CN112973449A

CN112973449A - Polyester composite reverse osmosis membrane with chlorine resistance and preparation method and application thereof

Info

Publication number: CN112973449A
Application number: CN201911277839.9A
Authority: CN
Inventors: 张轩; 姚宇健
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2021-06-18
Anticipated expiration: 2039-12-12
Also published as: CN112973449B

Abstract

The invention discloses a polyester composite reverse osmosis membrane with chlorine resistance and a preparation method and application thereof. The composite reverse osmosis membrane comprises a support layer and n composite layers consisting of a polypiperazine amide active layer and a polyester active layer, wherein the polyester structureThe formula is as follows:

Description

Polyester composite reverse osmosis membrane with chlorine resistance and preparation method and application thereof

Technical Field

The invention belongs to the technical field of reverse osmosis membranes, and relates to a polyester composite reverse osmosis membrane with chlorine resistance and a preparation method and application thereof.

Background

With the increasing shortage of water resources, the shortage of fresh water resources has become a global problem. The reverse osmosis technology has better market application prospect as the most economical and efficient seawater desalination and brackish water desalination technology. The reverse osmosis membrane material is used as the core of the technology, and the performance stability of the long-term operation of the reverse osmosis membrane material is related to the normal operation of a set of membrane water treatment system.

In the actual application of seawater desalination engineering, the composition of seawater is complex, and although water is subjected to pretreatment such as ultrafiltration and the like, seawater desalination membrane elements can still be polluted by existing suspended matters or insoluble salt, microorganisms (algae, mold, fungi) and the like. For the former, an acid-base cleaning process is generally adopted; in the latter case, the feed water may be sterilized in advance. In engineering application, common bactericides comprise hydrogen peroxide, sodium bisulfite and chlorine-containing bactericides (such as sodium hypochlorite), each bactericide has different disinfection effects, and the chlorine-containing bactericides have more obvious disinfection effects. Although the water is further pretreated, the bactericide still has a certain residue in the inlet water, and most of the existing reverse osmosis membranes have poor oxidation resistance and residual chlorine resistance. For example, aromatic rings and amide nitrogen in commercial reverse osmosis membrane separation layers are rapidly attacked by chlorine, resulting in a dramatic decrease in membrane performance (desalinization 1994,95,325). In addition, isophthaloyl dichloride is used to modify the surface of the reverse osmosis membrane, and although the chlorination condition is higher than 10000ppm · h, the rejection of monovalent ions by the membrane is lower than 90% (environ. The main reverse osmosis membrane cannot fundamentally solve the problem that the membrane material is oxidized due to the self characteristics of the polyamide material. Polyester has been studied as an effective chlorine resistant material, however, it has not been able to meet the standards of reverse osmosis process due to its low reactivity (j.membr.sci.2019,584, 282). Therefore, the development of a novel reverse osmosis membrane with chlorine resistance in the bulk is of great significance.

Disclosure of Invention

One of the objectives of the present invention is to provide a bulk chlorine resistant polyester, which has the following structural formula:

wherein R is₁,R₂Is selected from any one of the following: 1) r₁Is H, R₂Is H; 2) r₁Is CH₃、R₂Is H; 3) r₁Is H, R₂Is CH₃；4)R₁Is CH₃、R₂Is CH₃；5)R₁Is Cl, R₂Is H; 6) r₁Is H, R₂Is Cl; 7) r₁Is Cl, R₂Is Cl; 8) r₁Is Br, R₂Is H; 9) r₁Is H, R₂Is Br; 10) r₁Is Br, R₂Is Br; 11) r₁Is I, R₂Is H; 12) r₁Is H, R₂Is I; 13) r₁Is I, R₂Is I.

The bulk chlorine resistant polyester is polymerized from corresponding polyfunctional aromatic diphenol monomers, wherein the structural formula of the aromatic diphenol monomers is as follows:

It is a further object of the present invention to provide (PIP-PE) polymers prepared on the basis of the above bulk chlorine-resistant polyesters_nThe chlorine-resistant polyester composite reverse osmosis membrane comprises a supporting layer and n layers of polypiperazinylThe composite layer is composed of an amine active layer and a polyester active layer, and n is more than or equal to 1.

