Spectroscopic analysis reveals that extracellular polymeric substances drive PFOS adsorption in sewage sludge, indicating key mechanisms governing persistent chemical retention.
Key Points
To elucidate the molecular mechanisms by which extracellular polymeric substances regulate the adsorption and retention of perfluorooctane sulfonate on sewage sludge.
Applied a multi-spectroscopic framework using UV–vis, Raman spectroscopy with principal component analysis, and three-dimensional excitation–emission matrix fluorescence spectroscopy to track binding behavior.
Characterized chemical structural shifts with X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, and conducted adsorption kinetic assays comparing intact and extracellular polymeric substance-depleted sludge.
Spectroscopy revealed that PFOS binding initiates through electrostatic interactions with amide and protonated amine groups, transitioning to hydrophobic interactions with aromatic and C–H protein structures at elevated concentrations.
Adsorption kinetic experiments demonstrated that removing extracellular polymeric substances reduced sludge PFOS adsorption capacity, decreasing the equilibrium distribution coefficient (Log Kd) from 3.580 to 3.004.