| 摘要 |
<p>Barium sulfate scale is dissolved by contacting the scale with an aqueous solvent having a pH of about 8 to about 14 and comprising a chelating agent comprising a polyaminopolycarboxylic acid or salt of such an acid, and a synergist anion. The aqueous solvent containing the dissolved scale is regenerated by first acidifying the aqueous solvent containing a dissolved scale sufficiently to generate free alkaline earth metal ions without forming an insoluble alkaline earth metal precipitate. The aqueous solvent is then mixed with a liquid membrane emulsion comprising an immiscible liquid hydrocarbonaceous membrane phase containing an anionic surfactant and an oil soluble emulsifier enveloped around droplets of an internal aqueous phase comprising an aqueous solution in thepresence of an anion that forms an insoluble precipitate with the generated free alkaline earth metal ions. The free alkaline earth metal ions transfer from the aqueous solvent into the hydrocarbonaceous membrane phase and into the internal aqueous phase where the ions precipitate out as an insoluble salt or form a complex with a chelating agent. The scale-free aqueous solvent is separated from the emulsion by gravity and recovered. Thereafter, the pH of the scale-free aqueous solvent is increased to a pH of about 10 to about 14, preferably about 12, with potassium hydroxide to recover a regenerated solvent for reuse, in dissolving scale.</p> |
