Study on flocculation performance and mechanism of cationic polyacrylamide on montmorillonite: Insights from experiments and molecular simulations

To achieve efficient flocculation of fine montmorillonite particles, molecular simulation and flocculation test were investigated to explore the influence of cationic monomer on the performance of cationic polyacrylamide (CPAM) flocculating montmorillonite particles. Three cationic monomers including methylacryloxyethyl trimethyl ammonium chloride (DMC), acrylamide propyl trimethyl ammonium chloride (ATMAC), and methylacrylamide propyl trimethyl ammonium chloride (MAPTAC) were copolymerized with acrylamide (AM) to produce CPAM copolymers. The simulation results suggested the electrostatic interaction was the primary internal propelling force for the stable adsorption of three distinct CPAM copolymers on the montmorillonite/ water interface, followed by hydrogen bonding. Flocculation test indicated that CPAM has better flocculation effect on fine montmorillonite particles only when it has strong electrostatic adsorption and bridging capacity. This research establishes a theoretical foundation for the structural design of new flocculants for fine clay minerals.