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ZnO nanoparticles functionalized with APTES were obtained to evaluate their CH4 and CO2 adsorption at 298 K in a range between 0 and 10 bar. First, ZnO nanoparticles were obtained by a precipitation method and subsequently coated with (3-aminopropyl)triethoxysilane (APTES). As a preliminary study, the results were compared with previously reported naked nanoparticles in order to evaluate the influence of APTES coating on CO2 selectivity. UV-Vis, FT-IR spectroscopy, TGA, XRD, TEM/EDX, XPS and N2 adsorption at 77 K were used to characterize the evaluated material. It was observed that the amount of gas adsorbed on the surface of the nanostructure was very small in comparison with other materials traditionally used for this purpose but slightly higher than those obtained in naked nanoparticles evaluated in previous studies. The affinity of CO2 for the amines groups of the APTES ligand was also discussed.

The use of nanofluids in enhanced oil recovery processes has gained attention due to the possibility to intensify oil recovery from mature oil fields. When nanofluids are injected into oil wells, different mechanisms are involved such as wettability alteration, reduction of interfacial surface tension, increase in the viscosity of the aqueous solution, and decrease in oil viscosity. Silica nanoparticles are extensively used for nanofluid formulations but there are important obstacles to the use of nanofluids in enhanced oil recovery. Stability is the most evident, in addition to environmental and economic aspects, and the need to design suitable large-scale production processes for nanoparticle synthesis with the required characteristics. Thus, the present study aims to evaluate oil recovery using silica-based nanofluids from various sources (natural rice husk ash, sol-gel synthesis, and commercial nanosilica) under different operational conditions. Silica nanoparticles were characterized by XRF, XRD, TEM, FTIR, specific surface area, and XPS. Nanofluids with different nanoparticles concentration were characterized by their viscosity, surface tension, zeta potential, and stability. Oil recovery from an oil-saturated sand-packed bed increased due to the nanofluid injection after secondary recovery. An additional 5–10% oil recovery is achieved after flooding due to the injection of nanofluids, proving that silica from rice husk ash has comparable efficiency to other synthetic silica nanoparticles that are used in enhanced oil recovery.

Simple and cost-effective procedures for the direct integration of ferroelectric perovskite oxides into Ni structures are necessary to realize related multifunctional metallic microelectromechanical systems, such as dual-source energy harvesters. This is especially difficult in the case of lead-containing morphotropic phase boundary materials for high piezoelectric response because the two components are thermodynamically incompatible and the formation of NiOx or perovskite oxide reduction takes place depending on the processing conditions. We show here that low-temperature solution processing is an effective means to kinetically limit nickel oxidation, capable of providing BiFeO3–PbTiO3 films on Ni plates at only 500 °C. Bulk-like ferroelectric properties and a distinctive magnetoelectric response were attained. This perovskite system, not explored before on Ni, has a much larger switchable polarization than the widely studied Pb(Zr,Ti)O3, and it is shown here to present an excellent downscaling behavior of ferroelectric properties until the verge of the nanoscale.

Abstract The transport sector is in all probability the one that emits the greatest amounts of CO2 and other harmful gases into the atmosphere. Therefore, the emission of greenhouse gases from the combustion of fossil fuels must be significantly reduced to mitigate their harmful effects on the environment. In this sense, bio‐fuels obtained from lignocellulosic biomass are a solution to partially replace fuels from petroleum. However, the biggest challenge facing the scientific community is to decrease the amount of oxygen in bio‐fuels through catalytic hydrodeoxygenation (HDO) reactions. This review offers a broad perspective on the catalytic systems used so far in the HDO processes of model compounds present in bio‐fuels, analyzing in detail the advantages and disadvantages of each system to give a vision towards the future.

