白木通果胶对水中重金属铅、镉离子的吸附性能

The Adsorption Capability of Heavy Metal Lead Ions and Cadmium Ions in Water by Akebia trifoliata var.australis Pectin

本文研究白木通果胶对水中重金属铅离子和镉离子的吸附性能,考察溶液pH值、初始离子质量浓度、温度和吸附时间对铅、镉离子吸附容量和吸附率的影响。结果表明:所研究的变量显著影响果胶对铅、镉离子的吸附能力。果胶对Pb2+和Cd2+的吸附具有pH值依赖性,最佳吸附pH值为5.0。果胶吸附Pb2+和Cd2+的速度很快,40 min后基本都达到平衡,且吸附容量和吸附率随着温度的升高而降低。吸附热力学分析表明,果胶对Pb2+和Cd2+的吸附是非自发、放热的过程。采用郎格缪尔(Langmuir)和弗罗因德利希(Freundlich)模型分别模拟吸附过程,发现弗罗因德利希方程拟合效果优于郎格缪尔方程,表明Pb2+和Cd2+在白木通果胶上的吸附是多层吸附。经准一级和准二级动力学模拟,发现吸附过程遵循准二级动力学方程,吸附速率受化学吸附控制。结论:白木通果胶具有较高的吸附重金属离子的能力,可以作为一种替代吸附剂来处理含铅、镉的工业废水,减少重金属污染。

The adsorption of heavy metal lead ions and cadmium ions in water by Akebia trifoliata var.australis pectin was determined,and the effects of solution pH,initial ion mass concentration,temperature and adsorption time on the adsorption capacity and adsorption rate of lead ions and cadmium ions were investigated.The results indicated that the variables studied significantly affected the adsorption of lead ions and cadmium ions by pectin.It was also observed that the adsorption Pb2+and Cd2+by pectin was pH dependent and the optimum adsorption pH was 5.0.The Akebia trifoliata var.australis pectin could adsorb lead ions and cadmium ions at a fast rate,they almost achieved adsorption equilibrium after 40 min and the adsorption capacity and adsorption rate were decreased with the increase of temperature.Adsorption thermodynamics analysis showed that the adsorption of lead ions and cadmium ions by pectin was a non-spontaneous and exothermic process.The adsorption process was simulated by the Langmuir and Freundlich models.It was found that the fitting effect of Freundlich equation was better than that of Langmuir equation,indicating that the adsorption of lead ions and cadmium ions on Akebia trifoliata var.australis pectin was multi-layer adsorption.The kinetic data were analyzed using pseudo-first-order and pseudo-second-order kinetic models,and kinetics of Pb2+and Cd2+adsorption by pectin was better described by the pseudo-second-order equation.The adsorption rate was controlled by chemisorption.In summary,Akebia trifoliata var.australis pectin had a high ability to adsorb heavy metal ions and could be used as an alternative adsorbent to treat industrial wastewater containing lead ions and cadmium ions to reduce heavy metal pollution.