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Results from lab scale flotation show that when process water was re-used copper and cobalt recovery from an oxidized ore decreased respectively with 25% and 30% at the rougher stage bringing lower grade concentrate as well. The presence of thiosulphate ions contributed to slow down of NaHS consumption during sulphidisation of pure malachite and hindered collector adsorption. Elevated concentration of thiosulphate ions affected malachite surface properties and induced dissolution effects. DRIFT spectroscopy on activated malachite enabled to reveal the effects of thiosulphate ions presence with hydrophilic species being identified. [ABSTRACT FROM AUTHOR]

Abstract: Spectral variable selection is an important step in spectroscopic data analysis, as it tends to parsimonious data representation and can result in multivariate models with greater predictive ability. In this study, we used VIS-NIR (visible to near-infrared) diffuse reflectance and DRIFT (diffuse reflectance infrared Fourier transform in the mid-infrared range, MIR) spectroscopy to determine a series of chemical and biological soil properties. Multivariate calibrations were performed with partial least squares regression (PLSR) using the full absorbance spectra (VIS-NIR: 400–2500nm with 5-nm intervals; MIR: 4000–800cm−1 with 4-cm−1 intervals) and with a combination of PLSR and CARS (competitive adaptive reweighted sampling) to integrate only the most informative key variables. The CARS procedure has as yet not been applied in the field of soil spectroscopy. As set heterogeneity is crucial for an optimal calibration, we tested these approaches to a sample set of 60 agricultural samples covering a broad range of different parent materials, soil textures, organic matter contents and soil pH values. Soil samples were taken from the Ap horizon (0–10cm depth), air-dried and pulverised before the lab spectroscopic measurements were performed. In a cross-validation approach, the CARS–PLSR method was markedly more accurate than full spectrum-PLSR for all investigated soil variables and both spectral regions. With MIR data and CARS–PLSR, excellent results (indicated by a residual prediction deviation (RPD) greater than 3.0) were obtained for organic carbon (OC), nitrogen (N), microbial biomass-C (Cmic) and pH values; for hot water extractable C (Chwe), RPD was 2.60. The accuracies obtained with VIS-NIR data were considerably lower than those with the MIR spectra; best results were retrieved for pH and Cmic (approximately quantitative as indicated by RPD values between 2.0 and 2.5). The information content of the MIR data was substantially different from the VIS-NIR information, as indicated by 2D correlation analysis. We found an overall blurred 2D correlation pattern between both spectral regions with moderate to low correlation coefficients, which suggested that the heterogeneity of the studied soil sample population had led to a very complex blurring of overtones and combination bands in the NIR region. Statistical CARS selections were physically reasonable. MIR key wavenumbers for the studied C fractions were inter alia identified at the bands at 2920cm−1 and 2850cm−1 (both aliphatic CH-groups) and the region between 1740 and 1600cm−1 (CO-groups) and represent hydrophobic and hydrophilic compounds of soil organic matter. Important VIS-NIR wavelengths for assessing C fractions and N were located nearby the prominent water absorption band at 1915nm and the hydroxyl band at 2200nm. The simplicity of the approach, parsimony of the multivariate models, accuracy levels in the cross-validation and physically reasonable selections indicated a successful operation of the CARS procedure. It should be further examined with a larger number of samples using separate calibration and validation sets. [Copyright &y& Elsevier]

The demand for gas sensors that can detect gases selectively at low temperatures has increased steadily over recent years. Most devices use semiconducting metal oxides as sensing materials which often require high operation temperatures and suffer from a lack of selectivity. Semiconducting metal sulfides were found to be a reasonable alternative for the application in sensing devices at low temperatures. Since metal sulfides are a relatively new class of materials applied in gas sensors, there is little work on sensing mechanisms and overall sensing characteristics of these materials. In this work, the authors investigated the sensing performance of Bi 2 S 3 nanorods operated at 50 °C in the presence of several target gases and found a selective response to oxidizing gases. With the help of DC resistance measurements, diffuse reflectance infrared Fourier transform spectroscopy and work function measurements in a Kelvin Probe setup, the NO 2 and O 3 sensing mechanisms of Bi 2 S 3 nanorods were revealed. While initially sulfur vacancies were the predominant reaction sites, the formation of nitrates became the key reaction in higher NO 2 concentrations. Additionally, it was found that the reaction with O 3 healed sulfur vacancies effectively inhibiting the reaction with NO 2 .

Tri‐salts added: Pt on alumina catalysts can be used for converting methanol and water into hydrogen and carbon dioxide (see picture), for applications such as hydrogen storage. Both the activity and selectivity could be enhanced by coating these materials with a thin layer of a molten salt mixture of Li/K/Cs acetate. Potassium doping was identified by DRIFTS measurements to be an important factor for the boost in catalyst performance. [ABSTRACT FROM AUTHOR]

Abstract: There is a limited knowledge on the role of soil texture and clay mineralogy in governing the content and composition of organic matter (OM) associated with physically-separated fractions in major Thai soils. To extend the understanding in this context, we sampled a range of Thai soils representing four major mineralogy groups, i.e. siliceous, mixed mineralogy, kaolinitc, and smectitic soils. The clay fraction and four density fractions [two particulate OM, free-light (fPOM) and occluded (oPOM), <1.85gcm−3; and two heavy fractions, 1.85–2.60gcm−3 (HFOM1.85–2.60) and >2.60gcm−3 (HFOM>2.60)] of soils from the top- and sub-soil horizons with varying clay content (58–967gkg−1) and mineralogy were analyzed for organic carbon (OC) and total nitrogen (N) contents. Additionally, chemical composition of the OM in the clay fraction of soils from 0–20cm, 20–40cm and 40–70cm and the four density fractions from soils at 20–40cm depth was characterized using diffuse reflectance infrared Fourier transformed (DRIFT) spectroscopy. The OM associated with oPOM (OC only) and HFOM1.85–2.60 (OC and total N) fractions was significantly increased with increasing clay content among soil groups and the degree of association depended on the dominating clay mineral (albeit significantly at P <0.05 for some soil groups only). The relative proportion (%rA) of aliphatic-C in the clay and HFOM1.85–2.60 fractions significantly increased with increasing sand content, and significantly decreased with increasing clay content. Whereas, opposite relationships were observed for the aromatic-C and amide N (amide-II) with sand and clay contents, respectively. The organic-mineral fractions (clay or HFOM1.85–2.60) of the coarse-textured siliceous soils were enriched with aliphatic-C and depleted in amide N, whereas the organo-mineral fractions of the fine-textured soils were enriched with aromatic-C and amide N. Aliphatic-C represented the dominating organic structure in the siliceous soils, whereas aromatic-C and amide N represented typical forms of OM in the fine-textured soil groups. The present study provided insights into the role of soil texture and clay mineralogy in governing the content and composition of OM pools in Thai soils with relevance for sustaining soil fertility and mitigating C emissions. [Copyright &y& Elsevier]

