Mineralogy and organic geochemistry of phyllite from the Dewon-Pokrzywna deposit, the Opava Mountains (SW Poland)

Phyllites from the Dewon–Pokrzywna de posit in the Opava Mts., SW Po land, were in ves ti gated by XRD (Rietveld method), XRF, EPMA, SEM, and ATR-FTIR from the per spec tive of their po ten tial us age as a buffer and/or back fill ma te rial in a geo - log i cal re pos i tory of ra dio ac tive waste. Or ganic mat ter dis persed in the phyllite ma trix was ana lysed by GC-MS. Fine-grained Mg-Fe-mus co vite (13 to 29 wt.%), Fe-ripidolite (10 to 25 wt.%), de tri tal quartz (20 to 46 wt.%), and al bite (7 to 28 wt.%) ± microcline, illite or illite/smectite, and kaolinite are ma jor min er als in phyllite sam ples. The chlorite/mus co vite ra tio ranges from 0.65 to 1.1. Mg-annite in her ited from the pre cur sor rock is a mi nor con stit u ent. De tri tal il men ite is a dom i nant ac ces sory min eral. Ancylite-(Ce) oc curs in quartz-cal cite-ripidolite veins. Two types of phyllite have been dis tin guished based on the pro por tion of phyllosilicates to silt frac tion: ar gil la ceous (47 to 55 wt.% phyllosilicates) and silt-rich (28 wt.% phyllosilicates). Ar gil la ceous phyllite shows el e vated con tent of alu mina and mod er ate con cen tra tion of sil ica. It is highly en riched in Fe com - pared to phyllites from other lo cal i ties world wide. The BET spe cific sur face area of ar gil la ceous phyllite ranges from 1.73 to 3.64 m2/g. Whole-rock chem i cal com po si tion, min eral as sem blages, chlorite geothermometry, and the oc cur rence of aliphatic hy dro car bons sug gest that ar gil la ceous phyllite orig i nated from a pe lagic pelite protolith un der low-tem per a ture (260–370°C) greenschist to subgreenschist fa cies con di tions. Per sis tent biomarkers are in dic a tive of bac te rial deg ra da tion of plank tonic or ganic mat ter sus pended in a high wa ter col umn. En rich ment in Fe-rich chlorite and Mg,Fe-mus co vite, low vol - ume of in ter con nected pores with dom i nant mesopores sug gest that ar gil la ceous phyllite from the Dewon–Pokrzywna de - posit is a po ten tial can di date for a buffer and/or back fill ma te rial

Middle Jurassic black shales (Skrzypny Shale Formation) – palaeoenvironmental significance of one of the oldest deposits of the Pieniny Klippen Belt

This paper deals with a fragment of geological history of Middle Jurassic black spherosideritic shales outcropping in upper part of the Homole Gorge (Skrzypny Shale Formation, Niedzica succession). These important deposits belong to the Flackenmergel facies, widespread in oceanic Tethyan deposits. This formation represents one of the oldest rocks of the Pieniny Klippen Belt. Dark colour of these rocks (total organic carbon content in them amounts to about 1 wt.%) and the occurrence of siderite concretions indicate reducing conditions of their origin but oxidizing environment of waters above them in sedimentary basin. Oxic conditions of organic matter sedimentation are confirmed by the elevated values of pristine to phytane ratio. Moreover the results based on n-alkanes indicate mixed terrestrial/marine origin of organic matter with prevalence of the last one These information are slightly obliterated because of advanced thermal maturity of organic matter caused by postsedimentation processes. Microstructural features of deposits of the Skrzypny Shale Formation and the composition of clay minerals occurring in them indicate late diagenetic conditions. In SEM images we observe one-directional orientation of clay minerals and rotation of mica flakes, often chloritized. Clay minerals are represented by high-illitic illite/smectite, micas, post-biotitic chlorite and subordinately kaolinite. As follows from authors studies, these macroscopically nearly “mute” clay rocks, little interesting in outcrops, particularly when they occur in such attractive geological objects as the Homole Gorge, can be the source of important information concerning the history of sedimentation basins.//Praca przedstawia fragment historii geologicznej środkowojurajskich czarnych łupków sferosyderytowych ukazujących się w niewielkim odsłonięciu w górnej części wąwozu Homole (formacja łupków ze Skrzypnego, sukcesja niedzicka). Te ważne utwory należą do facji Fleckenmergiel szeroko rozpowszechnionej w oceanie Tetydy. Formacja łupków ze Skrzypnego reprezentuje jedne z najstarszych skał pienińskiego pasa skałkowego. Ciemna barwa badanych skał (zawartość całkowitego węgla organicznego około 1% wag.) oraz występowanie w nich konkrecji syderytowych, wskazują na warunki redukcyjne panujące w osadzie, natomiast na obecność natlenionych wód nad osadem w środowisku ich sedymentacji. Sedymentację substancji organicznej w warunkach raczej utleniających potwierdzają badania związków organicznych, tj. wysokie wartości stosunku pristan/fitan. Wyniki tych badań wskazują ponadto na mieszane, lądowo/morskie pochodzenie substancji organicznej z przewagą ostatniej z wymienionych. Informacje te są nieco zatarte z powodu dużej dojrzałości termicznej substancji organicznej spowodowanej procesami postsedymentacyjnymi. Cechy mikrostrukturalne utworów formacji łupków ze Skrzyponego oraz skład występujących w nich minerałów ilastych wskazują na warunki odpowiadające późnej diagenezie. W obrazach elektronomikroskopowych (SEM) widoczna jest bowiem jednokierunkowa orientacja minerałów ilastych i rotacja blaszek mik, często schlorytyzowanych. W składzie minerałów ilastych występuje zaś wysokoillitowy illit/smektyt, miki, pobiotytowy chloryt i podrzędnie kaolinit. Z przeprowadzonych badań wynika, że makroskopowo niemal „nieme” skały ilaste, niepozorne wyglądające w odsłonięciu, szczególnie jeśli występują obok atrakcyjnych obiektów geologicznych jak to ma miejsce w wąwozie Homole, są źródłem ważnych informacji dotyczących historii basenów sedymentacyjnych. Warto więc zwrócić na nie uwagę

