In Situ Raman Probing of Chlorphenol Degradation on Different Facets of K₃B₆O₁₀Br Single Crystal

Semiconductor photocatalysts with specific facets can induce high reactive activities has aroused wide attention. Here, we endeavor to gain quantitative insights into the intrinsic facet-dependent catalytic activities of K₃B₆O₁₀Br (KBB) crystal using in situ Raman technique under room temperature by photocatalysis dechlorination of 2,4-DCP as a model reaction. Using a well-defined sizable KBB single crystal (size: 28 mm × 20 mm × 9 mm) with high (211), (110), and (101) facet exposure, the time-resolved Raman spectra for different facets have been clearly tested, it shows that the Raman spectrum of (211) facet had a remarkable change compared with (110) and (101) facets when the crystal was immersed in the 2,4-DCP solution under light irradiation. Through DFT, we obtain qualitative details on the reaction mechanisms of photocatalyzed and provide a refined understanding of the elementary processes. It was found that the −OH contact mode between the pollutant and the crystal facet was the most effective mode, which can produce more ^•OH radicals than the other two modes. Moreover, the (211) facet offers the largest ratio of K atoms and surface energy, making the (211) facet more active than (110) and (101) facets

Unique Phase Behaviors in the Gemini Surfactant/EAN Binary System: The Role of the Hydroxyl Group

The hydroxyl group in the spacer of a cationic Gemini surfactant (12-3OH-12) caused dramatic changes of the phase behaviors in a protic ionic liquid (EAN). Here, the effects of the hydroxyl group on micellization and lyotropic liquid crystal formation were investigated through the surface tension, small-angle X-ray scattering, polarized optical microscopy, and rheological measurements. With the hydroxyl group in the spacer, the critical micellization concentration of 12-3OH-12 was found to be lower than that of the homologue without hydroxyl (12-3-12) and the 12-3OH-12 molecules packed more densely at the air/EAN interface. It was then interesting to observe a coexistence of two separated phases at wide concentration and temperature ranges in this 12-3OH-12/EAN system. Such a micellar phase separation was rarely observed in the ionic surfactant binary system. With the increase of surfactant concentration, the reverse hexagonal and bicontinuous cubic phases appeared in sequence, whereas only a reverse hexagonal phase was found in 12-3-12/EAN system. But, the hexagonal phases formed with 12-3OH-12 exhibited lower viscoelasticity and thermostability than those observed in 12-3-12/EAN system. Such unique changes in phase behaviors of 12-3OH-12 were ascribed to their enhanced solvophilic interactions of 12-3OH-12 and relatively weak solvophobic interactions in EAN

Phase Transition of a Quaternary Ammonium Gemini Surfactant Induced by Minor Structural Changes of Protic Ionic Liquids

The aggregation behaviors of a Gemini surfactant [C₁₂H₂₅(CH₃)₂N⁺(CH₂)₂N⁺(CH₃)₂C₁₂H₂₅]­Br₂^– (12-2-12) in two protic ionic liquids (PILs), propylammonium nitrate (PAN) and butylammonium nitrate (BAN), were investigated by means of several experimental techniques including small and wide-angle X-ray scattering, the polarized optical microscopy and the rheological measurement. Compared to those in ethylammonium nitrate (EAN), the minor structural changes with only one or two methylene units (−CH₂−) increase in cationic chain length of PIL, result in a dramatic phase transition of formed aggregates. The critical micellization concentration was increased in PAN, while no micelle formation was detected in BAN. A normal hexagonal phase was observed in the 12-2-12/PAN system, while the normal hexagonal, bicontinuous cubic, and lamellar phases were mapped in the 12-2-12/BAN system. Such aggregation behavior changes can be ascribed to the weaker solvophobic interactions of 12-2-12 in PAN and BAN. The unique molecular structure of 12-2-12 is also an important factor to highlight such a dramatic phase transition due to the PIL structure change

Effects of a Spacer on the Phase Behavior of Gemini Surfactants in Ethanolammonium Nitrate

The aggregation behavior of quaternary ammonium gemini surfactants (12-<i>s</i>-12) in a protic ionic liquid, ethanolammonium nitrate (EOAN), was investigated by small-angle X-ray scattering, freeze–fracture transmission electron microscopy, polarized optical microscopy, and rheological measurements. The rarely reported nonaqueous two phases in the ionic liquid were observed at lower 12-<i>s</i>-12 concentrations. The upper phase was composed of micelles, whereas only the surfactant unimers or multimers were detected in the low phase. At higher 12-<i>s</i>-12 concentrations, different aggregates were formed. The lamellar phase was observed in the 12-2-12/EOAN system, whereas the normal hexagonal phases in 12-<i>s</i>-12/EOAN (<i>s</i> = 3, 4, 5, 6, 8) systems and the micellar phase in the 12-10-12/EOAN system were observed. Such a dramatic phase transition induced by the spacer chain length was due to the unique solvent characteristics of EOAN compared to those of water and its counterpart ethylammonium nitrate

Nonaqueous Lyotropic Liquid-Crystalline Phases Formed by Gemini Surfactants in a Protic Ionic Liquid

The aggregation behaviors of three Gemini surfactants [(C_<i>s</i>H_2<i>s</i>-α,ω-(Me₂N⁺C_<i>m</i>H_2<i>m</i>+1Br^–)₂, <i>s</i> = 2, <i>m</i> = 10, 12, 14] in a protic ionic liquid, ethylammonium nitrate (EAN), have been investigated. The polarized optical microscopy and small-angle X-ray scattering (SAXS) measurements are used to explore the lyotropic liquid crystal (LLC) formation. Compared to the LLCs formed in aqueous environment, the normal hexagonal and lamellar phases disappear. However, with increasing the surfactant concentration, a new reverse hexagonal phase (H_II) can be mapped over a large temperature range except for other ordered aggregates including the isotropic solution phase and a two-phase coexistence region. The structural parameters of the H_II are calculated from the corresponding SAXS patterns, showing the influence of surfactant amount, alkyl chain length, and temperature. Meanwhile, the rheological profiles indicate a typical Maxwell behavior of the LLC phases formed in EAN

Formula development of sizing for basalt fiber. Part I: Role of film former

Sizing is a multi-element liquid system consisting of film former, coupling agent and other functional additives. In this article, Taguchi method with orthogonal array design was used to get an optimal formula of sizing for basalt fiber, and the role of film former in sizing was studied. The results showed film former promoted the sizing to spread on fiber surface, which increased the interaction area between the fiber and sizing. With the assistance of film former in sizing, a uniform layer was formed on fiber surface, which repaired the surface defect on basalt fiber with reduced stress concentration. The sizing with an appropriate concentration of film former had the capability to increase the tensile strength of a single filament with the best effect of forming a film on fiber surface.</p