Nanofiltration membrane for treating printing and dyeing wastewater and preparation method thereof

Abstract

The invention relates to the field of industrial wastewater treatment, and particularly discloses a nanofiltration membrane for treating printing and dyeing wastewater and a preparation method of the nanofiltration membrane. The preparation method comprises the following steps: S1, pouring an aqueous solution containing m-phenylenediamine, camphorsulfonic acid and triethylamine to the surface of a polysulfone ultrafiltration membrane, staying for 10-30s, and then removing the redundant aqueous solution on the surface; s2, pouring an organic solution containing trimesoyl chloride and an interface auxiliary polymerization agent to the surface of the membrane obtained in the step S1, reacting for 5-20 seconds, and then removing the redundant solution on the surface; s3, subjecting the membrane obtained in the step S2 to standing, heat treatment and water washing in sequence, and obtaining the nanofiltration membrane . The retention rate of the prepared nanofiltration membrane on NaCl under the filtering pressure of 0.5 MPa reaches 94% or above, the retention rate of MgSO4 reaches 99% or above, the flux of pure water is larger than 25 L / m < 2 > h, and the nanofiltration membrane has both high water flux and high salt retention rate.

Description

technical field [0001] The application relates to the field of industrial wastewater treatment, more specifically, it relates to a nanofiltration membrane for treating printing and dyeing wastewater and a preparation method thereof. Background technique [0002] Textile printing and dyeing is one of the traditional advantageous industries with the most international competitiveness in my country, but it discharges about 1.8 to 2 billion tons of saline wastewater every year, accounting for about 11% of the total wastewater discharge in the country. It is one of the key polluting industries in my country. Therefore, in order to reduce the discharge of wastewater in the field of textile printing and dyeing, reverse osmosis membranes are currently used to treat and reuse printing and dyeing wastewater. However, due to the high desalination rate of the reverse osmosis membrane, in the actual operation process, its operating pressure is high, generally not less than 1.5MPa, the wa...

AI Technical Summary

Problems solved by technology

However, the current nanofiltration membranes still have the following deficiencies: (1) the rejection rate of monovalent salts (such as NaCl) is not high: the rejection rate of conventional nanofiltration membranes to monovalent salts NaCl is generally below 50%; Low flow rate: especially for some special nanofiltration membranes, that is, nanofiltration membranes with a NaCl rejection rate of 90%. According to literature, patent reports or currently commercialized nanofiltration membranes, the water flux is usually not more than 20L / (m 2 h), unable to meet the demand for industrial reuse water; (3) High filtration pressure: The filtration pressure of existing literature reports and commercialized nanofiltration membranes is generally above 1.0 MPa, and some are even higher than the filtration pressure of low-pressure reverse osmosis, High energy consumption during industrial application; (4) Serious membrane pollution: the higher the filtration pressure, the more significant the compaction effect of the membrane surface fouling layer, the more serious the fouling phenomenon and organic and microbial pollution on the membrane surface, and the recovered water volume increases with time. The more pronounced the drop, the more frequent the chemical cleaning

[0004] Therefore, under the premise of a certain operating pressure, there will be a "trade-off effect" between the water flux and the salt rejection rate during the preparation of the nanofiltration membrane. Faced with the problem of increasing the water flux of the membrane, the desalination rate will always be lost

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