The Impact of Agricultural Use of Retisols on the Molecular Structure of Humic Substances

Agricultural soil use does not only affect the amount of soil organic matter, but also the molecular composition of humic (HAs) and fulvic acids (FAs). Changed hydrothermal conditions and composition of the incoming plant residues are reflected in the rate of humification and its products. The objective of this study was to compare the molecular composition of HAs and FAs isolated from Eutric Albic Stagnic Histic Retisol (Loamic), two Eutric Albic Retisols (Loamic)—mature and arable. Plots of mature Retisols are located at a middle taiga (Komi Republic, Russia) in a bilberry-green-moss birch-spruce forest. The plot of Retisols arable is located in the fields of the Syktyvkar state farm, which is 3.3 km northeast of mature Retisol plots. The development period is about 40 years, it is sowed with a pea-oat mixture. The results obtained indicate that soil reclamation essentially increases the proportion of aromatic components and decreases the content of carboxyl and ester groups in the humic substance (HS) structure. An increased extent of hydromorphism of Retisols leads to the enrichment of HS with aliphatic fragments.

Influence of Waste Glass Powder Addition on the Microstructure and Mechanical Properties of Autoclaved Building Materials

Lime quartz samples in which ground quartz sand was gradually substituted with waste glass powder (GP) were obtained under hydrothermal conditions to determine the influence of GP addition on the microstructure (observed by SEM), phase composition (analyzed by XRD), and compressive strength of autoclaved building materials. An additional series containing analytical grade NaOH and no GP was formed to evaluate the effect of sodium ions on tobermorite formation and its impact on the mechanical properties of the samples. GP addition hindered the formation of tobermorite during autoclaving. Instead, a higher amount of an amorphous and semi-crystalline C–S–H phase formed, leading to the densification of the composite matrix. Nevertheless, tobermorite-like structures were found during both XRD and SEM analyses, proving that the presence of small amounts of Al3+ ions allowed, to an extent, for the stabilization of the phase despite the high sodium content. The compressive strength values indicate that the presence of alkali in the system and the resulting formation of additional portions of C–S–H have a beneficial influence on the mechanical properties of autoclaved composites. However, the effect fades with increasing glass powder content which, together with a slight expansion of the samples, suggests that at high sand substitution levels, an alkali–silica reaction takes place.

Theoretical Studies on the Mechanism of deNOx Process in Cu–Zn Bimetallic System—Comparison of FAU and MFI Zeolites

In the present study we propose a more promising catalyst for the deNOx process to eliminate harmful nitrogen oxides from the environment. The study was performed with a computer calculation using density functional theory (DFT) based on an ab initio method. Two zeolite catalysts, FAU and MFI, were selected with additional Cu–O–Zn bimetallic dimer adsorbed inside the pores of both zeolites. Based on the analysis of preliminary studies, the most probable way of co-adsorption of nitric oxide and ammonia was selected, which became the initial configuration for the reaction mechanism. Two types of mechanisms were proposed: with hydroxyl groups on a bridged position of the dimer or a hydroxyl group on one of the metal atoms of the dimer. Based on the results, it was determined that the FAU zeolite with a bimetallic dimer and an OH group on the zinc atom was the most efficient configuration with a relatively low energy barrier. The real advantage of the Cu–Zn system over FAU and MFI in hydrothermal conditions has been demonstrated in comparison to a conventional Cu–Cu catalyst.

Anaerobic oxidation of aldehydes to carboxylic acids under hydrothermal conditions

Efficient anaerobic oxidation of aldehydes using iron(iii) nitrate under hydrothermal conditions is reported.

A series of POM-based compounds by tunning coordination groups and spacers of ligands: electrocatalytic, capacitive and photoelectrocatalytic properties

Seven polyoxometalate-based compounds were synthesized under hydrothermal conditions, namely [Co(H2Ptep)(HPtep)(H2O)2(PW11CoO39)]·4.5H2O (1), {[Cu(H3Ptep)2(H2Ptep)2][SiW12O40]}·(SiW12O40)2·8H2O (2), {Cu3(H2Ptpi)2(Ptpi)2(H2O)5[(PMo11CuO39)2]}·6H2O (3), [Co(H2Ptpi)2(HPtpi)2(SiMo12O40)2]·2H2O (4), [Co3(Ptpi)2(H2O)6(TeMo6O24)]·2H2O (5),[Co2Na(HPtpi)(H2O)7.5(TeMo6O24)]·3.5H2O (6), [Cu(HZtpi)(H2O)2(CrMo6(OH)6O18)]·5H2O (7) (Ptep = 1-[2-(3-Pyridin-4-yl-[1,2,4]triazol-4-yl)-ethyl]-piperazine, Ptpi = 1-[2-(3-Pyridin-4-yl-[1,2,4]triazol-4-yl)-propyl]-imidazol, Ztpi =...