Additives for salt rejection enhancement of a membrane

A process for preparing a thin film composite membrane, comprising:

• providing an aqueous phase comprising a polyamine and an organic phase comprising a polyfunctional acyl halide;
• introducing a salt rejection-enhancing additive in the aqueous phase, the salt rejection-enhancing additive able to form a complex with hydrolyzed polyfunctional acyl halide;
• applying the aqueous phase to a surface of a porous support membrane to form a coated support membrane;
• applying the organic phase to the coated support membrane to allow interfacial polymerization between the aqueous phase and organic phase, wherein hydrolyzed and non-hydrolyzed polyfunctional acyl halide are present during interfacial polymerization;
• forming a complex between the salt rejection-enhancing additive and the hydrolyzed polyfunctional acyl halide and interfacially polymerizing the polyamine and the non-hydrolyzed acyl halide to produce a discrimination layer of a thin film composite membrane comprising the porous support membrane and the discrimination layer, wherein the thin film composite membrane exhibits a salt rejection that is greater than the salt rejection of a thin film composite membrane prepared in the absence of the salt rejection-enhancing additive or a permeability coefficient (B-value) that is less than the permeability coefficient of a thin film composite membrane prepared in the absence of the salt rejection-enhancing additive,
• wherein the salt rejection-enhancing additive has the formula:
• or a salt thereof, wherein:
• n is a number between 10 and 15;
• and
• X is an alkyl chain having between 4 and 8 carbons;
• and
• wherein the aqueous phase or the organic phase or both comprises a phosphoramide as an additive.