| 摘要 |
<p>Metal-cleaning soln. comprises an aqs. soln. of an alkylene polyamine polyacetic acid chelating agent to which has been added 0.001-0.1% of a water soluble sulphide. The sulphide is capable of liberating sulphide ions. It is free from cations which are deposited on the metal surface. Prefd. compds. are Na sulphide, K sulphide, NH4 sulphide, thioglycolic acid and dithioethanol. For removal of surface deposits (esp. Cu or Cu compds.) from ferrous metals, e.g. in boilers, cleaning action is accelerated and re-deposition of removed Cu is prevented.</p> |
