Potassium (K+) phlogopite was transformed to a vermiculite-like mineral through a topotactic reaction under acidic conditions (pH 2) followed by hydrothermal treatment with Na+, Mg2+, Ca2+, and Al3+ cations. The resulting Na+-, Mg2+-, Ca2+-, and Al3+-altered phlogopites (Phl) denoted as Na-Phl, Mg-Phl, Ca-Phl, and Al-Phl, respectively. Na-Phl, Mg-Phl, and Ca-Phl all exhibited the same high adsorption capacity as natural vermiculite and the absorption of Cs+ and Sr2+ ions on these materials followed the Langmuir model. High-angle annular dark-field scanning transmission electron microscopy showed that Cs+ ions in the Mg-Phl layers were intercalated deep within the crystal structure, along specific interlayer regions. These adsorbed anhydrous Cs+ ions were firmly fixed at the centers of hexagonal rings positioned simultaneously in the upper and lower tetrahedral silicate sheets, whereas Sr2+ ions adsorb into the interlayer in the hydrous state. Al-Phl formed a hydroxyl-interlayered vermiculite and demonstrated significant selectivity for Cs+ at very low concentrations of the isotope. Consequently, the artificially altered phlogopites prepared in this study showed controllable and versatile adsorption capabilities making them significantly more suitable than natural vermiculite for Cs and Sr decontamination.

We report the preparation of organic-brucite (BR) hybrids using harmless sugar alcohols (xylitol, XYL, and sorbitol, SOR). Since XYL and SOR are solid materials at room temperature, the hybridization was investigated by comparing two separate methods, hydrothermal treatment and melt mixing. BR-sugar alcohol hybrids were successfully prepared by a melt intercalation method at 175 °C. X-ray diffraction and Fourier transform infrared spectroscopy analyses indicated that organic molecules were intercalated into the brucite layers, overcoming the barrier of hydroxyl bonds between the BR layers. Moreover, X-ray photoelectron spectroscopy and thermal analyses showed that the intercalated materials at 175 °C resulted in the formation of covalent Mg–O–C bond linkages on the interlayer surface of BR.Graphical abstractHighlights► Novel organic–inorganic hybrids based on brucite have been prepared by melt mixing procedure. ► Brucite-polyol hybrids were successfully prepared by a melt intercalation method. ► Covalent linkage between sugar alcohols and brucite layers was confirmed.

The adsorption and photodegradation behavior of methyl orange (MO) and fast green (FG) over ZnAl- and MgAl-based layered double hydroxide (LDH) adsorbents have been examined. ZnAl-LDHs were prepared with Zn/Al ratios of 2 to 4 by co-precipitation at pH 8. The ZnAl-LDHs and a commercial MgAl-LDH with a Mg/Al ratio of 3 were evaluated for their ability to adsorb MO and FG and for the photodegradation behavior of these dyes under UV irradiation. Structure analysis of the LDH–dyes-adsorbed complexes revealed that the adsorption produced two types of structures, an intercalation complex for MO and a surface-adsorbed complex for FG. The maximum adsorption of MO on the LDHs was significantly higher (more than tenfold) than FG. Results indicated the adsorption isotherms for the retention of both dyes by ZnAl- and MgAl-LDHs could be fitted to a Freundlich equation, showing a higher affinity for dyes on MgAl-LDH compared to those on ZnAl-LDH. The catalytic degradation ability of dye–LDH complex solid films on a quartz plate was superior to pure dye films under UV irradiation. The FG non-intercalated LDH complexes showed much faster photodegradation under UV irradiation than the MO–intercalated LDH complexes, which pointed to the important role of the LDH materials containing sensitized dyes in enhancing the generation of labile hydroxyl ions from the hydrophilic LDH surface.Highlights► Adsorption properties of anionic dyes on layered double hydroxides (LDHs) were examined. ► Different types of structures for dyes–LDH complexes were determined according to each dye. ► Photoinduced degradations of methyl orange and fast green over LDHs were evaluated. ► Presence of LDHs certainly accelerated the degradation reaction of dyes under UV irradiation.

A new natural mica/epoxy nanocomposite was formed through the exfoliation of a mica layer. The natural mica used was a potassium sericite (K-SE) whose interlayer was saturated with potassium cations. Powdered samples were separated through an air classifier into D50 = 13.6 µm (its median particle diameter), D10 = 7.9 µm, and D90 = 23.7 µm. An organophilic SE was prepared by an ion exchange reaction between the SE powder and alkylammonium solutions of various initial concentrations. As a typical procedure to forming a completely organically modified sample, the K-SE powder was treated with the highest alkylammonium concentration. This corresponded to an alkylammonium+/K+ mole ratio = 10.0 which was kept at 90 °C for four days. The nanocomposites were prepared by dispersing the organophilic SE in an epoxy resin (diglyxidyl ether of bisphenol A, DGEBA) with subsequent curing in the presence of nadic methyl anhydride (NMA) and benzyldimethylamine (BDMA) at 120–180 °C. Considerable exfoliation of the organically modified SE was achieved at a curing temperature of 180 °C. The morphology of the nanocomposite showed silicate nanolayers with extremely high aspect ratios that are at levels several dozens to hundreds of times greater than that of conventional exfoliated clay−polymer nanocomposites.