Fabrication of magnetic thiourea-modified Litchi-shell biochar for the adsorption performance of As(V) and Hg(II) in scallop and rice

Thiourea-modified magnetic litchi-shell biochar was successfully synthesized. • MTBC-700 had good adsorption performance for As(V) and Hg(II). • The removal rate of As(V) in scallop or rice was 90.64% or 76.59%. • The removal rate of Hg(II) in scallop or rice was 57.51% or 95.51%. A novel litchi-shell magnetic biochar modified by thiourea was successfully synthesized and been applied for the adsorption of the hazardous heavy metals in rice and scallop. It exhibited a high specific surface area and excellent pore volume by nitrogen adsorption-desorption experiment. Under optimal conditions, the adsorption performance and mechanism of heavy metals were separately investigated. The adsorption isotherms fitted the Langmuir model well, and the adsorption process was indicated as a spontaneous endothermic reaction by Gibbs free energy change (ΔG). The removal efficiencies of As(V), Hg(II), Pb(II), Cd(II), and Cr(VI) in scallop were 90.64%, 57.51%, 25.75%, 64.11%, and 39.60%, respectively. While the removal efficiencies in rice were 76.59%, 95.51%, 31.25%, 1.04%, and 25.18% in turn. The adsorbent possesses the advantages of simple preparation, easy separation, and excellent adsorption performance. It is an effective and applicable adsorbent for removing hazardous heavy metals in food. Download: Download high-res image (412KB) Download: Download full-size image