Patent ID: 6761774
Filing Date: 2004-07-13
Classification: C02F,C11D,C23G,F28G

Abstract:
A method of removing scale from a substrate, said method characterized by using a composition comprising(A) a chelating agent having at least two carboxylic acid functional groups; and (B) a basic agent selected from the group consisting of alkali metal hydroxides, said basic agent establishing a pH of from 7 to 14 in said composition to remove the scale from the substrate; wherein one of:i. the composition consists of a) at least one of citric acid and a derivative of citric acid that can be converted to citric acid by hydrolysis, b) the basic agent, and c) optionally, water; or ii. the chelating agent is at least one of adipic acid, malonic acid, succinic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, heptanedioic acid, itaconic acid, fumaric acid, glutamic acid, tartaric acid, ethyleneglycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid, and a derivative of any of the preceding acids that can be converted to the acid by hydrolysis.