The influence of silica nanoparticle geometry on the interfacial interactions of organic molecules: a molecular dynamics study

Abstract

The role of nanoparticle shape in the interaction and adsorption of organic molecules on the particle surface is an unexplored area. On the other hand, such knowledge is not only...

Interfacial interactions of humic acids with polystyrene nano-plastics in aqueous/ionic environments: a molecular dynamics exploration

“…This significant reduction in the negative potential is due to the screening of its surface charge by Na + ions that are adsorbed onto the interface of PS-Slab (Figure 4). The observed inferences are consistent with the idea of screening of surface charge with enhanced condensation of Na + ions 35,38,39 and consequently a decrease in Debye screening length. A similar trend is observed for the surface potentials calculated for PS-Slab at pH-4 and pH-7 at 0M and 0.5M NaCl.…”

“…4), which brings more water molecules to the interface. 35 The strong hydration layer observed at the interface of nano-plastics at pH 7 & 9 is also one of the reasons that keep the TNB molecules away from the vicinity of its interface. Hence, the reduction in the distribution of TNB molecules (RDF profiles, Fig.…”

“…Hydrogen bonding between the PS-Slab and the surrounding water molecules was calculated to get an insight into the structure of water molecules at its interface in different pH conditions. The following criteria were adopted for calculating the formation of hydrogen bond between the donor (OCarboxylate) and acceptor (HWater) is less than This can be ascribed to the polarizability of water molecules 35,36 induced by the negatively charged carboxylate groups present on the surface of the PS-Slab. However, with the addition of 0.5M NaCl electrolyte, a reduction in the number of h-bonds was observed, which can be inferred to the distortion in the structure of the h-bonds 37 between the carboxylate groups and the surrounding water molecules due to the Na + ions.…”

“…An increase in the density of water molecules with an increase in the pH of the aquatic environment is observed. The increase in the density of water molecules at the geometric interface of PS-Slab can be ascribed to the hydration of negatively charged carboxylate groups and is also due to the hydrated Na + ions condensed onto the interface (Figure4), which brings more water molecules to the interface 35. The strong hydration layer observed at the interface of nanoplastics at pH 7 & 9 is also one of the reasons that keep away the TNB molecules from the vicinity of its interface.…”

“…represents the average number of hydrogen bonds (h-bonds) formed at the interface of the PS-Slab between the carboxylate groups of polystyrene and the surrounding water molecules. The number of h-bonds increased with an increase in the pH of the aqueous solution.This can be ascribed to the polarizability of water molecules35,36 induced by the…”