2 research outputs found
Redox Conversion of Chromium(VI) and Arsenic(III) with the Intermediates of Chromium(V) and Arsenic(IV) via AuPd/CNTs Electrocatalysis in Acid Aqueous Solution
Simultaneous
reduction of CrÂ(VI) to CrÂ(III) and oxidation of AsÂ(III)
to AsÂ(V) is a promising pretreatment process for the removal of chromium
and arsenic from acid aqueous solution. In this work, the synergistic
redox conversion of CrÂ(VI) and AsÂ(III) was efficiently achieved in
a three-dimensional electrocatalytic reactor with synthesized AuPd/CNTs
particles as electrocatalysts. The AuPd/CNTs facilitated the exposure
of active Pd{111} facets and possessed an approximate two-electron-transfer
pathway of oxygen reduction with the highly efficient formation of
H<sub>2</sub>O<sub>2</sub> as end product, resulting in the electrocatalytic
reduction of 97.2 ± 2.4% of CrÂ(VI) and oxidation of 95.7 ±
4% of AsÂ(III). The electrocatalytic reduction of CrÂ(VI) was significantly
accelerated prior to the electrocatalytic oxidation of AsÂ(III), and
the effectiveness of CrÂ(VI)/AsÂ(III) conversion was favored at increased
currents from 20 to 150 mA, decreased initial pH from 7 to 1 and concentrations
of CrÂ(VI) and AsÂ(III) ranging from 50 to 1 mg/L. The crucial intermediates
of CrÂ(V) and AsÂ(IV) and active free radicals HO<sup>•</sup> and O<sub>2</sub><sup>•–</sup> were found for the
first time, whose roles in the control of CrÂ(VI)/AsÂ(III) redox conversion
were proposed. Finally, the potential applicability of AuPd/CNTs was
revealed by their stability in electrocatalytic conversion over 10
cycles
Photoresponsive iodine-bonded liquid crystals based on azopyridine derivatives with a low phase-transition temperature
<p>Halogen bonding interactions in the formation of liquid crystalline phases have been recognised in recent years. Here, we report a novel series of iodine-bonded liquid crystals using 1,2-diiodotetrafluorobenzene (1,2-DITFB) and azopyridine derivatives (AnAzPy), showing a smectic A phase and concurrent photoresponsive behaviour. These were characterised by using a polarising optical microscope, differential scanning calorimetry and UV-vis absorption spectroscopy. The formation of iodine bonding in the complexes was confirmed by X-ray photoelectron spectroscopy and Raman spectroscopy. Importantly, these iodine-bonded complexes demonstrated a low liquid crystal temperature range (30–50°C) among those reported for photoresponsive halogen-bonded liquid crystals. The molar ratio of the iodine-bonded donor and acceptor was 1:1 upon the self-assembly of the supramolecular complex molecule, as indicated by 1D-WAXD experiments of mixed samples of 1,2-DITFB and AnAzPy with different molar ratios. This study offers a new family of photoresponsive halogen-bonded liquid crystals and broadens the potential applications in their associated systems.</p