Dynamics of trace metal sorption by an ion-exchange chelating resin described by a mixed intraparticle/film diffusion transport model. The Cd/Chelex case
MetadataShow full item record
The time-evolution of Cd2+ ion sorption by Chelex 100 resin was studied in batch experiments as a function of time, pH, ionic strength, stirring rate, mass of resin and initial metal ion concentration. In the experimental conditions, the amount of resin sites are in excess with respect to the amount
of metal ion, leading to extensive depletion of metal in bulk solution when equilibrium is reached. The data were described using a mixed control mass transport model in finite volume conditions (MCM) that includes explicitly both intraparticle and film diffusion steps. Exact numerical computations and a new approximate analytical expression of this model are reported here. MCM successfully predicts the influence of pH and ionic strength on the experimental Cd(II)/Chelex kinetic profiles (which cannot be justified by a pure film diffusion controlled mechanism) with a minimum number of fitting parameters. The overall diffusion coefficient inside the resin was modelled in terms of the Donnan factor and the resin/cation binding stability constant. The values of the latter coefficient as a function of pH and ionic strength were estimated from the Gibbs-Donnan model. Even though MCM is numerically more involved than models exclusively restricted to film or intraparticle diffusion control, it proves to be accurate in a wider range of values of the mass transfer Biot number and solution/resin metal ratios.
Is part ofChemical Engineering Journal, 2017, vol. 317, p. 810-820
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Quattrini, Federico; Galceran i Nogués, Josep; Rey Castro, Carlos; Puy Llorens, Jaume; Fortin, Claude (CSIRO Publishing, 2019)The dynamic ion exchange technique (DIET) is proposed to provide speciation information, which can be used to establish links with metal bioavailability in natural waters. The experimental setup consists of a few milligrams ...
Competitive Cd2+/H+ complexation to polyacrylic acid described by the stepwise and intrinsic stability constants Calin, David; Companys Ferran, Encarnació; Galceran i Nogués, Josep; Garcés, Josep Lluís; Mas i Pujadas, Francesc; Rey Castro, Carlos; Salvador, José; Puy Llorens, Jaume (American Chemical Society, 2008)Stepwise constants can be used to describe competitive proton and metal binding to macromolecules with a large number of sites. With the aim of accessing information on the microscopic binding model, we report an expression ...
Dissolution and phosphate-induced transformation of ZnO nanoparticles in synthetic saliva probed by AGNES without previous solid-liquid separation. Comparison with UF-ICP-MS David, Calin; Galceran i Nogués, Josep; Quattrini, Federico; Puy Llorens, Jaume; Rey Castro, Carlos (American Chemical Society, 2019-02-26)The variation over time of free Zn2+ ion concentration in stirred dispersions of ZnO nanoparticles (ZnO NPs) prepared in synthetic saliva at pH 6.80 and 37 degrees C was followed in situ (without solid liquid separation ...