阅读说明：本技术 一种大通量荷正电聚酰胺杂化正渗透膜及其制备方法 (Large-flux positively-charged polyamide hybrid forward osmosis membrane and preparation method thereof ) 是由 宋维广 朱丽静 曾志翔 王刚 宋明海 于 2018-06-04 设计创作，主要内容包括：本发明公开了一种大通量荷正电聚酰胺杂化正渗透膜及其制备方法。所述制备方法包括：提供至少包含聚合物、荷正电单体、溶剂和引发剂的混合反应体系,加热所述混合反应体系得到制膜液,将其施加于基体表面形成液态膜,之后分别与水蒸汽、交联浴接触,得到具有交联互穿网络结构的荷正电聚合物基膜；将荷正电聚合物修饰的介孔纳米二氧化硅均匀分散于胺类单体水溶液中,得到杂化水相溶液；使所述具有交联互穿网络结构的荷正电聚合物基膜先与杂化水相溶液接触,再与酰氯油相溶液接触,进行界面聚合反应,获得大通量荷正电聚酰胺杂化正渗透膜。本发明可得到高通量、高选择性、高抗污染、低操作压力的正渗透膜,并且制备工艺简单,便于规模化生产。(the invention discloses a large-flux positively charged polyamide hybrid forward osmosis membrane and a preparation method thereof. The preparation method comprises the following steps: providing a mixed reaction system at least comprising a polymer, a positively charged monomer, a solvent and an initiator, heating the mixed reaction system to obtain a membrane preparation solution, applying the membrane preparation solution on the surface of a substrate to form a liquid membrane, and then respectively contacting with water vapor and a crosslinking bath to obtain a positively charged polymer-based membrane with a crosslinked interpenetrating network structure; uniformly dispersing mesoporous nano-silica modified by positively charged polymer in an amine monomer aqueous solution to obtain a hybrid aqueous phase solution; and (3) contacting the positively charged polymer base membrane with the cross-linked interpenetrating network structure with a hybrid aqueous phase solution, and then contacting with an acyl chloride oil phase solution to perform interfacial polymerization reaction, thereby obtaining the high-flux positively charged polyamide hybrid forward osmosis membrane. The invention can obtain the forward osmosis membrane with high flux, high selectivity, high pollution resistance and low operation pressure, and the preparation process is simple and convenient for large-scale production.)

1. a preparation method of a large-flux positively-charged polyamide hybrid forward osmosis membrane is characterized by comprising the following steps:

Providing a mixed reaction system at least comprising a polymer, a positively charged monomer, a solvent and an initiator, heating the mixed reaction system to obtain a membrane preparation solution, applying the membrane preparation solution to the surface of a substrate to form a liquid membrane, then contacting the liquid membrane with water vapor, and then contacting the liquid membrane with a crosslinking bath to obtain a positively charged polymer-based membrane with a crosslinked interpenetrating network structure;

Uniformly dispersing mesoporous nano-silica modified by positively charged polymer in an amine monomer aqueous solution to obtain a hybrid aqueous phase solution;

And (3) contacting the positively charged polymer base membrane with the cross-linked interpenetrating network structure with the hybrid aqueous phase solution, and then contacting with the acyl chloride oil phase solution to perform interfacial polymerization reaction, thereby obtaining the high-flux positively charged polyamide hybrid forward osmosis membrane.

2. the method according to claim 1, comprising: uniformly mixing a polymer, a positively charged monomer, a solvent and an initiator to form a mixed reaction system, heating the mixed reaction system to 40-120 ℃ and reacting for 0.1-50 h to obtain a membrane preparation solution, applying the membrane preparation solution to the surface of a substrate to form a liquid membrane, standing in a water vapor bath with the temperature of 15-100 ℃ and the relative humidity of 20-100 RH% for 0.1-100 min, and then immersing in a cross-linking bath consisting of 1-30 wt% of a cross-linking agent and water at the temperature of 0-80 ℃ to enrich and cross-link the positively charged polymer generated by the reaction on the surface of the membrane, thereby obtaining the positively charged polymer base membrane with a cross-linked interpenetrating network structure.

3. the production method according to claim 1 or 2, characterized in that: the mixed reaction system comprises 16-35 wt% of polymer, 2-20 wt% of positively charged monomer, 0.01-2 wt% of initiator and the balance of solvent.

