阅读说明：本技术 一种高通量低压复合反渗透膜及其制备方法 (High-flux low-pressure composite reverse osmosis membrane and preparation method thereof ) 是由 周兴蒙 刘涛 向豪 周子杰 单连杰 于 2019-11-08 设计创作，主要内容包括：本发明属于反渗透膜技术领域,尤其涉及一种高通量低压复合反渗透膜及其制备方法,包括如下：(1)将柠檬酸和三乙胺混合均匀,加入间苯二胺和水相改性剂,得间苯二胺水相溶液；(2)将均苯三甲酰氯溶解于有机溶剂,再加入油相改性剂,得均苯三甲酰氯油相溶液；(3)将多孔支撑层先于间苯二胺水相溶液中浸泡0.5-1min,再于均苯三甲酰氯油相溶液中浸泡0.5-1min,烘干,得到高通量低压复合反渗透膜。本发明通过在间苯二胺水相溶液和均苯三甲酰氯油相溶液中同时引入改性剂,提升低压复合反渗透膜的水通量,且具有较高的脱盐率。(The invention belongs to the technical field of reverse osmosis membranes, and particularly relates to a high-flux low-pressure composite reverse osmosis membrane and a preparation method thereof, wherein the preparation method comprises the following steps: (1) uniformly mixing citric acid and triethylamine, and adding m-phenylenediamine and a water phase modifier to obtain a m-phenylenediamine water phase solution; (2) dissolving trimesoyl chloride in an organic solvent, and adding an oil phase modifier to obtain a trimesoyl chloride oil phase solution; (3) and soaking the porous support layer in the m-phenylenediamine aqueous phase solution for 0.5-1min, then soaking in the trimesoyl chloride oil phase solution for 0.5-1min, and drying to obtain the high-flux low-pressure composite reverse osmosis membrane. According to the invention, the modifier is simultaneously introduced into the m-phenylenediamine aqueous phase solution and the trimesoyl chloride oil phase solution, so that the water flux of the low-pressure composite reverse osmosis membrane is improved, and the desalting rate is higher.)

1. The preparation method of the high-flux low-pressure composite reverse osmosis membrane is characterized by comprising the following steps of:

(1) uniformly mixing citric acid and triethylamine, adding m-phenylenediamine and a water phase modifier, stirring and dissolving to obtain a m-phenylenediamine water phase solution;

(2) dissolving trimesoyl chloride in an organic solvent, uniformly mixing, adding an oil phase modifier, and stirring for dissolving to obtain a trimesoyl chloride oil phase solution;

(3) and (3) soaking the porous support layer in the m-phenylenediamine aqueous phase solution obtained in the step (1) for 0.5-1min, then soaking in the trimesoyl chloride oil phase solution obtained in the step (2) for 0.5-1min, and drying to obtain the high-flux low-pressure composite reverse osmosis membrane.

2. The preparation method of the high-flux low-pressure composite reverse osmosis membrane according to claim 1, wherein the mass ratio of the citric acid to the triethylamine in the step (1) is 2: 1, and the total mass fraction of the citric acid and the triethylamine in the trimesoyl chloride oil-phase solution is 4-8%.

3. The method for preparing a high-flux low-pressure composite reverse osmosis membrane according to claim 1, wherein in the step (1), the mass fraction of the m-phenylenediamine in the m-phenylenediamine aqueous phase solution is 2% -3%, and the mass fraction of the aqueous phase modifier is 1% -3%.

4. The method for preparing a high flux and low pressure composite reverse osmosis membrane according to claim 1 or 3, wherein the aqueous phase modifier is one or more of N, N dimethylformamide, N dimethylacetamide, N-methylpyrrolidone and dimethylsulfoxide.

5. The method for preparing a high-flux low-pressure composite reverse osmosis membrane according to claim 1, wherein the mass fraction of trimesoyl chloride in the trimesoyl chloride oil-phase solution in the step (2) is 0.1-0.2%, and the mass fraction of the oil-phase modifier is 0.2-0.4%.

6. The method for preparing a high flux low pressure composite reverse osmosis membrane according to claim 1 or 5, wherein the oil phase modifier is one or more of n-butanol, isopropanol, n-hexanol, ethylene glycol butyl ether; the organic solvent is formed by mixing IsoparG and cyclohexane according to the volume ratio of 7: 3.

