CN116059855A - Preparation method and application of a titanium dioxide metal-organic framework forward osmosis membrane - Google Patents

Abstract

The invention provides a titanium dioxide metal organic framework (MIL-101 (Cr)/TiO) ₂ ) A preparation method and application of a forward osmosis membrane belong to the technical field of new materials, and solve the problems that the existing double-layer drainage noise reduction asphalt concrete pavement self-purification runoff pollution research bottleneck and the existing method are difficult to solve the problem that the asphalt pavement self-purification effect is poor. The invention is based on MIL-101 (Cr)/TiO which is a high-performance catalytic functional material ₂ Characterization of (c) and analysis of photocatalytic PropertiesDesigning MIL-101 (Cr)/TiO ₂ The surface water forward osmosis membrane is formed by a thin cover layer with the thickness of 5-25mm, which is a low-pollution and scaling reversible membrane and can help the pavement to automatically drain water, so that pollutants in the water runoff discharged from the pavement can be decomposed in the flowing process, the scaling phenomenon of the forward osmosis membrane can be relieved by increasing the flow rate of the surface water and changing the hydrodynamic conditions such as turbulence and the like of the surface water flow type, the self-purification of the asphalt pavement is realized, and the self-purification effect of the double-layer drainage noise reduction asphalt pavement is achieved.

Description

Preparation method and application of a titanium dioxide metal-organic framework forward osmosis membrane

technical field

The invention relates to a preparation method and application of a titanium dioxide metal-organic framework forward osmosis membrane, which belongs to the technical field of new materials.

Background technique

In recent years, with the widespread application of dense pavement, the pollution of urban road water runoff in my country has become increasingly serious, and researchers have gradually paid attention to the negative impact of urban road water runoff on urban ecological balance. Atmospheric wet deposition and rainwater scouring the road surface lead to dust in the atmosphere. Various organic matter, SS, and heavy metals such as Cu, Zn, and Pb in the road surface enter the road water runoff, causing water runoff pollution. In many cities, water runoff pollution is dealt with through the construction of urban water body comprehensive projects, but this method has not achieved good results in improving the entire water body of the city. Building a "sponge city" is a relatively comprehensive solution based on my country's water regime characteristics. Studies have shown that the metal-organic framework MIL-101 (Cr) has the ability to adsorb natural organic matter, and in the actual production process, one of the main problems faced by the ultrafiltration process is the natural organic matter existing in surface water. The excellent adsorption of MIL-101(Cr) to HA and BSA enables MIL-101(Cr) to remove the components that mainly cause membrane fouling in surface water, and at the same time control the time of adsorption treatment.

Ultrafiltration is the core industry of the third-generation water purification process, which has excellent water purification performance and low water production costs. However, during the filtration process, the intercepted pollutants will accumulate on the surface of the membrane, causing pollution to the membrane pores and the membrane surface, resulting in a continuous decline in the filtration flux, which seriously restricts the water production efficiency. Forward osmosis technology is a new type of membrane treatment technology. Although there are water treatment technologies such as microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membrane in the field of water treatment technology, with the continuous advancement of the national economic transformation strategy, " Environmental protection requirements such as "energy saving and emission reduction" and "zero discharge" are constantly increasing. Now it is urgent to develop water treatment technologies with lower energy consumption, better water quality and higher recovery rate. Forward osmosis is a low-pollution, scaling and reversible process. Unlike reverse osmosis, which is tightly compacted, the fouling layer of forward osmosis is thicker and looser. The water flux can be restored to the initial 80% to 90% by periodic osmosis backwashing technology. %, In addition, the fouling phenomenon of forward osmosis membrane can also be alleviated by increasing the feed liquid flow rate, changing the feed liquid flow pattern and other hydrodynamic conditions. Forward osmosis is different from the pressure-driven membrane process. It does not require high hydraulic pressure to overcome the problem of high osmotic pressure. It can be operated at low hydraulic pressure and room temperature, and can efficiently intercept almost all solutes and suspended substances. At the same time, due to the hydrophilicity of the forward osmosis membrane material, it can effectively reduce membrane fouling, and can be applied to wastewater treatment that is difficult to achieve with reverse osmosis technology, such as dyeing wastewater, garbage leachate, and membrane bioreactors. While reducing membrane fouling, it can reduce the cost of membrane cleaning and environmental pollution caused by chemical cleaning agents. Therefore, forward osmosis technology, which has the advantages of low energy consumption, low membrane pollution, and high water recovery rate, is the key technology of the new "zero discharge" technology.

