Study on Flotation Separation of Mercury (II) by sodium chloride- potassium iodide-octadecyl trimethyl ammonium chloride system

Abstract

Abstract:The flotation separation behaviours of mercury (II) by sodium chloride-potassium iodide-octadecyl trimethyl ammonium chloride system were studied.The effects of different parameters,such as the dosages of KI and octadecyl trimethyl ammonium chloride(OTMAC),various salts and acidity etc. on the flotation yield of Hg 2+ have been investigated.The results showed that by controlling pH 3.0, in the presence of 0.5 g NaCl,when 0.10 mol/L KI was 0.20 mL and 0.0050 mol/L OTMAC solution was 0.50 mL respectively, the formed water-insoluble ternary association complex of (OTMAc) IntroductionMercury is a kind of heavy metal with strong toxicity to humans,animals and the environment, and it is one of the main inorganic elements causing environmental pollution. The content of mercury in environment is an important factor in environmental monitoring. Since the content of Hg 2+ in environment is usually very low,separation and enrichment must be carried out before measurement. There are meny other methods to separate and enrich Hg(II),such as extraction separation [1][2] , column-chromatographic separation [3] , solid phase extraction separation [4] ,chromatographic separation [5] ,micellar high-performance liquid chromatography [6] .But all the aforesaid methods have used a organic solvent as extractant or need complicated instrumentation. Salt-ternary association complex-water system not only has the advantages of liquid-solid extraction system without organic solvent [7][8] , but also has characteristics such as rapid split-phase rate and clear interface between phases and less reagent.There have been some reports about flotation separation of metal ions by salt-ternary association complex-water system [9][10][11] .In this paper we have studied the flotation separation of mercury(II) by sodium chloridepotassium iodide-octadecyl trimethyl ammonium chloride system.The results showed that in the presence of 0.5 g NaCl,water-insoluble ternary association complex of (OTMAC) could be separated successfully from those metal ions without any masking agent by flotation at pH 3.0. A method of flotation separation of mercury(II) was established,and it has been used for the flotation separation of mercury (II) in the sample of synthetic water with satisfactory results. Compared this system with the organic solvent extraction flotation method and the forth flotation method [12][13] ,harmful organic solvent and complicated instrumentations were avoided in this method. added into to a 25 mL ground color comparison tube. Then adjust the pH with buffer solutions and dilute the mixture to 10.0 mL with water. 0.5 g NaCl was added and shaken adequately and they were kept still for a moment.1.00 mL salt-water sample in the lower layer was transferred into another 25 mL ground color comparison tube,and 1.5 mL of 0.001 mol/L 5-Br-PADAP ethanol solution and 3.0 mL of 0.1 mol/L borax solution and 0.5 mL of 10% TritonX-100 were added. The content of Hg 2+ was determined at 565 nm with reagent as blank after color apperance and dilution to ...