Effect of Heating Method on Physicochemical and Adsorption Properties of Expanded Vermiculite

A series of expanded vermiculites with a high expansion ratio were prepared with a vermiculite from Xinjiang, China as raw material by an intercalation microwave method and an intercalation calcination method, respectively. The phase composition and morphology of the products were characterized by X-ray diffraction and scanning electron microscopy, and the cation exchange capacity and methylene blue (MB) adsorption capacity of the expanded vermiculite prepared by the two different methods were analyzed. The results show that there is a significant difference in the expansion ratios of expanded vermiculite prepared by the two methods, and the expansion ratio of calcined expanded vermiculite (BCV) is 0.4 times greater than that of microwave expanded vermiculite (WCV). For adsorption in a methylene blue solution with a concentration of 300 mg/L, the calcined expanded vermiculite has a poor adsorption capacity for MB, while the microwave expanded vermiculite has a good adsorption performance for MB due to its higher cation exchange capacity with an adsorption capacity of 391.26 mg/g.