纳米零价铁改性氨基生物炭的制备及对Cd (Ⅱ)的吸附和解吸特性

通过化学负载方法成功制得纳米零价铁改性氨基生物炭复合材料（ABC/NZVI），对其进行表征和研究了其对重金属Cd（Ⅱ）的吸附和解吸特性。结果表明，改性后，ABC/NZVI具有氨基官能团并且表面负载了纳米零价铁，比表面积为244 m2·g-1，在水溶液中稳定悬浮的平均粒径是845 nm。ABC/NZVI对Cd（Ⅱ）的吸附大约在457 min内即可达到吸附平衡，吸附动力学可用伪二级动力学模型较好地拟合（R2≥0.990）；对Cd（Ⅱ）表现出优良的吸附性能，饱和吸附容量为12.4 mg·g-1，吸附/解吸等温线均呈现出明显的非线性，可用Langmuir模型较好地拟合（R2≥0.960），而且出现明显的解吸滞后现象，滞后系数（HI）为0.536。因此，ABC/NZVI对Cd（Ⅱ）的吸附可能为单分子层的化学吸附，主要的吸附机理可能涉及配合和沉淀两种作用。

Adsorption and desorption of Cd(Ⅱ) on amino biochar modified by nano zero valent iron

Amino biochar modified by nano zero-valent iron (ABC/NZVI) was prepared using chemical-modification methods.The characterization results revealed that the amino groups formed chemical bonds with the nano zero-valent iron (NZVI),which was successfully loaded onto the surface of the materials.The specific surface area of ABC/NZVI was about 244 m2·g-1,and the average particle size that could be stably suspended in aqueous solution was 845 nm.The results of adsorption kinetic experiments revealed that the adsorption achieved equilibrium within 457 min,and the data conformed with a pseudo-second order model.The adsorption/desorption was obviously non-linear,the experimental data obtained at 298 K was better fitted with the Langmuir isotherm (R2≥0.960),and the calculated maximum adsorption capacity of Cd(Ⅱ) was 12.4 mg·g-1.Significant desorption hysteresis (HI=0.536) was also observed.The adsorption of Cd(Ⅱ) on ABC/NZVI might be monolayer chemisorption,and the adsorption process might be related with complexation and precipitation.