Oxidation of pyrite (FeS2) and troilite (FeS) impurities in kaolinitic clays after calcination

Valorisation of locally available clays for producing blended cements is crucial for a widespread adoption of sustainable binders incorporating these materials. In some places, clays can be intermixed with small amounts of iron sulfides, which could eventually expand in the alkaline media of concrete and lead to cracking if clay particles are sufficiently fine. This study explored the stability of iron sulfides, namely troilite and pyrite, during calcination of clays and their influence in reactivity. It was found that both troilite and pyrite decompose and oxidize into hematite under typical calcination conditions for clays. Furthermore, there is no negative influence of the presence of iron sulfide phases on the reactivity of calcined clays. This shows that these clays are suitable for use in blended cements, provided that adequate quality control is conducted to ensure a complete decomposition of the iron sulfide phases.

Fabrication of Pd/CeO2 nanocubes as highly efficient catalysts for degradation of formaldehyde at room temperature

The highly active Pd/CeO2 nanocube interface guarantees a high percentage of metallic Pd and the surface active O species is responsible for the complete decomposition of formaldehyde.

A non-perturbative pairwise-additive analysis of charge transfer contributions to intermolecular interaction energies

A non-perturbative scheme for complete decomposition of energy and charge associated with charge transfer interaction into pairwise additive components.

ESTIMATION OF THE POSSIBILITY OF WASTEWATER PURIFICATION FROM PHARMACEUTICAL PREPARATIONS BY RADIATION METHOD

To assess the possibility of using radiation purification of aqueous solutions from contained pharmacological preparations by spectrophotometry, high-performance liquid chromatography and chemical analysis, the effect of the absorbed dose of ionizing radiation on the concentration of analytes in solutions was studied. The values of the radiation-chemical yield of destruction of the investigated pharmaceutical preparations, the formation of peroxide products of radiolysis were determined, and the values of absorbed doses sufficient for the complete decomposition of the substances under consideration were calculated. It was shown that at initial concentrations of ketoprofen of 1,1•10-4 M and diclofenac of 0,5•10-4 M, the values of absorbed doses required for their complete decomposition are 2,4 kGy and 0,85 kGy, respectively. The obtained values indicate the possibility of using radiation technology for the purification of aqueous solutions from those pharmaceutical preparations. Further research can clarify the necessary doses for sufficient destruction of various groups of drugs in concentrations found in wastewater

On complete decompositions of dihedral groups

Let G be a finite non-abelian group and B1, …, Bt be nonempty subsets of G for integer t ≥ 2. Suppose that B1, …, Bt are pairwise disjoint, then (B1, …, Bt) is called a complete decomposition of G of order t if the subset product Bi1 … Bit = {bi1 … bit | bij ∈ Bij, j = 1,2, …,t} coincides with G, where {Bi1 … Bit} = {B1, …, Bt} and the Bij are all distinct. Let D2n = ‹r,s| rn = s2 = 1, rs =srn-1› be the dihedral group of order 2n for integer n ≥3. In this paper, we shall give the constructions of the complete decompositions of D2n of order t, where 2 ≤ t ≤ n.