Abstract：A novel separation and enrichment method of cobalt using microcrystalline phenolphthalein as adsorbent was established. The effect of addition amount of α nitroso β naphthol (HL) and phenolphthalein, the type and dosage of salt, and acidity on the enrichment yield of Co2+ was investigated. The optimal separation and enrichment conditions of cobalt were obtained. The enrichment mechanism of Co2+ was discussed. The results showed that Co2+ could react with HL to form reddish brown chelate precipitate (CoL3) which was quantitatively adsorbed on microcrystalline phenolphthalein under the following conditions: at pH 5.0; in the presence of 1.0 g of NaCl; the dosages of 2.0 g/L HL and 5 % phenolphthalein solution were 0.60 mL and 0.10 mL, respectively. Consequently, Co2+ could be quantitatively enriched, while Zn2+, Mn2+, Al3+ and Cd2+ were not adsorbed under these conditions, realizing the quantitative separation of Co2+ from these ions. This method had been applied to the quantitative enrichment, separation and determination of micro Co2+ in synthetic water samples. The enrichment yield was 99.8 % 108.6 %.
