Terbium-doped layered yttrium hydroxychlorides (LYH:xTb) were explored for the simple and convenient detection of Cr(VI) in aqueous solution, where the effective overlap of excitation bands of LYH:xTb with absorption bands of Cr(VI) constructs a new inner filter effect system. The shielding of excitation light for LYH:xTb by adsorbed Cr(VI) was so effective that a feasible detection sensitivity could be achieved.
Pseudocarbynes,
defined as linear carbon chains stabilized by noncovalent
bonding to a metal cluster, were synthesized via laser ablation of
a liquid/metal interface, in this case, gold (Au) in ethanol. We present
UV–vis, Raman, and IR spectra that collectively demonstrate
the formation of Au-pseudocarbynes. The Au-pseudocarbynes presented
here likely consist of polyynes containing fewer than 16 carbon atoms
associated with subnanometer Au clusters. Their characteristic spectral
signatures are supported by density functional theory calculations
that highlight the interaction between the Au clusters and the π
network of −CC– chains. This class of molecules
represents a synergy between sp-hybridized carbon chains and small
metal clusters that stabilize one another.
Layered yttrium hydroxide, l-Y(OH), has been explored as a representative member of the layered rare earth hydroxide family (l-RE(OH); RE = rare earths) for removal and recovery of phosphate from aqueous solution. Compared to the hexagonal form, h-Y(OH), which has a weakly positive surface charge only at low pH, the layered polymorph composed of hydroxocation layers exhibited a high point of zero charge (pH ∼ 11) and significantly enhanced adsorptive ability for anions over a wide pH range. The Langmuir isotherm model and pseudo-second-order kinetic model were adopted to explain the phosphate adsorption on l-Y(OH). This new adsorbent revealed high capacity, efficiency, stability, selectivity, and reusability in adsorption of phosphate from a single electrolyte as well as natural waters containing competing anions. Essentially complete phosphate recovery from aqueous solutions at low phosphate concentrations (2.0 mg of P/L) was demonstrated with an adsorbent dosage of 0.025-0.5 g/L. The adsorption of phosphate was accompanied by an increase in the solution pH, suggesting a release of OH ions during the adsorption reaction. In particular, when Ce and Tb were co-doped (l-Y(OH):Ce,Tb), phosphate adsorption led to the characteristic D → F (J = 6, 5, and 4) emissions of Tb under commercial 312 nm UV irradiation. The photoluminescence of phosphate-adsorbed l-Y(OH):Ce,Tb provided evidence of the inner-sphere complexing mechanism involving the formation of Y(Ce,Tb)-O-P bonds through which the energy transfer can occur. The "luminescence-on" behavior of l-Y(OH):Ce,Tb by phosphate adsorption was employed to detect and recover phosphorus at low concentrations in deionized water, mineral water, tap water, and river water.
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