| 摘要 |
PROBLEM TO BE SOLVED: To provide a filtering method having a high filtering speed, in removing insoluble organic impurities present in the lower or intermediate layer of a double-layered solution, which contains at least two kinds of solutions immiscible to each other, using a filter aid. SOLUTION: The filter aid on a filter medium is precoated with a slurry comprising at least a hydrophobic organic solvent in the solution forming the lower layer of the double-layered solution and the filter aid before the double- layered solution is filtered.
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