Abstract: It is introduced briefly the modification way and result of lignosulphonate (LS) as coal-water slurry (CWS) additive and determination of the adsorption film thicknesses of the LS and modified lignosulphonate (MLS) on the smooth surface of coal and microscopic slide by the method of elliptical polarization. The size of the space steric hindrance between LS and MLS adsorbing on the solid surface were quantitatively compared.Results showed that the adsorption film thickness of MLS is doubled comparied to LS. The thicknesses are different on the lyophobic surface and hydrophilic surface. It is favorable for the increase of the adsorption film thickness by increasing the lyophobic chain. The determination of adsorption film thickness verifies the validity of the modification result.

Key words: lignosulphonate, adsorption film thickness, elliptical polarization, ESEM