The fractal characterization of supported nanoparticles is a useful tool for obtaining structural and morphological information that strongly impacts catalytic properties. We have synthesized and characterized Pt supported on TiO2 nanostructures. Triblock copolymers with thermosensitive properties were used as templating agents during the synthesis process. In addition to the several techniques used for the characterization of the materials, we carried out fractal analysis. The prepared materials showed a reduction in the band gap of TiO2 from 3.44 to 3.01 eV. The extended absorption in the 500–700 nm regions is mostly attributed to the presence of supported Pt nanoparticles. The ability of the nanostructured Pt/TiO2 catalysts to generate H2 in an aqueous solution was evaluated. The test reaction was carried out in the presence of methanol, as a hole scavenger, under simulated solar light. Pt/TiO2-3TB shows the highest rate of H2 (4.17 mmol h−1 gcat−1) when compared to Pt/TiO2-0TB (3.65 mmol h−1 gcat−1) and Pt/TiO2-6TB (2.29 mmol h−1 gcat−1) during simulated solar light irradiation. Pt/TiO2-3TB exhibits a more structured organization (fractal dimensions of 1.65–1.74 nm at short scales, 1.27–1.30 nm at long scales) and a distinct fractal behavior. The generation of hydrogen via photocatalysis can be linked to the fractal characteristics.

ZnSe, ZnSe-TiO2 microspheres and nanostructured TiO2 obtained by hydrothermal and sol–gel methods were tested against Staphylococcus aureus ATCC 25923 and Micrococcus lysodeikticus ATCC 4698 before and after lysozyme (Lys) loading. Morphological characterization of inorganic matrices and hybrid organic–inorganic complexes were performed by microscopy techniques (SEM, AFM and Dark Field Hyperspectral Microscopy). Light absorption properties of ZnSe, ZnSe-TiO2 and TiO2 powders were assessed by UV–visible spectroscopy and their ability to generate reactive oxygen species (•OH and O2•−) under visible light irradiation was investigated. Antibacterial activity of ZnSe, ZnSe-TiO2, TiO2, Lys/ZnSe, Lys/ZnSe-TiO2 and Lys/TiO2 samples under exposure to visible light irradiation (λ > 420 nm) was tested against Staphylococcus aureus and Micrococcus lysodeikticus and correlated with ROS photogeneration.

The control of catalytic performance using synthesis conditions is one of the main goals of catalytic research. Two series of Pt-Ti/SBA-15 catalysts with different TiO2 percentages (n = 1, 5, 10, 30 wt.%) were obtained from tetrabutylorthotitanate (TBOT) and peroxotitanate (PT), as titania precursors and Pt impregnation. The obtained catalysts were characterized using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), N-2 sorption, Raman, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), hydrogen temperature-programmed reduction (H-2-TPR) and H-2-chemisorption measurements. Raman spectroscopy showed framework titanium species in low TiO2 loading samples. The anatase phase was evidenced for samples with higher titania loading, obtained from TBOT, and a mixture of rutile and anatase for those synthesized by PT. The rutile phase prevails in rich TiO2 catalysts obtained from PT. Variable concentrations of Pt-0 as a result of the stronger interaction of PtO with anatase and the weaker interaction with rutile were depicted using XPS. TiO2 loading and precursors influenced the concentration of Pt species, while the effect on Pt nanoparticles' size and uniform distribution on support was insignificant. The Pt/PtO ratio and their concentration on the surface were the result of strong metal-support interaction, and this influenced catalytic performance in the complete oxidation of methane at a low temperature. The highest conversion was obtained for sample prepared from PT with 30% TiO2.

