Xiong Juan, Koopal Luuk K, Weng Liping, Wang Mingxia, Tan Wenfeng
College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, PR China.
College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, PR China; Physical Chemistry and Soft Matter, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands.
J Colloid Interface Sci. 2015 Nov 1;457:121-30. doi: 10.1016/j.jcis.2015.07.001. Epub 2015 Jul 2.
The effects of soil fulvic (JGFA) and humic acid (JGHA) on Pb binding to goethite were investigated with batch experiments and modeling. The CD-MUSIC and NICA-Donnan model could describe the Pb binding to, respectively, the binary Pb-goethite and Pb-HS systems. The adsorption of humic substances (HS) on goethite strongly depended on pH and was promoted by Pb binding. The mass amount of adsorbed JGFA (mg/g) was smaller than that of JGHA, but when expressed in number of particles/nm(2) the JGFA adsorption was higher. At low pH and low initial Pb concentration the linear additivity rule always underestimated Pb adsorption to goethite-HS complex, which was caused by the strong effect of adsorbed HS on the electrostatic potentials in the Stern layer region. At other conditions except the 450 mg/L JGHA in the 0.5 mmol/L Pb system the additivity rule predicted the experimental results reasonably well, and at high pH nearly all Pb is bound to goethite. At the same mass adsorbed, the effect of JGFA on Pb adsorption to goethite is stronger than that of JGHA, due to the fact that the JGFA particles were primarily adsorbed in the Stern layer, whereas JGHA particles were present in both Stern layer and diffuse layer. Therefore, the electrostatic potential profile of the goethite-JGFA complex is considerably different from that of goethite-JGHA complex and affects Pb binding strongly.
通过批量实验和建模研究了土壤富里酸（JGFA）和腐殖酸（JGHA）对铅与针铁矿结合的影响。CD-MUSIC模型和NICA-Donnan模型分别可以描述铅与二元体系中铅-针铁矿和铅-腐殖质的结合情况。腐殖质（HS）在针铁矿上的吸附强烈依赖于pH值，并且受铅结合的促进。JGFA的吸附质量（mg/g）小于JGHA，但以颗粒数/nm(2)表示时，JGFA的吸附量更高。在低pH值和低初始铅浓度下，线性加和规则总是低估了铅在针铁矿-HS络合物上的吸附，这是由于吸附的HS对斯特恩层区域静电势的强烈影响所致。在除0.5 mmol/L铅体系中450 mg/L JGHA之外的其他条件下，加和规则对实验结果的预测相当良好，并且在高pH值时几乎所有铅都与针铁矿结合。在相同吸附质量下，JGFA对铅在针铁矿上吸附的影响比JGHA更强，这是因为JGFA颗粒主要吸附在斯特恩层，而JGHA颗粒同时存在于斯特恩层和扩散层。因此，针铁矿-JGFA络合物的静电势分布与针铁矿-JGHA络合物的静电势分布有很大不同，并对铅的结合有强烈影响。
