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The thermal insulating performance of expanded vermiculite is closely related to expansibility. A novel method of Mg2+ modification was proposed to improve the vermiculite expansion ratio. The modification process was characterised by energy dispersive X-Ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric-differential scanning calorimeter and scanning electron microscopy. Moreover, the thermal expansion experiment was performed to investigate the expansion behaviours of Raw-V and Mg–V samples at various temperatures. The result indicated that the introduction of Mg2+ could increase the vermiculite interlayer water content through hydration interaction, and the expansion ratio increased 13.7% under the heating temperature of 900 °C after modification. To explain the interaction of magnesium ion and water molecules, a molecular dynamics model was developed, and the simulation results were validated using the binding energy calculation. The results of this study can provide a new perspective and theoretical guidance for the commercial process of vermiculite expansion. [ABSTRACT FROM AUTHOR]

Aimed to solve the problems of low adsorption capacity, complex preparation and difficult recovery for reported cesium ion adsorbents, a novel high-efficiency Cs+ adsorbent of vermiculite/zinc hexacyanoferrate (II) (VMT/ZnHCF) composite was prepared via in situ synthetic method. The structure and properties of this composite were comprehensively characterized using XRD, FTIR, SEM, TEM, and TG-DTA. The maximum Cs+ adsorption capacity was recorded to be 378.79 mg/g, and this value was significantly higher than the values recorded for other absorbents. This spontaneous and exothermic adsorption behavior could be explained by the Langmuir isotherm model and the pseudo-second-order kinetic model. In addition, this composite exhibited excellent selective adsorption ability towards Cs+ even in solutions containing high concentrations of Na+, K+, Ca2+, and Mg2+. The Cs+ adsorption mechanism was analyzed by conducting ion exchange experiments and using XRD, SEM, and XPS techniques. The Cs+ adsorption of the VMT/ZnHCF composite was synergistically achieved through the ion exchange of Na+ in vermiculite interlayers and Zn2+ in zinc hexacyanoferrate (II) lattices. A high-efficiency and simple preparation of cesium ion adsorbent has been developed in application of cesium ion wastewater treatment. This work can provide theoretical guidance to realize the non-hazardous treatment of radioactive wastewater. [Display omitted] • A novel high-efficiency Cs (I) adsorbent of VMT/ZnHCF was prepared via an in situ synthetic method. • VMT/ZnHCF obtained a maximum Cs (I) adsorption capacity of 378.79 mg/g significantly superior to other absorbents. • VMT/ZnHCF exhibited excellent selective adsorption ability towards Cs (I) in multicomponent metal ion solutions. • Cs (I) adsorption behavior is ascribed to synergistic ion exchange of Na+ and Zn2+ in VMT/ZnHCF. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel expanded vermiculite/xonotlite insulation composite was prepared via the hydrothermal method. • Vermiculite thermal expansion and nano xonotlite fiber synthesis were comprehensively studied. • The effect of intercalation on thermal insulating performance was systematically investigated. Natural disasters caused by global warming are threatening the survival of mankind. Reducing carbon emissions is an effective way to prevent global warming. In recent years, the construction industry is playing a dominant role in global energy consumption. Aimed to solve the problem of high energy consumption in the construction industry, a novel expanded vermiculite/xonotlite thermal insulation composite was successfully prepared via the hydrothermal method. The microstructure and thermal performance of the composite were systematically analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), laser flash analysis (LFA), and infrared thermal imaging. The test results indicated that xonotlite fibers could be inserted well into the interlayers of expanded vermiculite. And the intercalation of xonotlite greatly improved the thermal insulation performance of expanded vermiculite at high temperature. The thermal conductivity of this composite decreased with intercalation rate increasing. The composite with intercalation rate of 51.43 % had the lowest thermal conductivity of 0.2116 W/mK at 800 °C which was 55.36 % lower than the expanded vermiculite sample. Meanwhile, this composite had good thermal stability and high temperature resistance. In addition, the thermal expansion of vermiculite and the synthesis of nano-xonotlite fibers were comprehensively studied and discussed. This study will provide a new perspective and ideas for developing vermiculite-based thermal insulating materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel humidity self-regulating interior wall coating composite based on red mud was prepared. • The hygroscopicity of HRCRM were systematically investigated and analyzed. • Various properties of HRCRM were tested and the moisture absorption mechanism was analyzed. Aimed to resolve the problem of excessively high indoor humidity in subtropical areas and develop a new resource disposal technique for red mud, a novel humidity self-regulating interior wall coating composite based on red mud (HRCRM) was successfully prepared using red mud as a matrix material and vermiculite as a humidity regulator. The effects of component proportion, ambient humidity, exposure time on hygroscopicity of this composite were systematically investigated. This composite exhibited good humidity regulating ability with the largest water absorption rate of 16.38% under experimental conditions. Moreover, various properties were tested including surface drying time, hardness, adhesion, coating appearance, water resistance and reusability, meeting the national standard requirements well. The mechanism was comprehensively analyzed by XRD, TG-DTG, FESEM, and FTIR, indicating that the humidity self-adjusting function of HRCRM was realized by regulating the interlayer water storage of vermiculite. This study can provide theoretical and technical guidance for residential environment improvement in subtropical areas and comprehensive utilization of red mud. [ABSTRACT FROM AUTHOR]

• Modified vermiculite achieved a better expansibility under microwave irradiation. • A novel quantitative analysis method of microwave energy absorption was proposed. • Influence mechanism of Mg2+ modification on microwave absorption was analyzed. This work investigated the effect of microwave power on vermiculite expansibility for different exposure time and compared the changes after Mg2+ modification. The expansion ratio of the modified vermiculite sample reached up to 5.29 at 800 W with a significant increase of 23.89 % in contrast to the raw vermiculite sample. Aimed to quantify the microwave energy absorption of vermiculite, a novel method was proposed by employing water as a medium material due to its sensitivity to microwave energy. Using this method, the effect of microwave power on microwave energy absorption of vermiculite was studied. Meanwhile, the influence mechanism of Mg2+ modification on microwave energy absorption of vermiculite was analyzed by means of energy dispersive X-ray spectroscopy and thermogravimetric-differential scanning calorimeter. Mg2+ modification could significantly improve the microwave energy absorption ability of vermiculite, which was mainly ascribed to the increase of interlayer water content through Mg2+ hydration reaction. [ABSTRACT FROM AUTHOR]