Composite nanofiltration membrane and preparation method thereof

Abstract

The invention discloses a composite nanofiltration membrane which is obtained by taking a nanofiber membrane prepared from graphene oxide, resveratrol, carboxymethyl hydroxypropyl guar gum and polyethyleneimine as raw materials by adopting an electrostatic spinning method as a base membrane and depositing cucurbituril intercalated graphene on the surface of the nanofiber membrane. According to thecucurbituril intercalated graphene, the resveratrol is used as a co-solution intercalating agent and a reducing agent, so that the distribution of cucurbituril among graphene layers is effectively improved, the interlayer distance of graphene is remarkably increased through cucurbituril intercalation, and the separation capacity of a deposited graphene membrane is effectively improved; the composite nanofiltration membrane has good stability, high organic matter rejection rate and high water flux.

Description

technical field [0001] The invention belongs to the field of nanofiltration membrane preparation, and in particular relates to a composite nanofiltration membrane and a preparation method thereof. Background technique [0002] Membrane separation technology has the advantages of high efficiency, simple equipment, convenient operation, energy saving and environmental protection, etc. The separation performance of nanofiltration membrane is between reverse osmosis membrane and ultrafiltration membrane, because of its low energy consumption, high flux and the The good interception capacity is widely used in wastewater treatment, seawater desalination and material separation and purification and other fields. [0003] Existing single-layer nanofiltration membranes cannot meet the requirements of good retention performance and high water flux; in order to solve this problem, composite membranes are usually obtained by a composite method, which refers to coating ultrafiltration or...

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Problems solved by technology

[0003] Existing single-layer nanofiltration membranes cannot meet the requirements of good retention performance and high water flux; in order to solve this problem, composite membranes are usually obtained by a composite method, which refers to coating ultrafiltration or microfiltration base membranes One layer of separation layer with micro-nano pore size, which can use different materials as the base membrane and separation layer, but there is often a large difference in swelling degree between the base membrane and the separation layer, and the binding force between the two Weaker will cause the separation layer and the base membrane to separate during the later use and cleaning process and reduce the usability of the membrane; at the same time, the separation layer will significantly affect the interception performance and flux of the composite membrane, so the preparation has good selective screening ability The separation layer plays an important role; the traditional composite method includes interfacial polymerization method or surface coating method, because the dense functional layer of the structure is thicker, it will reduce the flux of the nanofiltration membrane, and to obtain a higher flux, it must Increasing the operating pressure will increase the operating cost; in addition, the interfacial polymerization method needs to consume a large amount of organic solvent, and the residue of the organic solvent will cause environmental pollution; therefore, it is urgent to research and develop a new composite nanofiltration membrane

[0004] The electrospinning method is to make the charged polymer solution or melt flow and deform in the electrostatic field. When the electric field force is large enough, the polymer droplets can overcome the surface tension to form a jet stream, and then evaporate through the solvent or the melt Cooling and solidification to obtain fibrous substances, the preparation of nanofiber membranes by electrospinning has become a major method for preparing nanofiber membranes. Nanofiber membranes have good adsorption and filtration capabilities due to their porous structure and large specific surface area. However, the simple nanofiber membrane as a filter membrane has the problem of low mechanical strength and poor separation performance; therefore, using electrospun membrane as the base membrane to compound functional layers on its surface can significantly improve the mechanical strength and separation performance of the composite membrane.

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