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CN-122006496-A - Modification method for industrial high-pressure reverse osmosis membrane

CN122006496ACN 122006496 ACN122006496 ACN 122006496ACN-122006496-A

Abstract

The present invention relates to the field of reverse osmosis membrane modification technology, and specifically discloses a method for modifying high-pressure industrial reverse osmosis membranes into household low-pressure reverse osmosis membranes. The method uses a two-step synergistic treatment process of "sodium hypochlorite pre modification alcohol post optimization" to accurately control the separation layer structure of the original industrial reverse osmosis membrane under mild room temperature conditions, achieving dual optimization of membrane porosity and hydrophilicity. The modified membrane increases the flux from 15.74LMH of the original industrial membrane to over 45.12LMH under 65psi household low-pressure conditions, and maintains a stable NaCl retention rate of over 96.5%. At the same time, it has the advantages of simple process, easy availability of raw materials, low modification cost, and strong compatibility with existing household reverse osmosis equipment. The present invention efficiently converts industrial membranes into household membranes, solves the industry pain points of insufficient flux and high preparation cost of household reverse osmosis membranes, and also realizes the secondary utilization of industrial membrane resources, which has the value of large-scale production and promotion.

Inventors

  • ZHANG KAIMING

Assignees

  • 新御(江苏)环保科技有限公司

Dates

Publication Date
20260512
Application Date
20260312

Claims (6)

  1. 1. A modification method for an industrial high-pressure reverse osmosis membrane is characterized by comprising the following steps of, S1, pre-modifying, namely immersing an original industrial reverse osmosis membrane in a sodium hypochlorite aqueous solution with the mass concentration of 0.4% -0.6%, and treating for 60-72 hours at the temperature of 20-25 ℃ to obtain a primary modified membrane; S2, post-optimizing treatment, namely washing the primary modified membrane with deionized water for 3-5 times, washing for 5-10min each time, removing residual sodium hypochlorite on the surface, soaking in an alcohol solution with the volume concentration of more than or equal to 95%, treating for 8-12min at the temperature of 20-25 ℃, taking out, and drying to obtain the household reverse osmosis membrane; The domestic reverse osmosis membrane has flux of 40LMH or more and NaCl retention rate of 96% or more under the test conditions of 65psi operation pressure, 25 ℃ and 500ppm NaCl aqueous solution.
  2. 2. The method for modifying an industrial high-pressure reverse osmosis membrane according to claim 1, wherein the original industrial reverse osmosis membrane in S1 is an aromatic polyamide composite reverse osmosis membrane and is adapted to an industrial high-pressure working condition of more than 100 psi.
  3. 3. The method for modifying an industrial high-pressure reverse osmosis membrane according to claim 1, wherein the mass concentration of the sodium hypochlorite aqueous solution in S1 is 0.5%, the treatment time is 64h, no stirring or slight stirring is carried out every 12h in the soaking process, the stirring speed is 40-60r/min, and the single stirring time is 3-6min.
  4. 4. The method for modifying an industrial high-pressure reverse osmosis membrane according to claim 1, wherein the alcoholic solution in S2 is 95% alcoholic solution or absolute alcoholic solution, and the treatment time is 10min.
  5. 5. The method for modifying an industrial high-pressure reverse osmosis membrane according to claim 1, wherein the drying treatment in S2 is natural drying or drying, the natural drying condition is drying for 2-3h under a ventilation environment of 20-25 ℃, and the drying condition is drying for 1-1.5h under a ventilation environment of 30-40 ℃.
  6. 6. The method for modifying an industrial high-pressure reverse osmosis membrane according to claim 1, wherein deionized water washed in S2 is free of free chlorine, and is negative in detection by chlorine test paper.

Description

Modification method for industrial high-pressure reverse osmosis membrane Technical Field The invention belongs to the technical field of preparation of reverse osmosis membranes for water treatment, and particularly relates to a modification method of an industrial high-pressure reverse osmosis membrane, wherein the modified membrane can be directly applied to preparation of membrane elements of household low-pressure reverse osmosis water purification equipment, so that efficient conversion of industrial membrane resources into the household field is realized. Background The Reverse Osmosis (RO) technology is a core technology of the household water purifying equipment, the reverse osmosis membrane is used as a core functional component, and the water making efficiency, the water quality and the user experience of the household water purifying equipment are directly determined by the water permeability and the salt rejection rate of the reverse osmosis membrane. The household reverse osmosis equipment is limited by household power supply conditions, equipment volume and installation space, and generally adopts a low-pressure operation condition of 50-80psi, and the core requirements of the reverse osmosis membrane are high water permeability flux and high salt rejection rate under low pressure. The design of the industrial reverse osmosis membrane is initially suitable for the high-pressure working condition of more than 100psi of the scenes of industrial high-salt wastewater treatment, sea water desalination and the like, and the separation layer adopts a compact aromatic polyamide structure so as to ensure the high-salt interception performance under high pressure. If the industrial membrane is directly applied to household low-pressure reverse osmosis equipment, the core problem of serious shortage of flux under low pressure exists, namely, the dense separation layer of the industrial membrane leads to large permeation resistance of water molecules, the flux is generally lower than 20LMH under the low pressure of 50-80psi, and the actual use requirement of 100-200L of daily water production of household equipment can not be met. In order to solve the above problems, attempts to modify an industrial membrane to adapt to a low-pressure working condition of a household have been made in the prior art, mainly by adopting a single chemical etching or physical stretching mode, but all of them have significant drawbacks: 1. The single chemical etching mostly adopts strong acid and strong alkali as etching agents, which is easy to excessively destroy the molecular skeleton of the aromatic polyamide separation layer of the industrial membrane, so that the salt rejection rate of the membrane is suddenly reduced to below 90%, and the effluent quality can not meet the household water purification standard; 2. The physical stretching modification requires special large-scale stretching equipment, the process is complex, the equipment investment cost is high, the stretched membrane has poor structural stability, the problems of membrane layer cracking, pore deformation and the like are easy to occur, and large-scale batch production is difficult to realize. Therefore, there is a need in the art for an industrial reverse osmosis membrane modification method that can achieve precise balance between improving membrane flux and maintaining high salt rejection rate at low pressure, has simple process, controllable cost and good membrane stability, promotes secondary utilization of industrial membrane resources, and reduces preparation and application costs of household reverse osmosis membrane. Disclosure of Invention Aiming at the technical problems that the flux is insufficient when an industrial reverse osmosis membrane is matched with a household low-pressure working condition in the prior art, the retention rate is easily reduced greatly, the process is complex and difficult to scale by the existing modification method, the invention provides the two-step collaborative modification method for optimizing sodium hypochlorite mild etching-alcohol pore canals, the high-efficiency and stable conversion from the industrial high-pressure reverse osmosis membrane to the household low-pressure reverse osmosis membrane is realized, the modified membrane has high water permeability and high salt retention rate at the household low pressure of 50-80psi, and the modification process is simple, raw materials are easy to obtain and the compatibility is strong. In order to achieve the above purpose, the invention is realized by the following technical scheme: a modification method for an industrial high-pressure reverse osmosis membrane comprises the following steps, S1, pre-modifying, namely immersing an original industrial reverse osmosis membrane in a sodium hypochlorite aqueous solution with the mass concentration of 0.4% -0.6%, and treating for 60-72 hours at the temperature of 20-25 ℃ to obtain a primary modified membrane; S2