Facile fabrication of highly porous MgO-modified biochar derived from agricultural residue for efficient Cd(II) removal from wastewater

MgO-modified biochar (MgO-BC) has demonstrated enormous potential for practical application of Cd(II) removal from wastewater. Exceptionally numerous MgO adsorption sites and enhanced porosity of MgO-BC are both critical for efficiency Cd(II) removal. However, the pursuit of high-content of MgO while maintaining unobstructed pore structure remains a challenge due to the blockage of BC pores by the MgO particles. Herein, we demonstrated that Mg(NO3)2 can synergistically enhance the porosity and MgO active site of biochar attributing to the oxidation of nitrate. The prepared MgO-BC exhibits highly porous framework structure. Remarkably, further adsorption results indicate the MgO-BC has outstanding adsorption capacity of Cd(II) in solution. The immobilized contaminant Cd(II) onto MgO-BC was predominantly attributable to the chemical and physical interaction, including ion exchange, cation-& pi; interaction, surface complexation and electrostatic interaction. This strategy demonstrates a novel route to develop efficient adsorbents by tailoring structure and metal oxide via nitrate activation.