The effect of structural order on nanotubes derived from Kaolin-group minerals

Kaolin-group clay minerals can be modified to form nanotubular and mesoporous structures with interesting catalytic properties, but knowledge of the best methods for preparing these structures is still incomplete. The objective of this study was to investigate intercalation/deintercalation as a method for the delamination and rolling of kaolinite layers in relation to structural order. To prepare nanotubular material, kaolinites of different crystallinities and halloysite (all from Polish deposits) were chosen. The experimental procedure consisted of four stages: (1) preparation of a dimethyl sulfoxide precursor intercalate; (2) interlayer grafting with 1,3-butanediol; (3) hexylamine intercalation; and (4) deintercalation of amineintercalated minerals using toluene as the solvent. Structural perturbations and changes in the morphology of the minerals were examined by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and transmission electron microscopy (TEM). The number of rolled kaolinite layers depended heavily on the efficiency of the intercalation steps. An increase in the structural disorder and extensive delamination of the minerals subjected to chemical treatment were recorded. Kaolinite particles which exhibited tubular morphology or showed rolling effects were observed using TEM. The nanotubes formed were ~30 nm in diameter, with their length depending on the particle sizes of the minerals

Rehydration Driven Na-Activation of Bentonite—Evolution of the Clay Structure and Composition

A new method of Na-activation of raw bentonite, rich in Ca-montmorillonite, consisting of combined thermal treatment at 200 °C, followed by immediate impregnation with aqueous solution of Na2CO3 of concentration corresponding to 0.5, 1.0, 1.5, or 2.0 cation exchange capacity (CEC) of clay, was investigated. Structural and compositional evolution of the activated solids after 1, 2, 3, and 4 weeks of storage was monitored by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). XRD analysis indicated that within the investigated period of ageing transformation to Na-rich montmorillonite required Na2CO3 concentration of at least 1.0 CEC. FTIR spectra showed that, depending on the Na2CO3 concentration and ageing time, formation of Na-rich montmorillonite was accompanied by precipitation of poorly crystalline calcite, amorphous calcium carbonate, gaylussite (a double calcium-sodium carbonate), and portlandite (Ca(OH)2)

Surface area and porosity of nanotubes obtained from kaolin minerals of different structural order

Mesoporous materials with pore diameters in the range 2-50 nm forming tubular or fibrous structures are of great interest due to their unique properties. Because they are commonly used as sorbents and catalyst carriers, knowledge of their surface area and porosity is critical. A modified intercalation/ deintercalation method was used to increase the efficiency of nanotube formation from kaolin-group minerals which differ in terms of their degree of structural order. Unlike previous experiments, in the procedure adopted in the present study, methanol was used instead of 1,3-butanediol for grafting reactions and octadecylamine intercalation was also performed. The samples were examined using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The specific surface area and porosity of previously described and newly formed materials were investigated by N adsorption/desorption. Compared to results described earlier, the percent yield of nanotubes obtained in the present study was significantly greater only in the case of 'Maria III' kaolinite, which has high structural order. This increase was obtained mainly by the grafting reaction with methanol. Highly ordered stacking of kaolinite-methanol intercalates was noticed and, thus, the amine intercalation was more efficient. In particular, the use of long-chain octadecylamine significantly increased the nanotube yield. The grafting reaction with methanol procedure yielded fewer nanotubes, however, when applied to poorly ordered samples ('Jaroszów' kaolinite and 'Dunino' halloysite). In the case of the 'Maria III' kaolinite, the diameter of the rolled layers observed by TEM was ~30 nm and corresponded to average diameters of newly formed pores (D N) determined using N adsorption/desorption, confirming that nanotubes contributed to an increase in surface area and total pore volume. In the case of 'Jaroszów' kaolinite and 'Dunino' halloysite mainly macropores (D N > 100 nm) and mesopores (20 nm > D N > 40 nm) were formed. The pores were attributed to interparticle and interaggregate spaces in the stacks of platy particles and to the small relative number of nanotubes

