Questions about som

Hi there, For the FA and HA, I am thinking that the FA is more acidic than HA since FA has more H+, and relatively it should has higher CEC. Since there will be more coo- that attract other cations such as fe3+ or al3+ and so on, FA "SOLUTION" (pure FA) will have higher CEC Refer back to lecture 17 slide 16, it says "CEC IS HIGH AT HIGH PH AND LOW AT LOW PH". Is it because coo- is organic anion that can lead to flocculation? (Since FA is so soluble that large amount of H+ being released with COO- leftover). Correct me if I am not thinking it in a right way. Thanks