Flow injection analysis of ethyl xanthate by gas diffusion and UV detection as CS2 for process monitoring of sulfide ore flotation.
A sensitive and robust analytical method for spectrophotometric determination of ethyl xanthate, CH(3)CH(2)OCS(2)(-) at trace concentrations in pulp solutions from froth flotation process is proposed. The analytical method is based on the decomposition of ethyl xanthate, EtX(-), with 2.0 mol L(-1) HCl generating ethanol and carbon disulfide, CS(2). A gas diffusion cell assures that only the volatile compounds diffuse through a PTFE membrane towards an acceptor stream of deionized water, thus avoiding the interferences of non-volatile compounds and suspended particles. The CS(2) is selectively detected by UV absorbance at 206 nm (epsilon=65,000 L mol(-1) cm(-1)). The measured absorbance is directly proportional to EtX(-) concentration present in the sample solutions. The Beer's law is obeyed in a 1x10(-6) to 2x10(-4) mol L(-1) concentration range of ethyl xanthate in the pulp with an excellent correlation coefficient (r=0.999) and a detection limit of 3.1x10(-7) mol L(-1), corresponding to 38 microg L(-1). At flow rates of 200 microL min(-1) of the donor stream and 100 microL min(-1) of the acceptor channel a sampling rate of 15 injections per hour could be achieved with RSD<2.3% (n=10, 300 microL injections of 1x10(-5) mol L(-1) EtX(-)). Two practical applications demonstrate the versatility of the FIA method: (i) evaluation the free EtX(-) concentration during a laboratory study of the EtX(-) adsorption capacity on pulverized sulfide ore (pyrite) and (ii) monitoring of EtX(-) at different stages (from starting load to washing effluents) of a flotation pilot plant processing a Cu-Zn sulfide ore.
Study of flotation conditions for cadmium(II) removal from aqueous solutions
Abstract Flotation conditions for cadmium(II) removal from aqueous solutions were investigated. Precipitate flotation techniques “of the first kind” (PFFK) and “of the second kind” (PFSK) were tested, using potassium ethyl xanthate (KEtX) as a precipitating agent for cadmium(II). The surfactants sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (HDTMA) were used as collectors for PFFK. The effects of KEtX and collector concentrations, induction time, bubbling time, solution pH and some foreign ions on cadmium(II) removal were studied. Under optimum conditions, cadmium(II) could be removed by PFFK by ∼93% and >99% using SDS and HDTMA, respectively. By PFSK, removal of about 64% for cadmium(II) was obtained. The two developed precipitate flotation methods were also tested for simultaneous removal of cadmium(II), nickel(II) and cobalt(II) from distilled water and tap water. The effectiveness of PFFK suggests its employment for metal-polluted wastewaters.
Comportement electrochimique de l'ethylxanthate sur differents types d'electrodes: platine, or, galene, mercure
Resume Le comportement electrochimique de l'ethylxanthate (C2H5OCS−2) a ete etudie par voltammetrie cyclique, polarographie et electrolyses a potentiel controle, dans la zone de pH 9–10. Sur electrodes de platine, or ou galene, l'oxydation conduit a la formation de dixanthogene (C2H5OCS2)2; le mecanisme de la reaction est complique par l'adsorption du xanthate et du dixanthogene. Sur electrode a gouttes de mercure, les polarogrammes presentent une vague anodique a −0,3 V, correspondant a l'oxydation du mercure en presence de xanthate, et a la formation de Hg(C2H5OCS2)2. Les courbes sont deformees par l'adsorption de C2H5OCS−2 et Hg(C2H5OCS2)2.