Modification of chitosan with carbamoyl benzoic acids for testing its coagulant-flocculant and binding capacities in removal of metallic ions typically contained in plating wastewater

Publication date: 15 January 2018
Source:Chemical Engineering Journal, Volume 332
Author(s): Marisela Martínez-Quiroz, Eduardo A. López-Maldonado, Adrián Ochoa-Terán, Georgina E. Pina-Luis, Mercedes T. Oropeza-Guzman
This paper proposes the use chitosan modified with carbamoyl benzoic acids as new coagulant-flocculant agents for metals removal from aqueous solutions. The grafted chitosan species as chitosan dianhydride (ChD) and chitosan dianhydride-amine (ChDA) improved the removal of Cu²⁺, Pb²⁺, Ca²⁺, Cr³⁺, Zn²⁺ and Ni²⁺, compared with chitosan alone. Zeta potential measurements predict doses and allowed to calculate binding constants between the new coagulant-flocculant agents and metallic cations (from 10⁴ to 10⁵M⁻¹). After the coagulation-flocculation, solids were analyzed by SEM and EDS. SEM images show the texture of solids depending on the functional group grafted on chitosan. EDS study of solids containing chitosan dianhydride-metals (average of all scanner areas) revealed the wt% of metals: Cr (10.45%), Cu (5.95%), Ni (5.22%), Zn (4.36%), Pb (1.37%), Cd (0.31%) and Ca (0.10%) For recovered solids containing chitosan dianhydride-amine-metals, the observed wt% appeared in the same order: Cr (12.44%), Cu (6.75%), Ni (5.75%), Zn (5.12%), Pb (1.82%), Cd (0.59%) and Ca (0.12%).

Graphical abstract

http://ift.tt/2xHTeFz