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Does temperature affect cation exchange capacity?
The effect of temperature on the CEC of soils and clays varied and depended on their major cation‐exchange materials; the ratio of the CEC measured at 10–20 °C to that measured at 50–60 °C was 0.36 to 0.59 for allophane, imogolite, and/or humus, 0.62 to 0.75 for kaolin minerals, and 0.90 to 0.99 for montmorillonites.
How does salt affect ion exchange chromatography?
An impure protein sample is loaded into the ion exchange chromatography column at a particular pH. A salt gradient is used to elute separated proteins. At low salt concentrations, proteins having few charged groups are eluted and at higher salt concentrations, proteins with several charged groups are eluted.
What happens during ion exchange?
ion-exchange reaction, any of a class of chemical reactions between two substances (each consisting of positively and negatively charged species called ions) that involves an exchange of one or more ionic components. Ions are atoms, or groups of atoms, that bear a positive or negative electric charge.
What is the effect of pH on cation exchange capacity?
Increasing the pH (i.e. decreasing the concentration of H+ cations) increases this variable charge, and therefore also increases the cation-exchange capacity.
What does ion exchange remove?
The ion exchange process is widely used for the removal of hardness (as in softening), heavy metals (as in waste treatment), radionuclides (as from power plants) and municipal water feeds (removal of nitrates, arsenic, perchlorate, hexavalent-chrome and others).
Why is ion exchange important?
Ion exchange resins are useful for the removal of water problems including hard water, scale buildup, nitrates and arsenic. Ion exchange resins are useful for the removal of water problems including hard water, scale buildup, nitrates, arsenic and more.
How is temperature used in ion exchange chromatography?
Despite the growing use of temperature in RPLC, temperature has been a relatively unexploited variable in ion-exchange chromatography. However, Rey and Pohl did demonstrate that column temperature was an effective means of increasing the separation between monovalent and divalent cations on a Dionex CS12A stationary phase [7].
What is the effect of temperature on chromatographic retention?
The effect of temperature on chromatographic retention is described by the general thermodynamic relationship governing equilibria: (1) dln k d T = Δ H 0 RT 2 where k is the retention factor, T is the temperature in Kelvin, R is the universal gas constant and Δ H0 is the enthalpy of exchange.
What happens to column separation when temperature increases?
If the column temperature is increased, the chromatographic separation process becomes faster. A rule of thumb for reversed-phase isocratic separation predicts a retention time decrease of 1–2% for each 1 °C column temperature increase.
How does temperature and column thermostatting affect diffusion?
As the column temperature rises, the mobile phase viscosity decreases, thereby the flow resistance in the column, and the system backpressure as well. Both, lower mobile phase viscosity and increased temperature improve diffusion during the chromatographic process.