ethanol, and dry to complete the modification of the silica sample.

Product determination:

The wetting angle was measured by the sessile drop method. The specific steps were: washing the quartz glass slide with deionized water, drying it in vacuum, and then placing the quartz glass slide on the sample platform; adjusting the platform to keep it level, turning on the light source, and adjusting the sample The quartz glass slide on the platform appears in the center of the screen. Deionized water was titrated on the surface of the quartz glass slide with a needle, and the shape of the oil droplets was recorded by a CCD camera in real time, and the wetting angle was determined. Measure 3 times, and the average value of the wetting angle calculated is the wetting angle determined by the product. The wetting angle of deionized water on the surface of the modified silica sample in this example was measured to be 120.663°. The larger the wetting angle of the water droplet on the silica sample, the better the hydrophobicity of the silica sample.

Example 6

The silica surface modification method of this embodiment is carried out according to the following method:

1. Use acetone and deionized water to ultrasonically clean the silica sample in turn, the cleaning times are 3 times, and each cleaning time is 5 minutes to obtain the cleaned silica sample.

2. Use a muffle furnace to heat the cleaned silica sample at a high temperature, so that the silica sample is continuously heated at 510° C. for 30 minutes. The cleaned silica sample was heated for 30 minutes at a high temperature, and the temperature of the high temperature heat treatment was 510° C. to obtain a cleaned silica sample. The high temperature heat treatment was performed in a muffle furnace.

3. After cleaning the surface of the silicon dioxide sample after the high temperature heat treatment, the silicon dioxide sample is placed in an electrolytic cell for electro-active hydroxylation treatment. Wherein, the electrolyte is a calcium chloride solution with a mass fraction of 0.025%, the voltage is 1.6 V/cm, and after 1 h, a silicon dioxide sample after electro-active hydroxylation treatment is obtained.

4. Mix the coupling agent KH560, benzene and methanol according to the volume ratio of 1:10:0.6, and shake for 5 minutes to obtain the novel coupling agent reaction solution of this embodiment.

The silica sample after electro-hydroxylation treatment was placed in the fully dispersed new coupling agent reaction solution, and vibrated for 5 minutes. At this time, methanol can effectively inhibit the hydrolysis of coupling agent KH560 and the condensation reaction of hydrolyzed products. The novel coupling agent reaction solution and the silica sample placed in the novel coupling agent reaction solution are put into the reaction kettle, and then the reaction kettle is placed in a vacuum drying box to carry out the constant temperature alkylation reaction. The isothermal alkylation was modified at a temperature of 90°C for 6 hours.

5. Take out the silica sample in the vacuum drying box, wash with ethanol, and dry to complete the modification of the silica sample.

Product determination:

The wetting angle was measured by the sessile drop method. The specific steps were: wash the quartz glass slide with deionized water, dry it in vacuum, and then place the quartz glass slide on the sample platform; adjust the platform to keep it level, turn on the light source, and adjust the sample. The quartz glass slide on the platform appears in the center of the screen. Deionized water was titrated on the surface of the quartz glass slide with a needle, and the shape of the oil droplets was recorded by a CCD camera in real time, and the wetting angle was determined. Measure 3 times, and the average value of the wetting angle calculated is the wetting angle determined by the product. The wetting angle of deionized water on the surface of the modified silica sample in this example was measured to be 119.62°. The larger the wetting angle of the water droplet on the silica sample, the better the hydrophobicity of the silica sample.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (8)

1. A method for modifying the surface of silica, comprising:

heating the cleaned silicon dioxide sample to 490-510 ℃ at high temperature, and continuously heating for 30-35 minutes to remove the silicon dioxide sample to the maximumResidual organic pollutants and adsorbed moisture on the surface of the silicon dioxide sample; then, carrying out electric excitation hydroxylation treatment on the silicon dioxide sample; the direct current electrically excites the surface of the silicon dioxide to promote the breaking of the Si-O-Si bond and the H in the water⁺、OH^-In combination, the surface hydroxyl groups of the silicon dioxide are effectively increased;

after the electric excitation hydroxylation treatment is finished, placing a silicon dioxide sample in a novel silane coupling agent reaction solution containing a coupling agent KH560, benzene and methanol, sequentially carrying out oscillation treatment and constant-temperature alkylation reaction, and obtaining a surface-modified silicon dioxide sample after the reaction is finished.

2. The method according to claim 1, wherein the novel coupling agent reaction solution has a volume ratio of the coupling agent KH560 to the benzene to the methanol of 1: (9-11): (0.5-0.7), the hydrolysis of KH560 can be effectively inhibited by adding proper methanol, mutual condensation of free coupling agent KH560 hydrolysate in the solution is weakened, and the dispersion stability of the silane coupling agent in the solution is enhanced.

3. The method according to any one of claims 1 to 2, wherein in the electrical stimulation hydroxylation treatment, the voltage is 1.5V/cm to 1.7V/cm, and the electrolyte is a magnesium chloride solution with a mass fraction of 0.025% to 0.030% or a calcium chloride solution with a mass fraction of 0.025% to 0.030%.

4. The method according to claim 3, wherein the time for the electrical stimulation hydroxylation treatment is 1-1.5 hours.

5. The method according to claim 1, wherein the electrical stimulation hydroxylation treatment is performed after heating the washed silica sample to 500 ℃ at an elevated temperature for 30 minutes.

6. The method according to claim 1 or 5, wherein the isothermal alkylation reaction is carried out at a temperature of 90 ℃ for 6-8 hours.

7. The method according to claim 1 or 5, wherein the shaking treatment time is 3 to 5 minutes.

8. The method of claim 1, wherein after the isothermal alkylation reaction, further comprising:

and cleaning the silicon dioxide sample subjected to the constant-temperature alkylation reaction by using ethanol, and drying to obtain the surface-modified silicon dioxide sample.

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