Esfandyari Bayat Ali, Junin Radzuan, Derahman Mohd Nawi, Samad Adlina Abdul
Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Malaysia.
Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Malaysia.
Chemosphere. 2015 Sep;134:7-15. doi: 10.1016/j.chemosphere.2015.03.052. Epub 2015 Apr 16.
The impact of ionic strength (from 0.003 to 500mM) and salt type (NaCl vs MgCl2) on transport and retention of titanium dioxide (TiO2) nanoparticles (NPs) in saturated limestone porous media was systematically studied. Vertical columns were packed with limestone grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolent-visible spectrometry. Presence of NaCl and MgCl2 in the suspensions were found to have a significant influence on the electrokinetic properties of the NP aggregates and limestone grains. In NaCl and MgCl2 solutions, the deposition rates of the TiO2-NP aggregates were enhanced with the increase in ionic strength, a trend consistent with traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Furthermore, the NP aggregates retention increased in the porous media with ionic strength. The presence of salts also caused a considerable delay in the NPs breakthrough time. MgCl2 as compared to NaCl was found to be more effective agent for the deposition and retention of TiO2-NPs. The experimental results followed closely the general trends predicted by the filtration and DLVO calculations. Overall, it was found that TiO2-NP mobility in the limestone porous media depends on ionic strength and salt type.
系统研究了离子强度（从0.003到500mM）和盐类型（NaCl与MgCl2）对饱和石灰岩多孔介质中二氧化钛（TiO2）纳米颗粒（NPs）传输和滞留的影响。垂直柱中填充有石灰岩颗粒。将纳米颗粒作为脉冲悬浮在水溶液中引入，并使用紫外可见光谱法生成柱出口处的突破曲线。发现悬浮液中NaCl和MgCl2的存在对NP聚集体和石灰岩颗粒的电动性质有显著影响。在NaCl和MgCl2溶液中，TiO2-NP聚集体的沉积速率随离子强度的增加而提高，这一趋势与传统的Derjaguin-Landau-Verwey-Overbeek（DLVO）理论一致。此外，NP聚集体在多孔介质中的滞留量随离子强度增加。盐的存在还导致纳米颗粒突破时间出现相当大的延迟。与NaCl相比，MgCl2被发现是TiO2-NPs沉积和滞留更有效的试剂。实验结果与过滤和DLVO计算预测的总体趋势密切相符。总体而言，发现TiO2-NP在石灰岩多孔介质中的迁移率取决于离子强度和盐类型。