The adsorption of NH and NO over fresh and thermally treated Fe-BEA catalysts were studied using in situ DRIFT spectroscopy to follow the evolution of different iron species before and after thermal treatment. Fe-BEA samples were prepared and thermally treated in air at 700 °C for 12, 24 and 48 h, and at 800 and 900 °C for 48 h. Compared to the fresh sample, the NH adsorption experiments indicate dealumination of the zeolite and iron oxide particle growth for the aged samples. Furthermore, the NO adsorption experiments show distinct absorption peaks which are assigned to isolated iron species, iron clusters and larger iron oxide particles. The thermally treated samples show migration of isolated iron species from the zeolite pores forming iron oxide particles. Further ageing results in a continuous migration and formation of larger iron oxide particles located on the external surface of the zeolite. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The dehydration behaviors of two different hydrated zinc borate species, Zn[B3O3(OH)5] · H2O and Zn[B3O4(OH)3], which are industrially important flame retardants, were studied by thermal gravimetric(TG) analysis and in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Dehydration onset temperatures of Zn[B3O3(OH)5] · H2O and Zn[B3O4(OH)3] were 129 and 320°C, respectively, at a 10°C/min ramp rate. A very small amount of boric acid was volatilized in addition to water vapor when both samples were heated at 250°C. A significant amount of water vapor was adsorbed by Zn[B3O3(OH)5] · H2O from air at 25°C. However, Zn[B3O4(OH)3] adsorbed a very small amount of water under the same conditions. Both zinc borates did not have a tendency to cake during storage. [ABSTRACT FROM PUBLISHER]

Abstract: The effect of PrO2 content (1–20wt.%) and temperature pretreatment on the structure and surface properties of PrO2–Al2O3-supported Pt catalysts was studied by XRD, XPS and DRIFTS of carbon monoxide adsorption. XRD analysis showed that platinum particle size decreases with the increase of PrO2 content for samples calcined at high temperature of 1023K. The intensity and position of the infrared bands were strongly dependent on the praseodymium oxide content and reduction temperature. Two kinds of Pt sites (Pt0 and Ptδ+) were recorded in reduced PrO2-containing samples. A better thermal stability of the Ptn PrO2-containing samples compared to Pt/Al2O3 was observed. [Copyright &y& Elsevier]

Abstract: Knowing the impact of warming on soil organic matter (SOM) is crucial for estimating future soil CO2 effluxes. Whether different soil fractions and carbon (C) complexes have different temperature sensitivities is still a matter of debate. To measure the temperature sensitivity of tropical forest soils with ongoing decomposition, we collected soil cores from three sites along an altitudinal gradient with a difference in mean annual soil temperature of about 8°C. The intact soil cores were incubated at 5, 15, 25 and 35°C, respiration rates quantified, and the soil cores reinstalled at the collection sites. This procedure was repeated after six months and after one year to quantify the impact of ongoing decomposition on the temperature sensitivity (Q10) of respiration. Changes in chemical composition were determined by infra-red spectroscopy, and C distribution was partitioned by fractionation into fine roots, particulate organic matter (POM) and mineral-associated organic matter (MOM) from soil sub-samples at the start of the experiment and after one year of decomposition. Despite the different provenances, the soils revealed the same respiration patterns with Q10 values of 1.43–1.58 at the start of the experiment and 2.02–2.21 after one year. Carbon use efficiencies were lower for more stable SOM. Chemical composition of bulk SOM did not change to a measureable extent after one year, and SOM dynamics could not be related to changes in Q10 values. Of the analysed properties, the largest impact seems to have been on the decomposition of organic matter from the POM fractions, which might have been responsible for the observed increases in Q10 values. [Copyright &y& Elsevier]

Abstract: The application of FTIR ATR (Fourier transform infrared attenuated total reflection), DRIFT (diffuse reflectance infrared Fourier transform) and FT Raman spectroscopy for the quantification of thiamine hydrochloride, or vitamin B1, in tablets was compared. PLS (partial least squares) calibration models were built and validated using the spectra of 40 samples containing vitamin B1 and excipients. To evaluate the predictive ability of these models, the relative standard errors of prediction (RSEP) were calculated. In the case of vitamin B1 determination from the Raman data, RSEP error values of 1.5 % and 2.1 % were obtained for the calibration and validation data sets, respectively. When DRIFT spectra were applied, the respective RSEP errors were found to be 2.1 % and 2.2 %. For ATR models, these errors amounted to 3.1 % and 3.2 %, respectively. Commercial tablets containing 25mg of thiamine hydrochloride were quantified using the developed models. Derived concentrations correlated strongly with the results of the reference analysis and yielded recoveries of 99.2–100.8 %. Each of the three applied spectroscopic techniques can be employed as fast and reliable alternatives to the standard pharmacopeial methods of vitamin B1 quantification in tablets. DRIFT spectroscopy has the highest potential to become a routine technique for the quantification of solid mixtures within the pharmaceutical industry. [Copyright &y& Elsevier]

Abstract: An exact wavelength separation of the spectrum cannot be accomplished when utilizing common ultraviolet (UV) light sources, so the dependence of photodegradation on wavelength cannot be done directly. The photodegradation of wood resulted in by laser irradiation on various wavelengths can be studied by comparing the changes in the DRIFT spectra of various wood materials. The analysis of the difference spectrum is a widely used method to investigate the changes in the infrared spectrum. As this procedure cannot be used to compare the changes quantitatively, a new indicator was introduced, termed Band Damage Index (BDI). The BDI and the results obtained by its analysis are going to be discussed. [Copyright &y& Elsevier]

Abstract: Three ultrafiltration membranes, polyether-sulfone (PES), polyacrylonitrile (PAN) and cellulose acetate (CA) have been tested in order to study fouling and the removal of natural organic matter (NOM) from three natural source waters having different physical and chemical characteristics. The physically reversible fouling depended on the system of feed water and membrane type. Physically reversible fouling was significant for the system which consisted of hydrophobic feed medium–hydrophobic membrane (Las P, Lasek S — PES) as well as for the system: hydrophilic feed medium–hydrophilic membrane (Zabie D — CA). The change of membrane properties (the contact angles) after the filtration was observed. The foulants remained after physical cleaning render the PES and PAN membranes more hydrophilic, while CA membrane became more hydrophobic. The filtration cakes extracted from the membranes were analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. According to spectra the water from Zabie D contained relatively more polysaccharide-like than protein-like substances, while the opposite relations between two groups were noted for Lasek S. The water form Lasek S demonstrated highest potential for fouling towards tested membranes. Las P sample showed more humic acid-like characteristics. [Copyright &y& Elsevier]

