Study on Determination of Trace Copper by Spectrophotometry after Flotation Separation Using Microcrystalline Adsorption System

Abstract

AbstractThe paper presents a novel method for the flotation separation of Cu2+ using microcrystalline adsorption system prior to the determination by spectrophotometry. The effects of different parameters, such as the dosages of NH4SCN and octadecyl trimethyl ammonium bromide (OTMAB), various salts on the flotation yield of Cu2+ have been investigated to select the optimum experimental conditions. The possible flotation separation mechanism of Cu2+ was discussed. The results showed that under the optimum conditions, octadecyl trimethyl ammonium bromide cation (OTMAB+) reacted with SCN‐ to produce the microcrystalline matter (Ms‐M) of (OTMAB+·SCN‐), the water‐insoluble ternary association complex of [Cu(SCN)4] (OTMAB)2 which produced by Cu2+ and SCN‐, OTMAB+ was quantificationally adsorbed on the surface of Ms‐M of (OTMAB2+·SCN‐) and was floated above water phase, the liquid‐solid phases were formed with clear interface. In this condition, K+, Na+, Ca2+, Mg2+, Al3+, Fe2+, Mn2+, Ni2+, Cd2+ and Co2+ could not be floated. Therefore, Cu2+ was separated completely from the above metal ions. A new method of determination of trace copper by flotation separation was established. The proposed method has been successfully applied to the determination of Cu2+ in plating waster water, and the results agreed well with AAS method. The recoveries were 93.3%∼107.8%, and the RSD was 1.9%∼2.1%.