4. The method of claim 2, wherein: the polymer comprises any one or the combination of more than two of polysulfone, polyethersulfone and polyacrylonitrile; and/or the positively charged monomer comprises any one or the combination of more than two of dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 4-vinylpyridine, 2-vinylpyridine and acrylamide; and/or the solvent comprises any one or the combination of more than two of N-methyl pyrrolidone, N '-dimethylformamide, N' -dimethylacetamide and acetone; and/or the initiator comprises any one or the combination of more than two of azodiisobutyronitrile, azodiisoheptonitrile and dibenzoyl peroxide; and/or the cross-linking agent comprises any one or the combination of more than two of glutaraldehyde, malic acid, sorbitol and glycerol; and/or, the substrate comprises a non-woven fabric.

5. The method according to claim 1, comprising: grafting a positively charged polymer on the surface of the mesoporous nano-silica through active radical polymerization to obtain the mesoporous nano-silica modified by the positively charged polymer, and then uniformly dispersing the mesoporous nano-silica in an amine monomer aqueous solution to obtain a hybrid aqueous phase solution.

6. The production method according to claim 1 or 5, characterized in that: the hybrid aqueous phase solution comprises 0.5-30 wt% of mesoporous nano-silica modified by positively charged polymers and 0.5-30 wt% of amine monomers.

7. The production method according to claim 1 or 5, characterized in that: the living radical polymerization comprises atom transfer radical polymerization and/or reversible addition-fragmentation chain transfer polymerization; and/or the diameter of the mesoporous nano silicon dioxide is 5-70 nm, and the aperture is 1-10 nm; and/or the positively charged polymer is formed by polymerizing the positively charged monomer, and the positively charged polymer comprises any one or the combination of more than two of poly (dimethylaminoethyl methacrylate), poly (diethylaminoethyl methacrylate), poly (4-vinylpyridine), poly (2-vinylpyridine) and polyacrylamide; and/or the amine monomer comprises any one or the combination of more than two of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, piperazine and ethylenediamine.

8. the method according to claim 1, comprising: and soaking the positively charged polymer base membrane with the cross-linked interpenetrating network structure in the hybrid water phase solution for 0.2-20 min, then taking out, soaking in the acyl chloride oil phase solution for 0.5-18 min, then taking out, and then carrying out heat treatment at 25-130 ℃ for 1-30 min to obtain the high-flux positively charged polyamide hybrid forward osmosis membrane.

9. the production method according to claim 1 or 8, characterized in that: the acyl chloride oil phase solution contains 0.2-20 wt% of acyl chloride monomer and organic solvent; preferably, the acyl chloride monomer comprises any one or a combination of more than two of isophthaloyl dichloride, terephthaloyl dichloride, phthaloyl dichloride and trimesoyl dichloride; preferably, the organic solvent includes any one or a combination of two or more of n-hexane, cyclohexane and n-octane.

10. A large-flux positively charged polyamide hybrid forward osmosis membrane prepared by the process of any one of claims 1-9; preferably, the forward osmosis membrane comprises:

a forward osmosis membrane-based membrane;

The modification layer is at least distributed on the surface of the forward osmosis membrane base membrane and is formed by positively charged polymers and has a cross-linked semi-interpenetrating network structure; and

A hybrid polyamide separation layer which is at least distributed on the surface of the forward osmosis membrane basal membrane and is formed by mesoporous nano-silica modified by positively charged polymer;

Preferably, the pure water flux of the large-flux positively-charged polyamide hybrid forward osmosis membrane is 19-57L m ^-2 h ^-1, and the rejection rate of sodium chloride is 75-99%.

Technical Field

The invention belongs to the technical field of membrane separation, and particularly relates to a large-flux positively-charged polyamide hybrid forward osmosis membrane and a preparation method thereof.

Background

the most common polyamide membranes are composite membranes consisting of a support layer and a separation layer, which have the advantage that the selectivity, permeability, chemical and thermal stability properties can be optimized by choosing a suitable separation layer and support layer, respectively. The hybrid membrane prepared by introducing the inorganic nano material into the separation layer of the polyamide composite membrane has the advantages of flexibility, easy processability and the like of a polymer membrane, has the advantages of solvent resistance, high strength, hydrophilicity, pollution resistance, antibacterial property and the like of the inorganic nano material on the surface, and is receiving increasingly wide attention.

