Study on Spectrophotometric Determination of Trace Copper after Flotation Separation using Microcrystalline Adsorption System Loaded with CuI

摘要

The paper presents a novel method for the flotation separation of Cu~(2+) using microcrystalline adsorption system loaded with CuI prior to the determination by spectrophotometry. The effects of different parameters, such as the dosages of KI, ascorbic acid and octadecyl trimethyl ammonium bromide (OTMAB), various salts and acidity etc. on the flotation yield of Cu~(2+) have been investigated. The possible flotation separation mechanism of Cu~(2+) was discussed. The results showed that under the optimum conditions, octadecyl trimethyl ammonium bromide cation (OTMAB~+) reacted with I~- to produce the microcrystalline matter (Ms-M) of (OTMAB~+·I~-), Cu~(2+) 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 (OTMAB~+·I~-) and was floated above water phase, the liquid-solid phases were formed with clear interface. In this condition, K~+, Na~+, Ca~(2+), Mg~(2+), Zn~(2+), Co~(2+), Al~(3+), Mn~(2+), Ni~(2+) and Fe~(2+) could not be floated. Therefore, Cu~(2+) was separated completely from the above metal ions. A new spectrophotometric method of determination of trace copper by flotation separation using microcrystalline adsorption system loaded with CuI was established. The proposed method has been successfully applied to the determination of Cu~(2+) in various environmental water samples, and the results agreed well with those obtained by AAS method.