1,264 research outputs found
Structural modifications induced by adsorption of pharmaceuticals from water on Y organophilic zeolite
No full textDomestic and commercial wastewaters contain a variety of organic wastewater contaminants such as pharmaceuticals
and personal care products. These compounds undergo incomplete removal in wastewater treatment plants
and they are found in the surface waters receiving the effluents of these plants. In the present work the removal of
several drugs (which differ in chemical properties and molecular dimensions) from water by Y organophilic zeolite
(SiO2/Al2O3 ratio equal to 200) was investigated. All selected drugs (erythromycine, carbamazepine, levofloxacin,
hydrochlorothiazide, ketoprofene, diclofenac) are ubiquitous contaminants in the sewage waters, nor effectively
removed by conventional activated sludge treatment and membrane bioreactors (MBRs). This study has a dual
purpose: i) to measure the sorption capacity of hydrophobic commercial zeolite material weighed against drugs
dissolved in water and to quantify aspects of their removal efficiency for potential use in wastewater and groundwater
remediation, and ii) to understand the zeolite structure features for adsorption of drugs in aqueous solutions.
Kinetics and adsorption isotherm batch data were obtained via HPLC-DAD. Breakthrough curves were obtained
by using 0.2x2 cm SS column and a standard HPLC equipment. Powder diffraction patterns were measured on a
Bruker D8 Advance Diffractometer equipped with Sol-X detector. Thermogravimetric (TG) and differential thermal
analyses (DTA) measurements were performed in air up to 900C using a STA 409 PC LUXX® - Netzch
at 10C/min heating. After adsorption, the X-ray diffraction patterns of untreated and exhausted samples show
relevant differences both in the intensity and position of the diffraction peaks, indicating that the zeolite crystal
structure was markedly modified by the pharmaceuticals adsorption experiment. Rietveld refinement demonstrated
that the adsorption of the tested pharmaceuticals in Y zeolite induces strong unit cell parameter variations as well
as remarkable distortion of the framework, thus confirming the adsorption of the drugs inside the channel system.
The results of this study indicate that Y zeolite is an efficient materials for the removal of selected contaminants in
wastewater remediation rate
Adsorption of antibiotics by organophilic zeolites
No full textDomestic wastewaters contain a variety of organic wastewater contaminants such as pharmaceuticals and personal care products. It has been proven that most of these compounds undergo both incomplete removal in wastewater treatment plants and slow natural degradation, consequently they are found in surface waters receiving effluent from treatment plants. In Italy, it was found that the most abundant residual drugs in surface waters were antibiotics. This class of pharmaceuticals are of particular concern because their presence in natural waters contributes to the spread of antibiotic resistance in microorganisms.
The aim of this work is to investigate the capability of hydrophobic commercial zeolites (Mordenite, Y, ZSM-5, Beta) in removing two test antibiotics Levofloxacin (FLX) and Erythromycin (ERY). The selected zeolites differ in topology, channel systems, free window apertures, hydrophobicity (SAR: Silica/Alumina Ratio) and thermal treatment (calcination).
The employment of zeolites as adsorbent materials has a dual potential use: 1) improve the wastewater and groundwater efficiency remediation and 2) test these siliceous porous materials in nanomedicine applications, like drug delivery systems (i.e. devices that enable for an accurate control the rate at which drug molecules are delivered into the bloodstream).
ERY adsorption was studied only on Y, MOR and Beta zeolites since its molecular dimensions are too large when compared to the ZSM-5 cage. From Fig. 1a it can be seen that ERY adsorption on calcined Beta decreases with the hydrophobicity of the material, showing that drugs adsorption depends on both ionic and hydrophobic interactions. Fig. 1b shows that FLX adsorption on Y is higher than that on MOR: this difference cannot be related solely to the molecular dimension, since the access window cross section in Y and MOR are comparable, hence they could be due to the dispersive interaction between the adsorbate and the zeolite pore walls. Finally, chromatographic, structural and thermogravimetric measurements demonstrate that the selected zeolites show fast adsorption kinetics and good removal properties for the studied antibiotics from water
The role of substrate materials on stabilization of CdO, 2CdO·CdSO4 and 2CdS·2CdO·CdSO4 from CdS powder film annealed in air
No full textThe relative stability of CdS and CdO with respect of substrates has been widely studied up to 500 °C, the upper temperature in many applications. The physical-chemical properties of the deposited films are often revealed to be influenced by deposition substrates. In this paper, using XRD, SEM and EDX methods, we have studied the oxidation/desulphurization of CdS to CdO and the intermediate stabilized materials therein (i.e. 2CdO·CdSO4 and 2CdS·2CdO·CdSO4), by using CdS films deposited on different substrates (i.e. nickel, Si-polycrystalline, glaze porcelain and α-Al2O3) which were annealed in air up to 800 °C. At the annealing temperatures used in this study, different phases were found to be stabilized on different substrates. The relative stability of CdO and 2CdO·CdSO4 phases is greater on α-Al2O3 than on glazed porcelain substrate. A mixed phase of CdO and 2CdO·CdSO4 was obtained at the annealing temperature of 800 °C if films are deposited on Ni and polycrystalline silica. The amount of the oxidized CdS (i.e. CdO and 2CdO·CdSO4) obtained by mixing CdS and Al2O3 powders at different Al2O3/CdS ratios and annealed up to 800 °C, were also investigated. Decreasing the Al2O3/CdS ratio, the interactions between Al2O3 and CdS particles are reduced, consequently the CdO stabilization is strongly retarded in favour of 2CdO·CdSO4, while reverse results was proven for high values of Al2O3/CdS ratio. The results show the role of the interface area between Al2O3 and Cd-materials for stabilization of CdO. A low interface area was also obtained by filling an α-Al2O3 crucible with CdS powder. After annealing, the CdO stabilization was strongly reduced, in line with the low Al2O3/CdS ratio sample. Spreading the CdS powder on the α-Al2O3 substrate, instead of drop coating deposition method, showed a remarkable CdO stabilization in line with the results obtained with drop coating method. To account for the role of the interface area a model is proposed (Stabilization model), based on surface energy, as responsible to phase stabilization to explain the nucleation – stabilization of the CdO and 2CdS·2CdO·CdSO4. The morphologies of the CdO and 2CdS·2CdO·CdSO4 resemble hexagonal-prism shapes and compact chips, respectively, while 2CdO·CdSO4 phases has a sponge-like appearance
Limited crystallite growth upon isothermal annealing of nanocrystalline anatase
No full textThe crystalline growth kinetics during isothermal sintering of two nanotitania powders synthesized by similar routes, but with and without the presence of chlorine in the synthesis batch, were studied by X-ray powder diffraction and modeled by several grain growth models. Both nanopowders contained anatase as the initial titania phase with similar crystallite dimension.
