Significance of Non-DLVO Interactions on the Co-Transport of Functionalized Multiwalled Carbon Nanotubes and Soil Nanoparticles in Porous Media

Abstract

Derjaguin−Landau−Verwey−Overbeek (DLVO) theory is typically used to quantify surface interactions between engineered nanoparticles (ENPs), soil nanoparticles (SNPs), and/or porous media, which are used to assess environmental risk and fate of ENPs. This study investigates the co-transport behavior of functionalized multiwalled carbon nanotubes (MWCNTs) with positively (goethite nanoparticles, GNPs) and negatively (bentonite nanoparticles, BNPs) charged SNPs in quartz sand (QS). The presence of BNPs increased the transport of MWCNTs, but GNPs inhibited the transport of MWCNTs. In addition, we, for the first time, observed that the transport of negatively (BNPs) and positively (GNPs) charged SNPs was facilitated by the presence of MWCNTs. Traditional mechanisms associated with competitive blocking, heteroaggregation, and classic DLVO calculations cannot explain such phenomena. Direct examination using batch experiments and Fourier transform infrared (FTIR) spectroscopy, asymmetric flow field flow fractionation (AF4) coupled to UV and inductively coupled plasma mass spectrometry (AF4-UV-ICP-MS), and molecular dynamics (MD) simulations demonstrated that MWCNTs-BNPs or MWCNT-GNPs complexes or aggregates can be formed during co-transport. Non-DLVO interactions (e.g., H-bonding and Lewis acid−base interaction) helped to explain observed MWCNT deposition, associations between MWCNTs and both SNPs (positively or negatively), and co-transport. This research sheds novel insight into the transport of MWCNTs and SNPs in porous media and suggests that (i) mutual effects between colloids (e.g., heteroaggregation, co-transport, and competitive blocking) need to be considered in natural soil; and (ii) non-DLVO interactions should be comprehensively considered when evaluating the environmental risk and fate of ENPs.

Biochar nanoparticles alleviate salt stress in tomato (Solanum lycopersicum) seedlings

“…29 And it is confirmed that nanomaterials have a high surface area to volume ratio, which makes them attractive for adsorbing chemicals onto their surface via van der Waals forces, electrostatic interactions, or chemical bonding. [33][34][35] Therefore, these and other studies support the idea that the size of biochar particles affects the soil's hydrological properties, having complex interactions with the saturated hydraulic conductivity and the larger aggregate content. 36,37 When the biochar particle size is on the nanoscale, the specific surface area will be greater, and the number of active adsorption sites for chemicals and general reactivity will increase, 38 such as the capacity for inorganic ions.…”

Probing the Reactions of Thiourea (CH4N2S) with Metals (X = Au, Hf, Hg, Ir, Os, W, Pt, and Re) Anchored on Fullerene Surfaces (C59X)

“…In order to calculate the adsorption energies of the various systems obtained after interactions, optimization of the gas molecule and the metal-doped fullerene nanocages are also necessary. 31 The thiourea (CH 4 N 2 S) gas molecule was optimized separately, and also, each of the surfaces, including the pure and doped fullerene surfaces, was geometrically optimized. The bond lengths of the optimized gas molecule and the pure fullerene surface were computed and are depicted in Figure 1 .…”

“…Geometric equilibration and energy minimization have been initially administered as a medium of ensuring stability and sensitivity of the designed systems. In order to calculate the adsorption energies of the various systems obtained after interactions, optimization of the gas molecule and the metal-doped fullerene nanocages are also necessary . The thiourea (CH 4 N 2 S) gas molecule was optimized separately, and also, each of the surfaces, including the pure and doped fullerene surfaces, was geometrically optimized.…”

Phosphorus-Enhanced and Calcium-Retarded Transport of Ferrihydrite Colloid: Mechanism of Electrostatic Potential Changes Regulated via Adsorption Speciation

“…Although these attractive interactions were much shallower than primary minimum interactions, their magnitudes are comparable to primary minimum interactions when charge heterogeneities are considered. 74 The binding energy between the negatively charged B and positively charged BPCa was lower than that between BPCa and Ca 5 (PO 4 ) 3 OH, suggesting that the non-DLVO interactions were more significant than the electrostatic interaction. Moreover, in the presence of calcium and at high pH, heteroaggregation had a strong influence on FHC transport.…”