Stability and Charge Characteristics of Allophane and Imogolite

Abstract

The colloidal stability and charge characteristics of allophane and imogolite were examined with attention to the fundamental features of the suspensions. The point of zero net charge (PZNC) of non-deferrated allophane was pH 5.9, and that of the deferrated, pH 5.1. Allophane coagulated near PZNC. PZNC of non-deferrated imogolite was pH 7.2, and that of the deferrated, pH 6.0. Imogolite coagulated under all alkaline conditions although net negative charge increased with pH above PZNC. The relative viscosity of imogolite was consistent with stability, the high viscosity corresponding to the coagulated thick fibers. The stability of allophane under alkaline conditions clearly decreased with the addition of imogolite by 10%. Imogolite is widely found in Andosols, and thus is considered to be one of the principal materials that disrupt the stability of soil suspension in particle size analysis.