Crystal growth curves at three isotherms per sample were sampled over a period of time up to 40 h. Temperature steps within different ranges (375, 425, and 475 °C for Cl-free sample; 500, 550, and 600 °C for Cl-containing sample) were chosen. The XRD analysis of samples heated at 900 °C revealed that, while the entire Cl-free sample was converted to rutile, only 10% of the Cl-containing sample had transformed to rutile with a very limited crystal growth. Direct comparison of the crystal growth curves showed different behavior which was modeled by different grain growth kinetic equations including a growth limiting factor. Although the generalized parabolic grain growth model with time exponent (so-called “Hofler-Averback equation” ) provided good fi ts for both the Cl-free and Cl-containing nanopowders at all temperatures, only the isothermal curve at 500 °C of the Cl-containing sample was satisfactorily fitted with a modified KJMA equation. The activation energy values of the grain growth are very similar and in line with the previously reported values. We conclude that the crystal size locking phenomenon observed for Cl-bearing anatase can be ascribed to the effects of chlorine ions adsorbed on grain surface as previously suggested. The blocked crystal growth of nanoanatase obtained by the reflux synthesis of organic solvents in the presence of hydrochloric acid as catalyst makes this material very appealing for devices that require a given nanosize and for the anatase phase in spite of the high temperature processing
Tin(IV) sulfide nanorods as a new gas sensing material
No full textNanosized tin disulfide (SnS2) powder was synthesized through a simple and inexpensive process, then characterized via thermal, chemical, structural and morphological analyses. Conductometric gas sensors based on thick films of synthesized SnS2 were fabricated by means of screen-printing technology and their sensing properties tested vs. aldehydes, ketones and other gaseous compounds. We found that, at working temperature of 300 °C, the SnS2 films showed a strong selectivity vs. the carbonyl group of aldehydes and ketones, proving that they can efficiently be detected even in complex mixtures with interferers. In comparison with its oxide counterpart, SnS2 proved to be more stable, in term of the long-term drift of the signal. On the base of the obtained results, practical applications of such a sensor have been addresse
Limited grain-growth during annealing of nanocrystalline anatase used in photovoltaic solar cells
No full textHow sea urchins face microplastics: Uptake, tissue distribution and immune system response
No full textPlastic pollution represents one of the major threats to the marine environment. A wide range of marine organisms has been shown to ingest microplastics due to their small dimensions (less than 1 mm). This negatively affects some biological processes, such as feeding, energy reserves and reproduction. Very few studies have been performed on the effect of microplastics on sea urchin development and virtually none on adults. The aim of this work was to evaluate the uptake and distribution of fluorescent labelled polystyrene microbeads (micro-PS) in the Mediterranean sea urchin Paracentrotus lividus and the potential impact on circulating immune cells. Differential uptake was observed in the digestive and water vascular systems as well as in the gonads based on microbeads size (10 and 45 μm in diameter). Treatment of sea urchins with particles of both sizes induced an increase of the total number of immune cells already after 24 h. No significant differences were observed among immune cell types. However, the ratio between red and white amoebocytes, indicative of sea urchin healthy status, increased with both particles. This effect was detectable already at 24 h upon exposure to smaller micro-PS (10 μm). An increase of intracellular levels of reactive oxygen and nitrogen species was observed at 24 h upon both micro-PS exposure, whereas at later time these levels became comparable to those of controls. A significant increase of total antioxidant capacity was observed after treatment with 10 μm micro-PS. Overall data provide the first evidence on polystyrene microbeads uptake and tissue distribution in sea urchins, indicating a stress-related impact on circulating immune cells
Limited grain-growth during annealing of nanocrystalline anatase used in photovoltaic solar cells
No full textCorrection to: When terminology hinders research: the colloquialisms of transitions of control in automated driving (Cognition, Technology & Work, (2022), 10.1007/s10111-022-00705-3)
No full textIn the original article, author affiliation published with error. The correct affiliations are: Davide Maggi—Institute for Transport Studies, Leeds, UK. Richard Romano—Institute for Transport Studies, Leeds, UK. Oliver Carsten—Institute for Transport Studies, Leeds, UK. Joost C. F. De Winter—Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands. The original article has been corrected.Human-Robot Interactio
Admiel Kosman, Siamo giunti a Dio
No full textInternational audienceSix poems from Israeli poet Admiel Kosman translated from the Hebrew into Italian. Selection of poems, presentation of the author, translation and notes by Davide Mano
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