The effect of sodium acetate buffer pretreatment on the clay minerals of some arid land soils and reference clays

Abstract

Abstract The pretreatment of soils with pH5 sodium acetate (NaOAc) buffer is widely used to remove carbonates from soils prior to dispersion and separation of clays for mineralogical analysis. The effect of this pretreatment on other minerals such as palygorskite and zeolite (analcime) was evaluated. Soil samples from Arizona and Egypt as well as reference samples of palygorskite and analcime spiked with CaCO3were used. The pretreatment of the soils and reference samples had no observable change in the mineralogy as indicated by X‐ray diffraction and SEM analysis. The study further suggests that the somewhat tedious and time consuming step can be avoided for the mineralogical analysis of many arid land soils. The common procedure for clay separation of calcareous soils for mineralogical analysis and study by X‐ray diffraction is to remove the carbonates by a pH5 sodium acetate pretreatment(1,2). For soils low in carbonates, the pretreatment may be feasible, but for highly calcareous soils the procedure is...