Simultaneous remediation of As(V), Cd(II) and Pb(II) in aqueous solution and soil using Fe/Ca-modified biochar.

A novel Fe/Ca-modified biochar (BC) derived from corn stalk was prepared in this study for the simultaneous adsorption and immobilization of arsenic, cadmium and lead in aqueous solution and soil, respectively. The adsorption experiment in aqueous solution indicated that 1Ca-Fe@BC exhibited excellent removal efficiency (, %) towards arsenic (46.3%), cadmium (76.3%) and lead (93.6%). The presence of cadmium and lead could enhance the adsorption efficiency of arsenic by facilitating the formation of ternary complexes with it. Moreover, both cooperative and competitive effects occurred between cadmium and lead adsorption. When the distribution coefficient of cadmium and lead was equimolar, cooperative adsorption prevailed. However, when the distribution coefficient deviated from this balance, competitive adsorption dominated with a higher affinity for lead. The soil culture experiment demonstrated that the utilization of 1Ca-Fe@BC could enhance the stability of arsenic, cadmium and lead in soil by enhancing soil cation exchange capacity and pH while reducing dissolved organic carbon. The competitive and cooperative effects of arsenic, cadmium and lead in soil were consistent with those found in aqueous solution. The results showed that 1Ca-Fe@BC exhibited an excellent remediation efficiency for both arsenic, cadmium and lead-contaminated aqueous solution and soil.