阅读说明：本技术 一种孔径可调的纳滤膜及制备方法 (Nanofiltration membrane with adjustable aperture and preparation method thereof ) 是由 陈幸培 陈健 陈睿东 叶泽昕 雷园园 陈建滨 卢志威 徐林清 于 2020-07-21 设计创作，主要内容包括：本发明公开了一种孔径可调的纳滤膜及制备方法,包括以下步骤：步骤一：聚丙烯腈微孔底膜的水解,在聚丙烯腈微孔底膜表面倾倒pH11～12的氢氧化钠水溶液,室温下接触60min后去除氢氧化钠水溶液,并使用纯水冲洗至中性,得到表面水解的聚丙烯腈微孔底膜；步骤二：纳米颗粒的沉积,选用不同粒径的亲水性纳米颗粒,将其分散在纯水中,并使用超声震荡60min；随后使用1wt％的稀硫酸将其pH调节至2.0；以抽滤的方式将纳米颗粒沉积至步骤一中得到的聚丙烯腈微孔底膜表面,并将其加热至一定温度进行热处理10min；最后使用纯水冲洗沉积纳米颗粒的聚丙烯腈微孔膜。通过本发明的实施,实现了纳滤膜的孔径调节,提高了分离效率,拓展了纳滤膜分离技术在特种分离领域的应用。(The invention discloses a nanofiltration membrane with adjustable aperture and a preparation method thereof, and the method comprises the following steps: the method comprises the following steps: hydrolyzing a polyacrylonitrile microporous base membrane, pouring a sodium hydroxide aqueous solution with the pH value of 11-12 on the surface of the polyacrylonitrile microporous base membrane, contacting for 60min at room temperature, removing the sodium hydroxide aqueous solution, and washing with pure water to be neutral to obtain the polyacrylonitrile microporous base membrane with the hydrolyzed surface; step two: depositing nano particles, namely selecting hydrophilic nano particles with different particle sizes, dispersing the hydrophilic nano particles in pure water, and oscillating for 60min by using ultrasonic; the pH was then adjusted to 2.0 using 1 wt% dilute sulfuric acid; depositing nano particles on the surface of the polyacrylonitrile microporous base membrane obtained in the step one in a suction filtration mode, heating the polyacrylonitrile microporous base membrane to a certain temperature, and carrying out heat treatment for 10 min; finally, washing the polyacrylonitrile microporous membrane deposited with the nano particles by using pure water. By implementing the method, the aperture of the nanofiltration membrane is adjusted, the separation efficiency is improved, and the application of the nanofiltration membrane separation technology in the field of special separation is expanded.)

1. The nanofiltration membrane with adjustable aperture and the preparation method thereof are characterized by comprising the following steps:

the method comprises the following steps: hydrolyzing a polyacrylonitrile microporous base membrane, pouring a sodium hydroxide aqueous solution with the pH value of 11-12 on the surface of the polyacrylonitrile microporous base membrane, contacting for 60min at room temperature, removing the sodium hydroxide aqueous solution, and washing with pure water to be neutral to obtain the polyacrylonitrile microporous base membrane with the hydrolyzed surface;

step two: depositing nano particles, namely selecting hydrophilic nano particles with different particle sizes, dispersing the hydrophilic nano particles in pure water, and oscillating for 60min by using ultrasonic; the pH was then adjusted to 2.0 using 1 wt% dilute sulfuric acid; depositing nano particles on the surface of the polyacrylonitrile microporous base membrane obtained in the step one in a suction filtration mode, heating the polyacrylonitrile microporous base membrane to a certain temperature, and carrying out heat treatment for 10 min; finally washing the polyacrylonitrile microporous membrane deposited with the nano particles by using pure water;

step three: fixing nano particles, dissolving a cross-linking agent in pure water to prepare an aqueous solution with the mass concentration of 0.5%, and adjusting the pH value to 2.0 by using a sulfuric acid solution with the mass concentration of 1.0% to serve as a cross-linking solution; and D, immersing the polyacrylonitrile microporous membrane deposited with the nano particles obtained in the step two into the crosslinking liquid, taking out the polyacrylonitrile microporous membrane after 30 seconds, and performing heat treatment for 2min in an oven at the temperature of 80 ℃ to finish the preparation of the nanofiltration membrane.

2. The nanofiltration membrane with the adjustable aperture and the preparation method of the nanofiltration membrane as claimed in claim 1, wherein the hydrophilic nanoparticles are one or two of silicon dioxide and titanium dioxide.

3. The nanofiltration membrane with the adjustable aperture and the preparation method of the nanofiltration membrane as claimed in claim 1, wherein the particle size of the nanoparticles is 10nm to 50nm, and the mass concentration of the nanoparticles is 0.5 wt% to 4.0 wt%.

4. The nanofiltration membrane with the adjustable aperture and the preparation method of the nanofiltration membrane as claimed in claim 1, wherein the heat treatment temperature is 70-85 ℃.

5. The nanofiltration membrane with the adjustable aperture and the preparation method of the nanofiltration membrane as claimed in claim 1, wherein the cross-linking agent is one or more of glutaraldehyde, glyoxal, citric acid and oxalic acid.

Technical Field

The invention relates to the field of separation membrane preparation, in particular to a nanofiltration membrane with adjustable aperture and a preparation method thereof.

