“…Hussain et al [ 51 ] found that the alkaline character of the CFA neutralizes the metal solution, which is linked to the removal efficiency. Notably, CFA is able to adsorb trace metals without being impacted by high ionic strength or notable amounts of Cl and Ca [ 67 ]. When the concentration of calcium (CaO) increases, CFA adsorption efficiency increases as well [ 27 ].…”