Halloysite/Ag2O (Hal/Ag2O) nanomaterials were prepared by growing Ag2O nanoparticles on the surface of nanotubular halloysite using silver nitrate solution under alkaline conditions. The nanomaterials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption. Good dispersion of Ag2O nanoparticles with average sizes of 6.07 ± 2.5 nm and 8.04 ± 3.8 nm was achieved in the nanomaterials when using different concentrations of alkali. The nanomaterial with 6.36% Ag2O (Hal/Ag2O-2) exhibited rapid adsorption to iodide (I−); adsorption equilibrium can be reached within 100 min. The adsorption capacity of I− on Hal/Ag2O-2 is 57.5 mg/g, which is more than 143 times higher than that of halloysite. The nanomaterial also showed a better adsorption capacity per unit mass of Ag2O due to the better dispersion and less coaggregation of Ag2O in the nanomaterial than in the pure Ag2O nanoparticles. Importantly, Hal/Ag2O-2 exhibited high selectivity for I−, and its I− removal efficiency was hardly affected by the coexistence of Cl−, Br−, or SO42−, as well as the initial pH of the solution. With an excellent adsorption performance, the prepared Hal/Ag2O nanomaterial could be a new and efficient adsorbent capable of the adsorption of radioactive I− from aqueous solution.

Polycrystalline cubic boron nitride (PcBN) was sintered in the temperature range of 1050-1650°C under an ultra-high pressure of 5.0 GPa for 20 min using an in situ synthesis method. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energydispersive spectrometry were used to study the compositional and morphological changes during the synthetic process. The results showed that rod-shaped TiB 2 crystals could be detected at 1150°C, and their quantity increased with sintering temperatures. The TiB 2 crystals distributed homogeneously and grew randomly among the cBN grain boundaries and interstitial spaces, ultimately forming an interlocking structure. The PcBN prepared at 1650°C exhibited optimal comprehensive mechanical properties, with a micro-hardness of 44.42 GPa and a flexural strength of 862.5 MPa. Moreover, based on the experimental results, the chemical reaction mechanism and the strengthening mechanisms occurred during the sintering process were also proposed to properly interpret the synthesis of PcBN.

The elimination of iodide (I−) from water is a tough subject due to its low adsorption tendency and high mobility. In this work, MCM-41/Ag2O nanomaterials were prepared, characterized, and employed to adsorb I− from water. The Ag2O nanoparticles were dispersed homogeneously in the pores or at the surface of the MCM-41 support, and the Ag2O nanoparticles in the pores had small particles sizes due to the confinement of the mesoporous channel. The prepared MCM-41/Ag2O nanomaterials exhibited a higher specific surface area than previously reported Ag2O-based composites. The adsorption of I− by the nanomaterials was able to reach equilibrium at 180 min. The MCM-41/Ag2O nanomaterials showed a better adsorption capacity per unit mass of Ag2O than pure Ag2O nanoparticles and previously reported Ag2O-based composites prepared using other supports. Furthermore, the MCM-41/Ag2O nanomaterials exhibited high selectivity for I− in the presence of high concentrations of competitive anions, such as Cl− or Br−, and could function in a wide range of pH. The chemical reaction between Ag2O and I− and the surface adsorption were the main adsorption mechanisms. These results indicate that MCM-41/Ag2O nanomaterials are a promising and efficient adsorbent material suitable for the removal of I− for practical application.