A preparation process of modified silicon dioxide adsorbent

Abstract

The invention relates to the technical field of silicon dioxide, and discloses a preparation process of a modified silicon dioxide adsorbent, wherein a solvent, KH560 modified silicon dioxide, a mercapto modifier, and triethylamine are added to a flask for reaction, and then a hydrolysis reaction is carried out in a sodium hydroxide aqueous solution to obtain the modified silicon dioxide adsorbent. The carboxyl group, mercapto group, and ortho-hydroxy Schiff base structure contained in the modified silicon dioxide adsorbent of the invention have a strong coordination effect on metal ions such as lead and mercury, significantly improve the adsorption performance of the silicon dioxide adsorbent on these metal ions, and show a very high adsorption capacity.

Description

Technical Field

[0001] The invention relates to the technical field of silicon dioxide, in particular to a preparation process of a modified silicon dioxide adsorbent. Background Art

[0002] At present, the main sources of water pollution in my country are mining wastewater, printing and dyeing wastewater, agricultural wastewater, etc. These wastewaters contain a large amount of heavy metal ions, organic dyes, pesticides, antibiotics and other pollutants. If the wastewater is not effectively treated, the pollutants will seriously damage the water body and the ecological environment. The adsorption method mainly uses adsorption materials to adsorb pollutants in wastewater. It has the advantages of diverse adsorption materials, simple operation, and recyclability.

[0003] Nano-silicon dioxide is cheap and easy to obtain, with a large specific surface area. The preparation methods of nano-silicon dioxide are diverse. It can usually be prepared by precipitation from sodium silicate and sulfuric acid; or by hydrolysis of tetraethyl orthosilicate; and nano-silicon dioxide is easy to be functionalized on the surface, and has good practical applications in adsorption materials and wastewater treatment. Patent CN106693924B discloses a nano-silicon dioxide adsorbent, a preparation method and its application, and discloses that a nano-silicon dioxide adsorbent is prepared using silicon dioxide nanoparticles, vinyl tris (2-methoxyethoxy) silane, polyetheramine, bromosalicylic acid aniline, 2-mercaptobenzothiazole, etc. as reactants, and has good adsorption performance for silver ions. The present invention aims to modify the surface of nano-silicon dioxide, introduce groups such as mercapto, o-hydroxy salicylaldehyde, etc., and improve the adsorption performance of nano-silicon dioxide for metal ions such as lead, cadmium, and mercury. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a process for preparing a modified silica adsorbent for adsorbing metals and dyes.

[0005] Technical solution: A preparation process of modified silica adsorbent:

[0006] Step S1, adding methanol, cysteine ​​methyl ester hydrochloride, and sodium hydroxide into a flask, stirring and adding 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde, distilling under reduced pressure after the reaction, washing with water, and recrystallizing the product with ethyl acetate to obtain a thiol modifier; the reaction formula is:

[0007]

[0008] Step S2, adding a solvent, KH560 modified silica, a mercapto modifier, and triethylamine into a flask, stirring to react, filtering, washing with ethanol, and drying to obtain an adsorbent precursor;

[0009] Step S3, add sodium hydroxide aqueous solution and adsorbent precursor to the flask, stir to carry out hydrolysis reaction, filter, wash with water, and dry to obtain modified silica adsorbent. The reaction mechanism is:

[0010]

[0011] Furthermore, in step S1, the molar ratio of cysteine ​​methyl ester hydrochloride, sodium hydroxide, and 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde is (2-2.2):(2-2.2):1.

[0012] Furthermore, the reaction in step S1 is carried out at 40-55° C. for 8-12 h.

[0013] Furthermore, in step S2, the solvent is toluene, N,N-dimethylformamide or N,N-dimethylformamide.

[0014] Furthermore, in step S2, the masses of the mercapto modifier and triethylamine are 40-200% and 1.6-10% of the mass of the KH560 modified silica, respectively.

[0015] Furthermore, the reaction in step S2 is carried out at 20-35° C. for 12-24 h.

[0016] Furthermore, the mass fraction of the sodium hydroxide aqueous solution in step S3 is 8-12%.

[0017] Furthermore, the hydrolysis reaction in step S3 is carried out at 80-90° C. for 5-8 h.

[0018] Technical effect: The present invention utilizes cysteine ​​methyl ester hydrochloride and 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxaldehyde to carry out Schiff base reaction to obtain a thiol modifier, and then uses triethylamine as a catalyst to utilize the thiol group of the modifier and the epoxy group of KH560 modified silica to carry out a thiol-epoxy reaction, and after an ester hydrolysis reaction, a modified silica adsorbent containing a thiol group, a carboxyl group and an o-hydroxy Schiff base structure is obtained.

