Nanofiltration membrane modification method and application thereof

The invention discloses a nanofiltration membrane modification method and application thereof. The modification method includes the four steps of base membrane pre-treatment, modification liquid preparation, base membrane modification and membrane forming. The modification method is simple in technological process, convenient to operate, low in cost and good in concentration effect, a modified nanofiltration membrane can greatly improve the detection accuracy of soluble organic nitrogen in water, and the defect that the concentration efficiency of a traditional commercial nanofiltration membrane is low is overcome. Under the condition of the same concentration proportion, the concentration effect of the modified nanofiltration membrane is better than that of the traditional nanofiltration membrane, the proportion of DIN/TDN is reduced to 40%-50% from 70%-90%, and the detection limit is increased by 30%-40%.