However, the polyamide composite membrane containing inorganic nano-materials prepared by interfacial polymerization also faces several significant problems: 1) the inorganic nano material has high surface energy and large specific surface area, is easy to agglomerate and is difficult to uniformly disperse in an aqueous phase or an oil phase solution of interfacial polymerization, and defects are easy to form in a polyamide film, so that the structure and the performance of the film are seriously influenced; 2) due to the inherent difference between polyamide and inorganic nano materials, the compatibility between the organic phase and the inorganic phase is poor, the interaction force is weak, the inorganic nano materials are easy to lose in the service process of the membrane, so that the performance of the membrane is damaged, secondary pollution is caused, and the problems become a main obstacle for further development and application of the polyamide membrane containing the inorganic nano materials in the separation layer.

Disclosure of Invention

The invention mainly aims to provide a large-flux positively-charged polyamide hybrid forward osmosis membrane and a preparation method thereof, so as to overcome the defects in the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

The embodiment of the invention provides a preparation method of a large-flux positively-charged polyamide hybrid forward osmosis membrane, which comprises the following steps:

Providing a mixed reaction system at least comprising a polymer, a positively charged monomer, a solvent and an initiator, heating the mixed reaction system to obtain a membrane preparation solution, applying the membrane preparation solution to the surface of a substrate to form a liquid membrane, then contacting the liquid membrane with water vapor, and then contacting the liquid membrane with a crosslinking bath to obtain a positively charged polymer-based membrane with a crosslinked interpenetrating network structure;

Uniformly dispersing mesoporous nano-silica modified by positively charged polymer in an amine monomer aqueous solution to obtain a hybrid aqueous phase solution;

And (3) contacting the positively charged polymer base membrane with the cross-linked interpenetrating network structure with the hybrid aqueous phase solution, and then contacting with the acyl chloride oil phase solution to perform interfacial polymerization reaction, thereby obtaining the high-flux positively charged polyamide hybrid forward osmosis membrane.

The embodiment of the invention also provides the large-flux positively-charged polyamide hybrid forward osmosis membrane prepared by the method.

Further, the forward osmosis membrane includes:

a forward osmosis membrane-based membrane;

The modification layer is at least distributed on the surface of the forward osmosis membrane base membrane and is formed by positively charged polymers and has a cross-linked semi-interpenetrating network structure; and

And the hybrid polyamide separation layer is at least distributed on the surface of the forward osmosis membrane basal membrane and is formed by mesoporous nano-silica modified by positively charged polymers.

compared with the prior art, the invention has the beneficial effects that:

1) The method comprises the steps of constructing a high-flux positive-charge polyamide hybrid positive osmosis membrane by an interfacial polymerization method by taking a positive-charge polymer membrane with a cross-linked interpenetrating network structure as a base membrane, taking an aqueous solution containing mesoporous nano-silica modified by a positive-charge polymer and an amine monomer as a water phase and taking an acyl chloride monomer oil solution as an oil phase, and obtaining the polyamide composite membrane with high flux, high selectivity, high pollution resistance and low operating pressure;

2) The invention adopts the uniformly dispersed mesoporous nano-silica to provide a nano-water channel, and can improve the water flux of the forward osmosis membrane; the introduction of the positively charged polymer can improve the south-of-the-road effect, thereby improving the rejection rate of salt ions by the forward osmosis membrane; the positively charged polymer-based membrane with the cross-linked interpenetrating network structure can improve the strength of the positive osmosis membrane and the adhesion fastness of the polyamide functional layer.

Detailed Description

In view of the defects in the prior art, the inventor provides a technical scheme of the invention through long-term research and massive practice, and mainly grafts a positively charged polymer on the surface of mesoporous nano-silica to generate the mesoporous nano-silica modified by the positively charged polymer, then prepares a large-flux positively charged polyamide hybrid forward osmosis membrane through an interface polymerization method, and uses the membrane in a forward osmosis separation process. The technical solution, its implementation and principles, etc. will be further explained as follows.

