Wet hydrogen peroxide catalytic oxidation (WHPCO) is one of the most important industrially applicable advanced oxidation processes (AOPs) for the decomposition of organic pollutants in water. It is demonstrated that manganese functionalized silicate nanoparticles with interparticle porosity act as a superior Fenton-type nanocatalyst in WHPCO as they can decompose 80% of a test organic compound in 30 minutes at neutral pH and room temperature. By using X-ray absorption spectroscopic techniques it is also shown that the superior activity of the nanocatalyst can be attributed uniquely to framework manganese, which decomposes H2O2 to reactive hydroxyls and, unlike manganese in Mn3O4 or Mn2O3 nanoparticles, does not promote the simultaneous decomposition of hydrogen peroxide. The presented material thus introduces a new family of Fenton nanocatalysts, which are environmentally friendly, cost-effective, and possess superior efficiency for the decomposition of H2O2 to reactive hydroxyls (AOP), which in turn readily decompose organic pollutants dissolved in water.
COBISS.SI-ID: 4863514
The structural properties of the mesoscopically confined drug and drug-drug and drug-matrix interactions were investigated in model drug-delivery systems prepared from nonfunctionalized and functionalized SBA-15 mesoporous silicate matrices, loaded with different amounts of indomethacin molecules. 1H MAS and 1H-13C CPMAS NMR spectroscopy indicated that only when the concentration of indomethacin within the mesopores becomes sufficiently high (when the mass fraction of indomethacin within the sample exceeds 0.15) do hydrogen bonds between the drug molecules become abundant. Nitrogen sorption analysis and comparison of 1H spin-lattice relaxation times in progressively loaded SBA-15 matrices suggested that at low loading concentrations indomethacin forms a layer on the silicate walls of the mesopores and that at moderate or high loading concentrations rigid nanoparticles that extend throughout the entire mesopore cross section are formed. 1H-29Si HETCOR NMR spectra indicated that the interaction between the indomethacin molecules and the silicate surface was moderate to weak. The 1H-13C CPMAS NMR spectrum of indomethacin embedded within the mesopores of SBA-15 closely resembled the spectrum of the bulk amorphous indomethacin and did not allow to draw firm conclusions about the molecular conformation and the packing of the drug molecules within the pores. On the contrary, variable-temperature 1H spin-lattice relaxation measurements showed that the mesoscopically confined indomethacin is significantly different from the bulk amorphous indomethacin. It does not become rubbery, and it exhibits a solid-solid transition at 363 K that is similar to the phase transition of the crystalline indomethacin solvate with tetrahydrofuran. When indomethacin is incorporated into the functionalized SBA-15 matrix, the interactions between the embedded drug molecules and the walls of the matrix are enhanced.
COBISS.SI-ID: 4893978
A new layered Ca-succinate coordination polymer, poly[[mu]3-succinato-calcium(II)], [Ca(C4H5O4)]n, was synthesized by reaction of CaCl2 2H2O and succinic acid in an aqueous medium under hydrothermal microwave conditions. The structure contains infinite layers of edge-sharing calcium pentagonal-bipyramidal polyhedra forming six-membered rings connected through succinate ligands. Such an assembly of inorganic building units is unique for calcium metal-organic framework-type structures. Adjacent layers are packed into a final pseudo-three-dimensional structure through weak C-H...O hydrogen bonds
COBISS.SI-ID: 4875034