¡ôIon exchange property
Reason of Charge:
Vermiculite is sheet silicate atomic structured of mica, but differs in that a change in the net charge of the silicate sheets results in the tightly held potassium atoms in the mica structure wholly or partly replaced, by other ions and their associated hydrate shells. In microscopic particles, vermiculite is differentiated from other clay minerals by a high silicon: aluminum (Si: Al) ratio of approximately 3:1, and a higher layer charge that results in a generally higher ion-exchange capacity.
CEC test
To establish CEC (cation exchange capacity) test, 100 g of each material was placed in a Buchner funnel and washed with 1-L NH4Cl 10 times. The final rinse solution was checked for ion concentrations, and if Aluminum (Al), Calcium (Ca), Magnesium (Mg), Potassium(K) or Sodium(Na) were greater than 0.1mg/ml, then washing was repeated until cation levels were below this concentration.
(From New Zealand Forest Research Institute, Measuring the cation exchange capacity of forest soils)
The standard materials were then saturated with cations by washing 5 times with 0.1M solution of Ca, Mg, K, Na and Al, followed by a rinse of ethanol to remove excess cations.Final volume of all wash solutions including ethanol was determined and solutions were analyzed for cations by ICP-AES. Cation exchange capacity was then determined by summation of cation loss from saturating solution.
Final CEC of each material was 2.2 34.8, and 49.3cmol/Kg for kaolinite, vermiculite and the organic matter, respectively. Which approved that vermiculite has a excellent ion exchange capacity.
Application
The ion exchange capacity (up to 1000 milliequivalents per kg) of vermiculite allows it to be used in fluid purification processes for waste water, chemical processing and the pollution control of air in mines and gases in industrial processes. In addition to its cation exchange properties expanded vermiculite will retain liquids within the inter-laminar voids of the individual particles as well as between the particles themselves.[1]
The water treatment is split into soften water treatment and water purification treatment, Ion exchange process includes condensation, filter, a |
