Purification and dissociation of raw palygorskite through wet ball milling as a carrier to enhance the microwave absorption performance of Fe3O4

Abstract The effect of ball-to-powder weight ratio on the crystal composition, microscopic morphology and pore structure of palygorskite was systematically studied by using the conventional wet ball milling process. The quartz can be effectively separated from palygorskite through low-speed centrifugal treatment in aqueous solutions, while the strength of ball milling has a significant influence on disaggregation degree of the crystal bundles. When the ratio is 1:2, the rod crystal bundles are well dissociated, while preserving the inherent aspect ratio of the nanofibers. After the treatment, the specific surface area, micropore volume and micropore area are increased from 206.87 m2/g, 0.0347 cm3/g and 76.07 m2/g to 255.03 m2/g, 0.0502 cm3/g and 109.42 m2/g, respectively. For the first time, the purified palygorskite was used as a template to prepare palygorskite/Fe3O4 nanocomposite using by hydrothermal method, for microwave absorbing applications. As expected, the introduction of palygorskite can effectively prevent the aggregation of the Fe3O4 magnetic particles. Meanwhile, the specific surface area of the composite is enlarged from 10.29 m2/g to 40.73 m2/g, as the weight ratio of Fe3O4 and palygorskite is 2:1, thus leading to enriched interface polarizations and hence resulting in a maximum reflection loss (RL) of −40.41 dB at 4.80 GHz, with effective absorption frequency that can be adjusted over 2–18 GHz by controlling thickness of the composite.