This research pioneers the application of microwave irradiation as an innovative strategy for one-pot synthesis and surfactant elimination (cetyltrimethylammonium bromide—CTAB) from MCM-41, introducing a rapid and efficient methodology. MCM-41 silica is widely utilized in various applications due to its unique textural and structural properties. Nonetheless, the presence of residual surfactants after synthesis poses a challenge to its effective application. MCM-41 synthesis, conducted in a microwave reactor at 60 °C, provided a result within 0.5 to 1 h. Comprehensive analyses of structural, chemical, morphological, and surface characteristics were undertaken, with a focus on the impact of synthesis time on these properties. Surfactant extraction involved the use of ethanol as a solvent at 120 °C for 6 min within the microwave reactor. The acquired particles, coupled with the properties of textural and structural features, affirmed the efficacy of the synthesis process, resulting in the synthesis of MCM-41 within 36 min. This study presents the first instance of one-pot synthesis and surfactant removal from MCM-41 using a microwave reactor. The proposed method not only addresses the surfactant removal challenge, but also substantially accelerates the synthesis process, thereby enhancing the potential for MCM-41’s application in diverse fields.

The aim of this study is to investigate the thermal behavior of Pinus wood pellets during torrefaction under different operational conditions, as well as to evaluate the potential application of the torrefied product in metallurgical processes. Torrefaction tests were carried out in an oxidizing atmosphere (245 °C) and in an inert atmosphere (270 and 290 °C) at residence times of 15 and 60 min. The results of torrefaction in inert atmosphere were also statistically evaluated. To evaluate the potential application of torrefied biomass in metallurgical processes, reactivity tests with CO2 were performed in the temperature range of 200–1000 °C. The results showed that high torrefaction temperature and residence time decreased the mass yield. Statistical analysis showed the possibility of combining high temperatures with low residence times, or vice versa, to obtain satisfactory mass yields. The experimental results showed the highest reactivity for the torrefied biomass obtained in an inert atmosphere, at 290 °C and 60 min. However, considering the mass yield and reactivity with CO2, the best torrefaction conditions for biomass with potential application in metallurgical processes were in an inert atmosphere, at 290 °C and a residence time of 15 min.

The demand for sustainable and low-cost materials for wastewater treatment is increasing considerably. In this scenario, geopolymers have gained great interest, due to their good mechanical properties, their ability to be produced from industrial waste and their adsorbent or catalytic properties. In this study, novel magnetic mining waste based-geopolymers were produced by incorporating a residue from phosphate waste rocks, which were extensively characterized (XRD, TGA/DTA, SEM, BET, XRF, FTIR, Mössbauer, ss-NMR and XPS). The materials produced showed formation of a dense framework, even with 75% incorporation of the residue. The iron oxides and their magnetic properties remained unchanged, and their application in advanced oxidation reactions were evaluated, in particular, as catalysts in ozonation reactions. All of the geopolymers presented catalytic activity in the ozonation reaction, with catalytic ozone decomposition values of up to 2.98 min−1, which is 99 times greater than non-catalyzed reactions. Moreover, the reuse (performed in three cycles) and hot filtration-like experiments demonstrated, respectively, the regenerability and heterogeneous catalytic properties of the produced materials, showcasing the potential of these waste materials for catalytic geopolymer production. demonstrating the potential of this waste to produce catalytic geopolymers.

This research explores the integration of DUT-67 metal organic frameworks into polyethyleneimine-based hydrogels to assemble a composite system with enough mechanical strength, pore structure and chemical affinity to work as a sorbent for water remediation. By varying the solvent-to-modulator ratio in a water-based synthesis path, the particle size of DUT-67 was successfully modulated from 1 μm to 200 nm. Once DUT-67 particles were integrated into the polymeric hydrogel, the composite hydrogel exhibited enhanced mechanical properties after the incorporation of the MOF filler. XPS, NMR, TGA, FTIR, and FT Raman studies confirmed the presence and interaction of the DUT-67 particles with the polymeric chains within the hydrogel network. Adsorption studies of methyl orange, copper(II) ions, and penicillin V on the composite hydrogel revealed a rapid adsorption kinetics and monolayer adsorption according to the Langmuir’s model. The composite hydrogel demonstrated higher adsorption capacities, as compared to the pristine hydrogel, showcasing a synergistic effect, with maximum adsorption capacities of 473 ± 21 mg L−1, 86 ± 6 mg L−1, and 127 ± 4 mg L−1, for methyl orange, copper(II) ions, and penicillin V, respectively. This study highlights the potential of MOF-based composite hydrogels as efficient adsorbents for environmental pollutants and pharmaceuticals.

