CN104984746A - Modification method for nano silicon dioxide - Google Patents

Abstract

The invention relates to a modification method for nano silicon dioxide. The modification method comprises the steps: firstly, carrying out surface modification on nano silicon dioxide by using an amino silane coupling agent; and then forming a compound initiating polymerization system by virtue of amino on an amino silane molecule and quadrivalent cerium to initiate a monomer for surface grafting polymerization of silicon dioxide. The nano silicon dioxide modified by the method is good in dispersion in an aqueous solution, overcomes the problem that the nano silicon dioxide is easy to agglomerate and has a huge application potential in treatment of environmental water pollution.

Description

A kind of nano silicon dioxide modification method

technical field

The invention relates to a method for modifying nano silicon dioxide, which belongs to the field of modification of inorganic silicon materials.

Background technique

With the advancement of global industrialization, water pollution by heavy metal ions has posed a great threat to human survival. Therefore, it is urgent to develop related separation technologies and materials. At present, there are many methods for separating and removing heavy metal ions, among which adsorption method is a simple and efficient method, and the adsorbent can be regenerated and recycled. With the development of nanotechnology, inorganic nano-adsorbent materials have begun to be applied to the treatment of environmental water pollution. Inorganic nano-adsorption materials have high specific surface area, many surface active sites, good adsorption effect, and high removal rate of pollutants. At the same time, this kind of adsorption material is easy to separate and elute, and can be recycled to reduce the waste of resources.

Nano-silica is an amorphous white powder, which is a non-toxic, odorless, and non-polluting material, and it is also a nano-powder material produced on a large scale in the world. As an excellent structural and functional material, nano-silica has high surface activity, high specific surface area, low specific gravity, high temperature resistance, corrosion resistance, non-toxic and non-polluting properties. In recent years, with the development of nano-silica preparation technology and the deepening of modification research, nano-silica has been widely used in many fields such as rubber, plastics, coatings, functional materials, communications, electronics, biology, and medicine. .

Nano-silica itself does not have the function of adsorbing heavy metal ions, but because there are a large number of hydroxyl groups on its surface, it can be modified by various adsorption materials. This patent adopts the method of graft polymerization to introduce a large number of amino groups on the surface of nano silicon dioxide. Due to the relatively small molecular weight of the grafted monomer, it can easily penetrate into the interior of the SiO2 particle aggregate, and at the same time react with the active points on the inner and outer particles, graft the polymer to the surface of the particle, and prevent the particle from agglomerating .

Contents of the invention

The invention provides a method for modifying nano-silica. In order to achieve the above object, the technical scheme adopted in the invention is as follows:

Step 1. Take the dried nano-SiO2, place it in a three-necked flask equipped with a condenser tube, add an organic solvent so that the mass-volume ratio of SiO2 to the organic solvent is 1:10-1:50, stir, and ultrasonically vibrate, so that Nano-SiO2 is uniformly dispersed in the organic solvent; then slowly add aminosilane coupling agent dropwise, heat, and reflux at constant temperature for 3 to 24 hours; filter with suction, wash the filter cake with absolute ethanol three times, and dry to obtain surface-modified nano-SiO2 ;

Step 2. Vacuumize the three-necked flask equipped with a stirrer, condenser tube and dropping funnel, then pass in an inert gas, repeat three times to fully discharge the air in the reactor, and then add surface-modified nano-SiO2, monomer and deionized water, so that the monomer concentration is 0.5-3mol/L; adjust the reaction temperature to 30-80°C, add 0.2mol/L nitric acid solution of cerium ammonium nitrate dropwise, so that the concentration of cerium ammonium nitrate in the system is 5-20mmol /L to initiate a polymerization reaction, the reaction time is 5-24h; after the reaction, filter with suction, and the filter cake is ultrasonically washed with benzene, acetone and distilled water in sequence; filter and vacuum-dry to obtain surface-grafted modified nano-SiO2.