It is a further object of the present invention to provide the above (PIP-PE)_nThe preparation method of the chlorine-resistant polyester composite reverse osmosis membrane comprises the following steps:

(a) preparation of polypiperazine amide active layer: preparing 0.1-3 wt% piperazine (PIP) aqueous solution, immersing the aqueous solution in contact with the surface of the supporting layer for 1-5 minutes, removing the redundant aqueous solution, immersing the surface in an organic phase solution containing 0.01-0.5 wt% trimesoyl chloride (TMC), contacting for 1-2 minutes, removing the redundant organic solution, and volatilizing to dry to obtain a polypiperazine amide active layer;

(b) preparation of polyester active layer: taking an aqueous solution of an aromatic diphenol monomer, adjusting the pH value to 10-13 by adopting an alkaline substance, and immersing and contacting the aqueous solution of the aromatic diphenol monomer with the surface of a polypiperazine amide active layer, removing redundant aqueous phase solution, immersing the surface of the aqueous solution of the aromatic diphenol monomer in organic phase solution containing trimesoyl chloride (TMC), removing redundant organic phase solution, and volatilizing until the organic phase solution is dry to obtain a polyester active layer;

(c) sequentially repeating the steps (a) and (b), preparing a polyester active layer on the surface of the polypiperazine amide film active layer, taking the polyester active layer as a repeating unit, and repeating for n times to obtain n layers of composite layers consisting of the polypiperazine amide active layer and the polyester active layer, wherein n is more than or equal to 1;

(d) end capping of the film: soaking the membrane prepared in the step (c) in an organic solution containing 1-4 wt% of active acyl chloride, carrying out oscillation reaction for 2-5 minutes, taking out, cleaning the surface of the membrane with the same pure organic solvent, and washing with water after the solvent is volatilized until no reaction residue exists on the surface of the membrane to obtain (PIP-PE)_nA chlorine resistant polyester composite reverse osmosis membrane.

Preferably, in the step (a), the support layer is a microfiltration flat membrane, an ultrafiltration flat membrane, a microfiltration hollow fiber membrane or an ultrafiltration hollow fiber membrane, and the material is selected from polyvinylidene fluoride (PVDF), Polyacrylonitrile (PAN), polysulfone (PSf) or Polyethersulfone (PES).

Preferably, in the step (b), the concentration of the aqueous solution of the aromatic diphenol monomer is 0.1-4 wt%; the alkaline substance is one or more of sodium hydroxide, sodium carbonate, potassium carbonate and triethylamine; the soaking time of the aqueous phase solution is more than or equal to 1 min; the concentration of the organic phase solution of trimesoyl chloride is 0.01-1.0 wt%; the organic solvent is one or more of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, xylene and isopropanol; the soaking time is more than or equal to 1 min.

Preferably, in step (c), 1. ltoreq. n.ltoreq.3.

Preferably, in step (d), the organic solvent is one or more of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, xylene, and isopropanol.

Preferably, in step (d), the active acid chloride is selected from one or more of isophthaloyl chloride, benzoyl chloride and trimesoyl chloride.

It is a fourth object of the present invention to provide the above (PIP-PE)_nThe chlorine-resistant polyester composite reverse osmosis membrane is applied to advanced sewage treatment, reclaimed water recycling, seawater desalination or preparation of high-quality drinking water.

Compared with the prior art, the invention has the following advantages:

(1) the reverse osmosis membrane has the body chlorine resistance due to the unique polyester structure, and can directly contact with the original desalting process containing high-concentration active chlorine, so that the strict requirement of the traditional commercial composite reverse osmosis membrane on the active chlorine content of raw water in the desalting process is broken through (0.1 ppm).

(2) The raw materials of the aromatic diphenol monomer are cheap and easy to obtain, an organic metal catalyst or high-temperature and high-pressure conditions are not needed, the process for preparing the membrane is simple and convenient, the composite reverse osmosis membrane has similar separation performance with a commercial membrane, the interception of monovalent salt ions is up to 98%, and the composite reverse osmosis membrane has great commercial value.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of ranges and any values set forth herein are not limited to the precise range or value and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The structural formula of each monomer used in the following examples is as follows:

example 1(PIP-DHBA)₁Preparation of reverse osmosis membranes

(1) Preparing a 1 wt% PIP aqueous solution, adjusting the pH to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of a polyether sulfone ultrafiltration membrane skin layer for 5min, removing the aqueous phase solution, and rolling residual water drops on the surface of the membrane by using a rubber roller;

(2) preparing 0.15 wt% TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane, contacting for 60s, pouring out the redundant organic phase solution, and washing with fresh n-hexane;

(3) preparing 2.0 wt% of 3, 5-dihydroxybenzoic acid (DHBA) aqueous solution, adjusting the pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the membrane surface;

(4) preparing 0.15 wt% of TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), pouring out the redundant organic phase solution after contacting for 120s, and flushing with fresh n-hexane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA)₁The membrane was air dried and stored in deionized water to be tested.

