Heavy Metals Bioremediation and Water Softening Using Ureolytic Metschnikowia Pulcherrima and Raoultella Planticola Strains

This study employed the ureolytic fungal Metschnikowia pulcherrima (29A) and bacterial Raoultella planticola (VIP) strains in Pb 2+ and Hg 2+ removal using the promising CaCO 3 bio precipitation technique. Out of fifty isolates, strains 29A and VIP were selected based on their highest ureolytic activity followed by MIC assay using 350 ppm of Pb 2+ and Hg 2+ . The maximum urease activity recorded 884 and 639 U/mL for 29A and VIP strains at 24 and 30h of incubation, respectively. Complete removal of Pb 2+ was achieved at 42h and 90h for 29A, VIP correspondingly, while Hg 2+ was totally removed at 60h and 102h for 29A, VIP respectively. Remarkable removal of Ca 2+ (>95%) was achieved by the end of the experiments, which would address the hardness problem in the water treatment process. Further, EDX, SEM and, XRD were used to characterize the remediated precipitates. EDX profiles showed characteristic peaks of C, O and, Ca 2+ besides Pb 2+ and Hg 2+ . SEM illustrated the presence of microbial imprints and calcinated cells in the remediated bioliths. However, XRD confirmed the transformation of soluble metals to insoluble forms entrapped in calcite or vaterite lattice. Such a bioremediation approach ensures the detoxification and sequestration of heavy metals in a stable and durable matrix; obstructing their leach from carbonate complex trap to the environment.

Photochemical conversion of CO2 to CO by a Re complex: theoretical insights into the formation of CO and HCO3− from an experimentally detected monoalkyl carbonate complex

DFT and DLPNO-CCSD(T) calculations proposed a pathway for the conversion of the experimentally detected monoarkyl carbonate complex to tetracarbonyl complex.

The Record of Environmental and Microbial Signatures in Ancient Microbialites: The Terminal Carbonate Complex from the Neogene Basins of Southeastern Spain

The Messinian microbialites of the Terminal Carbonate Complex (TCC) from the Neogene basins of southeastern Spain show both diversified morphologies and an excellent preservation of primary microbial microstructures. Their stratigraphic architecture, fabric (micro-, meso-, and macro-fabric), and mineralogical composition were investigated in eight localities from three sedimentary basins of southeastern Spain: The Sorbas and Bajo Segura basins and the Agua Amarga depression. Two recurrent microbialite associations were distinguished. Laterally linked low relief stromatolites predominated in Microbialite Association 1 (MA1), which probably formed in low energy lagoons or lakes with fluctuating normal marine to hypersaline water. The microfabrics of MA1 reflected the predominance of microbially induced/influenced precipitation of carbonates and locally (Ca)-Mg-Al silicates. Microbialite Association 2 (MA2) developed in high energy wave and tidal influenced foreshore to shoreface, in normal marine to hypersaline water. High-relief buildups surrounded by mobile sediment (e.g., ooids or pellets) dominated in this environment. MA2 microbialites showed a significant proportion of thrombolitic mesofabric. Grain-rich microfabrics indicated that trapping and binding played a significant role in their accretion, together with microbially induced/influenced carbonate precipitation. The stratigraphic distribution of MA1 and MA2 was strongly influenced by water level changes, the morphology and nature of the substratum, and exposure to waves. MA1 favorably developed in protected areas during third to fourth order early transgression and regression phases. MA2 mostly formed during the late transgressions and early regressions in high energy coastal areas, often corresponding to fossil coral reefs. Platform scale syn-sedimentary gypsum deformation and dissolution enhanced microbial carbonate production, microbialites being thicker and more extended in zones of maximum deformation/dissolution. Microbial microstructures (e.g., microbial peloids) and microfossils were preserved in the microbialites. Dolomite microspheres and filaments showed many morphological similarities with some of the cyanobacteria observed in modern open marine and hypersaline microbialites. Dolomite potentially replaced a metastable carbonate phase during early diagenesis, possibly in close relationship with extracellular polymeric substances (EPS) degradation. Double-layered microspheres locally showed an inner coating made of (Ca)-Mg-Al silicates and carbonates. This mineral coating could have formed around coccoid cyanobacteria and indicated an elevated pH in the upper part of the microbial mats and a potential dissolution of diatoms as a source of silica. Massive primary dolomite production in TCC microbialites may have resulted from enhanced sulfate reduction possibly linked to the dissolving gypsum that would have provided large amounts of sulfate-rich brines to microbial mats. Our results open new perspectives for the interpretation of ancient microbialites associated with major evaporite deposits, from microbe to carbonate platform scales.

The influence of the support nature and synthetic conditions on the structure-phase features and properties of the thermostable catalyst for dehydrogenation of cyclohexanol

The reported data relate to the influence of the nature of the aluminosilica support and of the temperature of its treatment with the ammoniaccarbonate solution containing ammoniac-carbonate complex of copper on the specific surface area, chemical and phase composition of the precursor of the active component and on the properties of copper-containing catalyst for dedhydrogenation of cyclohexanol. Elevation of the treatment temperature of amorphous silica (white carbon) with the ammoniac-carbonate solution results in an increase in the proportion of the chemically anchored precursor up to its complete bonding to the support to form the immobilized phase. A higher thermostability of the catalyst supported on white carbon with boehmite compared to the catalysts supported on pyrogenous silica is demonstrated.

Prospects of oil and gas potential of the Pripyat trough carbonate complex

Oil-geological work in the Pripyat oil and gas basin has been going on for over 70 years; to date, more then 80 oil and gas fields have been discovered there, but due to the ever-growing need for energy consumption, work on the identification of new resources is constantly continuing. Geochemical studies of oil deposits, as well as 3D modeling of the processes of generation, emigration and accumulation of hydrocarbons, taking into account all risk factors, made it possible to identify promising objects for oil and gas exploration in the subsalt and intersalt carbonate complexes. The calculated scales of generation, emigration and accumulation of hydrocarbons, carried out as a result of geochemical and basin modeling, turned out to be comparable and showed that the oil and gas source potential of the Devonian sediments of the Pripyat trough was realized by no more than one third.