Kimmeridgian hardground-sequence boundary from the Mesozoic margin of the Holy Cross Mountains (central Poland): implications for the evolution of the northern Tethyan carbonate shelf

The sedimentary succession in central Poland records significant changes in facies at the turn of the Planula and Platynota zones in the Upper Jurassic, expressed by the drowning of the ramp-type platform and development of an extensive isochronous marl horizon. The topmost level of the marl horizon is a regional hardground, which is interpreted as the third-order sequence boundary Kim 1. In some areas, the hardground was eroded and is only preserved as bored and encrusted clasts. The composition of the borings may indicate that colonization and recolonization of the clasts took place in an extremely shallow water environment. The overall low level diversity of clast-encrusting organisms and their occurrence on both sides of clasts indicates frequent overturning and high current activity. However, other extrinsic factors, such as salinity fluctuations, may have been involved. The final redeposition and burial of the clasts were related to subsidence through widespread reactivation of Paleozoic faults. Comparison with Middle Oxfordian–Lower Kimmeridgian sequences of central and southern Poland indicates that the carbonate ramp morphology and paleoenvironmental conditions were periodically subjected to significant modification during phases of extensional tectonics, with the development of fault-controlled intra-platform ridges and basins. These features may have been the NE continuation of parallel swells and basins developed in the southern part of the carbonate platform adjacent to the Tethys

Arsenic interactions with bog iron ores – As(III) and As(V) adsorption–desorption study

Arsenic is a toxic element, elevated concentration of which in the environment can result from both anthropogenic activity and natural geochemical processes. The contamination of water, especially groundwater, with As has been recognized as a major environmental problem (Choong et al. 2007). The mobility and toxicology of As is related to its valence state which can be (+III) or (+V), depending mainly on pH and redox conditions. Because even low As concentrations in drinking water causes severe health effects, the technologies of its effective removal are thought to be very important (Mohan & Pittman 2007). Among many methods developed for removing aqueous arsenic species, the adsorption onto iron oxyhydroxides or oxyhydroxide-rich sorbents is one of the most effective. Despite many studies, the factors affecting the adsorption processes, especially those related to the sorbent properties, are still far from being fully understood (e.g. Adra et al. 2016). In this work we investigated As(III) and As(V) adsorption and desorption by bog iron ores – natural ferruginous sediments which have been recently demonstrated to exhibit very good sorption properties. For this study four samples of bog iron ores, were collected at different sites in the Polish Lowlands: Kolechowice (KOL), Biadaszki (BD), Strzyżew (ST) and Dębe Małe (DM). They represent different bog iron ore types which, in spite of having diversified structures, mineral composition and, subsequently, physical and chemical properties, revealed good sorption affinities for trace elements in previous work (Rzepa et al. 2009). In batch experiments the influence of various factors on adsorption were studied, including initial As concentrations, initial pH values and competitive adsorption of As(III) and As(V). The effect of initial As concentrations was studied in the range of 0.01–20 mM As(III) or As(V) at pH 7.5. The influence of pH was evaluated by the adsorption of 5 mM As solution in the pH range of 2–12. The experiment of competitive adsorption of arsenite and arsenate was performed for various proportion of As(III) to As(V) in the range of initial concentrations 0.025–20 mM at pH 7.5. The bonding strength of As with bog iron ore surface was estimated on the basis of three-step desorption experiments, which were conducted for the samples previously treated with As(III) or As(V) at pH 7.5 and at constant 20 mM initial concentration of arsenic. Arsenic concentrations in filtered (filter with a 0.22 μm pore size) solutions after all the experiments were analyzed using AAS and UV-Vis spectrophotometry. The results showed that arsenic sorption depends on its oxidation state. All the bog iron ores bound more As(III) than As(V). The highest amount of As(III) was sorbed by ST sample (458 mmol/kg), lower by KOL (430 mmol/kg) and DM (427 mmol/kg), and the lowest by BD (333 mmol/kg). However, in the case of As(V), the order was different: the highest amount of As was sorbed by BD sample (264 mmol/kg), lower by ST (218 mmol/kg), and the lowest by DM (163 mmol/kg) and KOL (158 mmol/kg). The highest uptake (80–95%) of As(III) was noted at lower initial concentrations, while the highest uptake (60–70%) of As(V) was observed at higher initial concentrations. As(III) sorption effectiveness was >80% throughout the pH range of 4 to 9 and was almost independent on pH in that range. In contrast, the As(V) sorption was higher at slightly acidic pH and significantly decreased in alkaline conditions. At pH around 3, sorption efficiency of both As(III) and As(V) decreased, which is likely due to the increased solubility of iron oxyhydroxides (Zeng, 2004). The results of competitive sorption experiments revealed that at low concentrations of both As species reduction of sorption efficiency of As(III) occurred. Sorption of As(V) was also affected, but only if amount of As(III) was higher than As(V). On the contrary, at high As(V) and As(III) concentrations, As(V) did not influence As(III) sorption, but As(III) substantially increased sorption of As(V). Desorption of arsenic by foreign ligands resulted in extraction of more than 70% of absorbed As(III) and As(V). In the absence of the exchange ligand, i.e., in deionized water, desorption of As(V) and As(III) was considerably lower, but noticeable. This study shows that bog iron ores are very good arsenic sorbents. However, the extent of As removal seems to be affected by various factors including As species and the composition of the ores themselves. As(V) is immobilized less effectively than As(III), and the process is influenced by pH values. It is believed, that the uptake of As by bog ores is controlled primarily by iron oxyhydroxides, as main components of these rocks, but mechanisms predominant in As(III) and As(V) adsorption are different and affected by presence of e.g. phosphate and silicate ions (Ociński et al. 2011). There are no simple correlations between mineralogy and sorption capacity. Due to the variability in chemical and mineral composition of different types of bog iron ores, various levels of arsenic removal can be obtained. Such properties of the ores, combined with their ubiquity in many near-surface environments may be regarded as an incentive for the environmental protection practice

