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The contamination of water resources with arsenic is a serious environmental problem. This research investigated the use of a strategic agricultural waste for Brazil, i.e., corn cob as a low-cost, biodegradable, and eco-efficient material for As(V) adsorption. Arsenate removal from an aqueous solution with iron hydroxide impregnated corn cob (IHCC) was investigated under different pH values (2-10). FTIR spectra revealed that monodentate complexes were formed during the adsorption of arsenate on IHCC. Furthermore, SEM micrographs revealed a uniform distribution of Fe(III) and also As(V) on the IHCC. IHCC was efficient in the removal of arsenic from acidic solutions, mainly those having pH values between 2 and 3 at temperatures below 50°C. The adsorption kinetics followed the pseudo-second order model with an activation energy of 39.35 ± 6.99 kJ mol-1 implying that chemical reaction was the controlling step of arsenic adsorption by IHCC. In addition, arsenic adsorption on IHCC was (i) an entropically driven, (ii) spontaneous, and (iii) endothermic phenomenon (+23.82 kJ mol-1) and involved electrostatic adsorption and chemosorption (Qmax = 40 mg/g, at 25°C). Therefore, a promising sustainable and environmentally friendly solution for the use of IHCC was devised in the current work. [ABSTRACT FROM AUTHOR]

Mesoporous materials functionalized with STA(Silicotungstic acid) have been proved to be efficient catalysts for esterification reactions. In the investigation, impregnation method was applied for the synthesis of STA/MCM-41 catalysts. MCM-41 and STA(Silicotungstic acid) were used to silica source and active material respectively. The active material was loaded by dryimpregnation method after silica source. Molar ratios of catalysts were determined by 1.25, 2.5 and 5% (W/Si). Actually, this molar ratio values are very low for the impregnation method. But catalysts were successfully synthesized by applying impregnation method. And catalytic activities of STA/MCM-41 catalysts were investigated with an ethyl acetate reaction. On the other hand, the second reaction of STA/MCM-41(2.5%) catalyst was carried out in the presence of under identical conditions after the first reaction. Before and after reactions, the physical properties of the catalysts were determined by XRD, DRIFT, BET, SEM and Mapping analysis methods. [ABSTRACT FROM AUTHOR]

Effect of nickel on the catalytic performances of LaCoO 3 for CO oxidation is investigated, by partial substitution of Co with Ni atoms in the framework or by deposition of NiO on the surface of LaCoO 3 . Results show that the activity decreases in order of 10% Ni/LaCoO 3 > LaCoO 3 > LaCo 0.8 Ni 0.2 O 3 , with the CO ignition temperature of 60, 110 and 140 °C, respectively (reaction conditions: 0.5% CO/Ar and 7.5% O 2 /Ar, balanced with Ar; space velocity of 30000 mL g −1 h −1 ). Based on the characterizations such as XPS, H 2 -TPR, O 2 -TPD and CV measurements, we inferred that the high activity of 10% Ni/LaCoO 3 is attributed to a synergistic effect induced by NiO and LaCoO 3 , and the low activity of LaCo 0.8 Ni 0.2 O 3 is to the enrichment of La atoms on the surface, caused by the Ni incorporation. Long-time stability test indicates that 10% Ni/LaCoO 3 is stable in the reaction, with no appreciable loss of activity within 32 h. The highly active and stable activity of 10% Ni/LaCoO 3 suggests that impregnation of metal oxides on the surface of perovskite can be a feasible strategy for the preparation of industrial catalyst for CO oxidation. [ABSTRACT FROM AUTHOR]

The particulars of phase and structure formation during reaction sintering of materials based on boron carbide and silicon carbide are examined, and the actual technological aspects of reaction sintering are analyzed. The main physical and mechanical characteristics of reaction sintered material based on silicon carbide and boron carbide and their relation to the structure of the material are discussed. [ABSTRACT FROM AUTHOR]

Monofunctional hybrid materials based on Keggin-type heteropolyacids supported on mesostructured silica were used in isomerization of n-hexane. The heteropolyacids, namely H3PW12O40 or H4SiW12O40, were immobilized onto SBA-15 type silica by incipient wetness impregnation. The resulting catalysts were thoroughly characterized by N2 adsorption-desorption isotherms, XRD, 31P NMR, TGA and FT-IR. These hybrid materials were active for the gas-phase isomerization of n-hexane. Various reaction parameters and catalyst features were investigated: tungsten loading, reaction temperature, contact time, pressure and nature of the polyanion. All results could be explained by a competition of the mono- and bimolecular mechanisms. Supported tungstosilicic acid was intrinsically more selective than phosphotungstic counterpart and should be preferred for applications in isomerization of alkanes. A deactivation of the catalysts was observed due to the poisoning of acid sites by coke formation. [ABSTRACT FROM AUTHOR]