MIL-101(Cr) is a metal-organic framework widely used in gas separation, as a metal-organic framework with high water stability, in practical applications, the excellent adsorption capacity of MIL-101(Cr) is used to adsorb and remove pavement Pollutants in surface water bodies can alleviate the problem of water runoff in urban roads in my country.

TiO ₂ is a new type of inorganic chemical raw material. It has high chemical stability and activity, large specific surface area, high transmittance to visible light, and very strong absorption and shielding ability to ultraviolet rays. It is a high added value Functional fine inorganic materials. Due to its small band gap, wide spectral response, and high catalytic efficiency, it is one of the most widely used photocatalytic materials at present. It can be mixed and doped by various physical or chemical methods to obtain a variety of high-performance catalytic functions. Material. The preparation of nano-titanium dioxide by low-temperature controlled neutralization hydrothermal method adopts the best reaction conditions, the reaction temperature is about 15°C, the reaction pH value is 7.2, the concentration of titanium sulfate reaction solution is 0.5mol/L, and the low-cost inorganic titanium salt titanium sulfate is used as raw material Nano-titanium dioxide can be prepared, the particle size is 5-15nm, the particles are uniform, and the particle size distribution is narrow.

Drainage asphalt pavement, also known as permeable asphalt pavement, refers to a new type of asphalt concrete surface layer with a void rate of about 20% after compaction and can form drainage channels inside the mixture. - Open-graded asphalt mixture with void structure. Drainage asphalt pavement uses large-void asphalt mixture as the surface layer, which penetrates rainfall into the drainage functional layer, and drains the rainwater horizontally through the layer, thereby eliminating the road surface water film that brings many adverse effects on driving, and significantly improving the driving efficiency in rainy weather. safety and comfort. Drainage asphalt pavement usually uses modified asphalt, and the thickness of the drainage functional layer is 4-5cm. Because the gaps on the single-layer drainage pavement are easily blocked by dust and gravel, resulting in a sharp decline in its performance, and the service life of the single-layer drainage pavement is shorter than that of the traditional densely graded asphalt pavement. In order to solve these problems In recent years, the new technology of double-deck drainage and noise-reducing asphalt pavement has been proposed.

The double-layer drainage and noise reduction asphalt pavement is composed of two layers of drainage pavement, which is a composite structure. The upper layer adopts a fine-grained void skeleton structure layer with a thickness of about 3cm, and the lower layer adopts a thicker void skeleton structure layer with a thickness of about 5cm. The aggregate particle size of the double-layer drainage and noise-reducing asphalt pavement changes with the layer level. Generally, aggregates with a particle size of about 11-20mm are used in the bottom layer, and aggregates with a particle size of about 4-8mm are used in the upper layer. The double-layer drainage and noise-reducing asphalt pavement uses large-void asphalt mixture as the surface layer, which penetrates the rainfall into the drainage functional layer, and discharges the rainwater horizontally through the layer, thereby eliminating the water film on the road surface that brings many adverse effects to driving. Improve the safety and comfort of driving in rainy days; at the same time, due to the porous characteristics of the drainage asphalt pavement can greatly reduce traffic noise, it is also called double-layer drainage noise reduction asphalt pavement. After research, the negative pressure generated by the tires rolling on the road has a good cleaning effect on the road, and is very effective in the case of heavy rain. Therefore, although the gaps in the double-layer drainage and noise-reducing asphalt pavement are easily blocked by clay, dust, aggregates shed from the road surface, and debris on tires, the forward osmosis membrane formed on its surface is a low-pollution, reversible fouling membrane, which can pass through Periodic osmosis and backwashing technology restores the water flux to the initial 80% to 90%. In addition, by increasing the feed liquid flow rate and changing the feed liquid flow pattern such as turbulent flow and other hydrodynamic conditions to alleviate the fouling of the forward osmosis membrane, so as to achieve Self-purification effect of double-layer drainage noise reduction asphalt pavement.