This research is aimed at evaluating strategies for the adsorption and recovery of anthocyanins present in purple cabbage using natural and modified clays as adsorbent. In the batch adsorption experiments, the anthocyanin extracts were put in contact with the adsorbents, and different parameters were evaluated to determine the best conditions for their adsorption and recovery. It was noted that the highest levels of adsorption (28.0 mg g-1) occurred using a porous clay heterostructure (PCH) material as adsorbent, with a mass of 25 mg and 120 min of contact. Under the same conditions, the sepiolite only presented an adsorption capacity of 14.0 mg g-1. The desorption results showed that the 60% methanolic solution recovered 60% of the anthocyanins adsorbed on PCH, while the 80% ethanolic solution recovered 35% of those adsorbed on sepiolite. The eluted anthocyanin solutions showed a 98% lower sugar concentration than the crude extract, indicating the low affinity of the adsorbents for sugars. Six types of acylated cyanidins were identified via UPLC-QToF-MSE in the extract, and it was confirmed from the FTIR analyses that the highest affinity of the clays occurred with the anthocyanins that presented more organic acid in their structure. The results show that PCH and sepiolite have high selectivity for anthocyanins and low affinity for the sugars present in the plant extract, facilitating the process of partial purification and application of these pigments.

The massive use of petroleum and its possible exhaustion are driving the current research trend to study alternative raw materials from biomass for organic reactions. In this context, the present article presents a study of the catalytic esterification of levulinic acid, a platform molecule, with ethanol. Metal-organic framework (MOF) type compounds UiO-66-NH2 have been synthesized. Zirconium was incorporated, using zirconium chloride as a metal precursor, together with 2-aminoterephthalic acid as an organic binding agent. An alternative route of synthesis was proposed using more favorable conditions from an economic and environmental point of view, replacing dimethylformamide by 50 and 75% acetone as substitute solvent. The physicochemical properties of the materials were evaluated by X-ray diffraction (XRD), Infrared Spectrometry with Fourier Transform (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), microwave plasma atomic emission spectroscopy (MP-AES) and N2 adsorption to understand their morphology, crystalline, chemical and pore structure. The progress of the reaction was followed by gas chromatography and mass spectroscopy. The catalytic activity result of MOF25% in autoclave reactor, showed 100% of selectivity to ethyl levulinate and a turnover number (TON) of 66.18 moles of product/moles of Zr. This good catalytic performance obtained by partial solvent replacement in the synthetic material provides a more economical and eco-friendly process for ethyl levulinate generation.

The depletion of oil reserves and concerns about the environmental impact of the use and incorrect disposal of mineral lubricants have been promoting the development of bio-based lubricants. In this study, biolubricants obtained from fatty acids of castor oil were synthesized by esterification (>wt.%93), epoxidation (>wt.%92), and oxirane ring opening reactions using water (>wt.%92) or 2-ethylhexanol (>wt.%94) as nucleophilic agents. The frictional characteristics of the synthesized samples were obtained through tribological tests performed in a four-ball tester and compared with a commercial mineral oil. The sample obtained through oxirane ring opening with water showed the best frictional performance (FC = 0.0699 ± 0.0007) among the prepared samples, with equivalent wear rate (WSD = 281.2 ± 5.54 μm) and ca. 20% lower friction coefficient when compared to the commercial mineral oil, indicating its great potential for replacing mineral fossil oils.

