CN111777988B

CN111777988B - Hydrophobic material and preparation method thereof

Info

Publication number: CN111777988B
Application number: CN202010466613.XA
Authority: CN
Inventors: 彭剑峰; 魏攀龙; 曲久辉; 兰华春; 鞠佳伟
Original assignee: Research Institute For Environmental Innovation (suzhou) Tsinghua
Current assignee: Research Institute For Environmental Innovation (suzhou) Tsinghua
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2022-12-09
Anticipated expiration: 2040-05-29
Also published as: CN111777988A

Abstract

The invention relates to a hydrophobic material and a preparation method thereof. Based on the practical reasons that the river channel bottom mud is large in sludge amount, high in landfill or incineration cost, high in content of inorganic matters (sand grains and the like) in the river channel bottom mud and the like, the inorganic matters in the river channel bottom mud are used as raw materials for preparing the hydrophobic material, so that the resource utilization of the river channel bottom mud can be realized, the treatment cost of the bottom mud can be reduced, and the risk of secondary pollution is further avoided; the hydrophobic material prepared by taking the river sediment as the raw material has the hydrophobic property which is not weaker than that of modified sand of a manufacturer, reduces the cost for preparing the hydrophobic material and is beneficial to popularization and application of the hydrophobic material.

Description

Hydrophobic material and preparation method thereof

Technical Field

The invention relates to a hydrophobic material and a preparation method thereof.

Background

Along with the improvement of urban water environment regulation by each local government, the black and odorous water regulation becomes the key to the realization of the goals of improving the water environment quality and recovering the river ecological system. At present, the treatment method for the black and odorous water body mainly combines river dredging with other treatment means. A large amount of bottom mud is generated by dredging the river channel, and the problem of treatment and disposal of the bottom mud is an indispensable part in the treatment work of black and odorous water bodies. At present, the treatment means of the bottom mud of the river channel is mainly landfill or landfill after incineration. A large amount of river sediment occupies a large land area when being buried, the pollutant components in the river sediment are complex, and polluted water can permeate into underground water, so that the land and the underground water are polluted; although the land occupation area can be reduced to a certain extent and the secondary pollution of organic matters to the environment can be reduced by landfill after incineration, the pollution of substances which are difficult to decompose at high temperature, such as heavy metals in the bottom mud of the river channel, to the environment is still inevitable, in addition, the bottom mud incineration needs to consume a large amount of energy, the treatment cost is high, and therefore, in order to prevent the secondary pollution of the bottom mud to the environment and reduce the treatment cost of the bottom mud of the river channel, a method capable of realizing the continuous utilization and recycling of the bottom mud of the river channel is feasible.

At present, some methods for recycling bottom mud are also proposed, for example, the invention CN2019104218003 discloses a dredged sludge dewatering and curing calcium-magnesium-based composite material and a preparation method and application thereof, and the invention CN2011100359078 discloses a sintered light environment-friendly brick produced from river bottom mud and a manufacturing method thereof. Although the above two methods for realizing the recycling of the river sediment are certainly advisable, the method for producing the composite material by using the sludge needs to add an external material to realize the recycling of the sediment, so that the production cost is increased to a certain extent; the sintering process of the lightweight environment-friendly bricks wastes a large amount of energy, and thus there is no price advantage in competition with other products.

Disclosure of Invention

The invention aims to provide a hydrophobic material which takes bottom mud as a raw material so as to realize resource utilization of the bottom mud.

In order to achieve the purpose, the invention adopts the technical scheme that:

inspired by various phenomena (the self-cleaning property of lotus leaves, the water collection and color change functions of desert beetles, water striders freely walking on water surfaces, geckos freely walking on walls and the like) in nature, people research and discover that the formation of a hydrophobic surface is limited by a coarse structure (comprising a single-scale structure, a double-scale structure and a multi-scale structure) and surface free energy substances (such as hydrocarbon, fluorine-containing substances and the like), so that the hydrophobic material with various application functions is developed. At present, hydrophobic materials are widely applied to industry and daily life, and research and application of the hydrophobic materials at home and abroad mainly focus on preparation of silicon dioxide modified hydrophobic materials, so that the demand of raw materials, namely silicon dioxide, is remarkably increased, and the price of the silicon dioxide modified materials is high. Researches show that the river sediment contains partial organic matters and a large amount of inorganic matters such as sand grains, clay and the like, and provide a foundation for realizing the continuous utilization and resource utilization of the sediment. If utilize river course bed mud to prepare hydrophobic material, not only can not occupy national land resource, reduce the energy of handling river course bed mud, can also realize the recycle of resource simultaneously, realize sustainable development to can avoid causing secondary pollution's risk to soil and groundwater. Therefore, in order to solve the problem of treatment and disposal of a large amount of river sediment and reduce the production cost of the silica modified material, the invention develops the hydrophobic material taking the sediment as the raw material, and the hydrophobic material has the hydrophobic performance which is approximately the same as that of the silica modified material.

