An aqueous solution containing a fluorine-containing emulsifier in a low concentration of at least 1 ppm by mass and at most 1% by mass (e.g., coagulation waste water after an emulsion polymerization of a fluoropolymer and/or an aqueous solution obtained by washing with an aqueous solution a waste gas from a drying process and/or a heat treating process of the fluoropolymer) is subjected to vacuum concentration under a pressure of at most 100 kPa and a temperature of the aqueous solution of at most 100°C by means of a heating tube surface evaporation type concentrator equipped with a heat pump or the like, and the fluorine-containing emulsifier is recovered from a highly concentrated aqueous solution containing the fluorine-containing emulsifier in a higher concentration of at least 5% by mass. According to the present method, the fluorine-containing emulsifier can be recovered with a high yield from a low-concentration liquid such as coagulation waste water of a fluoropolymer.
含有含
氟乳化剂的低浓度
水溶液,其质量浓度至少为 1 ppm,最多不超过 1%(例如:含
氟聚合物乳液聚合后的凝结废
水和/或用
水溶液洗涤含
氟聚合物干燥过程和/或热处理过程中产生的废气而得到的
水溶液)、含
氟聚合物乳液聚合后的凝结废
水和/或用
水溶液洗涤含
氟聚合物干燥工序和/或热处理工序产生的废气后得到的
水溶液),在压力不超过 100 kPa 和
水溶液温度不超过 100°C 的条件下,通过配备热泵或类似装置的加热管表面蒸发型浓缩器进行真空浓缩、从高浓度
水溶液中回收含
氟乳化剂,高浓度含
氟乳化剂的质量浓度至少为 5%。根据本方法,可从低浓度液体(如含
氟聚合物的凝结废
水)中高产率地回收含
氟乳化剂。