The effect of mineral composition in the compound soil of soft rock and sand on special surface area and cation exchange capacity

Abstract

The X-ray diffraction method and gas adsorption method were used to investigate the mineral composition and special surface area of different soft rocks, sands, and composed soil. The results showed that (1) Montmorillonite, kaolinite, potash feldspar, calcite, quartz, plagioclase and illite, constitute the soft rock. Quartz, potash feldspar, plagioclase, calcite, montmorillonite, illite, and kaolinite constitute the soft rock in the Mu Us sandy land. There are several types of soft rocks, and there are some differences in the mineral composition of different types. The highest primary mineral content is 94.6% and the lowest 41%; the secondary mineral content is the highest 59% and the lowest is 5.4; (2) The special surface area of different types of soft rock is quite different, and the special surface area is up to 17.14 m2g−1, the lowest is 3.12 m2g−1, and the average content is 9.98 m2g−1. The cation exchange capacity is up to 7.25 cmol(+)/kg, and the lowest is 3.36 cmol(+)/kg; (3) The fitting formula of secondary minerals and specific decomposition of arsenic sandstone, aeolian sandy soil and composite soil is y = 2.423e0.0871x, and the correlation coefficient R2 = 0.8258. The fitting formula for the exchange capacity of secondary minerals and cations is y = 3.105e0.0348x, and the correlation coefficient R2 = 0.9235.