磁性生物炭对水中Pb^(2+)的吸附

Adsorption of Pb^(2+)from water on magnetic biochar

通过浸渍热解法,以硫酸铁为磁性前驱体制备磁性生物炭。利用FTIR、BET和振动样品磁强计分析磁性生物炭的官能团、比表面积和磁性等。基于Plackett-Burman实验、响应面法优化实验、吸附动力学实验、吸附等温线实验和吸附-解吸实验,研究磁性生物炭对Pb^(2+)的吸附性能。实验结果表明:磁改性可以有效提高生物炭比表面积至230.73 m^(2)/g,对应比饱和磁化强度可达16.02 emu/g;磁性生物炭具有羟基、羧基、醚键等官能团和一定芳香结构;吸附过程存在孔填充、静电吸附、离子交换、络合和阳离子-π吸附作用,且以化学吸附为主,符合准二级动力学方程;Langmuir和Freundlich等温吸附模型均有较好适用性;在酸性条件下磁性生物炭具有较高解吸率;在初始Pb^(2+)质量浓度为117.0 mg/L、磁性生物炭投加量为5.6 g/L、吸附时间为11.9 min的最佳吸附条件下,Pb^(2+)去除率可达91.88%。

Magnetic biochar was prepared by impregnation pyrolysis method with ferric sulfate as magnetic precursor.The functional groups,specific surface area and magnetic properties of the magnetic biochar were analyzed by FTIR,BET and VSM.The adsorption capability of the magnetic biochar to Pb^(2+)was studied through Plackett-Burman experiment,response surface methodology optimization experiment,adsorption kinetics experiment,adsorption isotherm experiment and adsorption-desorption experiment.The results show that:The specific surface area of biochar can be effectively improved to 230.73 m^(2)/g by magnetic modification,and the corresponding specific saturation magnetization can reach 16.02 emu/g;The magnetic biochar has hydroxyl,carboxyl,ether bond and other functional groups and a certain aromatic structure;There are pore filling,electrostatic adsorption,ion exchange,complexation and cation-πadsorption in the adsorption process,and chemical adsorption is the main process,which conforms to the quasi second-order kinetic equation;Langmuir and Freundlich isothermal adsorption models are applicable;At the same time,magnetic biochar has high desorption rate under acidic conditions;Under the optimal adsorption conditions of initial Pb^(2+)mass concentration 117.0 mg/L,magnetic biochar dosage 5.6 g/L and adsorption time 11.9 min,the removal rate of Pb^(2+)can reach 91.88%.