Hi all,

I want to predict the sorbed amount of 0.5 M sodium sulfate solution with my ferrihydrite powder. The measured specific surface area is 190 m2/g. I also found the topological polar surface area of sulfate ions to be 88.6 A^2. I am trying to using the following number to calculate for the sorbed volume (Vm): S = [Vm*Na]/[mx22400], where N = Avogadro constant; m = mass of sorbent; a = cross sectional area of sorbate.

However, I got a ridiculous result, so I am not sure which step did i do wrong? Or I should use another equation to solve this problem.

Any input/suggestions are highly appreciated!