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2019 1

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Influence of phosphate on deposition and detachment of TiO

Zhan Wang, Chongyang Shen, Yichun Du, Yulong Zhang, Baoguo Li

《环境科学与工程前沿(英文)》 2019年 第13卷 第5期 doi: 10.1007/s11783-019-1163-y

摘要: We examined influence of phosphate on transport of TiO2 NPs in soil. Deposition was reduced at higher pH and by adsorption of phosphate in soil. Release was more for NPs initially deposited at higher pH. Release was more for NPs initially deposited in the presence of phosphate. Surface roughness and charge heterogeneity play a role in the deposition/ release. The widespread use of TiO2 nanoparticles (NPs) makes inevitable their release into the soil. Phosphate is also widespread within soil, and is likely copresent with TiO2 NPs. However, the influence of phosphate on deposition/release— and thereby on transport— of TiO2 NPs in soil is yet to be elucidated. In this study we conducted saturated column experiments to systematically examine the transport of TiO2 NPs in soil amended with phosphate at different ionic strengths (ISs) (1, 10, 100 mmol/L NaCl) and pHs (4 and 9). Results show that the deposition of TiO2 NPs decreased with decreasing IS, increasing pH, and when soil absorbed phosphate. These observations are qualitatively in agreement with Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy calculations, because the repulsive energy barrier is larger and secondary minimum depth is smaller at a lower IS, higher pH, and in the presence of phosphate. Accordingly, both primary- and secondary-minimum deposition were inhibited. Interestingly, although the deposition was less at higher pH and in the presence of phosphate, the subsequent spontaneous detachment and detachment by reduction of solution IS in these cases were greater. In addition, the presence of phosphate in the solution can cause a small quantity of attached TiO2 NPs to detach, even without perturbations of physical and chemical conditions. Our study was the first to investigate the influence of phosphate on detachment of TiO2 NPs and the results have important implication for accurate prediction of fate and transport of TiO2 NPs in subsurface environments.

关键词: Phosphate     TiO2 nanoparticles     Transport     Soil     Deposition     Detachment    

标题 作者 时间 类型 操作

Influence of phosphate on deposition and detachment of TiO

Zhan Wang, Chongyang Shen, Yichun Du, Yulong Zhang, Baoguo Li

期刊论文