A preparation method of a composite membrane for selectively separating ammonia nitrogen, the composite membrane obtained by the preparation method and its application

Abstract

The invention relates to a preparing method for a composite membrane selectively separating ammonia nitrogen, the composite membrane obtained by the preparing method and application thereof. The preparing method comprises the following steps of: preparing membrane preparing liquid, wherein the membrane preparing liquid containing membrane preparing resin, polyvinylpyrrolidone, a hybridized additive and a solvent; the hybridized additive is phosphotungstic acid, phosphomolybdic acid or a mixture thereof; after being mixed uniformly and defoamed, the membrane preparing liquid is coated on a support membrane and is subjected to phase inversion to obtain the composite membrane. The composite membrane can selectively remove low-concentration NH4+ions from raw water and has not the capacity to remove other positive ions, such as Na+, Ca2+ and Mg2+, from the raw water, and thus, the composite membrane is particularly suitable for removing NH4+ from water containing low-concentration ammonia nitrogen and metal ions.

Description

【Technical field】 [0001] The invention relates to a preparation method of a composite membrane, in particular to a preparation method of a composite membrane capable of selectively separating ammonia nitrogen, a composite membrane obtained by the method, and an application of the membrane in water treatment. 【Background technique】 [0002] At present, there are many problems in drinking water sources in my country, such as high dissolved organic matter, high concentration of ammonia nitrogen, and peculiar smell in the water body. These raw waters that are polluted but can still be used after special treatment are usually called slightly polluted water sources. Common treatment methods for micro-polluted water sources include biological oxidation pretreatment, chemical oxidation pretreatment, enhanced coagulation treatment technology, activated carbon advanced treatment technology and membrane water treatment technology. [0003] Ammonium ion and sodium ion are two common ion...

AI Technical Summary

Problems solved by technology

Among them, biological methods (such as Xu Lei, engineering practice of A-A / O process method for treating high-concentration ammonia-nitrogen wastewater, "Green Technology" 2014 (2): 182-184) and chemical methods (such as Liu Guoyue et al., chemical precipitation method to treat high Experimental research on concentrated ammonia nitrogen wastewater, "Petrochemical Technology and Economics" 2013, 29 (6): 31-35) is suitable for the treatment of high concentration ammonia nitrogen wastewater, but it is difficult to realize the recovery and utilization of ammonia nitrogen, ion exchange adsorption method (Wang Wenchao et al., Clinoptilolite for the treatment of ammonia nitrogen wastewater, "Journal of Environmental Engineering" 2014, 8(3):1036-1040) is suitable for the selective separation of ammonium ions in low concentration ammonia nitrogen wastewater, but is not suitable for large-scale due to process limitations waste water treatment, only suitable for building small sewage treatment equipment

Existing reverse osmosis membranes can remove low-concentration ammonia nitrogen in wastewater, but they have no selectivity for ammonia nitrogen. While retaining ammonium ions, they also retain sodium ions, so the separation of ammonium ions and sodium ions cannot be achieved, and reverse osmosis The flux of the membrane is low, and the cost of water treatment is high

In addition, sodium ions and ammonium ions have the same charge, and their hydrated ions are also relatively close in size, which also aggravates the difficulty of their separation

Therefore, there is no composite membrane capable of separating these two ions in the prior art.

Images