Example 2(PIP-DHBA)₂Preparation of reverse osmosis membranes

(1) Preparing 3 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of the polyether sulfone ultrafiltration membrane skin layer for 5min, removing the aqueous phase solution, and rolling residual water drops on the surface of the membrane by using a rubber roller;

(3) preparing 2.0 wt% DHBA aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in (2) for 5min, and removing the excess aqueous phase solution on the membrane surface;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA)₂The membrane was air dried and stored in deionized water to be tested.

Example 3(PIP-DHBA)₃Preparation of reverse osmosis membranes

(1) Preparing 3.0 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of the polyether sulfone ultrafiltration membrane skin layer for 1min, removing the aqueous phase solution, and rolling the residual water drops on the surface of the membrane by using a rubber roller;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA)₃The membrane was air dried and stored in deionized water to be tested.

Example 4(PIP-DHMBA)₁Preparation of reverse osmosis membranes

(1) Preparing 0.5 wt% PIP aqueous solution, adjusting the pH to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of the skin layer of the polyether sulfone ultrafiltration membrane for 5min, removing the aqueous phase solution, and rolling the residual water drops on the surface of the membrane by using a rubber roller;

(2) preparing 0.01 wt% TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane, contacting for 60s, pouring out the redundant organic phase solution, and washing with fresh n-hexane;

(3) preparing 0.1 wt% of 3, 5-dihydroxy-4-methylbenzoic acid (DHMBA) aqueous solution, adjusting the pH to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHMBA)₁The membrane was air dried and stored in deionized water to be tested.

Example 5(PIP-DHMBA)₂Reverse osmosis membranePreparation of

(2) preparing 5 wt% TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane, and pouring out the excessive organic phase solution after contacting for 60s and washing with fresh n-hexane;

(3) preparing 4.0 wt% DHMBA aqueous solution, adjusting the pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in the step (2) for 5min, and removing the excess aqueous phase solution on the membrane surface;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHMBA)₂The membrane was air dried and stored in deionized water to be tested.

Example 6(PIP-DHMBA)₃Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHMBA aqueous solution, adjusting the pH to 13.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in the step (2) for 5min, and removing the excess aqueous phase solution on the membrane surface;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHMBA)₃The membrane was air dried and stored in deionized water to be tested.

Example 7(PIP-DHDMBA)₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% of 3, 5-dihydroxy-2, 6-dimethylbenzoic acid (DHDMBA) aqueous solution, adjusting the pH to 13.0 with triethylamine, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHDMBA)₁The membrane was air dried and stored in deionized water to be tested.

Example 8(PIP-DHDMBA)₂Reverse osmosisPreparation of a permeable Membrane

(3) preparing 2.0 wt% DHDMBA aqueous solution, adjusting the pH value to 10.0 with NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 1min, and removing the redundant aqueous phase solution on the surface of the membrane;

(4) 0.15 wt% of TMC petroleum ether solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after the organic phase solution is contacted for 120s, the redundant organic phase solution is poured out and is washed by fresh n-hexane;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHDMBA)₂The membrane was air dried and stored in deionized water to be tested.

Example 9(PIP-DHDMBA)₃Preparation of reverse osmosis membranes

(3) preparing 0.1 wt% DHDMBA aqueous solution, adjusting the pH value to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and then removing the redundant aqueous phase solution on the surface of the membrane;

(4) 0.15 wt% of TMC cyclohexane solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after the organic phase solution is contacted for 120s, the redundant organic phase solution is poured out and is washed by fresh n-hexane;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHDMBA)₃The membrane was air dried and stored in deionized water to be tested.

