A novel porous nanocomposite, cross-linked chitosan and polyethylene glycol (PEG) bead-supported MnFe2O4 nanoparticles (CPM), was developed as an efficient adsorbent to remove metalloid (As(III)) and heavy metals (Cd(II), Cu(II), and Pb(II)). The characteristics of CPM showed a porous structure, well dispersed MnFe2O4, and several of hydroxyl and amino groups ( OH, NH2). Batch experiments demonstrated that the best adsorption property of As(III), Cd(II), Cu(II), and Pb(II) was achieved within 8 h with maximum adsorption capacities of 9.90, 9.73, 43.94, and 11.98 mg/g, respectively. Competitive and synergistic effects (particularly precipitation) were included in the co-adsorption mechanism of As(III) and heavy metals. Thereinto, As(III) was partly oxidized by MnFe2O4 to As(V), and both were coordinated on MnFe2O4 nanoparticles. Pb(II) could also bind to MnFe2O4 by ion exchange and electrostatic attraction. Furthermore, Cd(II) and Cu(II) tended to be coordinated on chitosan. Therefore, CPM can serve as a remediation material for water and soil co-contaminated with As(III) and heavy metals.
