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Co-transport of Pb2+ and TiO2 nanoparticles in repacked homogeneous soil columns under saturation condition: Effect of ionic strength and fulvic acid

Fang, Jing, Zhang, Keke, Sun, Peide, Lin, Daohui, Shen, Bing, Luo, Yan
The Science of the total environment 2016 v.571 pp. 471-478
desorption, fulvic acids, ionic strength, lead, nanoparticles, soil, soil colloids, titanium dioxide
This study investigated the effects of suspended TiO2 nanoparticles (nTiO2) on the transport of Pb2+ in saturated repacked soil columns under different ionic strengths (IS) and in the presence of fulvic acid (FA). Also, the contribution of soil colloids to the mobility of Pb2+ was discussed. In the absence of nTiO2, little amount of Pb2+ was detected in the effluent even in the presence of FA. However, the presence of nTiO2 significantly enhanced the mobility of Pb2+ in soil columns under all tested conditions and nTiO2-associated Pb2+ was the major migration species of Pb2+. Increasing the solution IS decreased the nTiO2-associated Pb2+ migration due to the significant decrease in the mobility of nTiO2 in soil. FA remarkably increased the nTiO2-associated Pb2+ mobility in soil column, which was mainly to increase the mobility of nTiO2 in soil and decrease desorption rate of Pb2+ from nTiO2 during transport. Moreover, nTiO2 significantly enhanced the release of Fe-Al soil colloids, which in turn was also responsible for the enhancement of Pb2+ mobility in soil.