阅读说明：本技术 一种基于碳酸二甲酯的反渗透膜及其制备方法 (Reverse osmosis membrane based on dimethyl carbonate and preparation method thereof ) 是由 时孟琪 马晓迅 于 2020-05-28 设计创作，主要内容包括：本发明公开了一种基于碳酸二甲酯的反渗透膜及其制备方法,该方法以聚砜支撑膜作为基膜,以间苯二胺为水相单体,以均苯三甲酰氯为有机相单体,以绿色溶剂碳酸二甲酯为有机相共溶剂,以正庚烷为有机相溶剂,采用界面聚合法制备得到反渗透膜。整个过程中,碳酸二甲酯作为共溶剂,增强了水相和有机相的相容性,从而会加快水相单体(间苯二胺)往有机相扩散的速率,从而使界面聚合反应会更加剧烈,从而导致反渗透膜表面粗糙度增大,进而使增大了反渗透膜分离层表面粗糙度,提高反渗透膜通量。(The invention discloses a reverse osmosis membrane based on dimethyl carbonate and a preparation method thereof. In the whole process, the dimethyl carbonate is used as a cosolvent, the compatibility of a water phase and an organic phase is enhanced, so that the diffusion rate of a water phase monomer (m-phenylenediamine) to the organic phase is accelerated, the interfacial polymerization reaction is more violent, the surface roughness of the reverse osmosis membrane is increased, the surface roughness of a separation layer of the reverse osmosis membrane is increased, and the flux of the reverse osmosis membrane is improved.)

1. A preparation method of a composite reverse osmosis membrane based on dimethyl carbonate is characterized by comprising the following steps:

step 1, soaking a polysulfone support membrane in a water phase solution to prepare a support membrane containing a water phase component; the water phase solution is a mixed solution of m-phenylenediamine, triethylamine, camphorsulfonic acid and deionized water;

step 2, soaking the support membrane containing the aqueous phase component prepared in the step 1 in an organic phase solution to generate an aromatic polyamide composite reverse osmosis membrane; the organic phase solution is a mixed solution of dimethyl carbonate, trimesoyl chloride and n-heptane solution; the concentration of dimethyl carbonate in the n-heptane solution is 0.5-2.5 wt%.

2. The preparation method of a composite reverse osmosis membrane based on dimethyl carbonate according to claim 1, wherein in the step 1, the soaking time of the polysulfone support membrane in the aqueous solution is 10-50 s.

3. The method for preparing a composite reverse osmosis membrane based on dimethyl carbonate according to claim 1, wherein in the aqueous solution in the step 1, the concentration of m-phenylenediamine in deionized water is 1.4-2.6 wt%.

4. The preparation method of a composite reverse osmosis membrane based on dimethyl carbonate according to claim 1, wherein the concentration of triethylamine in deionized water in the aqueous solution in the step 1 is 0.4-1.8 wt%.

5. The method for preparing a composite reverse osmosis membrane based on dimethyl carbonate according to claim 1, wherein the concentration of camphorsulfonic acid in deionized water in the aqueous solution in the step 1 is 2.0-3.2 wt%.

6. The method for preparing a composite reverse osmosis membrane based on dimethyl carbonate according to claim 1, wherein in the step 2, the concentration of trimesoyl chloride in an n-heptane solution is 0.04-0.20 wt%.

7. The method for preparing a composite reverse osmosis membrane based on dimethyl carbonate according to claim 1, wherein in the step 2, the soaking time of the support membrane containing the aqueous phase component in the organic phase solution is 10-50 s.

8. The method of claim 1, wherein the aromatic polyamide composite reverse osmosis membrane prepared in the step 2 is heat-treated.

9. The preparation method of a composite reverse osmosis membrane based on dimethyl carbonate according to claim 8, characterized in that the heat treatment temperature is 60-100 ℃ and the heat treatment time is 1-10 min.

