Preparation method of modified quartz sand

Abstract

The invention relates to a preparation method of quartz sand, in particular to a preparation method of modified quartz sand for a filter material. By modifying the quartz sand, the problems that the binding force is not strong when the quartz sand is wrapped by phenolic resin and the adsorption capacity of the quartz sand to heavy metals is insufficient are solved at the same time.

Description

Technical Field

[0001] The present invention relates to a method for preparing quartz sand, and in particular to a method for preparing modified quartz sand for filtering filter material. Background Art

[0002] As a commonly used filter material in the field of water treatment, quartz sand is widely used in various water treatment systems due to its good physical and chemical stability. Its main function is to effectively remove impurities such as suspended matter, organic matter and microorganisms in water, thereby improving water quality and ensuring water safety. Quartz sand filter material can intercept and filter out solid particles in water through the pore structure between its particles. At the same time, its surface characteristics also enable it to have a certain removal effect on some soluble organic matter and microorganisms. It is one of the indispensable basic materials in the water treatment process.

[0003] Although quartz sand filter material shows good performance in water treatment, its adsorption capacity for organic matter is relatively weak, which limits its application effect in treating water sources containing high concentrations of organic matter. In order to improve the adsorption capacity of quartz sand for organic matter, the prior art usually adopts the method of wrapping phenolic resin on the surface of quartz sand. However, there is a significant problem with this method, that is, the binding force between phenolic resin and the surface of quartz sand is not strong enough, and the resin layer is prone to fall off or shrink during use, which affects the long-term stability and filtration efficiency of the modified quartz sand. Therefore, exploring a new technology that can effectively enhance the binding force between phenolic resin and quartz sand has become the key to improving the performance of quartz sand filter material.

[0004] With the acceleration of industrialization and urbanization, the problem of heavy metal pollution in water bodies has become increasingly serious, posing a serious threat to human health and the ecological environment. Although quartz sand filter media plays an important role in water treatment, its adsorption capacity for heavy metal ions is limited, and it is difficult to meet the demand for efficient removal of heavy metals in water. Therefore, it is particularly important to develop quartz sand filter media with enhanced heavy metal adsorption capacity. Improving the adsorption performance of quartz sand for heavy metals through modification technology can not only effectively reduce the heavy metal content in water bodies and protect water resources from pollution, but also provide strong support for drinking water safety and ecological environment protection, which has important practical significance and application value. Summary of the invention

[0005] In view of the above problems, the present invention modifies quartz sand, thereby solving the problem of weak bonding force of phenolic resin wrapped quartz sand and the problem of insufficient adsorption capacity of quartz sand for heavy metals.

[0006] Specifically, the present invention provides a method for preparing modified quartz sand, comprising the following steps:

[0007] (a) pre-treating quartz sand to enhance its surface activity;

[0008] (b) forming a polydopamine coating layer on the surface of the pretreated quartz sand;

[0009] (c) utilizing the reducing property of polydopamine to perform chemical plating of phenolic resin on the surface of quartz sand coated with polydopamine, wherein the phenolic resin contains titanium dioxide nanoparticles;

[0010] (d) cleaning and drying the chemically plated quartz sand to obtain modified quartz sand.

[0011] Specifically, the pretreatment in step (a) includes first cleaning the quartz sand with anhydrous ethanol and soaking it for 12-48 hours to remove surface grease and organic matter, and then drying it; then placing the dried quartz sand in a sodium hydroxide solution with a concentration of 3%-10%, and treating it at 50°C-70°C for 1-3 hours to enhance its surface activity.

[0012] Specifically, the concentration of the dopamine aqueous solution used in step (b) is 1 mg / mL-5 mg / mL, and the pH value is adjusted to

[0013] 8.0-9.5, processing time is 12-36 hours.

[0014] Specifically, after the polydopamine coating layer is formed in step (b), the quartz sand is washed with deionized water until the pH value of the washing water reaches 6.5-7.5.

[0015] Specifically, the solid content of the phenolic resin in step (c) is 50%-70%, the added amount of titanium dioxide nanoparticles is 3%-10% of the mass of the phenolic resin, and the particle size of the nanoparticles is less than 100 nm.

[0016] Specifically, the chemical plating in step (c) is carried out at 30°C-50°C, with a stirring speed of 50-200 rpm and a processing time of 3-6 hours.

[0017] Specifically, step (c) further includes a standing and curing step, and the standing time is 1-4 hours.

[0018] Specifically, the cleaning in step (d) uses anhydrous ethanol or deionized water, the number of cleaning times is 2-5 times, and the time of each cleaning is 5-30 minutes.

[0019] Specifically, the drying in step (d) is carried out at 50° C.-80° C. for 2-8 hours until the modified quartz sand reaches a constant weight.