Example 10(PIP-DHTMBA)₁Preparation of reverse osmosis membranes

(1) Preparing 0.5 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous solution with the surface of the skin layer of the polysulfone ultrafiltration membrane for 5min, removing the aqueous solution, and rolling the residual water drops on the surface of the membrane with a rubber roller;

(3) preparing 4.0 wt% of 3, 5-dihydroxy-2, 4, 6-trimethyl benzoic acid (DHTMBA) aqueous solution, adjusting the pH to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(4) preparing 0.15 wt% TMC n-dodecane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), and pouring out the excessive organic phase solution after contacting for 120s and washing with fresh n-hexane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHTMBA)₁The membrane was air dried and stored in deionized water to be tested.

Example 11(PIP-DHTMBA)₂Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHTMBA aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in (2) for 1min, and removing the excess aqueous phase solution on the membrane surface;

(4) preparing 0.15 wt% TMC toluene solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), pouring out the redundant organic phase solution after contacting for 120s, and flushing with fresh n-hexane;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% of BC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHTMBA)₂The membrane was air dried and stored in deionized water to be tested.

Example 12(PIP-DHTMBA)₃Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHTMBA aqueous solution by using Na₂CO₃Adjusting pH to 10.0, contacting the aqueous solution with the membrane surface prepared in (2) for 5min, and removing the excess on the membrane surfaceAn aqueous phase solution of (a);

(4) 0.15 wt% of TMC isopropanol solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after the organic phase solution is contacted for 120s, the redundant organic phase solution is poured out and is washed by fresh n-hexane;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out the end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHTMBA)₃The membrane was air dried and stored in deionized water to be tested.

Example 13(PIP-DHBA-Cl)₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% 4-chloro-3, 5-dihydroxybenzoic acid (DHBA-Cl) aqueous solution by using K₂CO₃Adjusting the pH value to 10.0, then contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and then removing the redundant aqueous phase solution on the surface of the membrane;

(4) preparing 1.0 wt% TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), pouring out the redundant organic phase solution after contacting for 120s, and flushing with fresh n-hexane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-Cl)₁The membrane was air dried and stored in deionized water to be tested.

Example 14(PIP-DHBA-Cl)₂Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHBA-Cl aqueous solution, adjusting the pH to 10.0 with NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 1 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-Cl)₂The membrane was air dried and stored in deionized water to be tested.

Example 15(PIP-DHBA-Cl)₃Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHBA-Cl aqueous solution, adjusting the pH value to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 4 wt% IPC normal hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-Cl)₃The membrane was air dried and stored in deionized water to be tested.

Example 16(PIP-DHBA-DCl)₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% of 2, 6-dichloro-3, 5-dihydroxybenzoic acid (DHBA-DCl) aqueous solution, adjusting the pH to 10.0 with NaOH, contacting the aqueous solution with the membrane surface prepared in step (2) for 5min, and removing the excess aqueous solution on the membrane surface;

(4) preparing 0.1 wt% TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), pouring out the redundant organic phase solution after contacting for 120s, and flushing with fresh n-hexane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DCl)₁The film was air dried and stored in deionized water until neededAnd (6) measuring.

Example 17(PIP-DHBA-DCl)₂Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHBA-DCl aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in (2) for 5min, and removing the excess aqueous phase solution on the membrane surface;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DCl)₂The membrane was air dried and stored in deionized water to be tested.

Example 18(PIP-DHBA-DCl)₃Preparation of reverse osmosis membranes

(4) preparing 0.15 wt% of TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), pouring out the redundant organic phase solution after contacting for 60s, and flushing with fresh n-hexane;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DCl)₃The membrane was air dried and stored in deionized water to be tested.

Example 19(PIP-DHBA-TCl)₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% of 2,4, 6-trichloro-3, 5-dihydroxybenzoic acid (DHBA-TCl) aqueous solution, adjusting the pH to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(5) preparing 1 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TCl)₁Film air-drying andstoring in deionized water to be tested.

Example 20(PIP-DHBA-TCl)₂Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHBA-TCl aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing redundant aqueous phase solution on the surface of the membrane;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 4 wt% IPC normal hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TCl)₂The membrane was air dried and stored in deionized water to be tested.

Example 21(PIP-DHBA-TCl)₃Preparation of reverse osmosis membranes

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 2min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TCl)₃The membrane was air dried and stored in deionized water to be tested.

Example 22(PIP-DHBA-Br)₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% of 4-bromo-3, 5-dihydroxybenzoic acid (DHBA-Br) aqueous solution, adjusting the pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the membrane surface;

(5) preparing 2 wt% TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out the end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-Br)₁The membrane was air dried and stored in deionized water to be tested.

