Adsorptive Behavior of Surfactants on Surface of Portland Cement

摘要

On the surface of Portland cement, four surfatants have different adsorptive behaviors: ethoxylated fatty alcohol sulfate (AES) belongs to LS type of adsorption; cetyl piridinium choloride (CPC) is kinetically controlled; condensates of naphthalene formaldehyde (NS) has a linear relationship of adsorbance vs. concentration; and ethyoxylated alkyl phenol (TX-10) does not be adsorbed. All adsorbed surfactants have hydrocarbon chain toward liquid phase and increase hydropholbicity of cement surface. Howeve, AES suffered a change of hydrophilic -> hydrophobic -> by - drophilic because of formation of adsorptive micelle. Both aES and NS only increase zeta - potential, but CPC changes zeta - potential from negative to positive. A modified stem double - layer model has been proposed to illustrate adsorptive characteristics of above surfactants.