[0020] Specifically, the quartz sand used has a particle size of 0.1-1.0 mm, a purity of not less than 98%, and does not contain impurities that are harmful to subsequent processing.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] First, the present invention pre-treats the surface of quartz sand, then uses dopamine to form a polydopamine coating layer in an alkaline environment, and uses the reducing property of polydopamine to achieve chemical plating of phenolic resin, thereby significantly enhancing the binding force of the resin layer on the outside of quartz sand, and effectively solving the problem of poor binding force, easy falling off or shrinkage of the phenolic resin wrapped on the outside of quartz sand in traditional technology. This innovative coating method ensures the close combination of the resin layer and quartz sand, maintains its coating and stability for a long time, thereby greatly improving the adsorption capacity of quartz sand for organic matter and optimizing its overall performance as a filter material.

[0023] Secondly, the present invention cleverly doped titanium dioxide nanoparticles into the phenolic resin. This innovative measure has brought significant and multi-faceted performance improvements to the modified quartz sand. Titanium dioxide nanoparticles not only enhance the modified quartz sand's ability to adsorb heavy metal ions, making it show a more excellent purification effect when treating water sources containing heavy metal ions; at the same time, these nanoparticles also fill the pores between quartz sand particles, improve the density and hardness of quartz sand, and thus enhance its wear resistance and compressive strength, making the modified quartz sand more durable when subjected to water flow impact and mechanical wear. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific embodiments.

[0025] Example 1

[0026] Raw materials and equipment

[0027] Quartz sand: particle size is 0.5-0.8mm, purity is 99%, and there are no harmful impurities.

[0028] Anhydrous ethanol: analytical grade.

[0029] Sodium hydroxide: analytical grade, prepared into 5% aqueous solution.

[0030] Dopamine: analytical grade, prepared into 2 mg / mL aqueous solution, pH adjusted to 8.5.

[0031] Phenolic resin: solid content 60%, added with 5% by mass of titanium dioxide nanoparticles (particle size <50 nm).

[0032] Deionized water.

[0033] Experimental equipment such as constant temperature stirrer, drying oven, pH meter, electronic balance, etc.

[0034] Preparation steps

[0035] Preprocessing:

[0036] Take an appropriate amount of quartz sand, clean it with anhydrous ethanol and soak it for 24 hours to remove surface grease and organic matter.

[0037] After drying, the quartz sand was placed in a 5% sodium hydroxide solution and treated at 60°C for 2 hours to enhance the surface activity.

[0038] After treatment, wash with deionized water until neutral, and dry for later use.

[0039] Polydopamine coating:

[0040] The pretreated quartz sand was placed in a 2 mg / mL dopamine aqueous solution with a pH of 8.5, stirred at a constant temperature (50 rpm), and reacted at room temperature for 24 hours.

[0041] After the reaction is completed, the quartz sand is washed with deionized water until the pH value of the washing water reaches about 7.0.

[0042] Phenolic resin chemical plating:

[0043] The phenolic resin (solid content 60%) containing 5% titanium oxide nanoparticles is uniformly coated on the surface of the polydopamine-coated quartz sand.

[0044] The chemical plating was carried out at 40° C. and a stirring speed of 100 rpm for 4 hours.

[0045] After chemical plating, let it stand and cure for 2 hours.

[0046] Cleaning and drying:

[0047] The modified quartz sand was cleaned with anhydrous ethanol for 3 times, each time for 15 min.

[0048] Dry in a drying oven at 60°C for 4 hours until constant weight is reached.

[0049] Comparative Example 1

[0050] The difference between Comparative Example 1 and Example 1 is that there is no polydopamine coating step, and the other steps are the same.

[0051] Comparative Example 2

[0052] The difference between Comparative Example 1 and Example 1 is that the phenolic resin does not contain titanium dioxide.

[0053] The modified quartz sand of Example 1 and Comparative Examples 1-2 were characterized.

[0054] Characterization methods

[0055] Resin layer bonding test:

[0056] Methods: Mechanical stirring and ultrasonic treatment were used to observe the shedding of the resin layer on the surface of modified quartz sand and record the shedding ratio.

[0057] Conditions: mechanical stirring speed 200 rpm, lasting 30 minutes; ultrasonic treatment power 100 W, lasting 15 minutes.

[0058] Organic matter adsorption capacity test:

[0059] Method: Standard phenol solution was used to carry out adsorption experiments to determine the adsorption capacity of modified quartz sand on organic matter.

[0060] Conditions: solution concentration 10 mg / L, adsorption time 2 hours, temperature 25°C, and residual phenol concentration was determined using a UV spectrophotometer.

[0061] Heavy metal adsorption capacity test:

[0062] Method: Use heavy metal ion Pb 2+ 、Cd 2+ Adsorption experiments were carried out on aqueous solutions to determine the adsorption efficiency of modified quartz sand for heavy metals.

