壳聚糖对污染土壤中吸附态Pb(Ⅱ)的吸附行为研究

Absorption of chitosan for lead (Ⅱ) from the contaminated soil

研究了壳聚糖作为萃取剂对污染土壤中Pb^(2+)的吸附行为,考察了溶液pH值、吸附时间和壳聚糖质量浓度对吸附行为的影响,分别用Langmuir、Freundlich吸附热力学模型和Lagergren一级、HO YS二级、Elovich方程和粒子内部扩散吸附动力学模型对吸附热力学和动力学进行分析。结果表明:当pH=5、温度为45℃时提取率达到最大,提取率为46.3%;吸附过程中吸热,吸附自发进行;吸附过程在热力学方面符合Freundlich方程,相关系数为0.998 7,在动力学方面符合Lagergren一级吸附动力学模型,相关系数为0.991 2。

The paper wishes to introduce our investigation of the ehitosan function in absorbing lead Ⅱ （Pb2 ＋ ） from the contaminated soil under different experimental conditions, such as the pH value, adsorption time and chitosan concentration Besides, it has also given evaluations to the thermodynamics models that can be applied to the adsorption of Pb^2＋ by chitosan for Langmuir and Freundlich, and to the kinetic models applied to the adsorption of Pb^2＋ by chitosan for the Lagergren first-order, HO YS second-order, Elovich equation and intraparticle diffusion, respectively. The results of our evaluations show that at a pH of 5 and temperature of 45 ℃, the removing rate can reach 46.3 % of Pb^2＋ from the contaminated soil sample. The function of the adsorption here mentioned includes physical adsorption and chemisorptions, through which the system can release heat and the negative value Of AG. It can also be concluded that the Freundlich thermodynamics model was found to be closely correlated with the experimental data （R2= 0.998 7 ）, while HO YS second-order kinetic model was found in conformity with ehe experimental data （ R2 = 0.991 2）. Thus, the resuhs of given study are expected to provide valuable references to the environmental migration and lowering of lead and soil contamination and enhanced extraction of lead by ehitosan.