Sorption of Perfluorinated and Pharmaceutical Compounds in Plastics: A Molecular Simulation Study

Abstract

The aim of the current study is to investigate the effect of temperature and degree of polymerisation on the thermodynamic interaction of perfluorinated compounds (PFCs) into plastics. The occurrence of contaminants of emerging concern such as pharmaceutical drugs, PFCs, microplastics (MPs), etc., in sources of drinking water have posed significant health risks to aquatic life and humans in recent years. These organic pollutants can interact with MPs and pose much higher health risks; consequently, MPs become a transport vector and thus alter their migration as well as occurrence in the environment. The purpose of this paper is to examine the adsorption mechanism of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and sulfamethazine (SMT)—relative to water—on polyethylene (PE) and polypropylene (PP) using an extended Flory–Huggins approach. The results suggest that in an aqueous environment, both PFOA and PFOS may be taken up preferentially by PP and PE, although less strongly by PE. The degree of polymerisation of PE and PP did not significantly influence the observed behaviour. In terms of sorption affinity, the observed affinity was PFOA>PFOS>SMT which was consistence for both PE and PP.

Adsorption of PFAS onto secondary microplastics: A mechanistic study

“…Although we are unable to verify it in this work, Khumalo et al hypothesized that plastic pore-filling could be an important mechanism of PFAS partitioning, especially at high temperatures due to polymer (pore) expansion. 56 Based on the Gibb's free energy (ΔG) we obtained (Figure 3 h), which ranged from -16.4 kJ/mol (for PFBA) to -22.5 kJ/mol (for PFOS), we concluded that the adsorption of the five PFAS to the secondary PET MPs is thermodynamically spontaneous at 25°C and would occur in surface waters. The ΔG of the adsorption of PFAS to the secondary PET MPs became more negative as temperature increased (Table S8), which is reasonable given that it is an endothermic process (ΔH = 14.0 to 41.0 kJ/mol).…”

Theoretical insights into the compatibility of template-monomer-crosslinker-solvent for cortisol molecularly imprinted polymer pre-polymerization

“…The modified Flory-Huggins approach was employed as implemented in the Blends module of Materials Studio and as applied in the previous studies. 31,34,35 Briefly, the mixing energy (E mix ), coordination number, and free energy were determined as estimated by sampling from energetically favorable configurations using the volume constraint method, yielding average properties over an ensemble of molecular configurations. 31 After the temperature-dependent interactions were determined, the binodal and spinodal curves were computed within the framework of the off-lattice Flory-Huggins theory, along with the critical point of the mixture, thereby yielding the binary phase diagram.…”