Adsorption property of lignin and naphthalene dispersants on coal-water interface

The adsorption amount and kinetics of two lignin series dispersants (SL and MSSL) and one naphthalene dispersant (FDN) on Datong coal surface were studied, the results show that the adsorbed amounts of SL and MSSL on coal surface were far more than that of FDN. However, the fitted parameters of Langmuir equilibrium constant K and adsorption rate constant k(a) of SL and MSSL were less than that of FDN, which indicat that the adsorption ability of SL and MSSL on coal surface was inferior to that of FDN, and the adsorption rate of SL and MSSL on coal surface was lower than that of FDN. The adsorption layer of dispersant on coal surface was studied by using IR and XPS methods, and the results show that the coal with adsorbed SL and MSSL have evident "red shift" phenomenon. Moreover, the adsorbed layer thickness of SL and MSSL on coal surface was 7.22 and 4.61 nm respectively, however, that of FDN was thinner, only 2.11 nm. It is generalized that the hydrogen bond is the main adsorption force of SL and MSSL on coal surface, the adsorbed amount is rather large, the adsorbed layer is rather thick, and the multi-point adsorption on coal surface is the main form. The main form of FDN adsorbed on coal surface is horizontal adsorption by pi-electron polarized adsorption, and the, adsorbed strength is rather large, but the adsorbed layer is rather thin.