• Supported bimetallic catalysts typically possess superior performances than monometal catalysts and the impregnation method has been widely applied for the bimetallic catalyst preparations. • Impregnation sequences could play their significant roles on the physical and chemical properties of supported bimetallic catalysts. • A host of characterizations from impregnation sequential effects were briefly evaluated by reviewing the recent representative literatures. • The investigation of the nature of active sites and the structural dynamics on bimetallic catalysts are prospected accordingly to enhance the fundamental understanding of sequential influences. • The appropriate measurement of reaction rates is much required to compare the bimetallic catalysts that are prepared by different sequences of impregnations. Supported bimetallic catalysts have been paid great attention regarding their excellent catalytic performances in chemical process. Notably, comparing to monometallic catalysts, the synergetic properties of dual-metal-based materials demonstrate unique physiochemical functionalities that single metal materials do not possess. The preparation of supported bimetallic materials is widely conducted with applying the impregnation method because of the straightforward and inexpensive technique. Wherein, the impregnation of dual metals on support could either undergo co-impregnation or sequential impregnations. It has been frequently reported that there are substantial differences in physiochemical properties and catalyst performances by impregnation sequences. Specifically, during the investigation of various sequential impregnated bimetallic catalysts, a host of characterization strategies are employed to compare the physical and chemical properties that play vital role to impact the catalyst activity/selectivity/stability. However, it is still not well understood regarding the impregnation sequential effects, such as the nature of bimetallic active sites and the dynamics of bimetallic surface structures along with reaction progress. This presenting perspective article is devoted to take a succinct review regarding the general sequential impacts on the physiochemical properties and further profoundly address the research outlook in this topic. [Display omitted]. [ABSTRACT FROM AUTHOR]

A series of manganese oxide catalysts supported on oxidized multi-walled carbon nanotubes for low temperature selective catalytic reduction of nitrogen oxides (NOx) with NH in the presence of excess O was prepared by a simple impregnation method. These catalysts were characterized by N adsorption, TEM, XRD and H-TPR methods. The effects of reaction temperature, MnOx loading, and calcination temperature were investigated. Under the reaction conditions of 483 K, 1 bar, NO = NH = 900 ppm, 5 vol% O, GHSV = 30,000 h, and 12 wt% MnOx, NOx conversion and N selectivity of 91 and 99 %, respectively, were obtained. The LTSCR activity was suppressed in the presence of 100 ppm SO and 2.5 vol% HO at reaction temperatures below 573 K, but it was reversible to its initial level after heating and sweeping the catalyst at 573 K for 2 h in Helium. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Tungstophosphoric acid (TPA)-containing mesoporous santa barbara amorphous (SBA)-15 materials were synthesized by impregnation of TPA into hydrothermally synthesized SBA-15. TPA was incorporated to the porous framework of silica with different W/Si ratios, using TPA hydrate as the acid source. The synthesized materials had a surface area range of 212-825 m2 g−1, depending on the TPA loading and exhibited Type IV adsorption-desorption isotherms. Energy dispersive spectrometry and X-ray photoelectron spectroscopy (XPS) analyses showed that TPA was successfully penetrated into mesopores of the SBA-15 material. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis of the pyridine adsorbed synthesized materials revealed the existence of Lewis and Brønsted acid sites in the synthesized materials. Their performances were tested in the degradation of polyethylene by thermogravimetric analysis. An increase in TPA content significantly lowered the degradation temperature and activation energy of the polyethylene degradation reaction. In the presence of TPA-incorporated SBA-15 catalyst, activation energy was reduced to approximately half-value of the value found in the absence of the catalyst. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2466-2472, 2012 [ABSTRACT FROM AUTHOR]

Abstract: Silica nanoparticles of diameter, 24–75nm and surface area, 875m2/g were synthesized using aero-gel route. Thereafter, nanoparticles were impregnated with reactive chemicals, and used as reactive adsorbent to study the removal of toxic nerve and blister chemical warfare agents and their simulants from solutions. Trichloroisocyanuric acid impregnated silica nanoparticles showed the best performance and indicated physisorption followed by chemisorption/degradation of toxicants. This indicated their suitability as universal decontaminant for nerve and blister agents. This system showed a decrease in t 1/2 from 1210 to 2.8min for the removal of king of chemical warfare agents, i.e., sulphur mustard. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of toxicants over impregnated silica nanoparticles. [Copyright &y& Elsevier]

