Effect of particle size of halloysite on the deflocculation of mutual flocs of allophane and halloysite at pH 6.5 in dilute xanthan polysaccharide solutions

The effect of the particle size of halloysite on the deflocculation of mutual floes of allophane and halloysite in the presence of anionic xanthan polysaccharide was investigated spectrophotometrically. Although allophane which flocculated at the i.e.p. (pH 6.5) exhibited polymeric (i) weak-stabilization (PWST), (li) flocculation (PFL), and (iii) stabilization (PST) with increasing addition of xanthan, allophane and halloysite which flocculated mutually at pH 6.5 inhibited the deflocculation, viz., PWST and PST. Halloysite with a smaller average particle size (i.e., 0.08,um in average diameter) than the suspended microaggregates (SMAs) of allophane inhibited significantly the deflocculation, suggesting that the halloysite particles flocculated around the allophane particles. Halloysite with a larger average particle size (i.e., 0.2 μn in average diameter) than the SMAs of allophane slightly inhibited the deflocculation, suggesting that the halloysite particles were attached to the center of the flocculated SMAs of allophane. The inhibitory effects of particle arrangements on the deflocculation of the mutual floes of allophane-montmorillonite and allophanekaolinite were also investigated comparatively.