Example 23(PIP-DHBA-Br)₂Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHBA-Br aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing redundant aqueous phase solution on the surface of the membrane;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% of BC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-Br)₂The membrane was air dried and stored in deionized water to be tested.

Example 24(PIP-DHBA-Br)₃Preparation of reverse osmosis membranes

(2) 0.15 wt% of TMC petroleum ether solution is prepared in advance, the organic phase solution is poured on the surface of the membrane, and after the organic phase solution is contacted for 60 seconds, the redundant organic phase solution is poured out and is washed by fresh petroleum ether;

(4) 0.15 wt% of TMC petroleum ether solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after 120 seconds of contact, the redundant organic phase solution is poured out and is washed by fresh petroleum ether;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% of IPC petroleum ether solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh petroleum ether to remove unreacted IPC monomer. Finally, will (PIP-DHBA-Br)₃The membrane was air dried and stored in deionized water to be tested.

Example 25PIP- (DHBA-DBr)₁Preparation of reverse osmosis membranes

(2) preparing 0.15 wt% TMC cyclohexane solution in advance, pouring the organic phase solution on the surface of the membrane, contacting for 60s, pouring out the redundant organic phase solution and washing with fresh cyclohexane;

(3) preparing 2.0 wt% of 2, 6-dibromo-3, 5-dihydroxybenzoic acid (DHBA-DBr) aqueous solution, adjusting the pH to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(4) 0.15 wt% of TMC cyclohexane solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after 120 seconds of contact, the redundant organic phase solution is poured out and washed by fresh cyclohexane;

(5) preparing 2 wt% IPC cyclohexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out the end capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh cyclohexane to remove unreacted IPC monomer. Finally, willPIP-(DHBA-DBr)₁The membrane was air dried and stored in deionized water to be tested.

Example 26(PIP-DHBA-DBr)₂Preparation of reverse osmosis membranes

(1) Preparing 0.5 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of the polyvinylidene fluoride ultrafiltration membrane skin layer for 5min, removing the aqueous phase solution, and rolling the residual water drops on the surface of the membrane with a rubber roller;

(3) preparing 2.0 wt% DHBA-DBr aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in (2) for 5min, and removing the excess aqueous phase solution on the membrane surface;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DBr)₂The membrane was air dried and stored in deionized water to be tested.

Example 27(PIP-DHBA-DBr)₃Preparation of reverse osmosis membranes

(1) Preparing 0.5 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of a polyacrylonitrile ultrafiltration membrane skin layer for 5min, removing the aqueous phase solution, and rolling residual water drops on the surface of the membrane by using a rubber roller;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DBr)₃The membrane was air dried and stored in deionized water to be tested.

Example 28(PIP-DHBA-TBr)₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% of 2,4, 6-tribromo-3, 5-dihydroxybenzoic acid (DHBA-TBr) aqueous solution, adjusting the pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in (2) for 5min, and removing the excess aqueous phase solution on the membrane surface;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing and contacting for 5min, removing the organic solution, and washing the membrane surface with fresh n-hexane to remove unreactedReacted IPC monomers. Finally, will (PIP-DHBA-TBr)₁The membrane was air dried and stored in deionized water to be tested.

Example 29(PIP-DHBA-TBr)₂Preparation of reverse osmosis membranes

(2) preparing 0.15 wt% TMC n-heptane solution in advance, pouring the organic phase solution on the surface of the film, contacting for 60s, pouring out the excessive organic phase solution, and washing with fresh n-heptane;

(3) preparing 2.0 wt% DHBA-TBr aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the membrane surface prepared in (2) for 5min, and removing the excess aqueous phase solution on the membrane surface;

(4) preparing 0.15 wt% TMC n-heptane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), contacting for 120s, pouring out the redundant organic phase solution, and flushing with fresh n-heptane;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% of IPC n-heptane solution in advance, and pouring the organic phase solution on the surface of the film prepared in (5) to carry out the end-capping reaction on the surface of the film. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-heptane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TBr)₂The membrane was air dried and stored in deionized water to be tested.

