Adsorption Characteristics of Naphthalene Sulfonate Formaldehyde Condensate with Different Molecular Weights

摘要

Naphthalene sulfonate formaldehyde condensate (FDN) consists of the hydrophobic naphthalene groups and hydrophilic sulfonate groups. Four FDN fractions with different molecular weights were prepared by using ultrafiltration. The adsorption characteristics of different fractions were investigated by ultraviolet spectrophotometer, Zeta potential meter and x-ray photoelectron spectroscopy. The adsorption of FDN with high molecular weight follows Langmuir model and belongs to monolayer adsorption on cement surface. The adsorption characteristic of unfractionated FDN displays the multilayer adsorption. The greater adsorption amount and the higher adsorption layer thickness of FDN with higher molecular weight can provide sufficient steric hindrances and electrostatic repulsion between the particles.