The present work provides a new approach to the water denitration process and a facile strategy of catalyst preparation for the efficient hydrogen generation. The main focus of the research reported here was nitrate removal from aqueous solutions and simultaneous hydrogen generation under UV-Vis-light irradiation. This is a very important aspect in case of practical applications, eliminating the external source of hydrogen. Aiming to get a deeper understanding on the role of surface structures (size and shape of nanoparticles) towards the reduction mechanism and to establish basic principles for an efficient process, Pt-Cu/TiO2 and Pt-Cu/TiO2 modified with well-defined Pt nanoparticles were employed. The synthesized materials were characterized using various physicochemical techniques and tested comparatively for: (i) nitrate catalytic reduction by hydrogen (dark reaction) and (ii) nitrate photocatalytic reduction by in-situ generated solar hydrogen. In order to enhance overall denitration reaction by combined photocatalytic and catalytic processes, photo-generated charges and in-situ generated H-2 as reducing agent were used. Improvement of catalytic performances of nitrate hydrogenation reaction (~100% NO3 over line conversion) related to intimate contact between Pt and Cu was obtained. The in-situ generated H-2 by water splitting over the studied catalysts reduces efficiently NO3 over line ions. Enhanced photo-catalytic activity toward solar H-2 production by deposited well-defined Pt nanoparticles (~10 nm) was achieved. In order to make possible decontamination of polluted waters using in-situ generated H-2 under light exposure, the future optimization of such photo-catalytic systems looks promising.

A multi-step ion-exchange methodology was developed for the fabrication of Cu(LaTa2O7)2 lamellar architectures capable of wastewater depollution. The (001) diffraction line of RbLaTa2O7 depended on the guest species hosted by the starting material. SEM and TEM images confirmed the well-preserved lamellar structure for all intercalated layered perovskites. The UV–Vis, XPS, and photocurrent spectroscopies proved that Cu intercalation induces a red-shift band gap compared to the perovskite host. Moreover, the UV–Vis spectroscopy elucidated the copper ions environment in the Cu-modified layered perovskites. H2-TPR results confirmed that Cu species located on the surface are reduced at a lower temperature while those from the interlayer occur at higher temperature ranges. The photocatalytic degradation of phenol under simulated solar irradiation was used as a model reaction to assess the performances of the studied catalysts. Increased photocatalytic activity was observed for Cu-modified layered perovskites compared to RbLaTa2O7 pristine. This behavior resulted from the efficient separation of photogenerated charge carriers and light absorption induced by copper spacer insertion.

Structural and functional changes induced by TiO2 addition to spherical zinc selenide together with lysozyme adsorption lead to valuable bioinorganic catalysts with enhanced activity. Spherical zinc selenide and its composite with TiO2 were obtained by hydrothermal method and subsequently modified by lysozyme adsorption. Morphological, structural and functional characteristics of zinc selenide based materials (ZnSe, TiO2-ZnSe) and their hybrids with lysozyme (Lys/ZnSe, Lys/TiO2-ZnSe) were investigated. TiO2 addition to ZnSe results in significant changes of surface composition, electrochemical behavior and lysozyme retention capacity. The lysozyme modified ZnSe and TiO2-ZnSe surfaces doubles the biocatalysts efficiency for 4-Methylumbelliferyl p-D-N,N',N ''-triacetylchitotrioside hydrolysis reaction compared to free lysozyme.

Super Duplex Stainless Steel (SDSS) alloys, due to their high strength, toughness, and corrosion resistance properties, are widely used in aggressive conditions. However, once SDSS is exposed to an elevated temperature environment during welding, forging, hot working, heat treatment, casting, and aging, the undesired sigma (sigma) phase can form, which reduces the corrosion resistance and toughness. In this study, the microstructural evolution of the sigma phase in SDSS type UNS S32760 F55 under heating was correlated with the thermodynamic functions of the phase transformations. Samples were isothermally aged at different temperatures in the range of 573.15-1373.15 K using two different time intervals, 30 min and 6 h, in both air and Ar gas. The results showed that the formation of the sigma phase depends on the cooling rate, as 3% of the sigma phase was formed in water quenched alloy. The peak of the transformation to sigma and secondary austenite phases was observed at 1023.15 K, which was strongly dependent on the aging time, rather than the aging environment. Electrochemical results revealed a good corrosion resistance for the as-received alloy in 3.5% NaCl solution. This study points out how the results obtained by calorimetry methods are used to express the microstructural evolution of an alloy into macroscopic thermodynamic parameters. The high-temperature thermodynamic data offer significant insights into the design of an alloy that can be used in harsh environments.

