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With the advent of increasingly loose nanofiltration membranes for dye desalination, synthesis methods based on interfacial polymerization and bio-inspired materials such as polydopamine (pDA) have been investigated. However, the long polymerization time of pDA greatly limits the synthesis and application of fast dye/salt separation membranes. In this work, prebiotic chemistry-inspired aminomalononitrile (AMN) was used as a binder to co-deposit the Mannich reaction of tetrakis(hydroxymethyl)phosphonium chloride (THPC) and polyethyleneimine (PEI) to form the positively charged selective layer rapidly. The optimum membrane had a water permeance of 30.7 LMH bar-1 and a rejection of positively charged Victoria blue B (VBB, 200 ppm) and Na 2 SO 4 (1 g/L) of 99.5 % and 9.9 %, respectively. Moreover, the results of a practical application test showed that it had excellent separation performance towards various positively charged dyes and salts. In addition, the actual application test results show that the membrane has good long-term stability during application. In terms of antifouling and antibacterial, the membrane has excellent antibacterial and antifouling properties., Further antibacterial tests were carried out, and the inactivation effect of the membrane on E. coli was also confirmed. The preparation method proposed in this work provides technical support for developing new dye/salt separation membranes. [Display omitted] • Synthesis of positively charged dye/salt separation membranes by Mannich reaction. • A prebiotic chemistry-inspired AMN coating was used for membrane preparation. • Positively charged dye/salt separation membranes with higher permeance. • The membranes prepared by Mannich reaction and AMN exhibited good antibacterial and antifouling properties. [ABSTRACT FROM AUTHOR]