Example 30(PIP-DHBA-TBr)₃Preparation of reverse osmosis membranes

(2) 0.15 wt% of TMC isopropanol solution is prepared in advance, the organic phase solution is poured on the surface of the membrane, and after the membrane is contacted for 60s, the redundant organic phase solution is poured out and washed by fresh isopropanol;

(4) 0.15 wt% of TMC isopropanol solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after 120 seconds of contact, the redundant organic phase solution is poured out and is washed by fresh isopropanol;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC isopropanol solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh isopropanol to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TBr)₃The membrane was air dried and stored in deionized water to be tested.

Example 31(PIP-DHBA-I)₁Preparation of reverse osmosis membranes

(2) preparing 0.15 wt% TMC toluene solution in advance, pouring the organic phase solution on the surface of the membrane, contacting for 60s, pouring out the redundant organic phase solution, and washing with fresh toluene;

(3) preparing 2.0 wt% of 3, 5-dihydroxy-4-iodobenzoic acid (DHBA-I) aqueous solution, adjusting the pH to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(4) 0.15 wt% TMC toluene solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after 120 seconds of contact, the redundant organic phase solution is poured out and washed by fresh toluene;

(5) preparing 2 wt% of IPC toluene solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end capping reaction on the surface of the membrane. After standing for 5min, the organic solution was removed and the membrane surface was rinsed with fresh toluene to remove the unreactedReacted IPC monomers. Finally, will (PIP-DHBA-I)₁The membrane was air dried and stored in deionized water to be tested.

Example 32(PIP-DHBA-I)₂Preparation of reverse osmosis membranes

(2) preparing 0.15 wt% TMC xylene solution in advance, pouring the organic phase solution on the surface of the membrane, contacting for 60s, pouring out the redundant organic phase solution, and flushing with fresh xylene;

(3) preparing 2.0 wt% DHBA-I aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(4) 0.15 wt% of TMC xylene solution is prepared in advance, the organic phase solution is poured on the surface of the membrane prepared in the step (3), and after 120 seconds of contact, the redundant organic phase solution is poured out and washed by fresh xylene;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC xylene solution in advance, pouring the organic phase solution on the surface of the film prepared in the step (5), and carrying out end capping reaction on the surface of the film. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh xylene to remove unreacted IPC monomer. Finally, will (PIP-DHBA-I)₂The membrane was air dried and stored in deionized water to be tested.

Example 33(PIP-DHBA-I)₃Preparation of reverse osmosis membranes

(2) preparing 0.15 wt% TMC n-dodecane solution in advance, pouring the organic phase solution on the surface of the membrane, contacting for 60s, pouring out the redundant organic phase solution, and washing with fresh n-dodecane;

(4) preparing 0.15 wt% TMC n-dodecane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), contacting for 120s, pouring out the redundant organic phase solution, and washing with fresh n-dodecane;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-dodecane solution in advance, pouring the organic phase solution on the surface of the film prepared in the step (5), and carrying out end capping reaction on the surface of the film. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-dodecane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-I)₃The membrane was air dried and stored in deionized water to be tested.

Example 34(PIP-DHBA-DI)₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% of 3, 5-dihydroxy-2, 6-diiodobenzoic acid (DHBA-DI) aqueous solution, adjusting the pH to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After 5min of standing contact, the organic solution was removed and fresh n-hexane was usedThe alkane washes the membrane surface to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DI)₁The membrane was air dried and stored in deionized water to be tested.

Example 35(PIP-DHBA-DI)₂Preparation of reverse osmosis membranes

(1) Preparing 0.5 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous solution with the surface of the microfiltration flat membrane skin layer for 5min, removing the aqueous solution, and rolling the residual water drops on the surface of the membrane by using a rubber roller;

(3) preparing 2.0 wt% DHBA-DI water solution, adjusting pH to 10.0 with NaOH, contacting the water phase solution with the membrane surface prepared in (2) for 5min, and removing the redundant water phase solution on the membrane surface;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DI)₂The membrane was air dried and stored in deionized water to be tested.

Example 36(PIP-DHBA-DI)₃Preparation of reverse osmosis membranes

(1) Preparing 0.5 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous solution with the surface of the microfiltration hollow fiber membrane skin for 5min, removing the aqueous solution, and rolling the residual water drops on the surface of the membrane with a rubber roller;

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-DI)₃The membrane was air dried and stored in deionized water to be tested.