In the current process of urbanization, urban water runoff pollution has become an important factor hindering urban development, and urban road water runoff also has a major impact on urban ecological balance, so more methods are needed to effectively prevent urban road water runoff pollution . Facing the widespread problem of water runoff pollutants on asphalt pavement, most of the currently used permeable asphalt pavements have higher construction requirements. Therefore, the modified double-layer drainage and noise-reducing asphalt pavement is a new pavement structure. At present, the problem of water runoff pollutants on asphalt pavement is very extensive, and the existing methods are difficult to effectively prevent urban road water runoff pollution. The technical route of my country's "sponge city" construction includes "seepage, stagnation, storage, purification, use, and drainage". Because the underlying surface of the city is very hard and cement is everywhere, the original natural ecological background and hydrological characteristics have been changed. Therefore, natural infiltration should be strengthened and infiltration should be given priority. The modified double-layer drainage and noise-reducing asphalt pavement can realize this function.

The present invention utilizes the novel metal organic framework material MIL-101 (Cr) and the novel inorganic chemical raw material TiO ₂ to obtain the high-performance catalytic functional material titanium dioxide metal organic framework (MIL-101 (Cr)/TiO ₂ through the low temperature control neutralization hydrothermal method) ), design a kind of MIL-101(Cr)/TiO ₂ covering the surface of double-layer drainage and noise-reducing asphalt pavement to form surface water forward osmosis membrane, and use MIL-101(Cr)/TiO ₂ as the pretreatment material of the forward osmosis process , improve the water quality of road water runoff, and at the same time use the porous structure and permeability characteristics of the double-layer drainage noise reduction asphalt pavement road itself to realize the self-purification of road runoff.

Contents of the invention

technical problem

The object of the present invention is the high-performance catalytic functional material MIL-101(Cr)/ _TiO obtained by the low temperature control neutralization hydrothermal method to achieve the method of self-purifying asphalt pavement, the method aims at the excellent adsorption capacity of MIL-101(Cr) Due to the characteristics of adsorption and removal of pollutants in road surface water and the advantages of TiO ₂ such as large band gap, wide spectral response and high catalytic efficiency, a kind of MIL-101(Cr)/TiO ₂ covering double-layer drainage noise reduction asphalt is designed The surface water forward osmosis membrane is formed on the surface of the pavement, and MIL-101(Cr)/TiO ₂ is used as the pretreatment material of the forward osmosis process. There is a vacancy in the research on the purification of runoff pollution on permeable modified asphalt concrete pavement, and the existing methods are difficult to achieve the self-purification effect of asphalt pavement.

Technical solutions

In order to solve the current research gap on self-purification runoff pollution of double-layer drainage and noise reduction asphalt concrete pavement, the existing methods are difficult to achieve the self-purification effect of asphalt pavement. The present invention designs a kind of MIL-101 (Cr)/TiO ₂ is covered on the surface of double drainage noise-reducing asphalt pavement to form surface water forward osmosis membrane, utilizes MIL-101 (Cr)/TiO ₂ as the pretreatment material of forward osmosis process At the same time, the self-purification of pavement runoff is realized by utilizing the porous structure and permeability characteristics of the components of the double-layer drainage and noise-reducing asphalt pavement itself. Firstly, TiO ₂ was pretreated by ultrasonic stirring, drying after washing, and grinding; secondly, Cr(NO ₃ )·9H ₂ O, phthalic acid, tetramethylammonium hydroxide and four different contents of TiO ₂ was magnetically stirred, heated, lowered to room temperature, refluxed and purified, and vacuum-dried to obtain MIL-101(Cr)/TiO ₂ containing four different TiO ₂ contents; then, the photocatalytic degradation of methylene blue (MB) The degradation efficiency of the composite photocatalytic material was measured to measure the photocatalytic performance of the composite photocatalytic material, and the optimal TiO ₂ addition amount was obtained by analyzing the MB degradation efficiency; then, the IMP-PI-SCT sound absorption coefficient tester and the water seepage meter were used for indoor research, and different gaps Test and analyze the water seepage coefficient of the double-layer drainage asphalt pavement with the highest rate, and get the optimal double-layer drainage and noise-reducing asphalt pavement PAC-10+PAC-13; finally, coat MIL-101(Cr)/TiO ₂ on the original pavement A thin overlay layer with a thickness of 5-25mm is used as a pavement forward osmosis membrane, and at the same time, the porous structure and permeability of the components of the double-layer drainage and noise reduction asphalt pavement are used to achieve the self-purification effect of the asphalt pavement.