A wide variety of solid sorbents has recently been synthesized for application in CO2 adsorption. Among them, mesoporous silicas deserve attention because of their ability to accommodate large concentrations of different chemicals as a consequence of their surface chemistry and tunable pore structure. Functionalized materials exhibit promising features for CO2 adsorption at high temperatures and low CO2 concentrations. This work aimed to assess the influence of the textural properties on the performance of CO2 adsorption on functionalized mesoporous silica. With this goal, several mesoporous silica foams were synthesized by varying the aging temperature, obtaining materials with larger pore diameter. Thus, the synthesized materials were functionalized by grafting or impregnation with 3-aminopropyltriethoxysilane, polyethylenimine, and tetraethylenepentamine as amine sources. Finally, the amino functionalized materials were assessed for CO2 capture by means of equilibrium adsorption isotherms at 25, 45, and 65°C. Among the most outstanding results, high aging temperatures favor the performance of impregnated materials by exposing greater pore diameters. Low or intermediate temperatures favor grafting by preserving an appropriate density of silanol groups.

At present, the trend towards partial replacement of petroleum-derived fuels by those from the revaluation of biomass has become of great importance. An effective strategy for processing complex biomass feedstocks involves prior conversion to simpler compounds (platform molecules) that are more easily transformed in subsequent reactions. This study analyzes the metal–organic frameworks (MOFs) that contain Zr metal clusters formed by ligands of terephthalic acid (UiO-66) and aminoterephthalic acid (UiO-66-NH2), as active and stable catalysts for the esterification of levulinic acid with methanol. An alternative synthesis is presented by means of ultrasonic stirring at room temperature and 60 °C, in order to improve the structural properties of the catalysts. They were analyzed by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, microwave plasma atomic emission spectroscopy, acidity measurement, and N2 adsorption. The catalytic reaction was carried out in a batch system and under pressure in an autoclave. Its progress was followed by gas chromatography and mass spectrometry. Parameters such as temperature, catalyst mass, and molar ratio of reactants were optimized to improve the catalytic performance. The MOF that presented the highest activity and selectivity to the desired product was obtained by synthesis with ultrasound and 60 °C with aminoterephthalic acid. The methyl levulinate yield was 67.77% in batch at 5 h and 85.89% in an autoclave at 1 h. An analysis of the kinetic parameters of the reaction is presented. The spent material can be activated by ethanol washing allowing the catalytic activity to be maintained in the recycles.

Surface characterization of polymer inclusion membranes (PIMs) using the polymers cellulose triacetate and polyvinyl chloride, containing different ionic liquids (ILs) as carriers, has been performed. Three different ILs have been tested: commercial trioctyl methylammonium chloride (Aliquat 336–AlqCl−) and two derivatives bearing the counter anion NO3− or SCN− (AlqNO3 and AlqSCN, respectively). Surface analysis was performed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) for both dry membranes and PIMs immersed for 4 days in ultrapure water to investigate the effect of the interaction of water with the membrane’s morphology and composition. XPS analysis of the PIMs revealed that immersion in ultrapure water causes a decrease in the atomic concentration percentage (A.C.%) of the specific IL atoms (Cl, S, and N) when compared with dry samples. Moreover, SEM images of the PIMs containing the IL AlqNO3 showed an alteration in the morphology of the membrane due to water contact at surface level, whereas no changes were observed at a bulk level. These changes in the surface composition of the water equilibrated PIMs may be associated with the solubilization of the IL in the water solution, which, therefore, may affect the reactivity of the membrane’s surface. To better understand this effect, PIMs containing both AlqCl and AlqNO3 as carriers were used for arsenic (V) transport. It was found that AlqCl was the most effective IL and that the effectivity of the PIM on As(V) removal was not affected after five cycles of the membrane’s reuse.