Example 37(PIP-DHBA-TI)₁Preparation of reverse osmosis membranes

(1) Preparing 0.5 wt% PIP aqueous solution, adjusting pH to 10.0 with triethylamine, contacting the aqueous phase solution with the surface of the ultrafiltration hollow fiber membrane skin for 5min, removing the aqueous phase solution, and rolling the residual water drops on the surface of the membrane with a rubber roller;

(3) preparing 2.0 wt% of 3, 5-dihydroxy-2, 4, 6-triiodobenzoic acid (DHBA-TI) aqueous solution, adjusting the pH to 10.0 by using NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in the step (2) for 5min, and removing the redundant aqueous phase solution on the surface of the membrane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing and contacting for 5min, removing the organic solutionAnd the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TI)₁The membrane was air dried and stored in deionized water to be tested.

Example 38(PIP-DHBA-TI)₂Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHBA-TI aqueous solution, adjusting pH to 10.0 with NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in (2) for 5min, and removing the excess aqueous phase solution on the surface of the membrane;

(5) the above steps (1) to (4) were repeated 1 time.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TI)₂The membrane was air dried and stored in deionized water to be tested.

Example 39(PIP-DHBA-TI)₃Preparation of reverse osmosis membranes

(5) the above steps (1) to (4) were repeated 2 times.

(6) Preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (5), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, will (PIP-DHBA-TI)₃The membrane was air dried and stored in deionized water to be tested.

COMPARATIVE EXAMPLE 1 PIP- (DHBA) at Low pH₁Preparation of reverse osmosis membranes

(3) preparing 2.0 wt% DHBA-TI aqueous solution, adjusting pH to 9.0 with NaOH, contacting the aqueous phase solution with the surface of the membrane prepared in (2) for 5min, and removing the excess aqueous phase solution on the surface of the membrane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min, the organic solution was removed and replaced with freshThe fresh n-hexane washes the membrane surface to remove the unreacted IPC monomer. Finally, PIP- (DHBA)₁The membrane was air dried and stored in deionized water to be tested.

COMPARATIVE EXAMPLE 2 PIP- (DHBA) short polymerization time₁Preparation of reverse osmosis membranes

(4) preparing 0.15 wt% of TMC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (3), pouring out the redundant organic phase solution after contacting for 30s, and flushing with fresh n-hexane;

(5) preparing 2 wt% IPC n-hexane solution in advance, pouring the organic phase solution on the surface of the membrane prepared in the step (4), and carrying out end-capping reaction on the surface of the membrane. After standing for 5min of contact, the organic solution was removed and the membrane surface was rinsed with fresh n-hexane to remove unreacted IPC monomer. Finally, PIP- (DHBA)₁The membrane was air dried and stored in deionized water to be tested.

EXAMPLE 40 testing of reverse osmosis Membrane Performance

The performance of the reverse osmosis membrane is characterized by placing the reverse osmosis membrane in a standard reverse osmosis test mold, directly measuring the flow rate P (liter, L) of the permeate at 2000ppm NaCl at 25 deg.C, pH 6.5-7.5 and pressure 1.55MPa (225psi), and calculating the water flux J (L m) according to the formula J (P/(SxT))^-2h^-1) Wherein S is the effective membrane area (m, m)²) And T is the measurement time period (hours, h). While according to the formula R (%) - (1-C)_P/C_f) x100 calculating the salt rejection, wherein R is the salt rejectionPercentage, C_pIs the solute concentration of the permeate, C_fIs the solute concentration of the test solution. The prepared reverse osmosis membrane was tested under the above standard membrane performance characterization conditions, and the test results are shown in table 1. As can be seen from the table, the basic desalination performance of the novel chlorine resistant polyester reverse osmosis membrane is comparable to that of the conventional polyamide reverse osmosis membrane.