In one aspect of the technical scheme of the invention, the invention relates to a preparation method of a large-flux positively-charged polyamide hybrid forward osmosis membrane, which comprises the following steps:

Providing a mixed reaction system at least comprising a polymer, a positively charged monomer, a solvent and an initiator, heating the mixed reaction system to obtain a membrane preparation solution, applying the membrane preparation solution to the surface of a substrate to form a liquid membrane, then contacting the liquid membrane with water vapor, and then contacting the liquid membrane with a crosslinking bath to obtain a positively charged polymer-based membrane with a crosslinked interpenetrating network structure;

Uniformly dispersing mesoporous nano-silica modified by positively charged polymer in an amine monomer aqueous solution to obtain a hybrid aqueous phase solution;

And (3) contacting the positively charged polymer base membrane with the cross-linked interpenetrating network structure with the hybrid aqueous phase solution, and then contacting with the acyl chloride oil phase solution to perform interfacial polymerization reaction, thereby obtaining the high-flux positively charged polyamide hybrid forward osmosis membrane.

In some embodiments, the preparation method may specifically include:

Uniformly mixing a polymer, a positively charged monomer, a solvent and an initiator to form a mixed reaction system, heating the mixed reaction system to 40-120 ℃ and reacting for 0.1-50 h to obtain a membrane preparation solution, applying the membrane preparation solution to the surface of a substrate to form a liquid membrane, standing in a water vapor bath with the temperature of 15-100 ℃ and the relative humidity of 20-100 RH% for 0.1-100 min, and then immersing in a cross-linking bath consisting of 1-30 wt% of a cross-linking agent and water at the temperature of 0-80 ℃ to enrich and cross-link the positively charged polymer generated by the reaction on the surface of the membrane, thereby obtaining the positively charged polymer base membrane with a cross-linked interpenetrating network structure.

the positively charged polymer-based membrane with the cross-linked interpenetrating network structure can improve the strength of the positive osmosis membrane and the adhesion fastness of the polyamide functional layer.

in some embodiments, the mixed reaction system comprises 16 to 35 wt% of a polymer, 2 to 20 wt% of a positively charged monomer, 0.01 to 2 wt% of an initiator, and the balance comprising a solvent.

In some embodiments, the polymer includes any one or a combination of two or more of polysulfone, polyethersulfone, polyacrylonitrile, and the like, but is not limited thereto.

In some embodiments, the positively charged monomer includes any one or a combination of two or more of dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 4-vinylpyridine, 2-vinylpyridine, acrylamide, and the like, but is not limited thereto.

further, the solvent includes any one or a combination of two or more of N-methylpyrrolidone, N '-dimethylformamide, N' -dimethylacetamide, acetone, and the like, but is not limited thereto.

Further, the initiator includes any one or a combination of two or more of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, and the like, but is not limited thereto.

further, the cross-linking agent includes any one or a combination of two or more of glutaraldehyde, malic acid, sorbitol, glycerin, and the like, but is not limited thereto.

Further, the substrate includes a non-woven fabric, but is not limited thereto.

In some embodiments, the preparation method may specifically include:

grafting a positively charged polymer on the surface of the mesoporous nano-silica through active radical polymerization to obtain the mesoporous nano-silica modified by the positively charged polymer, and then uniformly dispersing the mesoporous nano-silica in an amine monomer aqueous solution to obtain a hybrid aqueous phase solution.

in some embodiments, the hybrid aqueous phase solution comprises 0.5 to 30 wt% of the mesoporous nano-silica modified by the positively charged polymer and 0.5 to 30 wt% of the amine monomer.

In some embodiments, the living radical polymerization includes, but is not limited to, atom transfer radical polymerization, reversible addition-fragmentation chain transfer polymerization, and the like.

Further, the positively charged polymer includes a polymer formed by polymerizing the aforementioned positively charged monomer, and may be, for example, poly (dimethylaminoethyl methacrylate), poly (diethylaminoethyl methacrylate), poly (4-vinylpyridine), poly (2-vinylpyridine), polyacrylamide, and the like, but is not limited thereto.

The introduction of the positively charged polymer in the invention can improve the south-of-the-road effect, thereby improving the rejection rate of salt ions by the forward osmosis membrane.

Furthermore, the diameter of the mesoporous nano-silica is 5-70 nm, and the aperture is 1-10 nm. The invention adopts the uniformly dispersed mesoporous nano silicon dioxide to provide a nano water channel, and can improve the water flux of the forward osmosis membrane.