Background

The nanofiltration membrane materials for special separation in the current market are mainly a polypiperazine amide nanofiltration composite membrane prepared by interfacial polymerization and a nanofiltration membrane prepared by phase separation, but due to the reaction characteristic of interfacial polymerization, the aperture of the nanofiltration membrane is basically fixed, the nanofiltration membrane is difficult to adjust by changing the production process, and the application range in the field of special separation is small; the nanofiltration membrane prepared by phase separation can adjust the aperture of the nanofiltration membrane by changing the solid content of the membrane preparation liquid and the additive, so that the application range of the nanofiltration membrane in the special separation field is enlarged, but the separation layer of the nanofiltration membrane prepared by phase separation has larger thickness, so the permeation flux is lower, the separation efficiency in actual operation is influenced, and the application of the nanofiltration membrane separation technology in the special separation field is limited. Therefore, the nano-filtration membrane material with adjustable aperture and higher permeation flux is developed, and has very important economic benefit.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a nanofiltration membrane with adjustable aperture and a preparation method thereof, aiming at solving the problems that the nanofiltration membrane has lower permeation flux, influences the separation efficiency and has application limitation in the field of special separation.

In order to achieve the purpose, the invention provides the following technical scheme: a nanofiltration membrane with adjustable aperture and a preparation method thereof comprise the following steps:

the method comprises the following steps: hydrolyzing a polyacrylonitrile microporous base membrane, pouring a sodium hydroxide aqueous solution with the pH value of 11-12 on the surface of the polyacrylonitrile microporous base membrane, contacting for 60min at room temperature, removing the sodium hydroxide aqueous solution, and washing with pure water to be neutral to obtain the polyacrylonitrile microporous base membrane with the hydrolyzed surface;

step two: depositing nano particles, namely selecting hydrophilic nano particles with different particle sizes, dispersing the hydrophilic nano particles in pure water, and oscillating for 60min by using ultrasonic; the pH was then adjusted to 2.0 using 1 wt% dilute sulfuric acid; depositing nano particles on the surface of the polyacrylonitrile microporous base membrane obtained in the step one in a suction filtration mode, heating the polyacrylonitrile microporous base membrane to a certain temperature, and carrying out heat treatment for 10 min; finally washing the polyacrylonitrile microporous membrane deposited with the nano particles by using pure water;

step three: fixing nano particles, dissolving a cross-linking agent in pure water to prepare an aqueous solution with the mass concentration of 0.5%, and adjusting the pH value to 2.0 by using a sulfuric acid solution with the mass concentration of 1.0% to serve as a cross-linking solution; and D, immersing the polyacrylonitrile microporous membrane deposited with the nano particles obtained in the step two into the crosslinking liquid, taking out the polyacrylonitrile microporous membrane after 30 seconds, and performing heat treatment for 2min in an oven at the temperature of 80 ℃ to finish the preparation of the nanofiltration membrane.

Further, the hydrophilic nanoparticles are one or two of silicon dioxide and titanium dioxide.

Furthermore, the particle size of the nano-particles is 10 nm-50 nm, and the mass concentration of the nano-particles is 0.5 wt% -4.0 wt%.

Further, the heat treatment temperature is 70-85 ℃.

Further, the cross-linking agent is one or more of glutaraldehyde, glyoxal, citric acid and oxalic acid.

The invention has the beneficial effects that:

1. in the invention, hydrophilic nanoparticles with different particle sizes are selected as the separation layer material, so that the separation precision of the nanofiltration membrane can be adjusted by effectively utilizing the gaps among the nanoparticles, and the application range of the nanofiltration membrane separation technology in the field of special separation is expanded;

2. according to the invention, the hydrolyzed polyacrylonitrile microporous membrane is selected as the bottom membrane and is subjected to heat treatment, so that on one hand, the hydroxyl on the surface of the hydrophilic nanoparticles and the hydroxyl on the surface of the polyacrylonitrile microporous membrane are reacted to form chemical bonds, and the bonding strength between the separation layer and the microporous bottom membrane is increased; on the other hand, the nano particles which do not react with the microporous base membrane can be removed to form a single-layer separation layer, so that higher permeation flux is obtained;

3. in the invention, the nanoparticle separation layer treated by the cross-linking agent has better physical and chemical stability and higher hydrophilicity, so that the pollution resistance of the nanofiltration membrane is improved, and the application of the nanofiltration membrane separation technology in the special separation field is further expanded.

Drawings

Fig. 1 is a diagram illustrating flux variation trend of the nanofiltration membrane.

Detailed Description

A nanofiltration membrane with adjustable aperture and a preparation method thereof comprise the following steps:

the method comprises the following steps: hydrolyzing a polyacrylonitrile microporous base membrane, pouring a sodium hydroxide aqueous solution with the pH value of 11-12 on the surface of the polyacrylonitrile microporous base membrane, contacting for 60min at room temperature, removing the sodium hydroxide aqueous solution, and washing with pure water to be neutral to obtain the polyacrylonitrile microporous base membrane with the hydrolyzed surface;

step two: depositing nano particles, namely selecting hydrophilic nano particles with different particle sizes, dispersing the hydrophilic nano particles in pure water, and oscillating for 60min by using ultrasonic; the pH was then adjusted to 2.0 using 1 wt% dilute sulfuric acid; depositing nano particles on the surface of the polyacrylonitrile microporous base membrane obtained in the step one in a suction filtration mode, heating the polyacrylonitrile microporous base membrane to a certain temperature, and carrying out heat treatment for 10 min; finally washing the polyacrylonitrile microporous membrane deposited with the nano particles by using pure water;

step three: fixing nano particles, dissolving a cross-linking agent in pure water to prepare an aqueous solution with the mass concentration of 0.5%, and adjusting the pH value to 2.0 by using a sulfuric acid solution with the mass concentration of 1.0% to serve as a cross-linking solution; and D, immersing the polyacrylonitrile microporous membrane deposited with the nano particles obtained in the step two into the crosslinking liquid, taking out the polyacrylonitrile microporous membrane after 30 seconds, and performing heat treatment for 2min in an oven at the temperature of 80 ℃ to finish the preparation of the nanofiltration membrane.