10. A composite reverse osmosis membrane prepared by the method of any one of claims 1 to 9, wherein the composite reverse osmosis membrane is an aromatic polyamide composite reverse osmosis membrane having a flux of 3 L.m or more^-2·h^-1·bar^-1The retention rate is more than or equal to 98.50 percent.

[ technical field ] A method for producing a semiconductor device

The invention belongs to the technical field of preparation of composite reverse osmosis membranes, and particularly relates to a reverse osmosis membrane based on dimethyl carbonate and a preparation method thereof.

[ background of the invention ]

The membrane separation technology plays an important role in solving the water resource crisis as a modern novel and efficient chemical separation technology (Y.Okamoto, J.H.Lienhard, How RO membrane permeability and permeability factor process and energy use: A review, clarification, 2019,470: 114064.). Reverse osmosis membranes are one of the important types of separation membranes used in water treatment processes, and have been widely used in the fields of seawater/brackish water desalination, ultrapure water preparation, wastewater treatment, food concentration and the like. The selective permeability (flux, rejection) is an important evaluation index of reverse osmosis membranes (K.P.Lee, T.C. Arnot, D.Mattia, A view of reverse osmosis Membrane materials for desalination-concentration to date and future, Journal of Membrane Science,2011,370: 1-22.). On the premise of ensuring high rejection rate, flux improvement is important for improving the efficiency of the reverse osmosis membrane process, reducing the cost of the reverse osmosis membrane process and expanding the application range of the reverse osmosis membrane (D.Cohen-Tanugi, R.K.McGovern, S.H.Dave, J.H.Lienhard, J.C.Grossman, Quantifying the potential of ultra-permanent membranes for water purification, Energy & Environmental Science 2014,7: 1134-.

Currently, the most widely used reverse osmosis membrane is an aromatic polyamide thin layer composite reverse osmosis membrane (referred to simply as a polyamide reverse osmosis membrane) prepared by interfacial polymerization. It is believed that the separating layer (i.e., the polyamide thin layer) determines the separation performance of the membrane and contributes a significant portion of the mass transfer resistance. Therefore, optimizing the structure of the separation layer has been a hot spot in the research field of polyamide reverse osmosis membranes with high selective permeability. Since the larger the surface roughness of the separation layer, the larger the effective permeation area of the membrane and thus the larger the membrane flux, increasing the surface roughness of the separation layer is currently an effective method for increasing the flux of a reverse osmosis membrane. At present, adding a cosolvent into an aqueous phase or an organic phase is a common method for increasing the surface roughness of a separation layer. The method has the advantages of simplicity, effectiveness, low cost and the like.

An aqueous co-solvent (e.g., dimethylsulfoxide, which is a good solvent for the membrane) may damage the pore structure on the surface of the membrane, thereby impairing the rejection rate of the reverse osmosis membrane. The organic phase co-solvent does not present this problem because the separation layer is formed very rapidly, preventing the co-solvent from being formedContact with the basement membrane (Freer V., Nanoscale biology for used by interfacial polymerization, Langmuir,19(2003) 4791-4797.). Thus, organic phase co-solvents are more advantageous than aqueous phase co-solvents. However, all organic phase co-solvents used at present are non-green reagents, which have adverse effects on the environment. The best organic phase co-solvent currently is ethyl acetate (T.Kamada, T.Ohara, T.Shintani, T.Tsouu, Controlled surface morphology of polyamide membranes via the addition of co-solvent for improved performance, Journal of Membrane Science,467(2014) 303-. However, the flux of reverse osmosis membranes prepared with ethyl acetate was not high enough (less than 3 L.m)^-2·h^-1·bar^-1)。

[ summary of the invention ]

The invention aims to overcome the defects of the prior art and provides a reverse osmosis membrane based on dimethyl carbonate and a preparation method thereof; the method solves the problems that the cosolvent used in the prior art is polluted greatly, is not environment-friendly and can not obtain high reverse osmosis membrane flux on the premise of ensuring high reverse osmosis membrane rejection rate.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a preparation method of a composite reverse osmosis membrane based on dimethyl carbonate comprises the following steps:

step 1, soaking a polysulfone support membrane in a water phase solution to prepare a support membrane containing a water phase component; the water phase solution is a mixed solution of m-phenylenediamine, triethylamine, camphorsulfonic acid and deionized water;

step 2, soaking the support membrane containing the aqueous phase component prepared in the step 1 in an organic phase solution to generate an aromatic polyamide composite reverse osmosis membrane; the organic phase solution is a mixed solution of dimethyl carbonate, trimesoyl chloride and n-heptane solution; the concentration of dimethyl carbonate in the n-heptane solution is 0.5-2.5 wt%.