Adipocere is a late-stage postmortem decomposition product that forms from the lipids present in soft tissue. Its formation in aquatic environments is typically related to the presence of a moist, warm, anaerobic environment, and the effect of decomposer microorganisms. The ideal temperature range for adipocere formation is considered to be 21-45°C and is correlated to the optimal conditions for bacterial growth and enzymatic release. However, adipocere formation has been reported in cooler aquatic environments at considerable depths. This study aimed to investigate the chemical process of adipocere formation in a cold freshwater environment in Lake Ontario, Canada. Porcine tissue was used as a human tissue analogue and submerged at two depths (i.e., 10 and 30 feet) in the trophogenic zone of the lake. Samples were collected at monthly postmortem submersion intervals and analysed using diffuse reflectance infrared Fourier transform spectroscopy to provide a qualitative profile of the lipid degradation and adipocere formation process. Early stage adipocere formation occurred rapidly in the cold water environment and proceeded to intermediate stage adipocere formation by the second month of submersion. However, further adipocere formation was inhibited in the third month of the study when temperatures approached the freezing point. The depth of submergence did not influence the chemical conversion process as similar stages of adipocere formation occurred at both depths investigated. The study demonstrated that adipocere can form rapidly, even on small amounts of soft tissue, which may be representative of dismembered or disarticulated limbs discovered in an aquatic environment. [ABSTRACT FROM AUTHOR]

Abstract: A mechanistic study of the K-10 montmorillonite-catalyzed microwave-assisted oxidative self-coupling of benzylamine and cross coupling of benzylamines with anilines and aliphatic amines is described. The coupling of benzylamines readily produced benzylidene benzylamines, while reactions of benzylamine with aliphatic amines and anilines resulted in benzylidene alkylamines and benzylidene anilines. The mechanism of the reaction has been investigated by varying reaction conditions, kinetic studies, thermogravimetric analysis and DRIFT spectroscopy. The data obtained clarified the steps of this multistep reaction sequence and a mechanistic scheme has been proposed. [Copyright &y& Elsevier]

Abstract: In situ DRIFT spectroscopy is used in the current study to follow sorption/desorption of water vapor on several clay minerals that vary in surface charge and morphological character. Spectra of the dried sorbents indicate the significant effect of those factors on both liquid and vapor phase water remaining within the particles. Changes in the IR bands recorded during exposure to water vapor at 50% RH confirm the assignment of those bands to water. They also indicate that the dynamics of liquid phase sorption/desorption for all the sorbents investigated is consistent with the concept of capillary condensation within nanometer scale pores that was advanced in previous studies conducted with 1,2-dihaloethanes. The intraparticle accumulation of the vapor phase water, however, was found to be profoundly affected by both surface charge and particle morphology. These differences are attributed to the high polarity and hydration capabilities of water molecules. Band area changes documented during a second sorption/desorption cycle are nearly identical to those occurring during the first with regard to both timing and extent. They also confirm that some liquid phase water is retained by the sorbents even after five days of desorption and amounts of sorbed vapor phase water increase over the course of the experiments. [Copyright &y& Elsevier]

Abstract: High catalytic activity for selective catalytic reduction of NO x with dimethyl ether and methanol (DME- and methanol-SCR) has been found over a γ-alumina catalyst. The surface species involved in the DME-SCR reaction were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in combination with mass spectrometry and compared to the corresponding species observed during methanol-SCR. Dimethyl ether adsorbs mainly as methoxy groups (h name="sbnd" />CH3) on the catalyst surface, while methanol adsorbs as methoxy groups and molecularly. With increasing temperature, DME desorbs in two steps, whereas methanol desorbs first as methanol and at higher temperatures as DME. At higher temperatures, the two reducing agents display similar DRIFTS spectra showing first formaldehyde-like species and then formates on the surface. In the presence of NO or NO2, reactions between NO x species and carbon-containing species occur. Formohydroxamic acid (CHOorms isocyanates (NCO), and both are observed at temperatures relevant for DME-SCR. Since these species are likely intermediates for hydrocarbon-SCR over Ag/Al2O3, a partly similar reaction mechanism may be operational for DME-SCR over γ-Al2O3 despite the fact that Ag/Al2O3 does not catalyze DME-SCR efficiently. The difference is thus due to the reaction steps leading to the formation of formohydroxamic acid that with DME follow a more efficient route over γ-Al2O3 than over Ag/Al2O3. [Copyright &y& Elsevier]

Abstract: Recently, we have found that forming a slurry by mixing Ca oxide with biodiesel (approximately 10–15g of biodiesel per gram of Ca oxide) results both in protection against poisoning by atmospheric CO2 and H2O and, when the slurry is used as a catalyst, in a remarkable increase in reaction rate [M. Lopez Granados et al., Energy Fuel 23 (2009) 2259–2263]. By conducting catalytic tests and DRIFT studies with either sunflower oil or model compounds revealed that the presence of minute amounts of monoglycerides (MG) and/or diglycerides (DG) in the biodiesel were the reason for the reaction rate promotion. To observe this effect, the Ca oxide–biodiesel slurry must be pretreated with methanol for a few minutes before proceeding with the transesterification reaction. The DRIFT studies demonstrated that the transesterification of MG and DG during the pretreatment with methanol results in the releasing of glycerol, which then reacts with the catalyst surface, resulting in the formation of very active surface Ca glyceroxide species. In view of this information, it was also demonstrated that the two-step procedure of mixing biodiesel with the catalyst and then carrying out methanol pretreatment could be substituted with pretreatment of the Ca oxide with methanol containing a few milligrams of glycerol per gram of Ca oxide before proceeding with the reaction. In this latter case, the slurry was not required. The DRIFT studies demonstrated that this simpler pretreatment also resulted in the formation of very active surface Ca glyceroxide species. [Copyright &y& Elsevier]

Abstract: This paper deals with the photobleaching of acetylated wood. The acetylated spruce wood was irradiated by artificial sunlight emitted from xenon lamp with covering several kinds of band-pass filter. The lightness (L *) of acetylated wood increased with integral irradiance. The chroma (ΔC *) decreased by light-irradiation with wavelength from 430nm to 500nm. However, the light-irradiation including ultraviolet ray region made it decrease after increase with integral irradiance. The visible light made hue angle (h°) increase, however, the ultraviolet ray made it decrease. The lignin degradation and the production of carbonyl groups were observed by light-irradiation including ultraviolet ray. However, no remarkable changes in IR spectra were observed by visible light-irradiation. Photobleaching of acetylated wood was caused by mainly visible light without modifying the IR spectra of lignin. [Copyright &y& Elsevier]

