title: Description of transport mechanism during the elimination of copper(II) from wastewaters using supported liquid membranes and Acorga M5640 as carrier.
abstract: The kinetics of copper facilitated transport through a flat-sheet supported liquid membrane is investigated, using the commercially available oxime Acorga M5640 as ionophore, as a function of hydrodynamic conditions, stripping phase composition, concentration of copper(II), and pH of the source phase and carrier concentration in the membrane phase. The performance of the system is also compared using organic diluents of different nature (aliphatic or aromatic) and against other available oxime extractants (LIX 860, LIX 622, LIX 973N and LIX 84-I). A model is presented that describes the transport mechanism, consisting of diffusion through source side aqueous diffusion layer, a fast interfacial chemical reaction, and diffusion carrier and its metal complex through the organic membrane. The organic membrane diffusional resistance (delta(org)) and aqueous diffusional resistances (delta(aq)) were calculated from the proposed model, and their values were 9.3 x 10(-7) and 46565 s/cm, respectively. It was observed that the copper flux across the membrane tends to reach a plateau at high concentration of copper or low concentration of H+ owing to carrier saturation within the membrane and leads to a diffusion-controlled process. The values of the apparent diffusion coefficient (Dorg(a)) and limiting metal flux (Jlim) were calculated from the limiting conditions and found to be 5.2 x 10(-11) and 1.9 x 10(-9) mmol/cm2 s, respectively. The values of the bulk diffusion coefficient (Db,org) and diffusion coefficient (Dorg) calculated from the model were 4.8 x 10(-10) and 1.3 x 10(-10) cm2/s,respectively. The method had proven its feasibility to recover copper(II) from wastewaters.
authors.affiliation: Centro Nacional de Investigaciones Metalúrgicas (CSIC), Ciudad Universitaria, 28040 Madrid, Spain. fjalgua@cenim.csic.es
authors.forename: F J
authors.initials: FJ
authors.lastname: Alguacil
authors.forename: M
authors.initials: M
authors.lastname: Alonso
mesh_terms: D003300:Copper / Q000737:chemistry*; D004058:Diffusion; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D007700:Kinetics; D008567:Membranes, Artificial; D008956:Models, Chemical; D010091:Oximes / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*
chemical_list: D008567:Membranes, Artificial; D010091:Oximes; D014874:Water Pollutants, Chemical; D003300:Copper