腐殖酸对纳米TiO_2颗粒在多孔介质中迁移的影响

Influence of Humic Acid on Transfer of TiO_2 Nanoparticles in Porous Media

通过沉积柱试验,得到了不同浓度腐殖酸条件下纳米Ti O2颗粒的穿透曲线,研究发现,随着腐殖酸浓度的增加,C/C0值逐渐增大。同时考察了腐殖酸为5 mg/L时,不同p H值及离子强度下纳米Ti O2颗粒的穿透曲线变化,结果表明,p H值靠近等电点或离子强度增加均会导致C/C0值增大。为定量阐明腐殖酸存在时纳米Ti O2颗粒在多孔介质中迁移能力的变化,采用沉积理论计算了纳米Ti O2颗粒的去除效率、吸附效率及最大迁移距离,结果表明,当腐殖酸浓度由零增加到10 mg/L时,纳米Ti O2颗粒的最大迁移距离由0.143 6 m增加到0.496 6 m。最后,探讨了腐殖酸对纳米Ti O2颗粒在多孔介质中迁移的影响机制。

The breakthrough curves of TiO2 nanoparticles at different concentrations of humic acid were investigated by column experiments. The results indicated that the value of C/Co increased with the increasing concentration of humic acid. The variation of the breakthrough curves of TiO2 nanoparticles under different pH and ionic strength at a concentration of 5 mg/L of humic acid was also studied. The pH near the isoelectric point and the increase of ionic strength would enhance the value of C/Co. To illustrate the mobility of TiO2 nanoparticles in porous media quantitatively, the removal efficiency, the attachment efficiency and the largest transfer distance of TiO2 nanoparticles were calculated by deposition theory. When the concentration of humic acid increased from 0 mg/L to 10 mg/L, the largest transfer distance increased from 0. 143 6 m to 0.496 6 m. The mechanisms governing the transfer of TiO2 nanoparticles in porous media in the presence of humic acid were discussed.