Method for preparing ultra-low pressure contamination-resistance composite reverse osmosis membrane using chitosan

Abstract

The invention discloses a method for preparing an ultralow pressure fouling resistant composite reverse osmosis membrane through chitosan. The method comprises the following steps: dissolving chitosan with the deacetylation degree above 90 percent in acetic acid, and preparing solution A with the mass concentration of 1 to 10 percent after removing solid impurities in the solution; mixing crosslinking agent solution and hydrochloric acid through stirring to form solution B; and finally mixing solution A and solution B, spreading a mixed solution onto a polyamide carrier membrane, and preparing the ultralow pressure fouling resistant composite reverse osmosis membrane after drying. The obtained ultralow pressure fouling resistant composite reverse osmosis membrane has a crosslinked chitosan layer formed on a polyamide layer, thereby improving the hydrophilicity of the reverse osmosis membrane and the fouling resistance of the reverse osmosis membrane, and saving a great amount of power consumption during the operation with ultralow pressure.

Description

technical field [0001] The invention belongs to the field of membrane water treatment, and in particular relates to a production method of a composite reverse osmosis membrane with anti-pollution performance that can be applied under ultra-low pressure. Background technique [0002] At present, the common reverse osmosis composite membrane is to form a layer of polyamide separation layer through interfacial polymerization on the non-woven polysulfone support layer (for example, Chinese Patent No. CN1724130A, Chinese Patent No. CN1370796A, etc.). [0003] Although the above-mentioned polyamide composite membrane has good separation performance and permeation performance, it cannot avoid the current membrane fouling problem, such as the decrease of the permeation flow due to the adsorption or attachment of suspended or dissolved substances on the membrane surface, due to Membrane fouling is a problem. In order to obtain a certain flow rate of permeate, the pressure must be adj...

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Problems solved by technology

[0005] For example, Chinese Patent Publication No. CN1213985A discloses a "reverse osmosis composite membrane and its method for reverse osmosis treatment of water", wherein the reverse osmosis composite membrane is a low-pollution composite reverse osmosis membrane, using PVA to coat polyamide However, since the PVA molecules are not cross-linked, the PVA is easy to gradually dissolve in water during the use of the membrane, and eventually loses its protective layer effect.

[0006] Chinese Patent Publication No. CN1923348A discloses a "production method of low-pollution composite reverse osmosis membrane". In this method, a layer of hydrophilicity is coated on the polysulfone support layer, and then a layer of polyamide separation layer is formed by interfacial polymerization. Finally, a layer of hydrophilic material is coated on the polyamide separation layer. Although this method solves the pollution resistance problem of the membrane to a certain extent, the operating pressure of the membrane is still the traditional brackish water treatment pressure (1.6 MPa), there is not much improvement in energy saving

[0009] Chinese Patent Publication No. CN1375350A discloses a "manufacture of N-acetylated chitosan reverse osmosis membrane". In this patent, chitosan is used to directly cast reverse osmosis membrane, and the operating pressure of the reverse osmosis membrane prepared by this method is relatively low , is only 0.45MPa, thus limiting its range of use

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