Molybdates and tungstates sorption on organo-smectites as a process controlled by the type and amount of surfactant

Modification of a smectite with organic surfactants leads to the formation of an organo-mineral complex characterized by a positive charged (Bajda et al, 2015). The process involves the exchange of naturally occurring cations, eg. Ca2+, Mg2+, Na+, K+ by large organic cations of surfactants. This alteration makes it possible to use organo-smectites as sorbents to remove anionic forms of Mo(VI) and W(VI) from aqueous solutions. The concentration of molybdenum in the environment is significantly enhanced by anthropogenic inputs from coal-resource development, fly ash, sewage sludge and hard-rock mining activity (Kalembkiewicz, Sočo, 2009). W(VI) is released to the environment through its use in winter tires or by its applications in industry e.g. enriches alloys or electrotechnics (Gustafsson, 2003). The environmental behavior of molybdenum and tungsten once they dissolve becomes very complex as Mo(VI) and W(VI) anions occur as a monomer only in alkaline or neutral solutions. Bentonite from the Jelšovy Potok in Slovakia, rich in montmorillonite phase, was used in the sorption experiments (Bajda et al. 2015). Through the preparation of a series of experiments it was possible to define the impact of various surfactants, their amount and organo-smectites’ properties order on the sorption capacity and pH effect. Smectite has been modified with dodecyltrimethylammonium bromide (DDTMA), didodecyldimethylammonium bromide (DDDDMA), hexadecyltrimethylammonium bromide (HDTMA) and   dihexadecyldimethylammonium bromide (DHDDMA) in amounts of: 0.5, 1.0 and 2.0 of cation exchange capacity (CEC). Experiments of Mo(VI) and W(VI) sorption on organo-smectites were conducted under various concentrations of Mo(VI) and W(VI) (0 – 20 mM) and in wide range of pH’s (1-13). The effectiveness of modifications follows the order DDTMA-smectite-> HDTMA-smectite> DDDDMA-smectite > DHDDMA-smectite. The unmodified smectite did not remove Mo(VI) and W(VI) aninos from the aqueous solution at all. In the removal of Mo(VI), sorption efficiency follows the order: DDTMA-smectite > DDDDMA-smectite >  HDTMA-smectite> DHDDMA-smectite. In case of W(VI) the  efficiency of the removal can be place: DDDDMA-smectite> DDTMA-smectite> HDTMA-smectite> DHDDMA-smectite.  With an increasing concentration of Mo(VI) or W(VI) in the solutions, the sorption increases. The maximum sorption capacity in the removal of Mo(VI) was 1710 mmol Mo(VI)/kg in case of smectite modified with DDTMA at 0.5 CEC.  The best result of tungsten sorption was 5882 mmol W(VI)/kg and it was obtained for DDDDMA-smectite (0.5 CEC). Results showed that the sorption is more effective at a lower pH, in both Mo(VI) and W(VI) removal. The smectite modified with surfactant with double carbon chain (DDDDMA, DHDDMA) proved to be a better sorbent. With an increasing amount of surfactant attached to the smectite, the sorption efficiency increases