Due to its low solubility, carbamazepine (CBZ) exhibits slow and incomplete release in the gastrointestinal tract and, hence, variable pharmacokinetics and pharmacodynamic effect. Lots of methods have been devised to improve its solubility, the large number of proposed solutions being a sign that the problem is not yet satisfactorily solved. The persistent problem is that predictable release kinetics, an increased rate but within defined limits, are required to avoid high absorption variability. This paper presents a synthesis of a carbamazepine-β-cyclodextrin inclusion complex (CBZ-β-CD), the characterization of the physical mixture, CBZ, β-CD and the CBZ-β-CD inclusion complex using Fourier transform infrared spectroscopy, scanning electron microscopy, simultaneous thermal analysis and X-ray diffraction, formulation of chewable tablets, determination of the dissolution of carbamazepine in medium containing 1% sodium lauryl sulfate (LSS), and in simulated saliva (SS), mathematical modeling of release kinetics. The kinetics of total CBZ release from tablets containing CBZ-β-CD and super-disintegrant F-Melt in both SS and LSS followed two steps: a burst release in the first minutes and a slower release in intervals up to 60 min. The release in the second phase has been well described by the Higuchi and Peppas models, which advocate a controlled release by combined diffusion and with some phenomena of swelling and relaxation of the matrix generated by the crospovidone component of the F-Melt excipient.

Carbamazepine (CBZ) is a sodium channel blocker that has been recommended. [...]

Nowadays, efforts to develop novel light harvesters with high activity, stability and economy of precious metals it is fundamental in the field of photocatalysis. In this regard, coupling a low bad gap of p-type CuO with a high reactive n-type HLaTa2O7 protonated layered perovkite, is expected to produce enhanced charge carrier lifetime with beneficial impact on the photocatalytic activity. Therefore, a novel lamellar architecture was fabricated, via successive intercalation of n-butylamine followed by slowly introduction of smaller Cu2+ cations using HLaTa2O7 as host matrix to yield Cu2+/CuxLaTa2O7 layered compound. According to XRD data, the peak corresponding to (001) diffraction line of HLaTa2O7 host material was changed depending on the guest molecule in the interlayer (i.e. n-butylamine, copper). H2-TPR results of the fabricated Cu-based perovskite indicated the co-existence of both Cu2+ reduced in two steps on HLaTa2O7 surface and [Cu2+(amine)-]+ between host interlayers. A correlation between H2-TPR experiments and EDX analysis shows that 26 % Cu2+ was incorporated in between interlayer galleries of HLaTa2O7. The beneficial role of copper addition demonstrates increasing of the specific surface area up to 4.1 m2/g compared to unmodified host compound. The photocatalytic degradation of phenol under simulated solar light irradiation has been used to assess the activity of modified layered perovskites. Our finding strongly support Cu-based layered perovskite as a promising candidate for depollution reactions.

Several FeTi-SBA-15 magnetic nanocomposites were synthesized using different titanium precursors and synthesis methods. The obtained materials were characterized by X-ray diffraction (XRD), N-2-adsorption/desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Raman, UV-vis and X-ray photoelectron (XPS) spectroscopic techniques. The photocatalytic performances were evaluated in degradation of methyl orange (MO) and phenol as water pollutant sources. All the obtained samples were either paramagnetic or superparamagnetic. The biggest Ti amount was found for the one-step synthesized FeTi-SBA-15 sample for which the highest photocatalytic activity was evidenced. The photocatalytic behavior of this sample has been compared to that of a two steps prepared FeTi-SBA-15 samples, Fe-SBA-15 and a reference sample containing SBA-15 with 5 % P25 titania. These results revealed a significant effect of iron on the photocatalytic activity and a synergism of Ti and Fe species. Besides efficiency, FeTi-SBA-15 demonstrated a good stability over five-successive photocatalytic cycles in MO degradation thus providing arguments for their good suitability for purification of wastewaters.