7. The method for preparing a high flux and low pressure composite reverse osmosis membrane according to claim 1, wherein the drying temperature in step (3) is 80-100 ℃ and the drying time is 5-8 min.

8. The method of preparing a high flux low pressure composite reverse osmosis membrane according to claim 1 wherein the porous support layer comprises a nonwoven substrate layer and a porous polysulfone layer.

9. A high flux low pressure composite reverse osmosis membrane prepared by the method of any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of reverse osmosis membranes, and particularly relates to a high-flux low-pressure composite reverse osmosis membrane and a preparation method thereof.

Background

Water resources are indispensable resources for human beings and play a vital role in daily life and production activities of human beings. On one hand, with the increase of the industrialization process in the world, the water resource pollution is more and more serious, and the water pollution amount is increased year by year. On the other hand, with the rapid development process of human economy and population, the protection of the existing fresh water resources is neglected, and finally the existing fresh water resources are far from meeting the requirements of the development of human society. The reverse osmosis membrane separation technology has the advantages of high separation efficiency, good water quality, low floor area, low operation energy consumption, various membrane types and the like, various membrane elements such as BW brackish water membrane, high-concentration seawater membrane, low-pressure household membrane and the like are developed at present, and the membrane elements are widely applied to the fields of seawater desalination, brackish water desalination, household drinking water filtration, municipal sewage recycling and the like, and are regarded as the water treatment technology with the most prospect in the 21 world due to green and high efficiency.

The low-pressure reverse osmosis membrane has the advantages of large water yield and low energy consumption, and is widely applied to the fields of household drinking water filtration and industrial wastewater treatment at present. The conventional low-pressure reverse osmosis membrane is prepared by mainly adopting methods of reducing the concentration of raw materials and adding hydrophilic nano materials, wherein the former method can reduce the thickness of a surface desalting layer, and the latter method can improve the porosity and the hydrophilicity of the surface desalting layer, so that the low-pressure reverse osmosis membrane has high water flux. However, the above method has the following disadvantages: 1. the thinner desalting layer can cause the desalting rate of the low-pressure reverse osmosis membrane to be seriously reduced, the water quality requirement can not be met, meanwhile, the thinner desalting layer is not resistant to pressure scouring, and the service life can be greatly reduced; 2. the introduced nano material has the defects of easy agglomeration and precipitation and weak fixation in a desalting layer, and the flux of the low-pressure reverse osmosis membrane cannot be effectively increased in a large-scale industrialized manner.

In view of this, the invention is particularly proposed.

Disclosure of Invention

In order to solve the defects of low flux and low desalting rate of a desalting layer of a low-pressure reverse osmosis membrane in the prior art, the invention provides a high-flux low-pressure composite reverse osmosis membrane and a preparation method thereof, so that the flux and the desalting rate of the low-pressure reverse osmosis membrane are optimally balanced, and the reverse osmosis membrane keeps excellent performance under the low-pressure condition.

The invention is realized by the following technical scheme:

a preparation method of a high-flux low-pressure composite reverse osmosis membrane comprises the following steps:

(1) uniformly mixing citric acid and triethylamine, adding m-phenylenediamine and a water phase modifier, stirring and dissolving to obtain a m-phenylenediamine water phase solution;

(2) dissolving trimesoyl chloride in an organic solvent, uniformly mixing, adding an oil phase modifier, and stirring for dissolving to obtain a trimesoyl chloride oil phase solution;

(3) and (3) soaking the porous support layer in the m-phenylenediamine aqueous phase solution obtained in the step (1) for 0.5-1min, then soaking in the trimesoyl chloride oil phase solution obtained in the step (2) for 0.5-1min, and drying to obtain the high-flux low-pressure composite reverse osmosis membrane.

Preferably, the mass ratio of the citric acid to the triethylamine in the step (1) is 2: 1, and the total mass fraction of the citric acid and the triethylamine in the trimesoyl chloride oil-phase solution is 4% -8%.

Preferably, in the step (1), the mass fraction of the m-phenylenediamine in the m-phenylenediamine aqueous phase solution is 2% -3%, and the mass fraction of the aqueous phase modifier is 1% -3%.

Preferably, the aqueous phase modifier is one or more of N, N dimethylformamide, N dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; the organic solvent is formed by mixing IsoparG and cyclohexane according to the volume ratio of 7: 3.

