Roles of hydrogen bond and ion bridge in adsorption of two bisphenols onto montmorillonite: an experimental and DFT study

Reactions occurring at silicate minerals play a significant role in controlling phenolic endocrine disrupting chemicals' bioavailability and mobility. However, the underlying molecular mechanisms for BPA (bisphenol A) BPS S) onto montmorillonite (MMT) remain poorly understood. To decipher molecular-level interfacial configuration dominant reaction mechanism, batch experiments, X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), photoelectron spectroscopy (XPS) measurements, density functional theory (DFT) calculations were performed. Our adsorption experiments showed that MMT exhibits higher capacity than BPA. The XRD analysis also suggested could enter interlayer of MMT. FTIR XPS results revealed Ca atoms oxygen SiO4 tetrahedra involved process via non-covalent interactions. electrostatic potential sulfonyl O site hydroxyl H on molecule are more favorable interacting with surface sites molecule. DFT further confirmed stronger binding (001) tends to form ion bridges through groups In contrast, prefers its group hydrogen bonds groups. This study provides new insights into molecular-scale interactions control an important environmentally-relevant clay mineral, which affect fate behavior soil systems.