Adsorption of hydroxyethylcellulose or hydrophobically modified cellulose and anionic surfactant from their binary mixtures on particles

The adsorption of hydroethylcellulose (HEC) and hydrophobically modified HEC (HMHEC) and sodium dodecyl sulphate (SDS) from SDS-HEC and SDS-HMHEC binary aqueous solutions on particles has been investigated. The conformation of polymers adsorbed on particles has also been estimated by electron spin resonance. In the SDS-HEC system, the adsorption of HEC on alumina increases remarkably owing to the presence of SDS, while the amount of adsorbed SDS is unaffected by the presence of HEC. It is suggested that this remarkable increase in the adsorption is due to a complex formation between HEC and SDS on the alumina surface. A similar trend is observed for the SDS-HMHEC system. In both systems, the fraction of train segments in the adsorbed polymers is greater than that in the absence of SDS. The stability of alumina dispersion is enhanced by HEC or HMHEC adsorption. The adsorption of HEC or HMHEC on graphite exhibits a sharp increase with the polymer concentration, where the adsorbed amount of HMHEC is much larger than that of HEC because of its hydrophobicity owing to grafted alkyl chains. The amount of adsorbed HEC is almost constant in the presence of SDS, whereas a decrease in the adsorption of HMHEC on graphite in the presence of SDS occurs, probably because of the formation of an SDS-HMHEC complex in the bulk solution. The adsolubilization behaviours of 2-naphthol have also been discussed for both alumina and graphite systems. (C) 1997 Elsevier Science B.V.