Transport of engineered nanoparticles in soils and aquifers

Abstract

Transport and deposition behaviour of engineered nanoparticles (ENPs) in natural aquifers and soil systems is a key determinant of the fate of these materials in environmental systems. A growing number of experimental studies are being conducted worldwide to address transport and deposition of ENPs in porous media (PM). Here we comprehensively review the main mechanisms and factors affecting the mobility of the environmentally important ENPs in natural PM. A variety of different processes including those that promote mobility and result in elution from the PM and those that hinder their mobility and promote ENP retention can influence ENP’s mobility through soil and aquifer media. The most important contributing factors regarding ENP transport in PM include: the physicochemical properties of the ENP, the media, the hydrodynamics of the system, and the background solution characteristics. Results from several studies conducted on the most common and environmentally important ENPs have shown that under natural environmental conditions, different types of ENPs show different transport behaviour in soil and aquifer systems. Additionally, the importance of media matrix and mobile solution factors in governing mobility of ENPs varies from one type of ENP to another.

Dynamic microbial regulation of triiron tetrairon phosphate nanomaterials in the tomato rhizosphere

“…This suggests that Fe 7 (PO 4 ) 6 NMs formed larger aggregates in soil solution, resulting in an increase in particle size and the stability was still within the acceptable range. 33 Additionally, the electrostatic interaction between the negatively charged soil organic matter and the negatively charged NMs, as demonstrated by Peng et al (2017), 34 plays a role in maintaining the stable dispersion of Fe 7 (PO 4 ) 6 NMs (Fig. S1c †).…”

In situ nanoremediation of soils and groundwaters from the nanoparticle's standpoint: A review

“…This point is paramount: NPs which are strongly sorbed to soil constituents will therefore be immobilized and clog soil pores. On the other hand, NPs small enough to fit into small spaces between soil particles will travel farther than larger particles, before being trapped in the soil matrix (Fazeli Sangani et al, 2019).…”

Comparison of the colloidal stability, mobility, and performance of nanoscale zerovalent iron and sulfidated derivatives

“…Based on the groundwater pH of 6.5, nZVI (IEP = pH 7.5) was positively charged while S-nZVI (IEP = pH 5) and FeSSi (IEP = pH 5.5) were negatively charged. While electrostatic attraction was dominant between nZVI and sand (which is negatively charged) (Feriancikova and Xu, 2012), promoting heteroagglomeration; electrostatic repulsion was dominant between the sulfidated NPs and sand, which promoted their transport through the saturated column (Fazeli Sangani et al, 2019).…”