Ion exchange processes accompanied by ionic reactions

Kinetic Study of Lead Adsorption to Composite Biopolymer Adsorbent

“…The apparent diffusivity of lead ions was determined from the slope of the regression line as 5.85×10 -6 cm 2 ·s -1 . This value is slightly lower than the ionic diffusivity of lead in aqueous medium at infinite dilution, 9.3×10 -6 cm 2 ·s -1 (9), and is in fair agreement with the apparent lead diffusivity in Chelex 100 resin determined by Rao and Gupta (9), 3 -6×10 -6 cm 2 ·s -1 . Figure 6 shows the time dependence of lead adsorption to HA-M in different experimental conditions.…”

Kinetic Study of Lead Adsorption to Composite Biopolymer Adsorbent

“…The apparent diffusivity of lead ions was determined from the slope of the regression line as 5.85×10 -6 cm 2 ·s -1 . This value is slightly lower than the ionic diffusivity of lead in aqueous medium at infinite dilution, 9.3×10 -6 cm 2 ·s -1 (9), and is in fair agreement with the apparent lead diffusivity in Chelex 100 resin determined by Rao and Gupta (9), 3 -6×10 -6 cm 2 ·s -1 . Figure 6 shows the time dependence of lead adsorption to HA-M in different experimental conditions.…”

Kinetics of Sorption of Cu(II)−Ethylenediaminetetraacetic Acid Chelated Anions on Cross-Linked, Polyaminated Chitosan Beads

“…Such behavior was also due to diffusion in pores with different sizes (Jansson-Charrier et al, 1996;Saucedo et al, 1992). It is seen from Figure 12 that the resulting straight lines do not pass through the origin, probably indicating film diffusion control at the beginning of the sorption process, as is often encountered in SCM (Rao and Gupta, 1982).…”

“…The species within the particle simultaneously experience the same sequence in reverse order. The SCM was originally modified by Rao and Gupta (1982) for the description of sorption/ion-exchange processes in finite bath. If the rate of ion exchange is governed by the diffusion through the shell region at quasi-steady-state conditions, e.g., this model assumes a sharp boundary between the reacted shell of the particle and the unreacted core.…”

“…If the rate of ion exchange is governed by the diffusion through the shell region at quasi-steady-state conditions, e.g., this model assumes a sharp boundary between the reacted shell of the particle and the unreacted core. Table 1 lists the relations between fractional attainment of equilibrium X and the contact time t in HDM and SCM (Cortina and Miralles, 1997;Rao and Gupta, 1982).…”

Chromium(VI) Removal from Aqueous Solutions by Mg−Al−CO3 Hydrotalcite: Sorption−Desorption Kinetic and Equilibrium Studies

“…Ion-Exchange Models . Two models were selected to fit the data: the homogeneous diffusion model (HDM) based on Fick's law and the shrinking core model (SCM) based on modified Levenspiel's theory. − Table presents the linearized forms of the above models with film diffusion, particle diffusion, and chemical reaction.…”

Kinetic Study of Lead Adsorption to Composite Biopolymer Adsorbent

“…The apparent diffusivity of lead ions was determined from the slope of the regression line as 5.85×10 -6 cm 2 ·s -1 . This value is slightly lower than the ionic diffusivity of lead in aqueous medium at infinite dilution, 9.3×10 -6 cm 2 ·s -1 (9), and is in fair agreement with the apparent lead diffusivity in Chelex 100 resin determined by Rao and Gupta (9), 3 -6×10 -6 cm 2 ·s -1 . Figure 6 shows the time dependence of lead adsorption to HA-M in different experimental conditions.…”

Kinetics of Sorption of Cu(II)−Ethylenediaminetetraacetic Acid Chelated Anions on Cross-Linked, Polyaminated Chitosan Beads

“…Such behavior was also due to diffusion in pores with different sizes (Jansson-Charrier et al, 1996;Saucedo et al, 1992). It is seen from Figure 12 that the resulting straight lines do not pass through the origin, probably indicating film diffusion control at the beginning of the sorption process, as is often encountered in SCM (Rao and Gupta, 1982).…”

“…The species within the particle simultaneously experience the same sequence in reverse order. The SCM was originally modified by Rao and Gupta (1982) for the description of sorption/ion-exchange processes in finite bath. If the rate of ion exchange is governed by the diffusion through the shell region at quasi-steady-state conditions, e.g., this model assumes a sharp boundary between the reacted shell of the particle and the unreacted core.…”

“…If the rate of ion exchange is governed by the diffusion through the shell region at quasi-steady-state conditions, e.g., this model assumes a sharp boundary between the reacted shell of the particle and the unreacted core. Table 1 lists the relations between fractional attainment of equilibrium X and the contact time t in HDM and SCM (Cortina and Miralles, 1997;Rao and Gupta, 1982).…”

Chromium(VI) Removal from Aqueous Solutions by Mg−Al−CO3 Hydrotalcite: Sorption−Desorption Kinetic and Equilibrium Studies

“…Ion-Exchange Models . Two models were selected to fit the data: the homogeneous diffusion model (HDM) based on Fick's law and the shrinking core model (SCM) based on modified Levenspiel's theory. − Table presents the linearized forms of the above models with film diffusion, particle diffusion, and chemical reaction.…”

Kinetic Study of Lead Adsorption to Composite Biopolymer Adsorbent

“…The apparent diffusivity of lead ions was determined from the slope of the regression line as 5.85×10 -6 cm 2 ·s -1 . This value is slightly lower than the ionic diffusivity of lead in aqueous medium at infinite dilution, 9.3×10 -6 cm 2 ·s -1 (9), and is in fair agreement with the apparent lead diffusivity in Chelex 100 resin determined by Rao and Gupta (9), 3 -6×10 -6 cm 2 ·s -1 . Figure 6 shows the time dependence of lead adsorption to HA-M in different experimental conditions.…”

Kinetics of Sorption of Cu(II)−Ethylenediaminetetraacetic Acid Chelated Anions on Cross-Linked, Polyaminated Chitosan Beads

“…Such behavior was also due to diffusion in pores with different sizes (Jansson-Charrier et al, 1996;Saucedo et al, 1992). It is seen from Figure 12 that the resulting straight lines do not pass through the origin, probably indicating film diffusion control at the beginning of the sorption process, as is often encountered in SCM (Rao and Gupta, 1982).…”

“…The species within the particle simultaneously experience the same sequence in reverse order. The SCM was originally modified by Rao and Gupta (1982) for the description of sorption/ion-exchange processes in finite bath. If the rate of ion exchange is governed by the diffusion through the shell region at quasi-steady-state conditions, e.g., this model assumes a sharp boundary between the reacted shell of the particle and the unreacted core.…”

“…If the rate of ion exchange is governed by the diffusion through the shell region at quasi-steady-state conditions, e.g., this model assumes a sharp boundary between the reacted shell of the particle and the unreacted core. Table 1 lists the relations between fractional attainment of equilibrium X and the contact time t in HDM and SCM (Cortina and Miralles, 1997;Rao and Gupta, 1982).…”

Chromium(VI) Removal from Aqueous Solutions by Mg−Al−CO3 Hydrotalcite: Sorption−Desorption Kinetic and Equilibrium Studies

“…Ion-Exchange Models . Two models were selected to fit the data: the homogeneous diffusion model (HDM) based on Fick's law and the shrinking core model (SCM) based on modified Levenspiel's theory. − Table presents the linearized forms of the above models with film diffusion, particle diffusion, and chemical reaction.…”