Revealing Interfacial Interactions in PFOA Adsorption on Dolomite: A Molecular and Experimental Investigation for Advanced Water Treatment

Persistence and widespread contamination of perfluorooctanoic acid (PFOA) in water systems pose significant environmental and human health risks, However, the methods studied at present are expensive or have high technical requirements and are not used in practical application, necessitating effective and sustainable remediation strategies. Herein, this study investigates the adsorption behavior and interfacial interactions of PFOA on dolomite (DL) and calcined dolomite (CDL) using a synergistic experimental (batch extraction, XRD analyses, FTIR analyses, SEM and so on) and molecular simulation approach. Adsorption kinetics followed a pseudo-second-order kinetic model. DL achieved 94% adsorption within the first 2 hours, reaching equilibrium at 4 and 5 hours, respectively. The Langmuir isotherm model fitting results indicate maximum adsorption capacities of 2.16 mg g⁻¹ for DL and 2.58 mg g⁻¹ for CDL. Although the adsorption amount is not high, dolomite is a rich, low-cost and scalable material compared with other high-cost and efficient adsorbents, which can provide a very promising way for the removal of PFOA in practical water pollution systems. Molecular dynamics simulations show that hydrogen bonding controls the adsorption of PFOA on DL, while electrostatic interaction also contributes as a key adsorption mechanism. In addition, hydrophobic interaction is a ubiquitous mechanism that facilitates the adsorption of different perfluoroalkyl substances (PFASs) on various adsorbents by experimentation. CDL enhances the surface affinity by forming electrostatic interactions of positively charged Ca(OH)2 and the hydrogen bonding of Mg(OH)2. These findings provide mechanistic insights into and supporting data on dolomite’s potential as a tool for real-world pollutant removal. They also inform future advancements in sustainable water treatment technologies.