The invention is further improved in that:

preferably, in the step 1, the soaking time of the polysulfone support membrane in the aqueous solution is 10-50 s.

Preferably, in the aqueous phase solution in the step 1, the concentration of the m-phenylenediamine in the deionized water is 1.4-2.6 wt%.

Preferably, in the aqueous phase solution in the step 1, the concentration of triethylamine in deionized water is 0.4-1.8 wt%.

Preferably, in the aqueous phase solution in the step 1, the concentration of the camphorsulfonic acid in the deionized water is 2.0-3.2 wt%.

Preferably, in the step 2, the concentration of trimesoyl chloride in the n-heptane solution is 0.04-0.20 wt%.

Preferably, in the step 2, the soaking time of the support film containing the aqueous phase component in the organic phase solution is 10 to 50 s.

Preferably, the aromatic polyamide composite reverse osmosis membrane prepared in the step 2 is subjected to heat treatment.

Preferably, the heat treatment temperature is 60-100 ℃, and the heat treatment time is 1-10 min.

The composite reverse osmosis membrane prepared by any one of the preparation methods is an aromatic polyamide composite reverse osmosis membrane, and the flux of the composite reverse osmosis membrane is more than or equal to 3 L.m^-2·h^-1·bar^-1The retention rate is more than or equal to 98.50 percent.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a preparation method of a reverse osmosis membrane based on dimethyl carbonate, which is characterized in that a polysulfone support membrane is used as a base membrane, m-phenylenediamine is used as a water phase monomer, trimesoyl chloride is used as an organic phase monomer, a green solvent dimethyl carbonate is used as an organic phase cosolvent, and n-heptane is used as an organic phase solvent, and an interfacial polymerization method is adopted to prepare the reverse osmosis membrane. In the preparation process, firstly, a polysulfone support membrane is soaked in an aqueous phase solution to enable m-phenylenediamine and triethylamine in the aqueous phase solution to be adsorbed on the surface of a base membrane, then a process composite membrane is soaked in an organic phase solution, the m-phenylenediamine attached to the interface reacts with trimesoyl chloride in the aqueous phase to generate the aromatic polyamide reverse osmosis membrane, and in the whole process, dimethyl carbonate is used as a cosolvent to enhance the compatibility of the aqueous phase and an organic phase, so that the diffusion rate of an aqueous phase monomer (m-phenylenediamine) to the organic phase is accelerated, the interfacial polymerization reaction is more violent, the surface roughness of the reverse osmosis membrane is increased, and the flux of the reverse osmosis membrane is improved. However, it should be noted that if the compatibility between the aqueous phase and the organic phase is too high, the rate of diffusion of the aqueous monomer into the organic phase increases too much, which may cause the aqueous monomer to enter deeper regions of the organic phase, resulting in a thicker separation layer that is not conducive to increased flux through the reverse osmosis membrane, thus limiting the concentration of the co-solvent dimethyl carbonate. One reason for the choice of dimethyl carbonate in the present invention is that it is a "green" chemical product with promising future, safer and more environmentally friendly than the currently used organic phase solvents. In addition, at present, the best organic phase cosolvent reported in terms of preparing a reverse osmosis membrane with high permselectivity is ethyl acetate. Dimethyl carbonate has a lower solubility in water (2.9g/100mL) than ethyl acetate (8.3g/100 mL). In other words, dimethyl carbonate does not increase the thickness of the separation layer too much while increasing the surface roughness of the reverse osmosis membrane relative to ethyl acetate, thereby contributing more to the increase of the flux of the reverse osmosis membrane.