[0063] Conditions: solution concentration 5 mg / L (two heavy metal ions), adsorption time 4 hours, temperature 25°C, and use atomic absorption spectrometer to measure the residual heavy metal ion concentration.

[0064] Physical performance test:

[0065] Wear resistance: Use an abrasion tester to test the wear resistance of modified quartz sand and record the amount of wear.

[0066] Compressive strength: Use a pressure testing machine to test the compressive strength of modified quartz sand and record the crushing point pressure.

[0067] Compactness: The compactness of modified quartz sand is evaluated by measuring its bulk density.

[0068] Specific characterization data

[0069] Example 1

[0070] Resin layer bonding strength: After mechanical stirring and ultrasonic treatment, the resin layer shedding ratio is less than 1%.

[0071] Organic matter adsorption capacity: The phenol adsorption capacity reaches 2.47 mg / g.

[0072] Heavy metal adsorption capacity: for Pb 2+ The adsorption efficiency of Cd 2+ The adsorption efficiency is 91.7%.

[0073] Physical properties: In the wear resistance test, the wear amount was reduced by 28.6%, the compressive strength was increased by 19.3%, and the density was increased by 14.2%.

[0074] Comparative Example 1

[0075] Resin layer bonding strength: After mechanical stirring and ultrasonic treatment, the resin layer shedding ratio was 5.3%.

[0076] Organic matter adsorption capacity: The phenol adsorption capacity is only 1.78 mg / g.

[0077] Heavy metal adsorption capacity: for Pb 2+ The adsorption efficiency of Cd 2+ The adsorption efficiency is 91.5%.

[0078] Physical properties: wear resistance and compressive strength are slightly lower than those of Example 1, density is equivalent, wear loss is reduced by 22.1%, and compressive strength is increased by 15.4%.

[0079] Comparative Example 2

[0080] Resin layer binding force: After mechanical stirring and ultrasonic treatment, the resin layer shedding ratio is less than 1%, which is equivalent to Example 1. Organic matter adsorption capacity: The phenol adsorption capacity reaches 2.39 mg / g, which is slightly lower than Example 1.

[0081] Heavy metal adsorption capacity: for Pb 2+ The adsorption efficiency of Cd 2+ The adsorption efficiency is 49.3%, which is significantly lower than that of Example 1.

[0082] Physical properties: wear resistance and compressive strength are comparable to those of Example 1, but due to the lack of titanium dioxide filling, the density is slightly lower, the wear loss is reduced by 27.9%, and the compressive strength is increased by 18.9%.

Claims

1. A method for preparing modified quartz sand, comprising the following steps: (a) pre-treating quartz sand to enhance its surface activity; (b) forming a polydopamine coating layer on the surface of the pretreated quartz sand; (c) utilizing the reducing property of polydopamine to perform chemical plating of phenolic resin on the surface of quartz sand coated with polydopamine, wherein the phenolic resin contains titanium dioxide nanoparticles; (d) cleaning and drying the chemically plated quartz sand to obtain modified quartz sand.

2. The preparation method according to claim 1, characterized in that: The pretreatment in step (a) includes first cleaning the quartz sand with anhydrous ethanol and soaking it for 12-48 hours to remove surface grease and organic matter, and then drying it; then placing the dried quartz sand in a sodium hydroxide solution with a concentration of 3%-10% and treating it at 50°C-70°C for 1-3 hours to enhance its surface activity.

3. The preparation method according to claim 1, characterized in that: The concentration of the dopamine aqueous solution used in step (b) is 1 mg / mL-5 mg / mL, the pH value is adjusted to 8.0-9.5, and the treatment time is 12-36 hours.

4. The preparation method according to claim 1, characterized in that: After the polydopamine coating layer is formed in step (b), the quartz sand is washed with deionized water until the pH value of the washing water reaches 6.5-7.

5.

5. The preparation method according to claim 1, characterized in that: The solid content of the phenolic resin in step (c) is 50%-70%, the added amount of titanium dioxide nanoparticles is 3%-10% of the mass of the phenolic resin, and the particle size of the nanoparticles is less than 100nm.

6. The preparation method according to claim 1, characterized in that: The chemical plating in step (c) is carried out at 30°C-50°C, with a stirring speed of 50-200 rpm and a processing time of 3-6 hours.

7. The preparation method according to claim 1, characterized in that: After step (c), a standing and curing step is also included, and the standing time is 1-4 hours.

8. The preparation method according to claim 1, characterized in that: The cleaning in step (d) uses anhydrous ethanol or deionized water, the number of cleaning times is 2-5 times, and the time of each cleaning is 5-30 minutes.

9. The preparation method according to claim 1, characterized in that: The drying in step (d) is carried out at 50° C.-80° C. for 2-8 hours until the modified quartz sand reaches a constant weight.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The quartz sand used has a particle size of 0.1-1.0 mm, a purity of not less than 98%, and does not contain impurities that are harmful to subsequent treatment.