china university of geosciences(Beijing)
Palygorskite is a 2:1 type chain-layered structure hydrated magnesium aluminosilicate mineral with important resource and material attributes. The isomorphic substitution in the octahedron of palygorskite varies greatly with different genesis and occurrence, but the influence of isomorphic substitution in the octahedron on properties of palygorskite has not been reported. In this work, three representative palygorskites from Anhui Mingguang, Jiangsu Xuyi and Gansu Linze in China were taken as the research objects. The contents and octahedral occupation of Al, Mg and Fe of the three palygorskites were studied, and the effects of the octahedral occupation of Al, Mg and Fe on the types and contents of water, surface potential and acid sites, and the adsorption capacity for Pb2+ and Cd2+ of palygorskite were discussed. The results showed that Mingguang palygorskite was relatively rich in magnesium, while Xuyi and Linze palygorskites were relatively rich in aluminum and iron. The octahedra of Mingguang palygorskite was mainly occupied by Mg2+, showing three-octahedron characteristics; the octahedra of Xuyi palygorskite had relatively more Al3+, showing more two-octahedron characteristics; Linze palygorskite also showed two-octahedron characteristics, and the cation occupation was similar to that of Xuyi palygorskite. Due to the large number of vacancies at M1, Xuyi palygorskite had lower structural water content; isomorphic substitution of palygorskite had little effect on Zeta potential; Xuyi and Linze palygorskites with two-octahedron characteristics had higher Al content in octahedra, more acid sites, and better catalytic performance. In the heavy metal adsorption experiment, Mingguang palygorskite had the largest adsorption capacity for Cd2+, Xuyi palygorskite had the largest adsorption capacity for Pb2+, and Linze palygorskite had poor adsorption performance. This work can provide guidance and reference for the modification and application of palygorskite.