Furthermore, by limiting the soaking time of the polysulfone support membrane in the aqueous phase solution, the support membrane can have enough soaking time, and substances in the aqueous phase solution can be fully soaked on the surface of the support membrane.

Furthermore, the concentration of the m-phenylenediamine is limited, so that the m-phenylenediamine can be fully adsorbed on the surface of the support membrane in the soaking process.

Furthermore, the concentration of triethylamine and camphorsulfonic acid is limited to ensure that the interfacial polymerization reaction is fully performed.

Furthermore, the concentration of trimesoyl chloride is limited to ensure that the interfacial polymerization reaction is fully carried out.

Furthermore, the membrane structure is reasonable by limiting the reaction time of the interface, and the membrane is too thick due to overlong soaking time, so that the flux is reduced; too short a soaking time may result in insufficient membrane crosslinking degree and reduced rejection rate.

Furthermore, after the prepared aromatic polyamide composite reverse osmosis membrane is subjected to heat treatment, the interior of the composite membrane can be further crosslinked to generate a net structure, so that the strength of the whole membrane is enhanced.

The invention also discloses a reverse osmosis membrane based on dimethyl carbonate, which increases the surface roughness of the reverse osmosis membrane and simultaneously does not excessively increase the thickness of a separation layer because dimethyl carbonate is used in the preparation process, thereby being more beneficial to the improvement of the flux of the reverse osmosis membrane.

[ description of the drawings ]

FIG. 1 is a structural formula diagram of dimethyl carbonate;

FIG. 2 is a transmission electron microscope image of a separation layer of an aromatic polyamide composite reverse osmosis membrane prepared in example 4; the effective separation layer of the prepared reverse osmosis membrane is very thin and is only 29 nm;

FIG. 3 is an atomic force microscope showing a separation layer of an aromatic polyamide composite reverse osmosis membrane obtained in example 4; the prepared reverse osmosis membrane has a rough surface with the roughness as high as 115 nm;

FIG. 4 is a schematic view of a membrane performance testing apparatus according to the present invention.

[ detailed description ] embodiments

The invention discloses a method for improving flux of a reverse osmosis membrane by dimethyl carbonate, which comprises the following specific steps:

step 1, soaking a polysulfone support membrane in an aqueous phase solution for 10-50 s so that the support membrane is fully soaked by the aqueous phase solution; in the aqueous phase solution, deionized water is used as a basic solvent, wherein the concentration of m-phenylenediamine is 1.4-2.6 wt%, the mass concentration of triethylamine is 0.4-1.8 wt%, and the concentration of camphorsulfonic acid is 2.0-3.2 wt%.

2) Soaking the membrane treated in the step 1) in an n-heptane solution (organic phase solution) containing dimethyl carbonate (0.5-2.5 wt%) and trimesoyl chloride (0.04-0.20 wt%), and initiating interfacial polymerization to form a polyamide separation layer, wherein the interfacial polymerization reaction time is 10-50 s.

3) And (3) carrying out heat treatment on the composite membrane obtained in the step 2) at the temperature of 60-100 ℃ for 1-10 min to obtain the aromatic polyamide composite reverse osmosis membrane.

The invention has the advantages of simple process, low cost, easy implementation and the like. The aromatic polyamide composite prepared by the processThe permeable membrane has high flux (more than or equal to 3 L.m)^-2·h^-1·bar^-1) And high retention (98.50% or more): the cosolvent dimethyl carbonate used in the preparation process is green and environment-friendly, and the chemical structural formula of the dimethyl carbonate is shown in figure 1;

the verification shows that under the test conditions that the raw material liquid is 2000ppm sodium chloride aqueous solution, the pressure is 15.5bar and the temperature is 25 ℃, the water flux and the salt rejection rate can respectively reach 68 L.m^-2·h^-1(4.39L·m^-2·h^-1·bar^-1) And 98.69%.