Polymer and Water Quality Effects on Flocculation of Montmorillonite

Abstract

AbstractWyoming Na‐montmorillonite (SWy‐1) was equilibrated with two synthesized waters, representing Friant‐Kern Canal or a typical well water of San Joaquin Valley (EC 0.05 and 0.7 dS m−1, respectively). Adsorption isotherms and flocculation patterns of the clay with three anionic and one nonionic polyacrylamide polymers and cationic, nonionic and anionic derivatized guar polymers, were observed. Polymer solutions of concentrations 0, 5, 10, 20, 50, and 100 mg L−1 were prepared and clay was added at a concentration of 1 g L−1. The test tubes were shaken and then periodically photographed to record floc formation and settling. Adsorption was in the general order: cationic > nonionic > anionic with the exception of the nonionic guar which was adsorbed about equally as the cationic guar. Adsorption of anionic polymers was greater from well water than canal water, whereas the opposite was true for the cationic polymer. Significant polymer water quality interactions on flocculation were observed. Anionic polymers promoted flocculation in the well water for polymer concentrations ≥ 5 mg L−1, but enhanced clay suspension stability in canal water. Floc volume increased with increasing cationic and nonionic polymer adsorption, whereas changes in floc volume were insignificant with anionic polymers. An optimal polymer concentration was found with well water. Flocculation with cationic polymer was attributed to charge neutralization, whereas flocculation with anionic polymers was explained by bridging and osmotic attraction.