FIELD: organic chemistry. SUBSTANCE: method comprises conventional steps of contacting extract and solution at pH = 4-8, mixing resultant mixture, settling and separating phases. Novelty of method resides in fact that it employs, as extract, technical-grade lubricant comprising inert diluent, viz. machine oil having the following composition, wt.-%: oleic acid, 10-12; triethanolamine, 4.5-6.0; inert diluent-machine oil, the balance. Extraction step is carried out under conditions of adjusting pH value for at most 2 h. Extract/solution mixture is heated up to boiling point for 1-5 min., followed by adjusting pH to preset value for 10-15 min. EFFECT: higher efficiency. 2 cl, 2 dwg, 2 tbl