Abstract: Experimental evidences show that it is possible to produce methane from an exclusively inorganic way using CO2 and H2 on a Rh/γ-Al2O3 catalyst at low temperature and atmospheric pressure. New insights on the mechanism of methanation are given. The first step of the mechanism in the methanation reaction could be the chemisorption of CO2 on the catalyst. The second step is the dissociation of CO2 into CO and O adsorbed on the surface. The third step is the reaction of dissociated species with H2. Adsorption, dissociation of CO2 and the reaction of dissociated species with H2 are evidenced by in situ DRIFT experiments. The reaction could occur between the adsorbed species. However a reaction between adsorbed species and gaseous hydrogen cannot be excluded. XPS shows that the CO2 oxidizes the catalyst and this oxidation deactivates the catalyst. The conversion of CO2 also increases with temperature. Methane is the unique hydrocarbon molecule formed and obtained with almost 100% selectivity. No other hydrocarbonated products have been observed. [ABSTRACT FROM AUTHOR]

Abstract: The interaction of di-n-butyl phthalate (DBP as the internal donor) with AlEt3 cocatalyst was studied by DRIFT spectroscopy for the DBP/MgCl2 sample and supported TiCl4/DBP/MgCl2 catalysts. For DBP/MgCl2 sample, it was shown that AlEt3 partially removes all types of DBP complexes from the MgCl2 surface and adsorbs on surface sites released by the removal of DBP. In the case of supported catalysts, the cocatalyst predominantly removes more weak DBP complexes. In addition, the cocatalyst completely removes loosely coordinated DBP and surface complexes of phthaloyl chlorides formed at the catalyst preparation. A part of removed DBP can adsorb again on the catalyst surface as complexes with surface alkylaluminum chloride compounds. The external donor alkylalkoxysilane does not markedly influence the removal of DBP complexes from the catalyst surface. [Copyright &y& Elsevier]

Abstract: Dissolved and particulate organic matters from different stations and depths in the St. Lawrence estuarine system (Canada) were collected and extracted using humic substance (HS) fractionation protocols. The origin, composition, and fate of organic matter/HS were assessed by distribution characteristics, elemental and isotopic compositions, and infrared diffuse reflectance spectroscopy (DRIFTS). HS represented over 50% of dissolved organic matter in the Saguenay Fjord''s surface waters but this proportion decreased to 9–19% in the St. Lawrence Lower Estuary (SLLE). Fulvic acids were the dominant component (68–92%) of dissolved HS, especially in high salinity waters having very low humic acid content. Dissolved organic carbon (0.8–7.0mgL−1) and dissolved HS concentrations steadily decreased with downstream distance and depth. Isotopic and elemental data indicated that dissolved HS were mostly terrigenous, even in the SLLE deep waters. HS represented 62–100% of total particulate organic matter (POM) collected by sediment traps. Humin, the POM associated with the mineral matrix, was the dominant fraction of HS followed by humic acids and fulvic acids. The POM and its HS were mostly terrigenous in the fjord but mostly marine in the SLLE. Unlike its dissolved counterpart, a large part of the POM appeared to be mineralized in the water-column, even at relatively shallow (<200m) locations receiving large terrigenous inputs. At the upstream portion of the SLLE, it was estimated that 290μmolCcm−2 y−1 was lost during sinking and shortly after deposition, corresponding to an O2 demand of more than 360μmolO2 cm−2 y−1 assuming aerobic respiration. Distribution profiles indicated a rapid particulate HS removal during sinking (16–29%) and at the water–sediment interface (up to 70% total removal). These losses were especially important for N-containing molecules, aliphatic components, and marine non-humic POM. In contrast, humin was the most stable fraction. The interactions between POM and the mineral matrix appeared mediated by carboxylate groups. Differences in the composition of dissolved HS and particulate HS may explain their contrasting reactivities. Dissolved HS were nitrogen-poor, more oxidized, and depleted in aliphatic structures as compared to POM. The aliphatic content of dissolved and particulate HS was greater in marine samples (downstream) and decreased during diagenesis. The proportion of CH3 groups relative to CH2 groups was surprisingly high in dissolved fulvic acids, an important fraction of DOM. DRIFTS was particularly useful in providing information on HS structures and transformations. [Copyright &y& Elsevier]

Abstract: The interaction of AlEt3 cocatalyst with the internal donor (ethyl benzoate–EB) in the supported Ziegler–Natta (TiCl4/EB/MgCl2) catalysts and the EB/MgCl2 support was studied by DRIFT spectroscopy. For EB/MgCl2 samples, it was shown that AlEt3 firstly removed the more weak surface complexes of EB from the MgCl2 surface and competed with EB at adsorbtion for releasing sites of the MgCl2 surface. EB, as the external donor, keeps constant the initial content and distribution of surface complexes of EB at the interaction of the AlEt3/EB mixture with the EB/MgCl2 support. At the interaction of AlEt3 with the TiCl4/EB/MgCl2 catalysts one type of surface complexes of EB is mainly removed. A part of removed EB adsorbs again on the catalyst surface in the form of complexes with aluminum-containing compounds. At the interaction of the catalyst with the AlEt3/EB mixture the EB content in the catalyst changes slightly, but the distribution of different surface complexes of EB in the catalyst changes noticeably compared to that in the initial catalyst. EB, as the external donor, adsorbs both on surface MgCl2 sites released at the removal of the internal donor and on aluminum-containing compounds adsorbed on the catalyst surface. [Copyright &y& Elsevier]

[Display omitted] • Land-use change impacts on WEOM dynamics were assessed down to 1-m depth. • Agriculture under NT affected more WEOM composition than its concentration. • WEOM molecular weight and aromaticity decreased after LUC to agriculture under NT. • WEOM became N- and polysaccharide-rich after LUC. Most studies assessing land-use change (LUC) and management impacts on the soil organic carbon (SOC) budget mainly focused on total soil organic matter (SOM), neglecting its functional fractions such as water-extractable organic matter (WEOM). This may limit a better understanding of SOC dynamics along the soil profile as WEOM plays a key role in several soil and microbial processes. Here, we aimed to obtain a quantitative and qualitative assessment of WEOM dynamics to 1 m depth in areas after native vegetation conversion to long-term agriculture in Brazil. For this purpose, cropland areas under no-tillage (NT; ∼ 23 years old) and native vegetation (NV; i.e., Cerrado vegetation) were evaluated across a transect of 1000 km within Brazil's new agricultural frontier – the so-called MATOPIBA region. We combined spectroscopic analyses (UV–Vis and DRIFT spectroscopies), C and nitrogen (N) determination in different SOM pools (i.e., bulk SOM, WEOM, and microbial biomass), and microbial measurements [e.g., microbial biomass C (MBC) and N (MBN), and β-glucosidase activity] to better understand changes in WEOM dynamics induced by LUC. We observed that although SOC decreased along the soil profile after NV (4.2–20.7 g kg−1) conversion to NT (3.8–14.2 g kg−1), water-extractable organic C levels (3.6–79.3 mg L−1) were similar between land uses. On the other hand, an increase in water-extractable total N was observed after NV (0.4–4.6 mg L−1) conversion to NT (0.5–19.3 mg L−1). Although MBC and MBN levels decreased for most study sites, β-glucosidase activity increased after LUC indicating intensive microbial processing of SOM. As a result, WEOM had lower aromaticity and molecular weight (i.e., low values of SUVA254 and A2/A3) in NT than NV; and a relative decomposition of aliphatic and polysaccharides over aromatic and amine/amide was observed after LUC through DRIFT spectroscopy. Our study indicates that LUC had stronger impacts on WEOM quality than its quantity, with agricultural areas having more biochemical changes in WEOM than NV. [ABSTRACT FROM AUTHOR]