[0019] The carboxyl, mercapto and o-hydroxy Schiff base structures contained in the modified silica adsorbent of the present invention have a strong coordination effect on metal ions such as lead, mercury and cadmium, which significantly improves the adsorption performance of the silica adsorbent on these metal ions and shows a very high adsorption capacity. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should belong to the scope of protection of the present invention.

[0021] The KH560 of the present invention is γ-glycidyloxypropyltrimethoxysilane.

[0022] The CAS number of cysteine ​​methyl ester hydrochloride is 18598-63-53,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarboxaldehyde is CAS number 14969-32-5.

[0023] At 65°C, 200 mL of a 0.3 mol / L sodium silicate aqueous solution was added dropwise into a flask, and concentrated sulfuric acid was added dropwise at the same time to adjust the solution pH to 9. The stirring rate was controlled to 800 r / min, and the reaction was performed for 90 min. After cooling, the mixture was centrifuged and washed with water, and the precipitate was added to ethanol, centrifuged and dried to obtain nano-silicon dioxide.

[0024] Add 50 mL of toluene and 2 g of nano-silica into a flask, disperse by ultrasonic, then add 0.12 g of KH550, heat to 80°C, stir and react for 10 h, filter, wash with ethanol, and dry to obtain KH560 modified silica.

[0025] Example 1

[0026] (1) Add 10 mL of methanol, 10 mmol of cysteine ​​methyl ester hydrochloride, and 10 mmol of sodium hydroxide into a flask, stir, then add 5 mmol of 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde, stir and react at 55° C. for 8 h, evaporate under reduced pressure, wash with water, and recrystallize the product with ethyl acetate to obtain a thiol modifier.

[0027] (2) Add 80 mL of N,N-dimethylformamide solvent, 2 g of KH560 modified silica, 0.8 g of thiol modifier, and 0.032 g of triethylamine into a flask, stir and react at 25° C. for 12 h, filter, wash with ethanol, and dry to obtain an adsorbent precursor.

[0028] (3) Add 100 mL of 12% sodium hydroxide aqueous solution and 3 g of adsorbent precursor into a flask, stir and hydrolyze at 85° C. for 5 h, filter, wash with water, and dry to obtain a modified silica adsorbent.

[0029] Example 2

[0030] (1) Add 10 mL of methanol, 11 mmol of cysteine ​​methyl ester hydrochloride, and 11 mmol of sodium hydroxide into a flask, stir, then add 5 mmol of 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde, stir and react at 45°C for 12 h, evaporate under reduced pressure, wash with water, and recrystallize the product with ethyl acetate to obtain a thiol modifier.

[0031] (2) Add 100 mL of toluene solvent, 2 g of KH560 modified silica, 2 g of thiol modifier, and 0.085 g of triethylamine into a flask, stir and react at 20° C. for 24 h, filter, wash with ethanol, and dry to obtain an adsorbent precursor.

[0032] (3) Add 120 mL of 12% sodium hydroxide aqueous solution and 3 g of adsorbent precursor into a flask, stir and hydrolyze at 90° C. for 5 h, filter, wash with water, and dry to obtain a modified silica adsorbent.

[0033] Example 3

[0034] (1) Add 10 mL of methanol, 11 mmol of cysteine ​​methyl ester hydrochloride, and 11 mmol of sodium hydroxide into a flask, stir, and then add 5 mmol of 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde. Stir and react at 40° C. for 12 h. Distill under reduced pressure, wash with water, and recrystallize the product with ethyl acetate to obtain a thiol modifier.

[0035] (2) Add 120 mL of N,N-dimethylformamide solvent, 2 g of KH560 modified silica, 2.8 g of thiol modifier, and 0.14 g of triethylamine into a flask, stir and react at 35° C. for 18 h, filter, wash with ethanol, and dry to obtain an adsorbent precursor.

[0036] (3) Add 150 mL of 10% sodium hydroxide aqueous solution and 3 g of adsorbent precursor into a flask, stir and hydrolyze at 90° C. for 8 h, filter, wash with water, and dry to obtain a modified silica adsorbent.

[0037] Example 4

[0038] (1) Add 8 mL of methanol, 10 mmol of cysteine ​​methyl ester hydrochloride, and 10 mmol of sodium hydroxide into a flask, stir, then add 5 mmol of 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde, stir and react at 55° C. for 10 h, evaporate under reduced pressure, wash with water, and recrystallize the product with ethyl acetate to obtain a thiol modifier.