Preferably, in the step (2), the mass fraction of trimesoyl chloride in the trimesoyl chloride oil-phase solution is 0.1-0.2%, and the mass fraction of the oil-phase modifier is 0.2-0.4%.

Preferably, the oil phase modifier is one or more of n-butanol, isopropanol, n-hexanol, ethylene glycol and ethylene glycol butyl ether.

Preferably, the drying temperature in the step (3) is 80-100 ℃, and the drying time is 5-8 min.

Preferably, the porous support layer comprises a nonwoven base layer and a porous polysulfone layer.

The invention also provides the high-flux low-pressure composite reverse osmosis membrane prepared by the method.

The invention has the beneficial effects that:

(1) according to the invention, the oil phase modifier is added into the trimesoyl chloride oil phase solution, the solubility in Isopar G and cyclohexane solvent is high, and the oil phase modifier is introduced into a desalting layer, so that on one hand, the interfacial polymerization rate of m-phenylenediamine and trimesoyl chloride can be increased, the roughness of the polyamide desalting layer on the surface of the composite reverse osmosis membrane is increased, on the other hand, the acyl chloride functional group on the surface of the polyamide desalting layer can be promoted to be hydrolyzed into hydrophilic carboxyl, and the water yield of the low-pressure composite reverse osmosis membrane is improved while the desalting rate is kept.

(2) The method simultaneously introduces polar aprotic solvents (N, N dimethylformamide, N dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide) into the m-phenylenediamine aqueous phase solution as aqueous phase modifiers, and the aqueous phase modifiers have extremely strong hydrophilicity and swelling property, so that after being added into the m-phenylenediamine aqueous phase solution, the hydrophilicity of a porous polysulfone layer can be improved, the adsorption capacity of the m-phenylenediamine solution on the surface is increased, and the polymerization reaction is favorably carried out; on the other hand, the water phase modifier has swelling property, when the porous supporting layer is immersed in the m-phenylenediamine water phase solution, the water phase modifier can rapidly enter the porous polysulfone layer of the porous supporting layer, the hydrophilicity of the pore channels of the porous polysulfone layer is improved, and meanwhile, the pore channels can be swelled, the porosity of the porous polysulfone layer is improved, and therefore the water flux of the composite reverse osmosis membrane is increased.

(3) In the process of polyamide interfacial polymerization reaction, amino of m-phenylenediamine and acyl chloride groups of trimesoyl chloride are subjected to crosslinking reaction to form polyamide, and hydrochloric acid byproducts are generated and need to be removed in time, so that the forward progress of the polymerization reaction can be promoted, and the generated hydrochloric acid byproducts are prevented from corroding the composite reverse osmosis membrane; the invention adds two-phase organic buffer solution formed by citric acid and triethylamine into m-phenylenediamine aqueous phase solution, namely acid acceptor, which is beneficial to forward polymerization and protection of desalting layer of composite permeable membrane. Compared with the traditional sodium hydroxide acid receiving agent, the two-phase organic buffer solution receiving agent has stronger corrosivity, has wider pH value application range, is not easy to corrode a desalting layer, and cannot cause the reduction of the desalting rate of the desalting layer. In addition, the two-phase organic buffer solution system formed by the citric acid and the triethylamine has good stability, and the raw materials are low in price.

(4) Compared with the traditional method for reducing the concentration of the water phase liquid or the oil phase liquid, the method can improve the water flux of the membrane without changing the thickness of the desalination layer, thereby increasing the service cycle of the membrane element. Compared with the method for introducing the inorganic nano material into the m-phenylenediamine aqueous phase solution and the trimesoyl chloride oil phase solution, the method introduces the organic solvent which is easy to dissolve, and avoids the phenomenon that the desalination rate of a desalination layer is reduced because the nano material modified material is deposited and layered along with the prolonging of the standing time in use.

Drawings

FIG. 1 is an SEM photograph of a surface desalting layer of a modified reverse osmosis membrane obtained in comparative example 3;

FIG. 2 is an SEM image of a surface desalted layer of a high flux low pressure composite reverse osmosis membrane prepared in example 1.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific examples, but the present invention is not limited to these examples, and any modifications or substitutions in the basic spirit of the examples of the present invention are still within the scope of the present invention.

Preparation of high-flux low-pressure composite reverse osmosis membrane