A low-temperature route for the synthesis of the Re(IV) diphosphate starting from ReO4- is presented. The ReP2O7 polycrystals have been prepared in 63% yield by an interaction of NH4ReO4 with molten phosphoric acid at 673 K with subsequent cooling down to 298 K. The synthesized ReP2O7 was characterized by X-ray powder diffraction (XRPD) and DRIFT spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Complexes of bivalent iron stabilized in the FeZSM-5 zeolite matrix (α-sites) are known to be able to decompose nitrous oxide stoichiometrically to form oxygen anion radicals, O−, bound to iron (α-oxygen), Similar to O− radicals on V and Mo oxides, α-oxygen is highly reactive in respect to CO, H2, methane and other hydrocarbons. It participates in catalytic oxidation of benzene to phenol by nitrous oxide, providing selectivity close to 100%. In this work, adsorption measurements, IR spectroscopy, TPD, and isotope methods were used to describe an earlier unknown reaction of O− species with water, which proceeds at 5–200 °C via the hydrogen abstraction mechanism according to the equation The reaction leads to the hydroxyl groups formed on α-sites, and equivalent amount of O2 evolves into the gas phase from water. Desorption of the hydroxyl groups occurs at above 400 °C via their recombination into water and dioxygen, resulting in the reactivation of α-sites, High sensitivity of α-oxygen to water admixtures may be an important factor explaining some contradictory results reported in the literature on the behavior of α-oxygen. Because α-oxygen is a typical representative of anion radicals O−, this reaction may be relevant not only to the conventional oxidation catalysis over zeolites and metal oxides, but also to photocatalytic processes, where formation of O− is well documented. [Copyright &y& Elsevier]

We investigated the utility of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for the analysis and identification of sea turtle (Family Cheloniidae) and bovid (Family Bovidae) keratins, commonly used to manufacture historic artefacts. Spectral libraries are helpful in determining the class of the material (i.e., keratin versus plastics), but do not allow for inferences about the species source of keratin. Mathematical post-processing of the spectra employing discriminant analysis provided a useful statistical tool to differentiate tortoiseshell from bovid horn keratin. All keratin standards used in this study (n = 35 Bovidae; n = 24 Cheloniidae) were correctly classified with the discriminant analysis. A resulting performance index of 95.7% shows that DRIFTS, combined with discriminant analysis, is a powerful quantitative technique for distinguishing sea turtle and bovid keratins commonly encountered in museum collections and the modern wildlife trade. [ABSTRACT FROM AUTHOR]

Abstract: The excellent selectivity and activity of ruthenium-hydroxyapatite {RuHAp, HAp=Ca10(PO4)6(OH)2} in the aerobic oxidation of alcohols has been attributed to isolated, monomeric Ru3+ species as the active sites. Here we reinvestigated these catalysts by a DRIFT study of CO adsorption and by electron microscopy (STEM) combined with EDX analysis. The study revealed the presence of two major species: isolated Ru3+ ions and hydrated Ru3+-oxide particles. The latter structure has high redox activity; it is easily oxidized with oxygen to RuO2 and reduced by hydrogen or CO at ambient conditions. The amount of this phase in the catalysts correlates well with the alcohol oxidation activity in the liquid phase at close to ambient conditions. In contrast, the redox activity of isolated Ru3+ ions is significantly lower (or they might be completely inactive). These species may correspond to adsorbed Ru3+ ions, ion-exchanged Ru3+ at the outer surface of HAp, or Ru3+ ions in Ru-phosphate formed by a dissolution–redeposition process from HAp. Our final conclusion is that in RuHAp, the real active sites are small hydrated Ru3+-oxide nanoparticles (1–2 nm) located on the surface of HAp. Application of a low RuCl3 concentration and a short contact time between HAp and the aqueous RuCl3 solution during catalyst preparation help maximize the fraction of the Ru3+-oxide phase and thus the catalytic activity. [Copyright &y& Elsevier]

Abstract: Mesoporous silica films with a thickness of 500–900 nm were synthesized on a titanium substrate by the evaporation-induced self-assembly method (with 900–1200 rpm for 90 s) using cetyltrimethylammonium bromide (CTAB) as structure-directing agent and tetraethyl orthosilicate as the silica source. Prior to coating deposition, the titanium substrate was oxidized to increase the surface roughness up to 500 nm and to produce a thin titania layer. Just before the synthesis, the titania layer was made super hydrophilic by an UV treatment for 2 h to provide a better adhesion of the silica film to the substrate. Films with hexagonal and cubic mesostructures with a uniform pore size of 2.8 nm and a surface area of 1080 m2/g were obtained and characterized by different methods. An alternative approach for surfactant removal by gradual heating up to 250 °C in vacuum was applied. Complete removal of CTAB from the as-synthesized silica films was confirmed by infrared spectroscopy. [Copyright &y& Elsevier]

This study aims to establish the contribution of the water soluble and water insoluble organic fractions to total oxygen uptake rate during high rate composting process of a mixture of organic fraction of municipal solid waste and lignocellulosic material. This mixture was composted using a 20 l self-heating pilot scale composter for 250 h. The composter was fully equipped to record both the biomass-temperature and oxygen uptake rate. Representative compost samples were taken at 0, 70, 100, 110, 160, and 250 h from starting time. Compost samples were fractionated in water soluble and water insoluble fractions. The water soluble fraction was then fractionated in hydrophilic, hydrophobic, and neutral hydrophobic fractions. Each fraction was then studied using quantitative (total organic carbon) and qualitative analysis (diffuse reflectance infrared spectroscopy and biodegradability test). Oxygen uptake rates were high during the initial stages of the process due to rapid degradation of the soluble degradable organic fraction (hydrophilic plus hydrophobic fractions). Once this fraction was depleted, polymer hydrolysis accounted for most of the oxygen uptake rate. Finally, oxygen uptake rate could be modeled using a two term kinetic. The first term provides the oxygen uptake rate resulting from the microbial growth kinetic type on easily available, no-limiting substrate (soluble fraction), while the second term considers the oxygen uptake rate caused by the degradation of substrate produced by polymer hydrolysis. [ABSTRACT FROM AUTHOR]

