Langmuir吸附等温线方程的改进及其在沸石吸附重金属中的应用

Establishment of Semi-empirical Modified Langmuir Adsorption Isotherm Equation and Its Application in Zeolite Adsorption of Heavy Metals

从试验数据分析出发,基于经典Langmuir吸附等温线方程,通过引入虚拟重金属离子和平衡吸附面积分配参数的概念,并将传统的平衡吸附量概念转化为平衡吸附面积,成功建立了可用于分析重金属离子在沸石材料上多元吸附过程的改进式半经验吸附等温线方程和数据分析方法,并应用到重金属元素(Cu、Pb、Cd、Ni)在合成沸石上的吸附过程,结果令人满意。方程拟合结果表明:在一元吸附体系下,四种重金属离子的极限吸附面积顺序依次为Ni^2+>Cu^2+>Pb^2+>Cd^2+。在多元吸附体系中,由于重金属离子间的相互干扰,重金属离子的总极限吸附面积均小于各重金属离子在一元吸附体系下的极限吸附面积之和。在任何多元吸附系统中,无论初始浓度高低,Cu离子均占有吸附面积分配的优势,且随着初始浓度的增加其优势愈加明显或至少保持相对稳定。Pb离子的竞争优势主要体现在较高初始浓度,并且也随着初始浓度的增加而增加。Cd离子和Ni离子的优势地位则主要体现在较低初始浓度,且随着初始浓度的增加而逐步降低。

Based on experimental data and classical Langmuir adsorption isotherm equation,transforming concept of traditional equilibrium adsorption capacity to equilibrium adsorption area and introducing concept of fictitious heavy metal ion and partition coefficient of equilibrium adsorption area,modified semi-experienced adsorption isotherm equation and adsorption data analysis method were successfully set up,which fit for analyzing multivariate adsorption process of heavy metal ions on zeolite with satisfactory results.According to hypothesis and fitting results,it is indicated that the maximum adsorption area sequence in unitary adsorption system is Ni>Cu>Pb>Cd.In any multivariate adsorption system,the total maximum adsorption area is lower than sum of maximum adsorption area of each heavy metal in unitary adsorption systems.Cu always occupies a prominent position among all heavy metals no matter high-low of initial concentration and keep steady with increase of initial concentration.Competitive edge of Pb is shown under the condition of high initial concentration and rises with increase of initial concentration.Relatively,competitive edges of Cd and Ni are obvious when the initial concentration is low and gradually drop with increase of initial concentration.