A precipitation method was employed to purify sodium poly (oxyethylene)nonylphenylene ether carboxymethylates with 2 and 4 of EO(ethylene oxide),taking silvernitrate as precipitation agent.

• 用硝酸银作沉淀剂，采用沉淀法提纯了标称氧乙烯（EO）数分别为2和4的聚氧乙烯烷基酚醚羧甲基钠盐，纯度在99．8%25以上。