Efficient removal of Cr(VI) by the modified biochar with chitosan schiff base and MnFe2O4 nanoparticles: Adsorption and mechanism analysis

Cr(VI) contained the characteristic of water solubility, mobility and cell permeability in aqueous solution. As a result, the treatment of Cr(VI) in aqueous solution was very necessary before it was discharged into water body. A novel adsorbent of the modified biochar with chitosan schiff base and MnFe2O4 nanoparticles (CsSB/ MnFe2O4@BC) was prepared, characterized and applied into the elimination of Cr(VI) by batch adsorption process. CsSB/MnFe2O4@BC composites were characterized by some technologies (Such as SEM, TEM, XRD and FT-IR). The results showed that it was an irregular, wavy and heterogeneous surface, and it contained MnFe2O4 nanoparticles and functional groups of C -H, O-H and C-O-C stretching vibrations. The operational pa-rameters (For example, pH, concentration of Cr(VI), contact time and temperature) had an important influence on the adsorption capacity of Cr(VI) removal. The adsorption processes were best fitted to Pseudo-second order model and Freundlich model. Additionally, the maximum uptake capacity of Cr(VI) ions reached 125.34 mg/g. The possible mechanisms were ion exchange, surface complexation, electrostatic attraction, and pore adsorption. After five cycles, adsorption capacity of Cr(VI) by CsSB/MnFe2O4@BC still remained high, and reached 102.45 mg/g. Therefore, it was a simple, economical, efficiency and reuse adsorbent and could be used as an high efficient adsorbent in the treatment of Cr(VI) in aqueous solution.