Water chemistry in forested acid sensitive sites in sub-tropical Asia receiving acid rain and alkaline dust

This invention relates to synthetically derived zinc phlogopite substrates, of superior aspect ratio, effect pigments comprising such synthetically derived substrates and methods of forming said substrates. More specifically the disclosure describes an improved hydrothermal synthesis of zinc phlogopite suitable as a substrate for interference pigments, barrier and flame retardant applications.

Synthetic zinc phlogopite via hydrothermal preparation

How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence on succinate for the synthesis of sauconite identifying new mechanisms of clay formation in surface environments of rocky planets. The work demonstrates that seeding induces nucleation at low temperatures accelerating the crystallization process. Cryogenic and conventional transmission electron microscopies, X-ray diffraction, diffuse reflectance Fourier transformed infrared spectroscopy, and measurements of total surface area are used to build a three-dimensional representation of the clay. These results suggest the coevolution of clay minerals and early metabolites in our planet could have been facilitated by sunlight photochemistry, which played a significant role in the complex interplay between rocks and life over geological time.

/pdf/catalyzed-synthesis-of-zinc-clays-by-prebiotic-central-3npp2xptub.pdf

Catalyzed Synthesis of Zinc Clays by Prebiotic Central Metabolites.

Sauconites were synthesized hydrothermally from a homogeneous gel with stoichiometric chemical composition in a temperature range of 100-200°C for up to 14 d at autogenous pressure The synthetic products were characterized by XRD, SEM, TEM, ICP-AES, FT-IR and XPS The well-crystallized sauconite without impurities was obtained after 100°C treatment At 150 and 200°C, sauconite coexisted with small amount of hemimorphite (Zn 4 Si 2 O 7 (OH) 2 H 2 0) and willemite (Zn 2 SiO 4 ) The octahedral coordination of Zn in synthesized sauconite was confirmed by FT-IR and XPS spectra, comparing with those of natural mica containing Zn in the octahedral layer (hendricksite) The FT-IR spectra of synthetic sauconite showed the characteristic bands at 660 cm -1 for Zn-O vibration and 3635 cm -1 for 3Zn-OH stretching in the octahedral sheets, which are comparable to those of hendricksite The Zn(3p) peak of sauconite in XPS spectrum was observed which corresponded with that of hendricksite These results indicated that Zn in sauconite was coordinated octahedrally as Zn in hendricksite

SYNTHESIS AND CHARACTERIZATION OF Zn-SUBSTITUTED SAPONITE (SAUCONITE)

TRLFS characterization of Eu(III)-doped synthetic organo-hectorite.

Both refluxing reaction under atmospheric pressure and hydrothermal reaction under autogenous water vapor pressure of two kinds of starting slurry with the initial molar ratio Na:Zn:Li:Si= 0.7:5.4:0.6:8.0 and 1.4:5.4:1.2:8.0 made from Zn-Si homogeneous precipitates, lithium fluoride and sodium hydroxide successfully have yielded Zn-hectorites containing Zn 2+ instead of Mg 2+ in the trioctahedral sheets. Zn-hectorites have expansion of the basal spacing (d 001 ) by the treatment with ethylene glycol on powder X-ray diffraction (XRD) patterns, and characterized by Zn-O vibration in the around 660-670 cm -1 on fourier transform infrared spectrometer (FT-IR) spectra, peaks assigned to Zn2p on X-ray photoelectron spectrometer (XPS) spectra and thermal dehydroxylation at lower temperature on thermogravimetry and differential thermal analysis (TG-DTA). It has also clarified that Zn-hectorite synthesized by hydrothermal reaction under autogenous water vapor pressure is relatively large massive particles and has a larger CEC, although it has lower MB adsorptive ability compared to a commercial Mg-hectorite as reference.

SYNTHESIS AND PHYSICOCHEMICAL PROPERTIES OF Zn-HECTORITE

Hectorite containing Ni 2+ instead of Mg 2+ in the trioctahedral sheets has been synthesized at 300°C for 12 h under autogenous water vapor pressure by hydrothermal reaction of four kinds of starting slurry with the initial molar ratios Na:Ni:Li:Si = 07:54:06:80, 14:54:12:80, 14:48:12:80 and 14:48:12:75 made from Ni-Si homogeneous precipitates, lithium fluoride and sodium hydroxide The resulting Ni-hectorite has been characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FT-IR), thermogravimetry and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry The Ni-hectorite is relatively large massive plate-like particles with a characteristic tint of green and has similar structure to other hectorites, a smaller cation exchange capacity (CEC) and lower adsorptive ability of methylene blue (MB) compared to a commercial Mg-hectorite and a synthetic Zn-hectorite as reference It has also been clarified that the Ni-hectorite modified electrode shows a redox reaction Ni 2+ to Ni 3+ and Ni 3+ to Ni 2+ in cyclic voltammetry

Takahito Nakakuki

Papers

SYNTHESIS AND PHYSICOCHEMICAL PROPERTIES OF Zn-HECTORITE

HYDROTHERMAL SYNTHESIS AND PHYSIOCHEMICAL PROPERTIES OF Ni-HECTORITE

Impact of mineralogy on fixation and release of potassium in soils from three agroecological regions of bangladesh