Abstract: The influence of NO2 on the selective catalytic reduction (SCR) of NO with ammonia was studied over Fe-ZSM5 coated on cordierite monolith. NO2 in the feed drastically enhanced the NO x removal efficiency (DeNOx) up to 600°C, whereas the promoting effect was most pronounced at the low temperature end. The maximum activity was found for NO2/NO x =50%, which is explained by the stoichiometry of the actual SCR reaction over Fe-ZSM5, requiring a NH3:NO:NO2 ratio of 2:1:1. In this context, it is a special feature of Fe-ZSM5 to keep this activity level almost up to NO2/NO x =100%. The addition of NO2 to the feed gas was always accompanied by the production of N2O at lower and intermediate temperatures. The absence of N2O at the high temperature end is explained by the N2O decomposition and N2O-SCR reaction. Water and oxygen influence the SCR reaction indirectly. Oxygen enhances the oxidation of NO to NO2 and water suppresses the oxidation of NO to NO2, which is an essential preceding step of the actual SCR reaction for NO2/NO x <50%. DRIFT spectra of the catalyst under different pre-treatment and operating conditions suggest a common intermediate, from which the main product N2 is formed with NO and the side-product N2O by reaction with gas phase NO2. [Copyright &y& Elsevier]

Abstract: The state of internal donor (ID) in the supported titanium–magnesium (TiCl4/ID/MgCl2) catalysts for stereospecific propylene polymerization has been studied by diffuse reflectance infrared spectroscopy (DRIFT). The samples were prepared via interaction of highly dispersed MgCl2 with different IDs (ethyl benzoate, EB; di-n-butyl phthalate, DBP) and TiCl4. It was found that the DRIFT spectra of carbonyl groups of IDs adsorbed on MgCl2 could be best described as a superposition of several overlapping vibration bands from a variety of surface complexes. Within this model the content of individual EB and DBP complexes on the MgCl2 surface was calculated. In the case of EB, three main complexes were found on the MgCl2 support in about equal proportions. In the case of DBP, only one of three complexes was preferentially formed. The surface content of both EB and DBP was found to decrease in presence of TiCl4. At the same time TiCl4 had influenced the distribution pattern of EB but not DBP complexes. The most likely scenario of competitive adsorption of TiCl4 and IDs on the MgCl2 support is discussed. A model describing surface distribution of TiCl4 on MgCl2 is proposed for TiCl4/EB/MgCl2 and TiCl4/DBP/MgCl2 catalysts. [Copyright &y& Elsevier]

Abstract: The surface acidity of montmorillonite treated by conventional hydrothermal reaction with acids as well as ultrasonic- and microwave-assisted acid digestion was studied using diffuse reflectance FT-IR (DRIFT) spectroscopy of adsorbed pyridine molecules. An attempt for semi-quantitative measurement of Brønsted acidity generated during the acid digestion was also carried out. The conventional hydrothermal, ultrasonic- and microwave-assisted acid digestion yielded strong Brønsted acid sites of similar nature and strength, which retained pyridine up to 400–450 °C. Strong Lewis acid sites were also developed at higher temperature (>300 °C), which were able to retain pyridine at 450 °C. The results show that surface acidity of similar strength can be generated with conventional hydrothermal treatment at 80 °C for 4 h or ultrasonic-treatment at room temperature for 1 h or microwave-assisted acid digestion for 10 min using 3 N concentration of H2SO4. Therefore, microwave- and ultrasonic-assisted acid digestions are potential and rapid alternative methods to conventional hydrothermal acid digestion for preparing acid-activated clays. [Copyright &y& Elsevier]

Abstract: This paper deals with the photodegradation of wood in low atmospheric temperature region (−40 to 50°C), and discusses the changes in color and IR spectra. The color and IR spectra of wood hardly changed with photo-irradiation at −40°C but did at −20°C. Therefore, it is thought that the photo-energy causes the scission of chemical bonds or the production of radicals; however, heat energy is needed to yellow of wood (i.e., to produce quinone). In case of softwoods, the absorption of the carbonyl band consisted of two sub-bands, and the carbonyl band at around 1710cm−1 increased at lower temperature than that at around 1760cm−1 by light-irradiation. Such IR measurement due to lignin degradation means that the photodegradation of softwoods is faster than that of hardwoods. The color change by exposure to light in the low temperature was also caused by the degradation of lignin. [Copyright &y& Elsevier]

Abstract: The electrochemistry of dithiophosphinate (DTPI) adsorption on pyrite was investigated by cyclic voltammetry (CV) and diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy at oxidizing potentials under acid, neutral, and alkaline conditions. CV study showed that the mineral surface was covered by porous ferric oxyhydroxide species. Irreversible DTPI adsorption on the pyrite surface and inhibition of electron transfer to some extent were also observed from electrochemical work. Major collector species were determined from DRIFT spectroscopy study as adsorbed collector compound, DTPI°, and dimer of dithiophosphinate, (DTPI)2. Maximum adsorption density of DTPI was obtained in acid solution. It decreased sharply under neutral and alkaline conditions due to heavy surface oxidation at higher pH. [Copyright &y& Elsevier]

Abstract: The oxidation of reduced Ga species in ZSM-5 zeolite modified via anchoring of trimethyl gallium or by incipient wetness impregnation with a solution of gallium nitrate was studied. Reduction of such materials in hydrogen and evacuation at high temperature resulted in quantitative replacement of the Brønsted acidic protons by Ga+ ions. However, the extent of dealumination of the material prepared by incipient wetness impregnation was higher. Oxidation of univalent gallium species by nitrous oxide at 673 K by either preparation method led to the quantitative formation of charge-compensating [Ga3+(O2−)]+ fragments. Ga+ ions can also be oxidized at 573 K by water vapor, whereupon approximately 25% of the Ga+ ions are transformed into [GaO]+ with concomitant release of molecular hydrogen. Dissociative chemisorption of molecular hydrogen via oxidative addition of hydrogen atoms to Ga+ cations at 773 K resulted in the formation of gallium dihydride species, which are very stable and are decomposed only in vacuum above 673 K. Oxidation of such [Ga3+(H−)2]+ cations by N2O at 573 K gave positively charged [Ga3+(H−)(OH)−]+ species. At higher temperature (673 K), the latter are further oxidized by nitrous oxide, giving neutral GaOOH species and Brønsted acidic protons. The similarity of infrared spectra of ethane adsorbed on Ga/ZSM-5 and HZSM-5 at 298 K indicates weak polarization of ethane molecules by Ga+ cations. However, oxidative addition of ethane at 523 K led to the formation of [Ga3+(H−)(C2 )]+ species. Above 573 K the grafted ethyl fragments decomposed to gallium hydride species and ethylene. Indications were also found for subsequent oligomerization and aromatization of the resulting olefin. [Copyright &y& Elsevier]

