Molecular-level understanding on complexation-adsorption-degradation during the simultaneous removal of aqueous binary pollutants by magnetic composite aerogels

Abstract

Heavy metals and organic pollutants were universally co-existing in water, except for dissociated pollutants, their complexes have caused huge damage to the environment and humans too. Hence, two new kinds of microcrystalline cellulose modified hyper-branched chitosan aerogels and magnetic aerogels (HCS/MCCs, M-HCS/MCCs) were fabricated to realize the simultaneous adsorption of the dissociative pollutants and the advanced treatment of the complex pollutants. HCS/MCCs exhibited fast and efficient adsorption performance towards dissociated pollutants (Pb(II), Cu(II), Methyl orange and Congo red) in 240 min reaching a maximum adsorption capacity of 412.50, 425.14, 435.13, 538.46 mg/g in their mono-polluted solution, respectively. More importantly, M-HCS/MCCs showed a synergistic effect of adsorption-catalytic degradation in Cu(II)-MO and Pb(II)-CR binary-polluted systems, in which the evolution, configuration, free energy variation and total density-of-states (TDOS) of the complexes were figured out by Density Functional Theory (DFT) calculation. Both radical and non-radical pathways were discovered in the two process of self-catalysis of the complexes and activating-catalysis of magnetic nanoparticles for persulfate (PS), and the organics were degraded to CO2 and H2O ultimately. Finally, the synergistic effect of complexation-adsorption-catalytic degradation and removal mechanism were revealed.