Study on the mechanism of the effect of plasma modified APAM on the sedimentation of kaolinite particles

Abstract

In coal slime water treatment, traditional anionic polyacrylamide (APAM) faces challenges including difficulties in balancing charge density with hydrolysis degree and inadequate hydrophilicity. This study developed a plasma-modified APAM (P-APAM) and systematically investigated its enhancement mechanism for kaolinite particle flocculation and sedimentation. Experiments were performed with 5–20 s plasma treatments on APAM solutions, analyzing P-APAM properties such as viscosity, pH, conductivity, molecular chain structure, and functional group configuration. Parallel flocculation-sedimentation tests evaluated kaolinite treatment performance through settling velocity, supernatant turbidity, floc size, and Zeta potential measurements. Results revealed that 5 s plasma treatment strengthened hydrogen bonding while altering oxygen-containing functional group composition and arrangement in P-APAM molecules. The treatment promoted oxidative degradation of hydrophobic groups (–CH₃/–CH₂-), boosting hydration capacity and hydrophilicity while optimizing molecular chain flexibility and surface adaptability. The modified P-APAM formed compact floc structures (SK value = 0.612), achieving superior sedimentation rates, larger floc sizes, and enhanced flocculation efficiency at reduced dosages. Comprehensive experimental analysis confirmed that plasma-modified P-APAM substantially improved kaolinite flocculation and sedimentation performance. This research presents an innovative plasma-modified flocculant approach for clay mineral treatment in slime water, establishing an effective technical pathway for developing high-performance green flocculant systems with significant reference value for sustainable mineral processing.