In some embodiments, the amine monomer includes any one or a combination of two or more of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, piperazine, ethylene diamine, and the like, but is not limited thereto.

In some embodiments, the preparation method may specifically include:

And soaking the positively charged polymer base membrane with the cross-linked interpenetrating network structure in the hybrid water phase solution for 0.2-20 min, then taking out, soaking in the acyl chloride oil phase solution for 0.5-18 min, then taking out, and then carrying out heat treatment at 25-130 ℃ for 1-30 min to obtain the high-flux positively charged polyamide hybrid forward osmosis membrane.

Further, the acyl chloride oil phase solution comprises 0.2-20 wt% of acyl chloride monomer and an organic solvent.

Further, the acid chloride monomer includes any one or a combination of two or more of isophthaloyl dichloride, terephthaloyl dichloride, phthaloyl dichloride, trimesoyl dichloride, and the like, but is not limited thereto.

further, the organic solvent includes any one or a combination of two or more of n-hexane, cyclohexane, n-octane, and the like, but is not limited thereto.

wherein, as a more specific embodiment, the preparation method may comprise the steps of:

(1) Uniformly mixing a polymer, a positively charged monomer, a solvent and an initiator, heating the mixed reaction system to 40-120 ℃, reacting for 0.1-50 h to obtain a membrane preparation solution, applying the membrane preparation solution on the surface of a substrate to form a liquid membrane, staying for 0.1-100 min in a water vapor bath with the temperature of 15-100 ℃ and the relative humidity of 20-100 RH%, and then immersing the membrane preparation solution into a cross-linking bath consisting of 1-30 wt% of a cross-linking agent and water at the temperature of 0-80 ℃ to enrich and cross-link the positively charged polymer generated by the reaction on the surface of the membrane to obtain a positively charged polymer base membrane with a cross-linked interpenetrating network structure;

(2) grafting a positively charged polymer onto the surface of mesoporous nano-silica by active radical polymerization to obtain a hybrid nano-material, namely mesoporous nano-silica modified by the positively charged polymer, and uniformly dispersing the hybrid nano-material in an amine monomer aqueous solution to obtain a hybrid aqueous phase solution; wherein the mass content of the mesoporous nano-silica modified by the positively charged polymer is 0.5-30%, and the mass content of the amine monomer is 0.5-30%;

(3) Immersing the positively charged polymer base membrane with the cross-linked interpenetrating network structure prepared in the step (1) into the hybrid aqueous phase solution prepared in the step (2) for 0.2-20 min, taking out, and wiping off the excess aqueous phase solution on the surface of the membrane; and then soaking the membrane into an acyl chloride monomer oil phase solution with the mass content of 0.2-20% for 0.5-18 min, taking out, cleaning, and carrying out heat treatment at 25-130 ℃ for 1-30 min to obtain the large-flux positively-charged polyamide hybrid forward osmosis membrane.

as another aspect of the present invention, it also relates to a large-flux positively charged polyamide hybrid forward osmosis membrane prepared by the aforementioned process, comprising:

A forward osmosis membrane-based membrane;

The modification layer is at least distributed on the surface of the forward osmosis membrane base membrane and is formed by positively charged polymers and has a cross-linked semi-interpenetrating network structure; and

And the hybrid polyamide separation layer is at least distributed on the surface of the forward osmosis membrane basal membrane and is formed by mesoporous nano-silica modified by positively charged polymers.

preferably, the pure water flux of the large-flux positively-charged polyamide hybrid forward osmosis membrane is 19-57L m ^-2 h ^-1, and the rejection rate of sodium chloride is 75-99%.

By the technical scheme, the method uses the positively charged polymer membrane with a cross-linked interpenetrating network structure as a base membrane, uses the aqueous solution containing the mesoporous nano-silica modified by the positively charged polymer and the amine monomer as a water phase, uses the acyl chloride monomer oil solution as an oil phase, and constructs the high-flux positively charged polyamide hybrid positive osmosis membrane through an interfacial polymerization method, so that the polyamide composite membrane with high flux, high selectivity, high pollution resistance and low operation pressure can be obtained.

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are further described in detail with reference to some preferred embodiments, but the present invention is not limited to the following embodiments, and those skilled in the art can make insubstantial improvements and modifications within the spirit of the present invention and still fall within the scope of the present invention.