Resource utilization of rice husk biomass: Preparation of MgO flake-modified biochar for simultaneous removal of heavy metals from aqueous solution and polluted soil

摘要

In general, the remediation performance of heavy metals can be further improved by metal-oxide modified biochar. This work used MgO-modified rice husk biochar (MgO-5@RHB-450 and MgO-5@RHB-600) with high surface activity for simultaneous remediation and removal of heavy metals in soil and wastewater. The adsorption of MgO-5@RHB-450/MgO-5@RHB-600 for Cd(II), Cu(II), Zn(II) and Cr(VI) followed the pseudo-second order, with the adsorption capacities reaching 91.13/104.68, 166.68/173.22, 80.12/104.38 and 38.88/ 47.02 mg g(-1), respectively. The addition of 1.0 MgO-5@RHB-450 and MgO-5@RHB-600 could effectively decrease the CaCl2-extractable Cd concentration (CaCl2-Cd) by 66.2 and 70.0, respectively. Moreover, MgO-5@RHB-450 and MgO-5@RHB-600 facilitated the transformation of exchangeable fractions to carbonatebound and residual fractions, and reduced the exchangeable fractions by 8.1 and 9.6, respectively. The mechanisms for the removal of heavy metals from wastewater by MgO-5@RHB-450 and MgO-5@RHB-600 mainly included complexation, ion exchange and precipitation, and the immobilization mechanisms in soil may be precipitation, complexation and pore filling. In general, this study provides high-efficiency functional materials for the remediation of heavy metal pollution.