| 摘要 |
Acid-soluble and/or hydrolyzable obstructions are removed from conduits by contacting such obstructions with a composition containing the reaction product of sulfuric acid and a chalcogen-containing compound having the empirical formula R1 - CX - R2 wherein X is a chalcogen, R1 and R2 are independently chosen from hydrogen, NR3R4 or NR5, with at least one of R1 and R2 being other than hydrogen, R3 and R4 are independently chosen from hydrogen or monovalent organic radicals, and R5 is a divalent organic radical. Preferably, the molar ratio of the chalcogen-containing compound to sulfuric acid is about 1/4 or more. Compositions particularly useful for removing deposits containing hydrolyzable constituents have chalcogen compound/sulfuric acid molar ratios less than 2. The compositions may optionally contain other components such as surfactants and/or non-aqueous polar solvents which accentuate their activity toward hydrophobic materials. Compositions which have H2O/(chalcogen compound+H2SO4) molar ratios below about 2.5 are particularly useful for removing obstructions by partial or complete hydrolysis. Urea is a most preferred chalcogen-containing compound.
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