Abstract: Adsorption behaviour of PEI on silicon carbide powder was measured by using UV spectrum. The surface charge of SiC powder was changed greatly after
the addition of PEI, its IEP changed from pH=2.0 to pH=10.5. Adsorption isotherms of dispersant on the silicon carbide surface were investigated.
Their adsorption behaviour belongs to Langmuir monolayer adsorption type. The maximum amount of PEI--H⁺(pH=3.57) adsorbed on the SiC surface is
0.0172mg/mL and that of PEI--H⁺(pH=6.61) is 0.0208mg/mL. IR spectra were obtained to verify this adsorption effect.

Key words: polyethylene imine (PEI), quantitative adsorption, UV spectrum silicon carbid