Abstract: Sulfated zirconia, unpromoted or promoted with either 2 wt% iron or manganese, was investigated by in situ diffuse reflectance IR spectroscopy during activation, n-butane isomerization (323–378 K, 1–5 kPa n-butane), and regeneration. During activation at 773 K in N2 or O2, more than 95% of the adsorbed water was removed, and comparison of the resulting pattern of sulfur–oxygen vibrations with DFT calculations (A. Hofmann and J. Sauer, J. Phys. Chem. B 108 (2004) 14652) suggests as a major surface species. All catalysts underwent an induction period before maximum rates were measured, which at 1 kPa n-butane were 350 and 180 μmol g−1 h−1 for the Fe- or Mn-promoted catalyst (323 K) and 5 μmol g−1 h−1 for sulfated zirconia (358 K). During isomerization several bands increased in the range of 1700–1600 cm−1; the growth of a band at 1600 cm−1 was restricted to the period of increasing catalytic activity. The rate of isomerization was linearly correlated with the total area increase of the bands in this region, indicating that the absorbing species are either active surface intermediates or side products (possibly water) formed in an amount proportional to the active surface species. The rate per such species was much higher in the presence of Mn; that is, promoters facilitate reaction steps after the initial alkane activation. The promoted materials deactivated within hours under the applied conditions, but complete recovery of the spectral and catalytic properties of Mn-promoted sulfated zirconia was possible through regeneration in O2 at 773 K. Attempts to regenerate in N2 produced unsaturated surface species absorbing at 1532 and 1465 cm−1. [Copyright &y& Elsevier]

Abstract: DRIFT spectroscopic experiments are described here that build on our previous time-resolved in situ experiments using dihaloethanes as molecular probes. The earlier studies produced the first molecular level evidence for differences between clay minerals, humic substances, and lysimeter soils as sorbents for these chemicals. In the current study, spectroscopic experiments with several established field soils are combined with porosity characterizations derived from both N2 and CO2 isotherms. Density functional theory is used to generate porosity distributions from both types of isotherms which, in turn, are used here to define the microstructural character of the soil. Results from the combined techniques strongly suggest that sorption/desorption behavior of volatile organic chemicals (VOCs) can be understood in the context of soil particle architecture. The porosimetry provides evidence that the microstructural array in particles of three of the soils investigated is determined primarily by the platelet character of quasicrystalline clay minerals while that of another one of the soils, an Oxisol, appears to be dominated by its high iron oxide content. With all the soils, curve-fitting of the time-resolved DRIFT spectra indicates the presence of both a sorbed liquid and a persistently sorbed species that accumulate at different rates: band areas for the persistent species continue to increase during desorption. For the soils whose microstructure is dominated by clay minerals, rates of accumulation for both species increase and desorption of the sorbed liquid is facilitated after treatment with hypochlorite to partially remove organic matter. The treatment has little effect, however, on the sorption behavior observed with the Oxisol. The changes in sorption/desorption behavior correlate well with the differences in porosity distributions determined using N2. In contrast, CO2 determined microporosity (&#60;2 nm), while related to the organic matter content of the untreated soils, was not a good predictor of any of the observed effects. These results are entirely consistent with those obtained using lysimeter soils as sorbents and support our earlier hypothesis that the persistent species band can be attributed to vapor phase chemical entrapped within the pore network of the sorbent particles. Soil organic matter again appears to impact the retention process primarily by impeding the flow of both liquid and vapor phase chemical into and out of that pore network rather than by associating with the chemical itself. The implications of these results for other volatile organic pollutants and the potential role of surface tension forces within mesopores (2–50 nm) in promoting the formation of persistently sorbed chemical are also explored. [Copyright &y& Elsevier]

Abstract: We investigate the energy dependence of the UV laser irradiation on DRIFT spectra of wood. Changes in the spectra have been studied with 248.5nm wavelength of UV laser radiation. To monitor the energy dependence, a different number of laser impulses were directed towards the sample''s surface. It can be concluded that several chemical processes contribute to the effect of the UV laser radiation. The processes depend on several factors one of which is the amount of absorbed energy. The characteristics of wood species can be observed mainly at low energy irradiation in the changes of spectra since these characteristics disappear with increased energy, the absorption''s changes have become more and more uniform. Recording the spectra of treated sample, the spectra show the degree of the surface''s instantaneous degradation. The differences among the observed changes in spectra may originate from both the diversity of the original spectra (the features of wood species and surface properties) and the stage of degradation''s degree of sample. Changes in absorption become less pronounced with increasing energy. [Copyright &y& Elsevier]

Abstract: CuMgAl ternary hydrotalcites with a (Cu+Mg)/Al atomic ratio of 3.0 and a Cu/Mg atomic ratio of 5.0, 3.0, 1.0, 0.33, and 0.2 were synthesized by coprecipitation under low supersaturation. Powder X-ray diffraction (PXRD) of all of the samples showed the pattern characteristic of hydrotalcite without any detectable impurity phases, with the crystalline order, especially in the ab plane, improving with an increase in magnesium concentration. In situ PXRD studies revealed varying phase evolution processes depending on the concentration of magnesium; this observation was well complemented by in situ diffuse reflectance infrared Fourier transform (DRIFT) measurements. The thermal stability of these materials also improved with an increase in magnesium concentration, as indicated by TG-DTA-EGA measurements. However, a characteristic endotherm was noted at temperatures around 870 K accompanied by the evolution of CO2, the intensity of which increased with an increase in copper concentration. Catechol (CAT) and hydroquinone (HQ) were the main products noted in the hydroxylation of phenol over these materials, with H2O2 as oxidant and H2O as solvent. Variation of the substrate:catalyst mass ratio (10–500) showed that the activity passes through a maximum for a ratio of 100. The influence of reaction time indicated that the reaction was nearly complete in less than 60 min. Activity was enhanced by an increase in the concentration of copper, whereas the normalized activity (activity per unit copper concentration) showed an opposite trend. The structure–activity relationship of these samples, obtained through scanning electron microscopy, N2 adsorption measurements, X-ray photoelectron spectroscopy, and cyclic temperature-programmed reduction–oxidation measurements, corroborated such activity variations. [Copyright &y& Elsevier]