The organic solvent in the step 1 is any one of toluene, xylene, n-hexane, cyclohexane, dichloromethane, n-pentane, cyclopentane, dioxane and tetrahydrofuran as an organic solvent.

The aminosilane coupling agent in the step 1 is 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(β -Any one of aminoethyl-γ-aminopropyl)methyldimethoxysilane.

The monomer in step 2 may be any one of allylamine, acrylamide, N-isopropylacrylamide and N-vinylpyrrolidone.

The inert gas in the step 2 is argon or nitrogen.

In the step 2, the mass volume ratio of nano-SiO2 to deionized water is 1:5˜1:10.

The present invention has the following beneficial effects:

According to a nano-silica modification method provided by the present invention, the obtained silica particles have high grafting efficiency and can be better dispersed in the water phase. Since the introduced polymer molecule contains multiple amino groups, its performance is greatly improved. It has the ability to chelate and adsorb heavy metal ions. In addition, the modified nano-silica is easy to separate and elute, and can be recycled to reduce waste of resources, and has great application prospects.

Detailed ways

Example 1

Weigh 15g of dried nano-SiO2, add 500mL of toluene, fully stir and ultrasonically oscillate for 30min in a three-neck flask equipped with a condenser, so that nano-SiO2 is evenly dispersed in toluene. Then slowly add 0.5g of 3-aminopropyltrimethoxysilane dropwise, and heat to reflux for 8h. Suction filtration, the obtained product was washed three times with absolute ethanol, and dried to obtain surface-modified nano-SiO2.

Vacuumize the three-neck flask equipped with a stirrer, condenser tube and dropping funnel, then pass nitrogen gas, repeat three times to fully discharge the air in the reactor, then add surface-modified nano-SiO2, deionized water 80mL, N -isopropylacrylamide, and make the concentration of N-isopropylacrylamide 3mol/L; adjust the reaction temperature to 60°C, add dropwise 5mL of nitric acid solution of 0.2mol/L cerium ammonium nitrate to initiate polymerization, and the reaction time is 8h; after the reaction, suction filtration, the filter cake was ultrasonically washed with benzene, acetone and distilled water in sequence; filtered and vacuum-dried to obtain surface-grafted modified nano-SiO2.

Example 2

Weigh 25g of dried nano-SiO2, add 400mL of dioxane, fully stir and ultrasonically vibrate for 20min in a three-necked flask equipped with a condenser tube, so that nano-SiO2 is evenly dispersed in dioxane. Then slowly add 1g of 3-aminopropylmethyldiethoxysilane dropwise, and heat to reflux for 14h. Suction filtration, the resulting product was washed three times with absolute ethanol, and dried to obtain surface-modified nano-SiO2;

Vacuumize the three-neck flask equipped with a stirrer, condenser tube and dropping funnel, and then introduce argon, repeat three times to fully discharge the air in the reactor, then add surface-modified nano-SiO2, deionized water 150mL, Allylamine, and make the concentration of allylamine 1mol/L; adjust the reaction temperature to 80°C, add dropwise 7mL of 0.2mol/L cerium ammonium nitrate nitric acid solution to initiate polymerization, and the reaction time is 16h; after the reaction , suction filtration, and the filter cake was ultrasonically washed with benzene, acetone and distilled water in sequence; filtered and vacuum-dried to obtain surface graft-modified nano-SiO2.

Example 3

Weigh 20g of dried nano-SiO2, add 800mL of n-hexane, fully stir and ultrasonically vibrate for 30min in a three-neck flask equipped with a condenser, so that nano-SiO2 is evenly dispersed in n-hexane. Then slowly add 0.6g of 3-aminopropyltriethoxysilane dropwise, and heat to reflux for 10h. Suction filtration, the resulting product was washed three times with absolute ethanol, and dried to obtain surface-modified nano-SiO2;

Vacuumize the three-neck flask equipped with a stirrer, condenser tube and dropping funnel, and then introduce argon, repeat three times to fully discharge the air in the reactor, then add surface-modified nano-SiO2, deionized water 120mL, N-vinylpyrrolidone, and make the concentration of N-vinylpyrrolidone 1mol/L; adjust the reaction temperature to 40°C, add 6mL of nitric acid solution of 0.2mol/L cerium ammonium nitrate dropwise to initiate the polymerization reaction, and the reaction time is 12h; After the end, suction filtration, the filter cake was ultrasonically washed with benzene, acetone and distilled water in sequence; filtered and vacuum dried to obtain surface graft modified nano-SiO2.