The invention provides a hydrophobic material, which is obtained by carrying out hydrophobic modification on substrate sludge by ethanol and a modifier.

The hydrophobic material disclosed by the invention uses the bottom mud as a raw material, so that the production cost of the hydrophobic material is reduced, the problem of treatment and disposal of a large amount of bottom mud is solved, the continuous utilization and resource utilization of the bottom mud are realized, and the secondary pollution to the environment in the process of treatment and disposal of the bottom mud is prevented.

The hydrophobic material of the invention adopts ethanol and modifier for hydrophobic modification, and the modified material can be recycled, thus having environmental friendliness.

Preferably, the modifier is one or more of fluorine-containing silane, fluorine-containing sulfonate and fluorine-containing acrylate, and the preparation process using the modifier is simple and quick, has mild reaction conditions, is easy to control and is suitable for large-scale production and application.

Further preferably, the fluorine-containing silane is perfluorooctyltrimethoxysilane or perfluorodecyltrimethoxysilane.

Further preferably, the fluorine-containing sulfonate is lithium perfluoro zinc-based sulfonate.

Further preferably, the fluorine-containing acrylate is a trifluoromethyl acrylate.

In the invention, the perfluorooctyl trimethoxy silane is most preferably used, and the prepared hydrophobic material has the best hydrophobic property and the lowest cost.

Preferably, when the modifier is liquid, the volume ratio of the ethanol to the modifier is 30-50: 1; when the modifier is solid, the modifier is fed in the form of solution with the mass fraction of 5-20%, and the volume ratio of the ethanol to the modifier solution is 30-50: 1; the volume ratio of the ethanol to the modifier is set within the range, which is beneficial to improving the solubility of the modifier in the ethanol, so that the hydrophobic property is ensured, the using amount of the modifier is saved, and the cost is reduced.

Further preferably, the volume ratio of the ethanol to the modifier or modifier solution is 40: 1.

Preferably, the bottom mud is river bottom mud.

The second aspect of the invention also provides a preparation method of the hydrophobic material, wherein ethanol and a modifier are adopted to carry out hydrophobic modification treatment on the bottom mud.

Preferably, the hydrophobic modification treatment is to dissolve the bottom sludge in the mixed solution of the ethanol and the modifier, and fully stir the mixture to ensure that the bottom sludge is fully contacted with the modifier, so as to improve the hydrophobic modification effect.

Preferably, the preparation method further comprises pretreating the substrate sludge before the hydrophobic modification treatment, wherein the pretreatment comprises washing and drying. And removing partial impurities in the bottom sludge to be treated through pretreatment, and dehydrating the washed bottom sludge, so that the hydrophobic treatment effect is improved.

Preferably, the volume ratio of the pretreated precipitate to the mixed solution of the ethanol and the modifier is controlled to be 1: 0.5-3, so that the raw material cost is reduced while the hydrophobic treatment effect is ensured.

Further preferably, the washing process comprises diluting the bottom mud with tap water and/or middle water, fully stirring, standing for precipitation, and removing supernatant.

Further preferably, the drying temperature is 50-70 ℃, and the temperature range is set, so that the energy consumption can be reduced while the moisture removal effect is ensured.

Still more preferably, the volume ratio of the tap water and/or the reclaimed water to the bottom mud is 1: 0.5-3.

Still more preferably, the standing time is 10 to 30min.

Still more preferably, the number of repetitions is 2 to 4.

Still more preferably, the drying temperature in the pretreatment is 60 ℃.

Preferably, the preparation method further comprises the step of carrying out post-treatment on the substrate sludge after the hydrophobic modification treatment, wherein the post-treatment comprises filtration and drying, and the hydrophobic material obtained through the post-treatment can be directly applied to industry or daily life and is more convenient to package, transport and store.