The Rietveld refinement studies of pyromorphite-vanadinite and mimetite-vanadinite solid solution series

Mimetite Pb 5 (PO 4 ) 3 Cl, vanadinite Pb 5 (VO 4 ) 3 Cl and pyromorphite Pb 5 (PO 4 ) 3 Cl belong to the apatite supergroup. They form in oxidation zones of lead ore deposits. These minerals have high thermal stability (Dong et al. 2002) and low solubility (Flis et al. 2011) thus they have many applications. Pyromorphite and mimetite are especially used to immobilize lead in contaminated soils and hazardous industrial wastes (Ma et al. 1993, Kim et al. 2005, Bajda et al. 2007), it is therefore important to know the impact of various factors on their properties. Crystal structure of apatites corresponds to the general formula M 5 (TO 4 ) 3 X, where M are bi - valent cations distributed on two distinct crystallographic sites, TO 4 is a trivalent oxyanion and X is a monovalent anion. The structure and chemistry of apatite allow for numerous substitutions of metal cation and anionic complexes (Hughes & Rakovan 2002, Pan & Fleet 2002). It was found that substitutions cause variations in the unit cell parameters and chemical properties of these minerals (Botto et al. 1997), but there are no articles presenting variations in the whole series. Therefore, these researches present changes of lattice parameters for pyromorphite-vanadinite and mimetite-vanadinite solid solution series. Pyromorphite, mimetite and vanadinite crystallize in hexagonal symmetry (the space group P6 3 /m) (Dong et al. 2002, Pan & Fleet 2002). They form continuous isomorphic series. The aim of study was to examine how lattice parameters of pyromorphite-vanadinite and mimetite-vanadinite solid solutions series change with increasing vanadium content and characterize these pheno mena. Crystallographic studies were conducted on synthetic pyromorphite, mimetite and vanadinite and minerals with intermediate compositions Pb 5 (TO 4 ) 3 Cl, where T = P + V or As + V, of various P/V or As/V ratios. Samples were analyzed by X-Ray diffraction (XRD) using RIGAKU Smartlab X-Ray diffractometer with Cu radiation in a 10° to 110° 2Θ range at a step size of 0.02 2Θ and a rate of 2 s per step. The phase identification was carried out using the X’Rayan computer program and X-ray standard patterns in the form of ICDD files (card 19-0701, 19-0683 and 43-1461). The unit-cell refinement and Rietveld structure refinement were made using the FullProf Suite computer program package (Rodriguez-Carvajal 1993). The Rietveld refinement has shown systematic changes in unit cell parameters of studied samples depending on their chemical composition. Dimensions of unit cell parameters of pyromorphite-vanadinite solid solution series increase linearly with the substitution of vanadate ions in the structure of pyromorphite. Lattice parameter “a” increase in the range of 9.987–10.325 Å, while lattice parameter “c” increase in the range of 7.33–7.343 Å. In case of the mimetite-vanadinite solid solution series, lattice parameter “a” increase (10.251–10.325 Å range), whereas lattice parameter “c” decrease (7.442–7.343 Å range) linearly with the substitution of vanadate ions in the structure of mimetite. This situation indicates the equivalent position of the tetrahedral TO 4 in the structure of lead apatite

