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Study on Flotation Separation of Trace Copper in Water Samples Using Microcrystalline Adsorption System Prior to the Determination by Spectrophotometry

The paper presents a novel method for the flotation separation of Cu2+ using microcrystalline adsorption system and the determination of trace Cu2+ in water samples by spectrophotometry. The effects of different parameters,such as the dosages of KI, ascorbic acid (AA) and cetyl trimethyl ammonium bromide (CTMAB),various salts and acidity on the flotation yield of Cu2+ have been investigated. The possible flotation separation mechanism of Cu2+ was discussed.The results showed that under the optimum conditions, CTMAB cation (CTMAB+) reacted with I- to produce the microcrystalline matter (Ms-M) of (CTMAB+·I-), Cu2+ could be reduced to Cu+ by ascorbic acid,and then Cu+ reacted with I- to form the precipitation of CuI.The precipitation of CuI was quantificationally adsorbed on the surface of Ms-M of (CTMAB+·I-) and was floated above water phase. While Zn2+,Ni2+,Co2+, Mn2+, Fe2+ and Al3+ could not be floated.Therefore, Cu2+ was separated completely from the above metal ions. The proposed method has been successfully applied to the determination of trace Cu2+ in various environmental water samples by spectrophotometry after flotation separation using microcrystalline adsorption system, and the results agreed well with those obtained by GFAAS method.The recoveries were 98.4%~106.8%, and the RSD was 1.1%~1.6%.