KxMnO2 materials with birnessite-type structure are synthetized by two different methods which make it possible to obtain manganese oxides with different degrees of crystallinity. The XPS results indicate that the sample obtained at high temperature (KMn8) exhibits a lower oxidation state for manganese ions as well as a denser morphology. Both characteristics could explain the lower capacity value obtained for this electrode. In contrast, the sample obtained at low temperature (KMn4) or by hydrothermal method presents a manganese oxidation state close to 4 and a more porous morphology. Indeed, in this case higher capacity values are obtained. At current density of 30 mA g−1, the KMn8, KMn4, and HKMn samples display a capacity retention of 88, 82, and 68%, respectively. The higher capacity loss obtained for the HKMn compound could be explained considering that the incorporation of Zn2+ in the structure gives rise to the stabilization of a ZnMn2O4 spinel-type phase. This compound is obtained in the discharge process but remains in the charge stage. Thus, when this spinel-type phase is obtained the capacity loss increases. Moreover, the stabilization of this phase is more favorable at low current rates where 100% of retention for all samples, before 50 cycles, was observed.

This research aims to study the possible improvement of methylene blue (MB) removal from aqueous solution by hybrid adsorbent-catalysts (AdsCats) prepared through the incorporation of activated carbon derived from Luffa cylindrica fibers (LAC) to TiO2 photocatalysts. LAC with a specific surface area of 1170 m2/g was prepared by chemical activation with phosphoric acid at 500 °C. TiO2/LAC composites with 70 and 90 wt.% Degussa P25 titania content were prepared. The materials were characterized by N2 physical adsorption, XRD, FTIR, and XPS. The AdsCats displayed a very good dispersion of TiO2 over LAC, a surface area of close to 200 or 400 m2/g, depending on the composition, and high crystallinity, showing the presence of anatase and rutile phases. MB removal was studied in two different scenarios: under UV-light after reaching adsorption equilibrium, and under UV-light once the liquid effluent and the AdsCats were in contact. The MB removal by LAC has proved to be very efficient, highlighting the predominant role of adsorption over photodegradation. The prepared AdsCats have also been compared with their components. The results showed that TiLAC hybrids have superior photocatalytic performance than P25, showing TiLAC-7/3 90% MB removal with respect to the initial concentration just after 30 min of UV light irradiation for both studied scenarios.

During the last two decades, Dye Sensitized Solar Cells (DSSCs) have received a great deal of attention as a promising, low-cost alternative to conventional silicon photovoltaic devices. Natural dye molecules can be used as a sensitizer for their low cost, good light absorbance, easy preparation process, and biodegradability. In this study, dyes were obtained from wine lees, the last by-product of winemaking process, supplied by a venetian winery (Italy). Polyphenols, like tannins and anthocyanins, which were extracted from winemaking lees, were adsorbed on a nanostructured ordered mesoporous titanium dioxide, previously treated at different temperatures (400−600 °C). Both dyes and titania semiconductor samples were studied with different techniques. The tests were carried out on prototypes to evaluate the cell power and the photocurrent generated under simulated solar light irradiation. The obtained solar energy conversion efficiencies are comparable to those that were reported in literature by using organic dyes extracted from vegetables, fruits, and plants. It is significant that these dyes are largely available and cost effective, since recovered from a waste otherwise to be disposed of, opening up a perspective of feasibility for inexpensive and environmentally friendly dye solar cells to generate green electricity and transforming agri-food waste into a resource.

The CaO solid derived from natural quail eggshell was calcined and employed as catalyst to produce biodiesel via transesterification of sunflower oil. The natural quail eggshell was calcined at 900°C for 3 h, in order to modify the calcium carbonate present in its structure in CaO, the activity phase of the catalyst. Both precursor and catalyst were characterized using Hammett indicators method, X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), CO2 temperature-programmed desorption (CO2-TPD), X-ray photoelectronic spectroscopy (XPS), Fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N2 adsorption-desorption at −196°C, and distribution particle size. The maximum biodiesel production was of 99.00 ± 0.02 wt.% obtained in the following transesterification reaction conditions: XMR (sunflower oil/methanol molar ratio of 1 : 10.5 mol : mol), XCAT (catalyst loading of 2 wt.%), XTIME (reaction time of 2 h), stirring rate of 1000 rpm, and temperature of 60°C.

Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM+BF4 and phenyltrimethylammonium chloride or TMPA+Cl−) were studied by X-ray photoelectron spectroscopy (XPS), contact angle, differential scanning calorimetry (DSC) and impedance spectroscopy (IS) measurements performed with dry samples after 24 h in contact with the IL-cations BMIM+ and TMPA+. IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS) seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM+ membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM+ on the transport of H+ across wet Nafion/BMIM+ doped membranes.

Reports about the influence of cerium-oxide nanoparticles (nCeO2) on plants are contradictory due to their positive and negative effects on plants. Surface modification may affect the interaction of nCeO2 with the environment, and hence its availability to plants. In this study, the uncoated and glucose-, levan-, and pullulan-coated nCeO2 were synthesized and characterized. The aim was to determine whether nontoxic carbohydrates alter the effect of nCeO2 on the seed germination, plant growth, and metabolism of wheat and pea. We applied 200 mgL-1 of nCeO2 on plants during germination (Ger treatment) or three week-growth (Gro treatment) in hydroponics. The plant response to nCeO2 was studied by measuring changes in Ce concentration, total antioxidative activity (TAA), total phenolic content (TPC), and phenolic profile. Our results generally revealed higher Ce concentration in plants after the treatment with coated nanoparticles compared to uncoated ones. Considering all obtained results, Ger treatment had a stronger impact on the later stages of plant development than Gro treatment. The Ger treatment had a stronger impact on TPC and plant elongation, whereas Gro treatment affected more TAA and phenolic profile. Among nanoparticles, levan-coated nCeO2 had the strongest and positive impact on tested plants. Wheat showed higher sensitivity to all treatments.

The separation of a mixture of C5−C9 n-paraffins was achieved by Inverse Gas Chromatography (IGC) by using boehmite; AlO(OH), in a packed column with short exposure times and temperatures; from 45 °C to 52 °C. The boehmite was characterized by XRD; ATG; SEM; IR spectroscopy and N2 adsorption. The material exhibited a low crystalline boehmite (AlOOH) structure and presented high hydration (pseudoboehmite). The reverse gas chromatography measurements showed that the elution temperatures of the C5−C9 n-paraffins were low compared with those obtained for other adsorbents. The differential heat of adsorption values ensures the satisfactory separation of the components in the C5−C9 mixture under suitable chromatographic conditions.

Investigations into nanoporous materials and their applications continue to afford a wealth of novel materials and new applications [...]

An alternative method for the introduction of aluminum into the STW zeolitic framework is presented. HPM-1, a chiral STW zeolite with helical pores, was synthesized in the pure silica form, and an aluminum source was added by in situ generated seeds. Displacements of the peak positions in the Al samples were found in the X-ray diffractograms, indicating the possible incorporation of the heteroatom into the framework. Using an analysis of the 29Si and 27Al magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra, we concluded that the aluminum was effectively introduced into the framework. The (AlTETRAHEDRAL/AlOCTAHEDRAL) ratio and its textural properties were studied to explain the catalytic ethanol conversion results at medium temperatures. The sample with the lowest Si/Al ratio showed the best results due to its higher surface area and pore volume, in comparison to those observed for the sample with the highest Si/Al ratio, and due to its higher bulk tetrahedral aluminum content, in comparison to the intermediate Si/Al ratio sample. All catalysts were selective to ethylene and diethyl ether, confirming the presence of acidic sites.