Further preferably, the filtration is performed using a screen.

Further preferably, the mesh number of the screen is 80-120 meshes, more preferably, a 100-mesh screen is used, the screen is selected to ensure the filtering efficiency, if the mesh size of the screen is too small, the filtering speed is too slow and easy to block, and if the mesh size of the screen is too large, more modified bottom mud is taken away by the filtrate, so that the yield of the hydrophobic material is reduced.

In the invention, the filtered modified filtrate can be reused, so that the cost is saved, and the modification effect of the reused modified filtrate can be reduced, and whether the filtrate needs to be reused can be determined according to actual needs.

Further preferably, the drying temperature in the post-treatment is 50-70 ℃, and the temperature range is set, so that the consumed energy is the least.

Still more preferably, the drying temperature in the post-treatment is 60 ℃.

The third aspect of the invention provides an application of the hydrophobic material in preparing an anti-seepage and waterproof material of a structure and/or in sponge city reconstruction engineering.

The fourth aspect of the invention also provides a river sediment treatment method, wherein ethanol and a modifier are adopted to carry out hydrophobic modification treatment on the river sediment.

The fifth aspect of the invention provides an application of the method for treating the river sediment in river pollution treatment and/or ecological restoration engineering.

Based on the practical reasons that the river channel bottom sludge is large in sludge amount, high in landfill or incineration cost, high in content of inorganic matters (sand grains and the like) in the river channel bottom sludge and the like, the inorganic matters in the river channel bottom sludge are used as raw materials for preparing the hydrophobic material, so that the resource utilization of the river channel bottom sludge can be realized, the treatment cost of the bottom sludge can be reduced, and the risk of secondary pollution is further avoided; the hydrophobic material prepared by taking the river sediment as the raw material has the hydrophobic property which is not weaker than that of modified sand of a manufacturer, simultaneously reduces the cost for producing the hydrophobic material, and is beneficial to popularization and application of the hydrophobic material.

Due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages:

the hydrophobic material is obtained by performing hydrophobic modification on the bottom mud through ethanol and a modifier, has hydrophobic property, reduces production cost, solves the problem of treatment and disposal of a large amount of bottom mud, realizes continuous utilization and recycling of the bottom mud, and prevents secondary pollution to the environment in the process of treatment and disposal of the bottom mud.

Drawings

FIG. 1 is a flow chart of the bottom mud preparation of the hydrophobic material of example 1.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It is to be understood that these examples are for the purpose of illustrating the general principles, essential features and advantages of the present invention, and that the present invention is not limited by the following examples. The implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not indicated are generally the conditions in routine experiments.

Example 1

The flow of preparing the hydrophobic material by taking the dredging sediment of the river bottom of the water body of the black and odorous riverway as an implementation object is shown in the attached figure 1.

Firstly, carrying out pretreatment on the desilting bottom mud:

1. washing, diluting the river sediment with tap water or reclaimed water (according to the volume ratio of 1: 1-1: 2), fully stirring for 3-5 min, standing and precipitating for 10min, separating, discharging supernatant, repeatedly diluting, stirring, precipitating, and separating for 2-3 times, and reserving precipitate for later use;

2. drying, namely drying the precipitate remained in the step 1 at the temperature of 60 ℃ for later use;

and then modifying the pretreated precipitate, wherein the modification stage comprises the following steps:

3. modifying, dissolving the precipitate obtained in the step 2 in a mixed solution of ethanol and a modifier (perfluorooctyl trimethoxy silane) (the volume ratio of the ethanol to the modifier is 40: 1), wherein the volume ratio of the precipitate to the mixed solution is 1: 1-2, and fully stirring to finish the modification process of the precipitate;

4. filtering, stopping stirring after the step 3 is finished, filtering the mixed solution by adopting a screen with the specification of 100 meshes, and keeping filter residues for later use, wherein the modifier filtrate can be reused;

5. and (5) drying, namely drying the filter residue reserved in the step (4) according to the method in the step (2) to obtain a finished product.

