| 摘要 |
The scales are removed without forming a ppt. by contacting the surface with an aqs. soln. of a complexing agent (I) comprising monomethyl thiourea and/or monoethyl thiourea and a suitable acid pref. with agitation at 120-160 degrees F. Pref. acid is HCl, H3PO4 or H2SO4 and soln. contains a corrosion inhibitor. Pref. 2 moles of I are used per mole of Cu in the scale. The surface may be pretreated with an aq. alkaline soln. of an oxidising agent. |