Example 4

Under optimized pH conditions (pH=7-9), the adsorption temperature is 25-45°C, and the adsorption time is 1-2h. The modified nano-silica particles prepared in Example 1 have the following adsorption rates for heavy metals . Where C0 is the concentration of metal ions in the solution before adsorption (μg/mL), C is the average concentration of metal ions in the solution after adsorption (μg/mL), η is the adsorption rate and η=(C0-C)/C0. The used modified nano-silica is washed with hydrochloric acid (1-5mol/L) and washed with acetone to resolve the adsorbed metal ions, and can be recycled after being dried.

C0(μg/mL) C (μg/mL) η(%) Ni2+ 10 0.02 99.8 Mn2+ 10 0.01 99.9 Cr3+ 10 0.08 99.2 Hg2+ 10 0.01 99.9 Cd2+ 10 0.05 99.5

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes and substitutions that can be easily imagined by those skilled in the art within the technical scope disclosed in the present invention should be covered. Within the protection scope of the present invention.

Claims (6)

1. a nano-silicon dioxide modified method, is characterized in that, described step is as follows:

Get dried nanosized SiO_2, be placed in the there-necked flask that condenser pipe is housed, add organic solvent, make the mass volume ratio of SiO2 and organic solvent be 1:10 ~ 1:50, stir, and sonic oscillation, make nanosized SiO_2 in organic solvent dispersed; Then slowly drip amino silicane coupling agent, heating, constant temperature backflow 3 ~ 24 hours; Suction filtration, filter cake absolute ethanol washing three times, dries the nanosized SiO_2 after obtaining surface modification;

The there-necked flask that agitator, condenser pipe and addition funnel are housed is vacuumized, then pass into inert gas, in triplicate fully to discharge the air in reactor, then add the nanosized SiO_2 after surface modification, monomer and deionized water, make monomer concentration be 0.5 ~ 3mol/L; Regulate reaction temperature to 30 ~ 80 DEG C, drip the salpeter solution of 0.2mol/L ammonium ceric nitrate, make ammonium ceric nitrate concentration in system be 5 ~ 20mmol/L, initiated polymerization, the reaction time is 5 ~ 24h; After reaction terminates, suction filtration, filter cake uses benzene, acetone and distilled water supersound washing successively; Filter, vacuum drying obtains the nanosized SiO_2 of surface graft modification.

2. the nano-silicon dioxide modified method of one according to claim 1, it is characterized in that, described step a) in organic solvent be any one in toluene, dimethylbenzene, n-hexane, cyclohexane, carrene, pentane, pentamethylene, dioxane, oxolane.

3. the nano-silicon dioxide modified method of one according to claim 1, it is characterized in that, described step a) in amino silicane coupling agent be any one in 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyltriethoxy diethoxy silane, N-(β-aminoethyl-γ-aminopropyl) methyl dimethoxysilane, it accounts for 0.1% ~ 5% of SiO2 consumption.

4. the nano-silicon dioxide modified method of one according to claim 1, is characterized in that, described step b) in monomer can be any one in allyl amine, acrylamide, NIPA and NVP.

5. the nano-silicon dioxide modified method of one according to claim 1, is characterized in that, described step b) in inert gas be argon gas or nitrogen.

6. the nano-silicon dioxide modified method of one according to claim 1, is characterized in that, described step b) in the mass volume ratio of nanosized SiO_2 and deionized water be 1:5 ~ 1:10.