Hello everyone,
I am working on the adsorption of copper by biochar. I was asked to measure the Cation Exchange Capacity (CEC) of the adsorbent.
Would you kindly introduce me the method or procedure to measure CEC?
Somebody introduced me Chapman method. But, the book is old and I don't have access to it.
Sincerely,
Hi Mohammad,
Many methods exist, the most common being the use of an index cation for saturation (Cs-, K-, Na-, Ca-sample) and measurement after displacement by another (e.g. NH4OAc, CoHex, CsCl)
Isotopic dilution also works well, (e.g. Clays and Clay Minerals 52(4):421-431)
Still, many bias come from the preparation step of the material, and or the measurement of CEC itself.
(e.g. Applied Clay Science 119 (2016) 393–400, or 34 (2006) 38–46 )
Since you work on Biochar I recommand you read a reference such as (Biochar A guide to analytical methods, ed. Singh et al, 2017, chapter 7. determination of CEC in biochar, Graber et al.).
Then, you might choose a preparation of the sample and CEC measurement for two reasons,
i) Minimizing the possible bias,
ii) Being able to compare with references methods used in orther works.
I guess using two different methods is a good way to improve accuracy.
Hopping it will help
I am a bit unclear as to why you need CEC when you are working with copper. I would think you would want to measure the absorption saturation point for copper. If you run that like a CEC method, then you would saturate with copper and displace with, say, ammonium. See the methods that Dr. Dagnelie recommends.
Dear Mark,
Thank you very much.
Based on your comment, it seems that Cation Exchange is not a mechanism for Copper adsorption. Is that true?
Biochar CEC could be estimated by silver thiourea method using ICP-MS.