Sorption of organic compounds by organo-zeolites

Organic compounds such as BTEX and PAHs are one of the most common contaminants in water system. These contaminants would take decades to degrade and they have harmful effects on human health (Qin et al., 2008). Several treatment methods have been developed to remove those contaminants from industrial wastewater. They include ion-exchange, filtration, adsorption and the use of various types of sorbents for example zeolites (Kibazohi et al., 2004; Mathur et al., 2007; Aivaliotiet al., 2012; Almeida et al. 2012). Natural clinoptilolite (Cp) from the Bystré deposit in Slovakia and zeolite Na-X synthesized from fly ash has been modified with a hexadecyltrimethyl ammonium bromide (HDTMA) in amounts of 1.0 and 2.0 of external cation exchange capacity (ECEC) of the zeolites (Szala et al., 2013). The sorption properties of unmodified zeolites and organo-zeolites in terms of aqueous solutions of benzene, ethylobenzene, toluene, p-xylene (BTEX) and their mixtures as well as anthracene, naphthalene, benzo[a]pyrene, dibenzo[a,h]anthracene (PAHs) and their mixtures at different concentrations were evaluated. The results showed that the modification of the zeolite Na-X  and Cp with HDTMA improves the sorption properties. Modification in the amount of 1.0 ECEC proved to be the best in terms of p-xylene, anthracene, naphthalene, benzo[a]pyrene, dibenzo[a,h]anthracene. On the other hand benzene, ethylobenzene and toluene were adsorbed the most effectively by 2.0 ECEC modification of Na-X and Cp. Based on experimental data, the removal efficiencies for BTEX follows the order: p-xylene > toluene > benzene > ethylobenzene, for POHs: dibenzo[a,h]anthracene > benzo[a]pyrene > anthracene > naphthalene. P-xylene and naphtalene were adsorbed in the greatest quantity and benzene and anthracene in the lowest quantity from the mixtures of BTEX and PAHs, respectively. The sorption efficiency depends on the physicochemical properties of the organic compounds (dipole moment, molar mass, molecule structure and the time of the sorption process) as well as natural Cp and synthetic zeolite Na-X properties, such as Si/Al ratio, texture parameters and external cation exchange capacity. With an increasing concentration of the hydrocarbons in the solution the sorption capacity increases (Szala et al., 2015). Natural Cp is a better sorbent than synthetic zeolite Na-X in case of BTEX sorption, while PAHs are adsorbed more effectively by zeolite Na-X and its modifications. The mechanism of the sorption consists on the dissolving of the organic compounds into the organic layer of the surfactant (on the zeolites’ surface) as well as on the organic compounds’ penetration into the mesopores

The effect of gluconic acid secretion by phosphate-solubilizing Pseudomonas putida bacteria on dissolution of pyromorphite Pb_{5}(PO_{4})_{3}Cl and Pb remobilization

The purpose of this study was to investigate the effect of bacterially produced gluconic acid on the dissolution of pyromorphite and Pb remobilization. Pyromorphite Pb_5(PO_4)_3Cl is formed as a product of the phosphate-induced treatment of Pb-contaminated sites. This very stable mineral greatly decreases the bioavailability of Pb. In this study, bacterial and abiotic batch experiments on the dissolution of pyromorphite were carried out. In the microbial experiments, the mineral was dissolved in the presence of the phosphate solubilizing soil bacterium, Pseudomonas putida. The bacterial growth medium was supplemented with glucose, which under natural conditions can be supplied to microbes via symbiosis with plants. P. putida acquired P from pyromorphite and enhanced its dissolution. Elevated Pb concentrations were observed in the suspensions with bacteria. The bacterial secretion of 16.5 mM gluconic acid played a significant role in Pb remobilization; the pH of the solution dropped down from an initial 7.4 to 3.5. In the abiotic experiments, pyromorphite was dissolved at several concentrations of gluconic acid and at an acidic to neutral pH range. Both acidification and formation of stable Ph-gluconate ligands enhanced the dissolution of pyromorphite and caused Pb remobilization

Structural and vibrational behaviour of pyromorphite-vanadinite solid solution series