Featured Application: In this work, an inexpensive and available material, as volcanic glass, is used to absorb metals from wastewater and then it is used to the separation of light liquid-olefins.Abstract: Raw porous volcanic glass from Cuba was used as an adsorbent for Cu2+ removal from dyes after activation with an acid solution. After Cu2+ adsorption, it was also evaluated its capacity to separate n-paraffins from a mixture by inverse gas chromatography (IGC), and the results were compared with those obtained with bare volcanic glass without copper. The main goal of this work is to highlight the great applicability of natural volcanic glass, which can be reused without pretreatment as an adsorbent. The results from copper adsorption were quite promising, considering the availability and low cost of this material; the sample without acid treatment turned out to be the most adequate to remove copper. Moreover, the results from IGC revealed that the separation of paraffins from the mixture was achieved with both bare volcanic glass and glass containing Cu, although greater heat adsorption values were obtained when copper was present in the sample due to the stronger interaction between paraffin and copper. The high availability and low cost of this porous material make it a potential and attractive candidate to be used in both heavy metal removal and paraffin separation for industrial purposes.

Fenton’s reaction is often used to decompose stable substances in wastewater. In this study, experiments based on the effect of porous phosphate heterostructures as catalyst sorbent of Fe2+ synthesised by different procedures were planned. The examined PPH-Fe/H2O2 as oxidant in a heterogeneous process under mild conditions at pH 5 was found to be very efficient for discoloration of a simulated wastewater containing 50 mg L−1 of a commercial azo dye (Reactive Black 5) reaching 95% of decolourization. Under the described conditions total visual decolourization was achieved after 360 min. This study can provide a simple, effective, and economic system ideal for the treatment of toxic and nonbiodegradable azo dyes.

In this article, the preparation and application of gold and cerium catalysts supported on zirconium-doped mesoporous silica SBA-15 was studied. These materials have been prepared by two different methods and characterized to investigate their textural properties, dispersion of the active phases and oxidation states. Both materials exhibit a marked catalytic activity. The size of the gold nanoparticles is directly related to the CO conversion rate and to the selectivity towards CO 2 exhibiting a strong temperature dependence. An X-ray photoelectron spectroscopic study of the composition and chemical state of the nanoparticles indicates the presence of Au in a metallic state. Transmission electron microscopic micrographs indicate that the best catalyst shows a higher dispersion of Au in spite of its lower gold surface content.

The present work reports adsorption/desorption studies of benzothiophene (BT) onto SBA-15 loaded with Fe, Pd and Cu employing in situ FT-IR spectroscopy and batch liquid-phase adsorption methods. The adsorbents were prepared by post-synthesis impregnation of metal salts onto pure siliceous SBA-15 by solid mixture and incipient wetness methods. The adsorbents were characterized by nitrogen adsorption isotherms, TEM, X-ray diffraction and X-ray photoelectron spectroscopy (XPS). The incorporated metals, in different oxidation states, were dispersed as nanoparticles on the mesoporous channels of SBA-15. The surface area decreased significantly for samples with incorporated metals, especially for those prepared by solid-mixture impregnation (Cu and Pd), although the hexagonal arrangement and the average pore size remained virtually unaltered. As revealed by batch adsorption isotherms, the incorporation of metals effectively increased the retention of the adsorbent towards the sulphur compound in the following order: Pd < Fe > Cu. DRIFT spectra (under in situ adsorption/desorption conditions) of the samples containing Fe and Pd showed that adsorption of BT onto the former is mainly reversible, whereas BT seems to be chemisorbed in the latter and did not desorb readily upon thermal treatment under He flow.

A series of mesoporous silica-supported nickel catalysts (2.2 wt% Ni) were prepared by impregnation employing the incipient wetness technique using Ni(II) formate as the impregnation salt. Three different atmospheric conditions were employed during the thermal treatment: air, He and H 2 . The catalysts were characterised by chemical analysis, XRD, N 2 adsorption at −196°C, H 2 -TPR, H 2 -TPD and XPS. A direct relationship was found between catalytic activity in the gas-phase hydrogenation of acetonitrile and the Ni 2p 3/2 binding energy assigned to the Ni 0 atoms of the reduced catalysts, where the catalytic activity decreased with increasing binding energy. The best catalyst obtained was that prepared by thermal decomposition in air and subsequent reduction in a hydrogen atmosphere; this catalyst displayed a high metallic surface and a low value for the Ni 2p 3/2 binding energy of Ni 0 .