Data from: Effects of soil particles and convective transport on dispersion and aggregation of nanoplastics via small-angle neutron scattering (SANS) and ultra SANS (USANS)

Terrestrial nanoplastics (NPs) pose a serious threat to agricultural food
production systems due to the potential harm of soil-born micro- and
macroorganisms that promote soil fertility and ability of NPs to adsorb
onto and penetrate into vegetables and other crops. Very little is known
about the dispersion, fate and transport of NPs in soils. This is because
of the challenges of analyzing terrestrial NPs by conventional microscopic
techniques due to the low concentrations of NPs and absence of optical
transparency in these systems. Herein, we investigate the potential
utility of small-angle neutron scattering (SANS) and Ultra SANS (USANS) to
probe the agglomeration behavior of NPs prepared from polybutyrate adipate
terephthalate, a prominent biodegradable plastic used in agricultural
mulching, in the presence of vermiculite, an artificial soil. SANS with
the contrast matching technique was used to study the aggregation of NPs
co-dispersed with vermiculite in aqueous media. We determined the contrast
match point for vermiculite was 66% D 2 O / 33% H 2 O. At this condition,
the signal for vermiculite was ~50-100%-fold lower that obtained using
neat H 2 O or D 2 O as solvent. According to SANS and USANS, smaller-sized
NPs (50 nm) remained dispersed in water and did not undergo size reduction
or self-agglomeration, nor form agglomerates with vermiculite.
Larger-sized NPs (300-1000 nm) formed self-agglomerates and agglomerates
with vermiculite, demonstrating their significant adhesion with soil.
However, employment of convective transport (simulated by ex situ stirring
of the slurries prior to SANS and USANS analyses) reduced the
self-agglomeration, demonstrating weak NP-NP interactions. Convective
transport also led to size reduction of the larger-sized NPs. Therefore,
this study demonstrates the potential utility of SANS and USANS with
contrast matching technique for investigating behavior of terrestrial NPs
in complex soil systems.