The water contact angles of the original sediment and the finished product are measured by adopting a video optical contact angle measuring instrument, and the comparison of the hydrophobic performances of the original sediment and the finished product is shown in a table 1:

TABLE 1

As can be seen from Table 1, the original sediment has no hydrophobicity, the hydrophobicity of the modified finished product can reach 130 degrees, and the water contact angle of the common modified sand with hydrophobicity sold in the market is in the range of 90-150 degrees, so that the hydrophobicity of the hydrophobic material of the invention can reach the middle-upper level of the common modified sand with hydrophobicity sold in the market, and the hydrophobic material can completely replace the modified sand of manufacturers. And the cost of the finished product of the embodiment is about 30% lower than that of the common modified sand sold in the market, has obvious price advantage and is suitable for popularization and utilization.

Example 2

Pretreating the bottom mud of the black and odorous river according to the method in the embodiment 1, and then screening a modifier;

modifying the pretreated black and odorous river sediment according to the modification conditions of the embodiment 1 and measuring the water contact angle of the pretreated black and odorous river sediment, wherein the perfluorinated octyl lithium sulfonate is prepared into an aqueous solution with the mass fraction of 10%, and then a mixed liquid is prepared according to the volume ratio of the perfluorinated octyl lithium sulfonate aqueous solution to the ethanol of 1: 40; dissolving stearic acid in 0.02% sodium hydroxide solution by mass to prepare 10g/L sodium hydroxide stearate mixed solution, and then preparing mixed liquid according to the volume ratio of the sodium hydroxide stearate mixed solution to ethanol being 1: 40. The results of the modifier screens are shown in table 2:

TABLE 2

The results in Table 2 show that the modified perfluorooctyltrimethoxysilane, perfluorodecyltrimethoxysilane, perfluorooctyllithium sulfonate, trifluoromethyl acrylate and stearic acid all have hydrophobicity, the water contact angle is over 122 degrees, the hydrophobicity of all the modified sand reaches the middle and upper level of the common modified sand with hydrophobicity, and the hydrophobicity of the first four modifying agents is better than that of modifying agent 5. Wherein, the modified perfluoro octyl trimethoxy silane has the highest hydrophobic performance, the water contact angle reaches 130 degrees, and the modifier is preferably perfluoro octyl trimethoxy silane from the aspects of modification effect and production cost.

The above embodiments are only for illustrating the technical idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention, and not to limit the protection scope of the present invention by this means. All equivalent changes and modifications made according to the spirit of the present invention should be covered in the protection scope of the present invention.

Claims

1. A method for preparing a hydrophobic material is characterized by comprising the following steps: dissolving the bottom sludge in a mixed solution of ethanol and a modifier for hydrophobic modification treatment; the modifier is one or more of fluorine-containing silane, fluorine-containing sulfonate and fluorine-containing acrylate; the bottom mud is the bottom mud of a river channel,

the preparation method further comprises the steps of pretreating the bottom mud before the hydrophobic modification treatment, wherein the pretreatment comprises washing and drying, the volume ratio of the pretreated sediment to the mixed liquid of the ethanol and the modifier is controlled to be 1.5 to 3, and the washing process comprises the steps of stirring and diluting the bottom mud by using tap water and/or neutral water, standing for precipitation and removing a supernatant; the drying temperature is 50 to 70 ℃.

2. The method for preparing a hydrophobic material according to claim 1, wherein: the modifier is one or more of perfluorooctyl trimethoxy silane, perfluorodecyl trimethoxy silane, perfluorooctyl lithium sulfonate and trifluoromethyl acrylate.

3. The method for preparing a hydrophobic material according to claim 2, wherein: when the modifier is liquid, the volume ratio of the ethanol to the modifier is 30 to 50; when the modifier is a solid, the modifier is fed in the form of a solution with the mass fraction of 5-20%, and the volume ratio of the ethanol to the modifier solution is 30-50.

4. The method for preparing a hydrophobic material according to claim 1, wherein: the volume ratio of the tap water and/or reclaimed water to the bottom mud is (1) 0.5-3, the standing time is 10-30min, and the washing process is repeated for 2-4 times.

5. The method for preparing a hydrophobic material according to claim 1, wherein: the preparation method also comprises the step of carrying out post-treatment on the substrate sludge after the hydrophobic modification treatment, wherein the post-treatment comprises filtration and drying.

6. The method for preparing a hydrophobic material according to claim 5, wherein: performing the filtration by using a screen, wherein the mesh number of the screen is 80 to 120 meshes; the drying temperature is 50 to 70 ℃.

7. Use of a hydrophobic material obtained by a method according to any one of claims 1 to 6 for the preparation of a barrier, waterproofing material for structures and/or for sponge city renovation projects.