Inhibition of silica scale using amine-terminated polyoxyalkylene

A method for inhibiting silica scale formation in an aqueous reverse osmosis system including a reverse osmosis membrane, wherein the method comprises the steps of:

• adding an anti-scalant to a source of feed water having a pH of less than 9.5 and containing silica, and
• passing the resulting feed water through the reverse osmosis system such that a portion passes through the reverse osmosis membrane to produce a permeate stream having a reduced concentration of silica with the remaining portion of feed water forming a reject stream having a higher concentration of silica;
• wherein the anti-scalant comprises a non-ionic, tertiary amine-terminated polyoxyalkylene represented by:
• wherein Y and Y′ are independently selected from hydrogen or alkyl;
• R1 is a C1 to C20 hydrocarbon moiety:
• R2 is a C10 to C14 hydrocarbon moiety;
• and E is a terminal end group selected from hydrogen, alkyl, NR1R2;
• L is a linking group selected from a direct bond between the oxyalkylene repeating unit —(CH2CH(Y)O)— and the nitrogen atom, or a C1 to C20 hydrocarbon moiety;
• n is an integer from 2 to 1000;
• and m is an integer from 0 to 1000.