Influence of synergistic effect of polyacrylamide and surfactant on dewatering performance of flotation clean coal

The moisture content of flotation clean coal products is a critical factor influencing their calorific value, making dewatering research vital for the efficient utilization of coal. In this study, cationic polyacrylamide (CPAM) was employed as a high molecular weight flocculant and filter aid to investigate the mechanisms by which the anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethylammonium bromide (DTAB), and nonionic polyoxyethylene lauryl ether (Brij L23) affect the dewatering of flotation clean coal. The influence of these surfactants on the dewatering performance of flotation clean coal in conjunction with CPAM was examined through filter aid experiments, density functional theory, zeta potential measurements, agglomeration of flotation clean coal particles, and Nuclear Magnetic Resonance (NMR) analysis. The results indicated that DTAB and SDS exhibited a larger positive electrostatic potential compared to Brij L23, demonstrating stronger electrostatic adsorption on the molecules of flotation clean coal. However, the -OSO3 groups in SDS interacted more strongly with the molecules of flotation clean coal than the tertiary amine groups in DTAB. The ether and hydroxyl groups in Brij L23 interacted weakly with the molecules of flotation clean coal. The surfactants increased the compactness and structural complexity between particles within the flocs, leading to an increase in the fractal dimension of the flocs. Additionally, the surfactants enlarged the pores within the filter cake of flotation clean coal, which was beneficial for the removal of moisture.