title: Flow injection analysis of ethyl xanthate by gas diffusion and UV detection as CS2 for process monitoring of sulfide ore flotation.
abstract: 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.
authors.affiliation: Centro de Ciências e Humanidades Universidade Presbiteriana Mackenzie, São Paulo, Brazil.
authors.forename: Thiago G
authors.initials: TG
authors.lastname: Cordeiro
authors.forename: Pilar
authors.initials: P
authors.lastname: Hidalgo
authors.forename: Ivano G R
authors.initials: IG
authors.lastname: Gutz
authors.forename: Jairo J
authors.initials: JJ
authors.lastname: Pedrotti
mesh_terms: D002246:Carbon Disulfide / Q000032:analysis* / Q000737:chemistry; D004058:Diffusion; D017022:Flow Injection Analysis / Q000379:methods; D005740:Gases / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet / Q000295:instrumentation / Q000379:methods; D013871:Thiones / Q000032:analysis*
chemical_list: D005740:Gases; D013871:Thiones; C004918:ethylxanthate; D002246:Carbon Disulfide