Preparation method of nanofiltration membrane for intercepting nitrate and resource utilization of concentrated solution

Abstract

The invention provides a preparation method of a polyethersulfone nanofiltration membrane with good nitrate interception efficiency and high filtration flux and resource utilization technology of concentrated liquid. First, the prepared polyethersulfone material base film is sequentially immersed in anhydrous piperazine-m-phenylenediamine-2,4-diaminobenzenesulfonic acid aqueous phase solution and trimesoyl chloride-n-hexane organic solution, by means of interfacial polymerization The surface is coated with a nanofiltration thin layer, and then the nanofiltration thin layer is impregnated and modified with sodium hydroxide-absolute ethanol aqueous solution to improve the water flux of the nanofiltration membrane. polyethersulfone nanofiltration membrane. The invention also adopts the nitrate concentrated solution intercepted by the nanofiltration membrane to prepare the electrochemical intercalation electrolyte of natural flake graphite, and realizes the green preparation of expandable graphite and the resource utilization of the nitrate concentrated solution. The method of the invention has simple process and convenient operation, and provides a feasible path for water body eutrophication pollution control and nanofiltration membrane concentrated liquid resource utilization, and has broad application prospects.

Description

technical field [0001] The invention belongs to the technical field of nanofiltration membrane preparation, and relates to a nitrate-retaining polyethersulfone nanofiltration membrane and a preparation method thereof, and a preparation method for preparing expanded graphite by resource utilization of nanofiltration concentrated liquid. Background technique [0002] In recent years, the problem of nitrate pollution in surface water and groundwater has aroused widespread concern. Nitrate nitrogen wastewater mainly comes from agricultural irrigation, landfill leachate, industrial nitrogenous wastewater and livestock wastewater. Although the toxicity of nitrate nitrogen itself is very low, the increase of nitrate concentration in the water body will cause eutrophication of the water body, and under certain conditions, nitrite conversion and amination reactions can occur, which in turn deteriorates the quality of the water environment and destroys the water ecological balance. ....

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Problems solved by technology

Patent CN 111545064 A discloses a method for preparing a modified nanofiltration membrane using carboxylated nano-cellulose crystals. In the preparation method, carboxylated nano-cellulose crystals are added to piperazine aqueous phase solution, and oil phase trimesoyl chloride is mixed with A polymerization reaction occurs at the interface to obtain a composite nanofiltration membrane modified by carboxylated nanocellulose crystals. This preparation method does not use toxic additives and improves the flux and retention performance of the nanofiltration membrane by introducing carboxylated nanocellulose crystals. However, Although the nanofiltration membrane made by this method has a high interception effect on divalent ions, the interception rate to monovalent chloride ion is less than 40%.

[0006] On the other hand, the effective treatment of the nanofiltration concentrate has become one of the current technical problems. If it is not effectively disposed of, it will inevitably cause secondary pollution. Therefore, the reasonable disposal of the concentrate has become a constraint for the nanofiltration membrane separation project. One of the technical bottlenecks in the application of

At present, the disposal technology of concentrated liquid is more harmless, such as evaporation, coagulation, advanced oxidation technology, etc., but there are few reports on the resource utilization of nanofiltration concentrated liquid for material production and material preparation.

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