We have explored an efficient strategy to enhance the overall photocatalytic performances of layered perovskites by increasing the density of hydroxyl group by protonation. The experimental procedure consisted of the slow replacement of interlayer Rb+ cation of RbLaTa2O7 Dion-Jacobson (DJ) perovskite by H+ via acid treatment. Two layered perovskites synthesized by mild (1200 °C for 18 h) and harsh (950 and 1200 °C, for 36 h) annealing treatment routes were used as starting materials. The successful intercalation of proton into D-J interlayer galleries was confirmed by FTIR spectroscopy, thermal analyses, ion chromatography and XPS results. In addition, the ion-exchange route was effective to enlarge the specific surface area, thus enhancing the supply of photocharges able to participate in redox processes involved in the degradation of organic pollutants. HLaTa_01 protonated layered perovskite is reported as a efficient photocatalyst for photomineralization of trichloroethylene (TCE) to Cl− and CO2 under simulated solar light. The enhanced activity is attributed to combined beneficial roles played by the increased specific surface area and high density of hydroxyl groups, leading to an efficiency of TCE mineralization of 68% moles after 5 h of irradiation.

Studies on the nitrate reduction reaction have shown that the bimetallic catalysts may be more efficient compared to the monometallic ones. To reduce nitrate, it is necessary to activate the precious metal by addition of a promoting second metal. Some studies have pointed out the relevance of the structure and geometry of the metal particles in the final mechanism of nitrate reduction. Well-defined nanoparticles could be used to catalyze structure-sensitive reactions with practical importance (pollution control). Our investigation aimed to make deeper insight into NO3- catalytic reduction and photocatalytic reduction mechanisms. Two types of Pt-Cu supported on TiO2 materials were employed in order to study the nitrate removal from aqueous phase and the ability of obtaining and using the in situ generated solar H2 as reducing agent. The prepared catalysts were characterized and tested in photocatalytic/catalytic reduction of nitrate in aqueous solution in water splitting reaction. A correlation between the catalytic/photocatalytic performances of the supported Pt-Cu catalysts and their associated physicochemical and adsorption properties has been made. The catalysts activity for the nitrate reduction can be directly related to the interactions between platinum and copper. Deposition with Pt nanoparticles was found to contribute to enhance the photocatalytic activity toward H2 production from aqueous solution. Our future research aims at optimizing the photocatalytic system having as future possible applications for hydrogen production using sunlight and water as the hydrogen source.

The formation and growth of gold nanoparticles (AuNPs) were investigated in pH 7 buffer solution of bovine serum albumin (BSA) at room temperature. The processes were monitored by UV-Vis, circular dichroism, Raman and electron paramagnetic resonance (EPR) spectroscopies. TEM microscopy and dynamic light scattering (DLS) measurements were used to evidence changes in particle size during nanoparticle formation and growth. The formation of AuNPs at pH 7 in the absence of BSA was not observed, which proves that the albumin is involved in the first step of Au(III) reduction. Changes in the EPR spectral features of two spin probes, CAT16 and DIS3, with affinity for BSA and AuNPs, respectively, allowed us to monitor the particle growth and to demonstrate the protective role of BSA for AuNPs. The size of AuNPs formed in BSA solution increases slowly with time, resulting in nanoparticles of different morphologies, as revealed by TEM. Raman spectra of BSA indicate the interaction of albumin with AuNPs through sulfur-containing amino acid residues. This study shows that albumins act as both reducing agents and protective corona of AuNPs.

