Zn/Al类水滑石磁性生物炭复合材料的制备及其对Pb^2+的吸附性能

Preparation of Magnetic Biochar Zn/Al-LDH Composites and its Adsorption Capacity to Pb^2+

以油茶果壳为原料,采用化学沉淀法及水热合成法,成功制得了Zn/Al类水滑石磁性生物炭复合材料(LMB)。研究了LMB的添加量、吸附时间、pH值对Pb^2+吸附的影响及吸附动力学、吸附热力学。结果表明:LMB吸附Pb^2+的过程符合拟二级动力学,化学吸附为反应速率控制步骤。Elovich模型拟合结果表明LMB吸附Pb^2+存在慢化学反应吸附过程,是由反应速率和扩散因子决定的非均相扩散的吸附-脱吸过程。颗粒内扩散模型分段拟合说明吸附过程伴随着多线性且吸附过程中颗粒内扩散不是唯一的速率控制步骤。吸附等温线表明,LMB对Pb^2+的吸附符合Langmuir模型,为单分子层化学吸附。LMB对Pb^2+的单分子层最大吸附质量比为213.0 mg/g。

A series of magnetic biochar Zn/Al-LDH composites was successfully fabricated by chemical precipitation and hydrothermal synthesis using Camellia oleifera shells.The effects of addition amount of LMB,adsorption time and pH on the adsorption of Pb^2+,adsorption kinetics and adsorption thermodynamics were studied.The results demonstrated that the adsorption of Pb^2+by LMB was in accordance with pseudo-second order kinetics,and chemical adsorption was the control step of reaction rate.The Elovich model fitting results demonstrated that the adsorption of Pb^2+by LMB has a slow chemical reaction adsorption process,which was a non-homogeneous diffusion adsorption and desorption process determined by reaction rate and diffusion factor.The piecewise fitting of the intraparticle diffusion model shows that the adsorption process is accompanied by multiple-linearity and intraparticle diffusion during adsorption is not the only rate control step.The adsorption isotherm demonstrated that the adsorption of Pb^2+by LMB fitted well with the Langmuir model and is a monolayer chemical adsorption.The maximum adsorption capacity of LMB for the monolayer of lead ions was 213.0 mg/g.