Beneficial effect

In general asphalt pavement, the double-layer drainage and noise-reducing asphalt pavement can remove the pavement water in time and eliminate the adverse effect of the road surface water film. Water runoff pollutants mainly come from atmospheric wet deposition, rainwater scouring the road surface, etc. Through these methods, dust in the atmosphere, various organic matter in the road surface, SS, and heavy metals such as Cu, Zn, and Pb enter the road water runoff, and the double-layer Drainage and noise reduction asphalt pavement can only remove road surface water in time, but cannot self-purify pollutants in water runoff. Therefore, there is a need for a method to achieve the self-purification of the road surface, help the road surface to drain automatically, and ensure that the pollutants in the water runoff discharged from the road surface can be decomposed during the flow process, so as to achieve the self-purification effect of the asphalt pavement. At present, in order to deal with the widespread problem of water runoff pollutants on asphalt pavement, the most widely used method is to use permeable asphalt pavement, in addition to the application of new bottom-type storm water outlets, but these measures cannot alleviate urban road pollution. Water runoff pollution problem. Therefore _, under the premise that there is an urgent need to develop new modified asphalt roads, the present invention designs a MIL-101 (Cr )/TiO ₂ covers the surface of the double-layer drainage and noise-reducing asphalt pavement to form a surface water forward osmosis membrane. Layer drainage and noise reduction asphalt pavement, effectively preventing water runoff pollution on urban roads.

Description of drawings

Fig.1 Schematic layout of MIL-101(Cr)/TiO ₂ covered double-layer drainage and noise reduction asphalt pavement

1-MIL-101(Cr)/TiO ₂ 2-PAC-10 Drainage Noise Reduction Asphalt 3-PAC-13 Drainage Noise Reduction Asphalt

Fig. 2 Schematic layout of MIL-101(Cr)/TiO ₂ forward osmosis membrane covering double-layer drainage and noise reduction asphalt pavement

1-MIL-101(Cr)/TiO ₂ forward osmosis membrane 2-PAC-10+PAC-13 double-layer drainage noise reduction asphalt pavement 3-surface water 4-surface water after self-purification

Detailed ways

The invention provides a preparation method and application of a titanium dioxide metal-organic framework forward osmosis membrane, and the specific implementation steps are as follows:

Add titanium dioxide (TiO ₂ ) samples into 0.5 mol/L sodium hydroxide (NaOH) solution, ultrasonically stir, wash and dry, add the dry powder to 1 mL tetrabutyl titanate and then add it to 40 mL ethanol and stir for 30 Minutes, then vacuum-dried at 65°C for 8 hours, and ground to obtain pretreated TiO ₂ ;

Weigh 5mmol Cr(NO ₃ )·9H ₂ O and 5mmol phthalic acid with a molar ratio of 1:1 and dissolve them in 25mL deionized water, stir and dissolve, add 0.458mL tetramethylammonium hydroxide, mix and stir for 30 minutes, Then weigh 0 mg, 200 mg, 400 mg and 800 mg of TiO ₂ into the above mixed solution, stir it magnetically for 1 hour, then transfer the mixture to a polytetrafluoroethylene liner autoclave, heat it at 180 ° C for 24 hours, and drop to After room temperature, the product was refluxed and purified with N-dimethylamide (DMF) at 110°C, absolute ethanol at 60°C and deionized water at 80°C in sequence, and vacuum-dried at 100°C for 18 to 24 hours to obtain MIL- 101(Cr), MIL-101(Cr)/TiO ₂ (200), MIL-101(Cr)/TiO ₂ (400) and MIL-101(Cr)/TiO ₂ (800);

Adopt X-ray diffractometer to analyze the crystal structure of above four kinds of MIL-101(Cr)/TiO ₂ , adopt scanning electron microscope energy spectrum analyzer to analyze the microcosmic morphology characteristics of above-mentioned four kinds of MIL-101(Cr)/ _TiO2 , adopt ultraviolet Visible spectrophotometric measurement and comparison of the above four kinds of MIL-101 (Cr)/TiO ₂ light absorption properties, using the specific surface area and mesoporous micropore analyzer to obtain the above four kinds of MIL-101 (Cr)/TiO ₂ The specific surface area, According to the information of pore size distribution and pore volume, the photocatalytic properties of the above four kinds of MIL-101(Cr)/TiO ₂ were measured by the degradation efficiency of photocatalytic degradation of methylene blue, and the performance of MIL-101(Cr)/TiO ₂ was analyzed. MB degradation efficiency finally obtained the optimal TiO ₂ addition amount;

