A novel calcium-based magnetic biochar (Ca-MBC), made by pyrolyzing the mixture of rice straw, iron oxide (Fe₃O₄) and calcium carbonate (CaCO₃), was developed in this study for remediation of co-pollution of arsenic and cadmium. Characteristics of the material showed that Fe₃O₄ and CaCO₃ were adhered on the surface of biochar. The experiments on the effects of pH, adsorption kinetics and isotherm revealed that the Ca-MBC had a great ability to adsorb arsenic and cadmium within 0.5 h for cadmium and 12 h for arsenic with a maximum adsorption capacity of 6.34 and 10.07 mg g^-1, respectively, and that the adsorption of both metals was pH-dependent from 2 to 12 with an optimal pH of pH 5. The mechanism of co-adsorption of Cd(II) and As(III) included both competitive and synergistic effects. The presence of As(III) enhanced Cd(II) adsorption by 3-16% while Cd(II) addition suppressed As(III) adsorption by 15-33%. The synergistic effects on As(III) and Cd(II) adsorption had resulted from the electrostatic interaction and the formation of type B ternary surface complexes. These new insights provide valuable information for the application of Ca-MBC as a potential adsorbent in treatment of water contaminated with As(III) and Cd(II).

本研究开发了一种新型的基于钙的磁性生物炭（Ca-MBC），该材料通过热解稻草，氧化铁（Fe ₃ O ₄）和碳酸钙（CaCO ₃）的混合物而制得，可用于共污染食品。砷和镉。材料的特性表明Fe ₃ O ₄和CaCO ₃附着在生物炭的表面上。对pH，吸附动力学和等温线影响的实验表明，Ca-MBC具有强大的吸附能力，在0.5 h内对镉和12 h内砷和镉的吸附能力最大，最大吸附量为6.34和10.07 mg g ^-1。，并且两种金属的吸附均在2至12的pH值范围内变化，最佳pH值为5。Cd（II）和As（III）的共吸附机理包括竞争和协同作用。As（III）的存在将Cd（II）的吸附提高了3-16％，而Cd（II）的添加将As（III）的吸附抑制了15-33％。静电相互作用和B型三元表面配合物的形成对As（III）和Cd（II）的吸附具有协同作用。这些新见解为将Ca-MBC用作潜在吸附剂处理被As（III）和Cd（II）污染的水提供了有价值的信息。