“…The main methods for the metal ions uptake from industrial wastewaters are reverse osmosis, solvent extraction, ion exchange, chemical precipitation, membrane filtration, electrolytic methods, and adsorption [ 16 , 17 , 18 ]. However, these techniques have high operational cost and in the case of trace level concentrations may be ineffective for the adsorption of some types of toxic metal ions [ 16 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Therefore, a candidate facing the heavy metal ions pollutions is the use of adsorption technology [ 35 , 36 , 37 , 38 , 39 ], and specifically by using chitosan as an adsorbent.…”