Clean Technologies and Environmental Policy (2018) 20:427–433
Application of nanotechnology in removal of NAPLs
from contaminated aquifers: a source clean‑up experimental study
· Nathaly Lopes Archilha
· Raaid Al‑Imari
Received: 15 August 2017 / Accepted: 4 January 2018 / Published online: 13 January 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
This work investigates the removal of non-aqueous phase liquids (NAPLs) from groundwater resources using nanotechnology.
We present results of a series of multiphase ﬂuid displacement experiments conducted in a naturally occurring sandstone
rock. These experiments involve injection of an aqueous suspension of silica nanoparticles to remove a trapped NAPL phase.
Speciﬁcally, the eﬀect of nanoparticle concentration on the eﬃciency of the NAPL removal is studied. Our results show that
silica nanoparticles successfully remobilised the trapped NAPL phase and resulted in 13% increase in its removal eﬃciency.
The optimal concentration for NAPL removal eﬃciency is found to be 0.3 wt%.
Keywords Nanotechnology · Porous media · Removal of organic contaminants · Non-aqueous phase liquids (NAPLs)
Cleaning the subsurface groundwater resources contami-
nated with non-aqueous phase liquids (NAPLs) has been
the subject of extensive research in the recent decades (Soga
et al. 2004; Trellu et al. 2016). New technologies which oﬀer
eﬀective contaminant removal eﬃciencies at lower costs are
always in demand. When dealing with removal of NALP
form contamination source (i.e. source remediation), the
main mechanism to overcome is capillary trapping (Wilson
1990). It is well established that removal of a non-wetting
ﬂuid from porous media by injection of the wetting phase
is always less than 100% eﬃcient (Wilson 1990). The wet-
ting phase is a ﬂuid that has a higher tendency to spread on
a solid surface in the presence of another non-wetting ﬂuid
(Craig 1971). As a result, a portion of a non-wetting phase
will remain trapped in the porous media. Capillary trap-
ping has previously been directly observed in micro-model
studies (Jeong et al. 2000). More recently, non-destructive
3D imaging techniques, such as X-ray computed micro-
tomography, have enabled direct observation of capillary
trapping of non-wetting ﬂuids in naturally occurring porous
media (Iglauer et al. 2011; Berg et al. 2013; Pak et al. 2015).
Capillary trapping is governed by the competition between
the capillary, viscous, and gravitational forces. Speciﬁcally,
the relative importance of the viscous to capillary forces is
measured using capillary number (N
= μV/σ) where μ is
viscosity (Pa s), V is velocity (m/s), and σ is the interfacial
tension (IFT) in N/m.
Bioremediation is one of the widely practiced and cost-
eﬀective technologies that uses microbes to degrade the con-
taminant in situ (Aulenta et al. 2006; Daghio et al. 2017).
Another successful NAPL removal method involves injec-
tion of surfactants to reduce the IFT between the aqueous
and the oil phases (Mulligan et al. 2001; Paria 2008; Cher-
aghian and Hendraningrat 2016). This reduces the capillary
forces and hence eases the remobilisation and removal of the
trapped NAPL phase. Within this context, among the more
recent technologies is the use of nanoﬂuids (nanoparticle
suspensions) to improve the eﬃciency of NAPL removal
at microscopic level. More speciﬁcally, reactive nanoparti-
cles (NPs) such as zero-valent iron (Fe
) NPs are successful
in in situ degradation of some contaminants (speciﬁcally
chlorinated ones) into less harmful ones (Tosco et al. 2014).
Further, recent developments in industrial-scale manufactur-
ing of engineered NPs at low cost makes NP-based NAPL
Electronic supplementary material The online version of this
article (http s://doi.org/10.1007 /s100 98-018-1487 -5) contains
supplementary material, which is available to authorized users.
* Tannaz Pak
Teesside University, Middlesbrough, UK
Brazilian Synchrotron Light Laboratory (LNLS), Campinas,