Abstract: Three CaNaA zeolites, in which, respectively, 49%, 65% and 83% of the Na+ cations were exchanged with Ca2+ ions, along with a NaA sample were studied by thermogravimetry, temperature-programmed DRIFT spectroscopy and MAS NMR. Thermogravimetric desorption profiles of the Ca2+ exchanged zeolites show a low-temperature peak between 423 and 508K as well as two high-temperatures peaks at 853 and 973K, which are missing in case of the NaA sample. Three main bands at 3603–3611, 3495–3510 and 3552–3565cm−1, of which the first two are due to bridging Si–OH–Al groups located in 8- and 6-rings, respectively, whereas the third corresponds to Ca(OH)+ groups dominate the DRIFT spectra of zeolite samples exchanged with Ca2+ ions. The intensity of the band at 3603–3611cm−1 decreases significantly until it vanishes almost completely at 823K. A simultaneous decreases of the intensity of the band of Ca(OH)+ groups is indicative of a low-temperature dehydroxylation process between these two species. The intensity of the other Si–OH–Al group bands at 3495–3510cm−1 shows almost no change up to 823K, thus suggesting that these groups participate in a high-temperature dehydroxylation process. A weak band in the region 3670–3680cm−1 is attributed to Al–OH groups of extra-framework aluminum species formed during dehydration of the CaNaA zeolites. Peaks at 4.3 and 5.2ppm in the 1H MAS NMR spectra are assigned to Si–OH–Al groups in 8- and 6-rings, respectively. 27Al MAS NMR spectra show two main peaks at 57.3 and 78.7ppm, which are due to tetrahedrally coordinated aluminum and calcium alumosilicate groups. A weak signal between 12 and 13ppm ascribed to octahedrally coordinated aluminum disappears at higher temperatures. [Copyright &y& Elsevier]

The supported catalysts for ethylene polymerization were prepared by interaction of 2,6-bis[1-(2,6-dimetilphenylimino)-ethyl]pyridineiron(II) dichloride (LFeCl2) with silica and alumina. The catalysts exhibit high and stable activity at ethylene polymerization in presence of Al(i-Bu)3 as co-catalyst. LFeCl2 interaction with surface functional groups of the supports was studied by means of DRIFTS. LFeCl2adsorbed on the support surface mainly retains its structure. LFeCl2 is strongly bounded to the support due to formation of multiple bonds between LFeCl2 and surface functional groups of the supports. DRIFTS data on the state of the surface iron compounds have been obtained using CO as probe molecule. [ABSTRACT FROM AUTHOR]

The mechanism of dithiophosphinate (DTPI) adsorption on chalcopyrite was investigated by diffuse reflectance Fourier transformation (DRIFT) spectroscopy and by cyclic voltammetry (CV) at various pHs. CV experiments showed that the redox reactions occurred at a certain degree of irreversibility on the chalcopyrite surface in the absence of a collector due to preferential dissolution of iron ions in slightly acid solution and irreversible surface coverage by iron oxyhydroxides in neutral and alkaline solutions. In the presence of DTPI, CV experiments failed to identify the type of the adsorbed DTPI species and electrochemical processes occurring on chalcopyrite due to formation of an electrochemically passive surface layer preventing electron transfer. However, DRIFT spectroscopy tests showed this passive layer to be mainly CuDTPI + (DTPI)2. Both CV and DRIFT spectroscopy established that the activity of collector species decreased with increasing pH due to formation of stable hydrophilic metal oxyhydroxides on the chalcopyrite surface. [Copyright &y& Elsevier]

Reduction in hydrogen at 773 K of gallium-modified HZSM-5 zeolite prepared by incipient wetness impregnation results in complete substitution of acidic hydroxyl groups. The modification of the zeolite with gallium suppresses dealumination of the hydrogen form due to substitution of protons by gallium species. When the reduction at 773 K is followed by evacuation, coordinatively unsaturated Ga+ ions are formed. These species can be reversibly oxidized by nitrous oxide at 673 K. Alternatively, these Ga+ ions adsorb molecular hydrogen at lower temperatures resulting in several types of hydride species. The latter species are completely decomposed only in vacuum at relatively high temperatures (773 K). We propose that the oxidation of gallium upon cooling of reduced samples to room temperature in hydrogen can be attributed to an oxidative addition of H2 resulting in the formation of gallium dihydrides. [Copyright &y& Elsevier]

This study aims to investigate the nature of interactions between pyrite and sodium diisobutyldithiophosphinate (DTPI), a dithiophospinate type collector, with respect to the pulp potential (Eh), and pH. Cyclic voltammetry (CV) technique was employed at certain potential ranges and slightly acidic, neutral and alkaline solutions in order to identify the electrochemical behaviour of pyrite and DTPI individually, as well as the possible mutual reactions occurring among pyrite surface and DTPI. In addition, the change in the hydrophobicity of the pyrite surface was also evaluated in the absence and presence of DTPI as a function of Eh and pH through electrochemical contact angle measurements. These two phases were complemented by DRIFT spectroscopy analysis with polarized and DTPI induced pyrite samples at various potential values so as to determine the origin of species forming on pyrite surface. At the end of the study, all these three distinct methods indicated that the adsorption of DTPI on the pyrite surface relied on chemical mechanisms rather than an electrochemical interaction. [Copyright &y& Elsevier]

The interaction of sodium stearate with titania pigment particles from aqueous suspension has been investigated using thermal analysis and infrared spectroscopy combined with electrochemical studies. Thermogravimetric analysis (TGA) was used both to determine the adsorption isotherm and to investigate the interaction behavior. Monolayer coverage is determined to be 0.95 mg/m2; however, unlike the case with organic solvents, multilayer adsorption occurs. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, combined with TGA, revealed that the surface monolayer is chemically bound. DRIFT spectroscopic data also indicated that the stearate bridged across two aluminum atoms. Subsequent stearate layers were physisorbed to the stearate monolayer and were readily removed with acetone washing. [Copyright &y& Elsevier]

Two supported Ru catalysts were prepared by the chemical vapor deposition of Ru3(CO)12 on MgO and SiO2 (MOCVD). TEM, XRD, and static H2 chemisorption measurements confirmed that the Ru particle size was about 2 nm on both supports. Using in situ DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy at atmospheric pressure it was found that the adsorption of CO on the reduced samples is clearly influenced by the supports whereas the adsorption of CO on the oxidized Ru catalysts is essentially independent of the support. O2 chemisorption measurements showed that a thin RuO2 surface layer was formed on both catalysts under oxidizing conditions at room temperature. The observed C–O stretching frequencies were found to be in good agreement with HREELS and LEED data reported for the RuO2(1 1 0) single crystal surface. The catalytic activity was assessed under high-vacuum conditions using the TAP (temporal analysis of products) reactor by co-feeding CO and O2. These conditions ensured that heat and mass transfer limitations were absent. Both supported Ru catalysts were found to be highly active and stable under the CO oxidation conditions even down to room temperature. The deactivation of the catalysts observed at room temperature was reversible and independent of the support. The turnover frequencies (number of CO2 molecules per metal surface site per second) derived from steady-state measurements are in good agreement with data reported for the RuO2(1 1 0) single crystal surface under UHV conditions. Based on the results of the DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) and the kinetic measurements supported RuO2 is identified as the catalytically active phase. In addition, the turnover frequencies are in good agreement with data reported for Ru/SiO2 at atmospheric pressure. Thus, both the materials and the pressure gap were bridged successfully. [Copyright &y& Elsevier]