Jilin University, Key Laboratory of Groundwater Resources and Environment, Ministry of Education, No.2519, Jiefang Road, Changchun, 130021, China.
The University of Tokyo, Department of Urban Engineering, Graduate School of Engineering, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
Sci Rep. 2017 Aug 30;7(1):9943. doi: 10.1038/s41598-017-09699-9.
Titanium dioxide nanoparticle (TiO NP) discharged into water bodies can affect ecosystems and human health adversely. We studied the properties of residual TiO NPs with and without gentle mixing (to simulate a natural environment more closely) and after settling for 12-h periods. Surface complexation, dynamic particle size changes, and TiO NP destabilization in synthetic and lake waters were investigated. The accumulation of inert ions (Na and Cl) in the diffuse layer which was not discussed in other studies was supposed to be the main reason that aggregation occurred slowly and continuously. PO stabilized and destabilized TiO NPs at 10 mM and 100 mM, respectively. Destabilization occurred because high ionic strength overwhelmed increased negative charges of TiO NPs by complexation with PO. TiO NP destabilization was achieved in approximately 12 h in synthetic and lake waters, and is attributed to the slow diffusion of ions into aggregates. Despite the presence of moderately high concentrations of natural organic matter, which tends to stabilize TiO NPs, the addition of 20 mM PO destabilized the TiO NPs in lake water. Smaller aggregate sizes formed compared with those before destabilization, which indicates that stable residual TiO NPs could exist in aquatic environments after extended periods.
二氧化钛纳米颗粒（TiO NP）排入水体后，会对生态系统和人类健康产生不利影响。我们研究了经过温和混合（更接近自然环境）和沉降 12 小时后的残留 TiO NP 的性质。研究了合成水和湖水中原位 TiO NP 的表面络合、动态粒径变化和失稳情况。与其他研究不同的是，我们假设在扩散层中积累的惰性离子（Na 和 Cl）是导致聚集缓慢而连续发生的主要原因。PO 在 10mM 和 100mM 时分别稳定和不稳定 TiO NP。失稳是因为高离子强度通过与 PO 络合而超过了 TiO NP 的增加的负电荷。TiO NP 在合成水和湖水中约 12 小时内失稳，这归因于离子缓慢扩散到聚集体中。尽管存在中等浓度的天然有机物，这些有机物往往会稳定 TiO NP，但添加 20mM PO 会使湖水中的 TiO NP 失稳。与失稳前相比，形成的较小聚集体表明，稳定的残留 TiO NP 可能在水体中存在很长时间。