EXAMPLE 41 testing of Long-term chlorine resistance of reverse osmosis membranes

The performance of the reverse osmosis membrane is characterized by placing the reverse osmosis membrane in a standard reverse osmosis test mold, directly measuring the flow rate P (liter, L) of the permeate at 2000ppm NaCl at 25 deg.C, pH 6.5-7.5 and pressure 1.55MPa (225psi), and calculating the water flux J (L m) according to the formula J (P/(SxT))^-2h^-1) Wherein S is the effective membrane area (m, m)²) And T is the measurement time period (hours, h). While according to the formula R (%) - (1-C)_P/C_f) x100 calculating the salt rejection, wherein R is the percent salt rejection, C_pIs the solute concentration of the permeate, C_fIs the solute concentration of the test solution. This experiment was conducted by subjecting a commercial membrane SW30 and the reverse osmosis membranes prepared in examples 1-65 to a static chlorination test in which the active chlorine solution was NaClO at an initial concentration of 200ppm and the solution was changed every 24 hours. After soaking for a certain time, the membrane was taken out and washed with deionized water, and then the basic separation performance was tested, and the test results are shown in table 1. From the results, it can be seen that the commercial SW30 reverse osmosis membrane can only keep the retention rate of sodium chloride at about 10% under the chlorination condition of 100000 ppm-h, which indicates that the active layer structure has been completely destroyed. The bulk chlorine resistant polyester reverse osmosis membranes of examples 1-39 maintained greater than 90% rejection of sodium chloride under the same chlorination conditions. In conclusion, the composite reverse osmosis membrane with chlorine resistance in the body prepared by the invention has excellent interception performance, has lasting chlorine resistance and has wide industrial application prospect.

TABLE 1 separation Performance and chlorine resistance test of reverse osmosis membranes

Performance test conditions: 2000ppm NaCl, 25 deg.C, pH 6.5-7.5, and pressure 1.55MPa (225 psi).

Chlorination conditions are as follows: 200ppm NaClO, soaking for 500 hours at 25 deg.C and pH 6.5-7.5.

Claims

1. Bulk chlorine resistant polyester characterized by the structural formula:

2. Prepared based on the bulk chlorine resistant polyester of claim 1 (PIP-PE)_nThe chlorine-resistant polyester composite reverse osmosis membrane is characterized by sequentially comprising a supporting layer, n layers of polypiperazine amide active layers and polyester active layersN is more than or equal to 1.

3. The (PIP-PE) of claim 2_nThe preparation method of the chlorine-resistant polyester composite reverse osmosis membrane is characterized by comprising the following steps:

(a) preparation of polypiperazine amide active layer: preparing 0.1-3 wt% of piperazine aqueous solution, immersing and contacting the aqueous phase solution with the surface of the supporting layer for 1-5 minutes, removing the redundant aqueous phase solution, immersing the surface in an organic phase solution containing 0.01-0.5 wt% of trimesoyl chloride, contacting for 1-2 minutes, removing the redundant organic phase solution, and volatilizing to dry to obtain a polypiperazine amide active layer;

(b) preparation of polyester active layer: taking an aqueous solution of an aromatic diphenol monomer, adjusting the pH value to 10-13 by adopting an alkaline substance, and immersing and contacting the aqueous solution of the aromatic diphenol monomer with the surface of a polypiperazine amide active layer, removing redundant aqueous phase solution, immersing the surface in an organic phase solution containing trimesoyl chloride, removing redundant organic phase solution, and volatilizing to dry to obtain a polyester active layer;

4. The method according to claim 3, wherein in the step (a), the support layer is a microfiltration flat membrane, an ultrafiltration flat membrane, a microfiltration hollow fiber membrane or an ultrafiltration hollow fiber membrane.

5. The method according to claim 3, wherein in the step (a), the material of the support layer is selected from polyvinylidene fluoride, polyacrylonitrile, polysulfone or polyethersulfone.

6. The method according to claim 3, wherein in the step (b), the concentration of the aqueous solution of the aromatic diphenol monomer is 0.1-4 wt%; the alkaline substance is one or more of sodium hydroxide, sodium carbonate, potassium carbonate and triethylamine; the soaking time of the aqueous phase solution is more than or equal to 1 min; the concentration of the organic phase solution of trimesoyl chloride is 0.01-1.0 wt%; the organic solvent is one or more of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, xylene and isopropanol; the soaking time is more than or equal to 1 min.

7. The method according to claim 3, wherein in the step (c), n is 1. ltoreq. n.ltoreq.3.

8. The method according to claim 3, wherein in the step (d), the organic solvent is one or more selected from petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, xylene, and isopropanol.

9. The method according to claim 3, wherein in step (d), the active acid chloride is selected from one or more of isophthaloyl chloride, benzoyl chloride and trimesoyl chloride.

10. The (PIP-PE) of claim 2_nThe chlorine-resistant polyester composite reverse osmosis membrane is applied to advanced sewage treatment, reclaimed water recycling, seawater desalination or preparation of high-quality drinking water.