Fatima Boukhlifi I am not using Uv visible for CEC measurement. it is the simple standard experimental method.
actually, I don't know the concentration of methylene blue solution to carry out the experiment and could not find any concentration in the literature.
please find the standard procedure for the experiment attachment below
in this article concentration of methylene blue solution is not mentioned. I just found that during titration we add 5ml or 0.5ml of methylene blue solution increment in slurry but I could not found how to prepare or what concentration of methylene blue solution required for titration