Dispersion stability of organoclay in octane improved by adding nonionic surfactants

Dispersion stability of organoclay (surfactant-modified montmorillonite) in nonpolar solvents can be dramatically improved by adding nonionic surfactants sorbitan monoleate (Span 80), sorbitan trioleate (Span 85) and 1-oleoyl-rac-glycerol (GMO). The effects of the surfactants on the basal spacing, size and surface potential of organoclay were investigated. The increase of the basal spacing of organoclay indicated that the surfactants have intercalated into the organoclay interlayer, which promoted the exfoliation of organoclay. Correspondingly, the reduction of the size of organoclay particles was observed. We also measured the surface potential of organoclay and found it increased with the surfactant concentration and then reached a constant value. The adsorption behavior of surfactants on the particles and the variation of the surface potential of the particles were in consistent with the dispersion stability of organoclay in nonpolar solvents. We believe that the improvement of the dispersion stability caused by adding a nonionic surfactant is the result of the combination of steric and electrostatic effects.