Pyromorphite Pb5(PO4)3Cl and vanadinite Pb5(VO4)3Cl belong to the apatite supergroup. They are secondary minerals formed in the oxidation zones of lead ore deposits. Both crystallize in hexagonal symmetry with the space group P63/m (Dong et al. 2002). The crystal structure of these two minerals allows to accommodate both metal cations and anionic complexes. It is the reason, why pyromorphite and vanadinite forms solid solution series. Isovalent replacement of P with V is one of the most common anionic substitution. Lead apatites are one of the least soluble along apatites group minerals and characterized by high thermal stability (Dong et al. 2002, Flis et al. 2011). Characteristic properties of apatite structure cause that these minerals are successfully used in many fields, especially for the immobilization of toxic waste and lead-contaminated soil (Ma et al. 1993, Chen et al. 1997, Dong et al. 2002, Kim et al. 2005). So far, pyromorphite and mimetite are the most known and used for the immobilization of lead. Pyromorphite and mimetite are isostructural with vanadinite, therefore it has been predicted that this mineral is also important for the environment. Accordingly, the aim of this study was to characterize of the pyromorphite-vanadinite solid solution series. This research present systematic changes in the structure of these minerals. Pure pyromorphite and vanadinite and minerals with intermediate compositions Pb5(TO4)3Cl, where T = P + V, of various P/V ratios were synthesized  from aqueous solutions at 298 K and pH = 3.5. Synthetic solids were analyzed by X-Ray diffraction (XRD), infrared absorption spectroscopy (FTIR) and Raman spectroscopy. Based on the X-Ray analysis, it was found that synthetic precipitates represent homogeneous phases of pyromorphite and vanadinite, which have intermediate chemical composition. Diffraction peaks of pyromorphite-vanadinite solid solution series were shifted due to replacement of PO4 by VO4. Replacement of PO4 by VO4 anions is causing changes in the structure of apatite and hence these shifts. Unit cell parameters of studied solid solutions show a linear variation. In the FTIR and Raman spectra of pyromorphite-vanadinite solid solutions series, the bands which are characteristic for vibrations of P-O bonds of the PO4 tetrahedra as well as vibrations of V-O bonds of the VO4 tetrahedra appeared. Analysis of Mid-IR spectra and Raman spectra also allowed to observe correlation between the band positions and the extent of the anionic substitution among the studied series. The structure of pyromorphite and vanadinite is generally similar, although they vary in chemical composition. Causes of variability are probably connected with the properties of individual ions.The project was financed with resources of the National Science Centre, Poland, granted based on decision no. DEC-2013/09/N/ST10/00677

Analysis of the porosity degree during laser-assisted cladding of bioactive glass on titanium substrates with highly refined grain structure

Titanium alloys, due to their exceptional mechanical properties and biocompatibility, are commonly used to produce medical implants nowadays. However, the presence of such elements as aluminium and vanadium can be harmful to human health. One of the possible solutions could be replacing the titanium alloys with commercially pure titanium (cpTi) with highly refined grain structure. One of the most promising methods in manufacturing medical implants with improved biological fixation is laser cladding in which bioactive glass coatings are imposed on metallic substrates. The aim of this work is to present a 3D numerical modelling of the above mentioned additive manufacturing process. The obtained model is able to predict the stress-strain and temperature distributions as well as porosity degree during the processing. Porosity affects the bioactivity of medical implants as it significantly improves their ability to bonding with host tissues

Synthesis, molecular modelling and biological evaluation of novel heterodimeric, multiple ligands targeting cholinesterases and amyloid beta

Cholinesterases and amyloid beta are one of the major biological targets in the search for a new and efficacious treatment of Alzheimer’s disease. The study describes synthesis and pharmacological evaluation of new compounds designed as dual binding site acetylcholinesterase inhibitors. Among the synthesized compounds, two deserve special attention—compounds 42 and 13. The former is a saccharin derivative and the most potent and selective acetylcholinesterase inhibitor (EeAChE IC50 = 70 nM). Isoindoline-1,3-dione derivative 13 displays balanced inhibitory potency against acetyl- and butyrylcholinesterase (BuChE) (EeAChE IC50 = 0.76 μM, EqBuChE IC50 = 0.618 μM), and it inhibits amyloid beta aggregation (35.8% at 10 μM). Kinetic studies show that the developed compounds act as mixed or non-competitive acetylcholinesterase inhibitors. According to molecular modelling studies, they are able to interact with both catalytic and peripheral active sites of the acetylcholinesterase. Their ability to cross the blood-brain barrier (BBB) was confirmed in vitro in the parallel artificial membrane permeability BBB assay. These compounds can be used as a solid starting point for further development of novel multifunctional ligands as potential anti-Alzheimer’s agents