[0039] (2) Add 120 mL of N,N-dimethylformamide solvent, 2 g of KH560 modified silica, 4 g of thiol modifier, and 0.2 g of triethylamine into a flask, stir and react at 20° C. for 24 h, filter, wash with ethanol, and dry to obtain an adsorbent precursor.

[0040] (3) Add 150 mL of 12% sodium hydroxide aqueous solution and 3 g of adsorbent precursor into a flask, stir and hydrolyze at 80° C. for 8 h, filter, wash with water, and dry to obtain a modified silica adsorbent.

[0041] In Comparative Example 1, nano-silicon dioxide is used as the adsorption material.

[0042] In Comparative Example 2, KH560 modified silica was used as the adsorption material.

[0043] In Comparative Example 3, the adsorbent precursor (prepared in Example 1) is used as the adsorption material.

[0044] Add 500 mL of water and lead nitrate to the flask to prepare a Pb solution with a mass concentration of 100 mg / L. 2+ The solution was then added with 50 mg of adsorption material and stirred for 1-3 h at room temperature. The Pb 2+ The concentration of the solution is used to calculate the adsorption capacity Q.

[0045] Q=(C0-C1)×V / m. C0 is the Pb before adsorption 2+ The concentration of the solution, C1 is the concentration of Pb after adsorption 2+ is the concentration of the solution, V is the volume of the solution, and m is the mass of the adsorbent material.

[0046] Table 1 Pb 2+ Adsorption capacity test

[0047]

[0048]

[0049] Add 500 mL of water and mercuric nitrate to the flask to make a Hg concentration of 100 mg / L. 2+ The solution was then added with 50 mg of adsorption material and stirred for 1-4 h at room temperature. Hg 2+ The concentration of the solution is used to calculate the adsorption capacity Q.

[0050] Q = (C0-C1) × V / m. C0 is Hg before adsorption 2+ The concentration of the solution, C1 is the Hg 2+ is the concentration of the solution, V is the volume of the solution, and m is the mass of the adsorbent material.

[0051] Table 2Hg 2+ Adsorption capacity test

[0052]

[0053] Add 500 mL of water and mercuric nitrate to the flask to prepare a Cd solution with a mass concentration of 100 mg / L. 2+ The solution was then added with 50 mg of adsorption material and stirred for 1-3 h at room temperature. Hg 2+ The concentration of the solution is used to calculate the adsorption capacity Q.

[0054] Q = (C0-C1) × V / m. C0 is the Cd before adsorption 2+ The concentration of the solution, C1 is the concentration of Cd after adsorption 2+ is the concentration of the solution, V is the volume of the solution, and m is the mass of the adsorbent material.

[0055] Table 3Cd 2+ Adsorption capacity test

[0056]

[0057] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A process for preparing a modified silica adsorbent, characterized in that: The preparation process comprises the following steps: Step S1, adding methanol, cysteine ​​methyl ester hydrochloride, and sodium hydroxide into a flask, stirring and adding 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde, distilling under reduced pressure after the reaction, washing with water, and recrystallizing the product with ethyl acetate to obtain a thiol modifier; Step S2, adding a solvent, KH560 modified silica, a mercapto modifier, and triethylamine into a flask, stirring to react, filtering, washing with ethanol, and drying to obtain an adsorbent precursor; Step S3, adding sodium hydroxide aqueous solution and adsorbent precursor into a flask, stirring to carry out hydrolysis reaction, filtering, washing with water, and drying to obtain a modified silica adsorbent; In the step S1, the molar ratio of cysteine ​​methyl ester hydrochloride, sodium hydroxide, and 3,3'-dihydroxy-[1,1'-biphenyl]-4,4'-dicarbaldehyde is (2-2.2):(2-2.2):1; In the step S2, the masses of the mercapto modifier and triethylamine are 40-200% and 1.6-10% of the mass of the KH560 modified silica, respectively.

2. The preparation process of the modified silica adsorbent according to claim 1, characterized in that: The reaction in step S1 is carried out at 40-55° C. for 8-12 hours.

3. The preparation process of the modified silica adsorbent according to claim 1, characterized in that: The solvent in step S2 is toluene or N,N-dimethylformamide.

4. The preparation process of the modified silica adsorbent according to claim 1, characterized in that: The reaction in step S2 is carried out at 20-35° C. for 12-24 h.

5. The preparation process of the modified silica adsorbent according to claim 1, characterized in that: The mass fraction of the sodium hydroxide aqueous solution in step S3 is 8-12%.

6. The preparation process of the modified silica adsorbent according to claim 1, characterized in that: The hydrolysis reaction in step S3 is carried out at 80-90° C. for 5-8 hours.

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