The present work proposes the simultaneous removal of these classes of pollutants by a catalytic hydrotreatment processes. For this purpose, bimetallic Pd-Cu catalysts (with mass ratio Pd:Cu of 4:1) supported on macroporous strong base anion resin were prepared by different methods. The catalysts were characterized (by XRD, SEMEDX, XPS, AAS and H-2 chemisorption) and tested in a continuous flow system. The selected catalyst preparation protocol consists in a two-step method, which implies the deposition of palladium by ion exchange and the subsequent deposition of copper by controlled reaction on the surface of the pre-reduced palladium. The effectiveness of the catalyst in the simultaneous reduction of nitrate and hydrodechlorination of 4-chlorophenol was demonstrated. By adjusting the initial pH and the flow rate of the aqueous solution, nearly complete hydrodechlorination of 4-chlorophenol can occur together with selective nitrate reduction at a conversion of 95% and a selectivity to N-2 of 92% (this value contains the contribution of all gaseous products, including the eventually formed NOx). The bimetallic catalyst was found to remains relatively stable after 100 h of test time.

Nanosized ZnO has been prepared following a non-polluting, straightforward, and flexible combustion synthesis method, using as biofuels starch and cellulose, and as zinc source nitrate and acetate. While the crystallite size and the surface area of the ZnO materials are to a certain extent sensible of the post-thermal processing temperature, the defect chemistry is dependent on reductant/oxidant ratio. The obtained ZnO materials, particularly the oxides obtained from carbohydrate-nitrate precursors present considerable photodegradation activity upon two hazardous EDCs phenolic wastes and excellent antimicrobial efficiency against planktonic Gram negative and positive strains. Both results can be explained by an optimum defects configuration of these oxides. The photocatalytic and biocidal efficiency associated with the easy and complete recovery from the treated wastewaters proves the potential toward environmental remediation applications of these "two in one" formulations.

Single ZnO crystallites assembled into porous hierarchical structures have been prepared by topotactic thermal decomposition of in situ obtained zinc oxalate precursors, whose synthesis involves a redox reaction between 1,2-ethanediol and nitrate ion. For the first time it was demonstrated that post-synthesis protocols of the precursors (e.g. ultrasound irradiation, hydrolytic decomposition) master the hydrogen bonds formed between oxalate chains, allowing that way the adjustment of materials properties (morphology, porosity and optical) and a rational introduction of different dopants (Eu3+/Er3+). The ZnO surface reactivity is confirmed by the significant biocidal activity of the obtained materials against Gram-positive and Gram-negative planktonic and biofilm-embedded cells, superior to those reported in the literature for other ZnO-based materials or antibiotics, associated also with a good biocompatibility.

Pt-Cu/TiO2 catalysts were prepared by two reductive deposition methods, using a thermosensitive triblock copolymer as template agent. The prepared catalysts were characterized using X-Ray Diffraction, SEM microscopy, EDX, UV-Vis Diffuse Reflectance Spectroscopy and CO pulse chemisorption measurements. The CO oxidation over Pt-Cu/TiO2 materials was evaluated in order to investigate the impact of preparation methods on the catalytic performances.

In this study, we report the synthesis and characterization of RbLaTa2O7 layered perovskite obtained by conventional solid-state reaction at 1100 degrees C at two reaction times, 10 h and 18 h. XRD results showed that prolonging the reaction time highly affected the phase composition of the obtained solids. The photocatalytic test results indicate that RbLaTa-10h sample shows better performance for abatement of trichloroethylene (TCE) compared to RbLaTa-18h, under simulated solar light irradiation. The enhanced photocatalytic activity is attributed to the larger amount of surface -OH groups which are responsible for generation of strongly oxidizing hydroxyl radicals. Significant values of TCE conversion, after 18 h of reaction time, makes the obtained layered perovskite suitable candidate for the photocatalytic abatement of harmful chlorinated compounds.