The IMP-PI-SCT sound absorption coefficient tester and water seepage meter were used to test the single-layer drainage asphalt pavement and PAC-10+PAC-13 double-layer drainage asphalt pavement with different void ratios of PAC-10 and PAC-13 respectively. Test and analyze the water seepage coefficient to determine the structure combination of double-layer drainage asphalt pavement with the optimal drainage and noise reduction function;

Spray MIL-101(Cr)/TiO ₂ on the double-layer drainage asphalt pavement with the optimal drainage and noise reduction function to form a thin overcoat layer with a thickness of 5-25mm as the pavement forward osmosis membrane, while using the double-layer drainage asphalt The porous structure, permeability and adsorption characteristics inside the pavement structure achieve the self-purification effect of asphalt pavement.

Claims (1)

1. A preparation method and application of titanium dioxide metal-organic framework forward osmosis membrane, characterized in that the specific steps of the method are as follows: (1) Add the titanium dioxide (TiO ₂ ) sample into 0.5mol/L sodium hydroxide (NaOH) solution, stir it ultrasonically, wash it and then dry it, add the dry powder to 1mL tetrabutyl titanate and then add it to 40mL ethanol Stirring in medium for 30 minutes, then vacuum drying at 65°C for 8 hours, and grinding to obtain pretreated TiO ₂ ; (2) Dissolve 5mmol Cr(NO ₃ )·9H ₂ O and 5mmol phthalic acid with a molar ratio of 1:1 in 25mL deionized water, stir to dissolve, add 0.458mL tetramethylammonium hydroxide, mix and stir 30 minutes, then weighed 0mg, 200mg, 400mg and 800mg of TiO ₂ into the above mixed solution, stirred magnetically for 1 hour, then transferred the mixture to a polytetrafluoroethylene liner autoclave, heated at 180°C for 24 hours After cooling down to room temperature, the product was refluxed with N-dimethylamide (DMF) at 110°C, absolute ethanol at 60°C, and deionized water at 80°C in turn to purify the product, and vacuum-dried at 100°C for 18 to 24 hours. Obtain MIL-101(Cr), MIL-101(Cr)/TiO ₂ (200), MIL-101(Cr)/TiO ₂ (400) and MIL-101(Cr)/TiO ₂ (800); (3) Analyze the crystal structure of the above four kinds of MIL-101(Cr)/TiO ₂ by X-ray diffractometer, and analyze the microscopic morphology characteristics of the above four kinds of MIL-101(Cr)/TiO ₂ by scanning electron microscope energy spectrum analyzer , using UV-visible spectrophotometry to measure and compare the light absorption properties of the above four kinds of MIL-101(Cr)/TiO ₂ , using the specific surface area and mesoporous micropore analyzer to obtain the above four kinds of MIL-101(Cr)/TiO ₂ According to the specific surface area, pore size distribution and pore volume information, the photocatalytic properties of the above four MIL-101(Cr)/TiO ₂ were measured by the degradation efficiency of photocatalytic degradation of methylene blue, and the analysis of MIL-101(Cr)/TiO The MB degradation efficiency of TiO ₂ finally obtained the optimal TiO ₂ addition amount; (4) The IMP-PI-SCT sound absorption coefficient tester and water seepage meter are used to test the single-layer drainage asphalt pavement with different void ratios of PAC-10 and PAC-13 and the double-layer drainage of PAC-10+PAC-13 Test and analyze the water permeability coefficient of the asphalt pavement, and determine the structure combination of double-layer drainage asphalt pavement with the optimal drainage and noise reduction function; (5) Spray MIL-101(Cr)/TiO ₂ on the double-layer drainage asphalt pavement with the optimal drainage and noise reduction function to form a thin overcoat layer with a thickness of 5-25mm as the road surface forward osmosis membrane. The porous structure, permeability and adsorption characteristics of the layer drainage asphalt pavement structure can achieve the self-purification effect of the asphalt pavement.

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