Structural Transformations of Hydrolysates Obtained from Ti-, Zr-, and Ti, Zr-Solutions Used for Clay Pillaring: Towards Understanding of the Mixed Pillars Nature

Structural characteristics of hydrolysates formed from the aqueous Ti-, Zr-, and Ti, Zr-pillaring solutions prepared from inorganic precursors (TiCl4 and ZrOCl2), was investigated and compared with that of precipitates obtained from the same solutions after a slight alkalization of pH to the values reported for the conditions of clay pillaring. The materials were recovered by lyophilization and subsequently subjected to calcination at 500, 800 and 1000 °C. Of special interest was the effect of pH on the possible formation of mixed Ti, Zr-oxide species. Powder X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) analysis showed that even a relatively moderate alteration of pH in Ti-, Zr-, or Ti, Zr-precursor solutions caused substantial changes in the outcome of hydrolytic transformations, manifested by different phase and/or chemical composition of the resulting hydrolysates. Analysis of thermal evolution of hydrolysates showed that alkalization facilitated the transformation of anatase into rutile in materials obtained from Ti-pillaring solution, but retarded tetragonal to monoclinic zirconia conversion in samples derived from Zr-pillaring agent. The most striking effect was observed for the mixed Ti, Zr-pillaring solution, where an increase of pH enabled the formation of zirconium titanate as the only crystalline phase, rather than a multiphase mixture of anatase, monoclinic zirconia and zirconium titanate obtained from the more acidic precursor. The finding supports the model of mixed Ti-O-Zr network in props generated in Ti, Zr-pillared montmorillonites

Bentonite from the Central Slovakia Volcanic Field – A prospective raw material for Polish industry

This paper summarizes information about recently worked bentonite deposits in Slovakia and presents the results of studies on bentonite from the Central Slovakia Volcanic Field (CSVF). The authors compared the mineralogy of commercial bentonites exploited in the Stara Kremnička (Jelšový potok), Kopernica, and Hliník nad Hronom deposits. X-ray diffraction (XRD), chemical analyses and microscopy showed that the main component is montmorillonite (37–88%), followed by opal C/CT (5–25%), clinoptilolite (up to 15%), feldspars (3–12%), quartz (up to 8%), biotite (2–5%), and kaolinite (up to 2%). The microscopic imaging provided information valuable for the technological assessment of bentonites, particularly the evaluation of mineralogy determined by XRD. The low variability of the mineral composition of commercial bentonites exploited in the western CSVF, together with the significant reserves and localization of deposits close to the Polish–Slovak state border prove that this raw material deserves more attention from Polish industry

Composites of Laponite and Cu–Mn Hopcalite-Related Mixed Oxides Prepared from Inverse Microemulsions as Catalysts for Total Oxidation of Toluene

Composites of Laponite and Cu–Mn hopcalite-related mixed oxides, prepared from hydrotalcite-like (Htlc) precursors obtained in inverse microemulsions, were synthesized and characterized with XRF, XRD, SEM, TEM, H2 temperature-programmed reduction (TPR), and N2 adsorption/desorption at −196 °C. The Htlc precursors were precipitated either with NaOH or tetrabutylammonium hydroxide (TBAOH). Al was used as an element facilitating Htlc structure formation, and Ce and/or Zr were added as promoters. The composites calcined at 600 °C are mesoporous structures with similar textural characteristics. The copper–manganite spinel phases formed from the TBAOH-precipitated precursors are less crystalline and more susceptible to reduction than the counterparts obtained from the precursors synthesized with NaOH. The Cu–Mn-based composites are active in the combustion of toluene, and their performance improves further upon the addition of promoters in the following order: Ce < Zr < Zr + Ce. The composites whose active phases are prepared with TBAOH are more active than their counterparts obtained with the use of the precursors precipitated with NaOH, due to the better reducibility of the less crystalline mixed oxide active phase