Abstract: The operating conditions of SRE (steam reforming of ethanol) reaction were evaluated by thermodynamics, in considering of the application requirements in hydrogen concentration and energy consumption. Under the select operating conditions, 5% CuNi/SiO2 catalysts with different Cu/Ni ratios prepared through incipient-wetness co-impregnation were tested for SRE. The catalysts were reduced with NaBH4 at room temperature, and again reduced by H2 at 623K prior to temperature-programmed SRE testing to remove surface oxygen. The SRE reaction products indicate a reaction scheme involving ethanol dehydrogenation to acetaldehyde, wherein acetaldehyde steam reforming and acetaldehyde decomposition compete, and with subsequent CO conversion to CO2 via water gas shift reaction. The catalysts with Cu/Ni≥1 showed higher ethanol conversion, higher acetaldehyde conversion, higher selectivity of acetaldehyde steam reforming, and lower coking at temperatures below 673K than the Ni-rich catalysts. Analyses by XRD, XPS, and EXAFS indicate that the Cu-rich catalysts had formed an alloy structure with Ni-enriched surface. The catalyst with Cu/Ni=1 showed the highest performance in ethanol conversion, acetaldehyde conversion, the selectivity of acetaldehyde steam reforming, and the stability against particle sintering. [Copyright &y& Elsevier]

Abstract: The degree of interaction between selected organic biocides (tebuconazole, propiconazole, and IPBC) and wood under supercritical conditions was investigated using a supercritical fluid chromatograph. The biocides were carried through a sawdust column by CO2 at various conditions. Retention times differed markedly both between the examined biocides and between physical conditions. Tebuconazole showed a higher affinity for wood than the other biocides. For all biocides, wood affinity was highest and, thus, fluid affinity lowest, at lowest pressures. [Copyright &y& Elsevier]

Abstract: Alumina nanoparticles in the size range of 2–30nm and surface area 375m2/g were synthesized using aerogel route and then characterized using N2–BET, SEM, TEM, XRD, FTIR and TGA techniques. Thereafter, these were impregnated with reactive chemicals and tested for their potential by conducting studies on kinetics of adsorption of 2-chloroethylethylsulphide (2-CEES) under static conditions. Kinetics was studied using linear driving force and Fickian diffusion model. The kinetics parameters such as equilibration constant, equilibration capacity, diffusional exponent and adsorbate–adsorbent interaction constant were also determined. AP-Al2O3 with 10% impregnation of MoVPA (V3) and NaOH showed the maximum (574mg/g) and minimum (88mg/g) uptake of 2-CEES among impregnated systems respectively. All impregnated systems except NaOH impregnation showed the values of diffusional exponent to be <0.5, indicated the diffusion mechanism to be Fickian, whereas AP-Al2O3 with and without NaOH impregnation showed the diffusional mechanism to be anomalous. Hydrolysis and dehydrohalogenation reactions (identified using GC/MS technique) were found to be the route of degradation of 2-CEES. [Copyright &y& Elsevier]

Abstract: The article describes a convenient synthesis and Cr(VI) extraction efficiency of a novel p-tert-butylcalix[8]areneoctamide impregnated Amberlite (XAD-4) resin. Using p-tert-butylcalix[8]arene macrocyclic building block, two strategies have been developed; i.e., derivatization of p-tert-butylcalix[8]arene framework with sophisticated ionophoric groups having efficiency to extract oxoanions from aqueous media and, impregnation of p-tert-butylcalix[8]arene derivative onto the polymeric support. Liquid–liquid and solid–liquid extraction experiments have been performed to evaluate the Cr(VI) extraction efficiency of both p-tert-butylcalix[8]arene derivative and the impregnated resin. From the results, it has been deduced that solid-phase extraction method is more convenient and efficient than liquid–liquid extraction process. The impregnated XAD-4 resin has been found regenerable with better extracting efficiency as compared to the simple p-tert-butylcalix[8]areneoctamide ionophore. [Copyright &y& Elsevier]

Three nickel-based catalyst systems, Ni/γ–Al2O3, Ni/BaTiO3, and Ni–0.75wt%La–BaTiO3, were investigated for the CO2 reforming of CH4. The temperature of CH4 decomposition on catalyst Ni/γ–Al2O3 is the lowest and the relative content of H2 is the highest; but the temperature of CH4 decomposition on catalyst Ni–0.75 wt%La–BaTiO3 is the highest and the relative content of H2 is the lowest. The amount of carbon deposition via CH4 decomposition decreases with the increase of rare earth La and the temperature of decomposition also declines gradually. Different active coke species were formed on different catalysts. The higher activity of coke species is, the easier the reaction with activated CO2 is. The coke species were investigated by the XPS technique. Several surface coke species existed on catalysts after the reaction. The surface species with the binding energy near 282 and 286 ev are the main coke species. These species resulted in the catalyst deactivation. By analyzing the coke on catalyst, it was found the catalyst Ni–0.75wt% La–BaTiO3 suppressed the formation of coke species whose binding energy is near 282 and 286 ev. [ABSTRACT FROM AUTHOR]

A series of RuO2 · xH2O/carbon aerogel (CA) composite electrode materials was prepared by a chemical precipitation method. Ultrasonication was used to accelerate the chemical reaction and improve the dispersion of RuO2 · xH2O particles on the surface and the pores of the aerogel. The structure and morphology of the as-prepared composite were characterized by N2 adsorption isotherm, X-ray diffraction (XRD), and field emission-scanning electron microscopy (FE-SEM). The results showed that the CA had a pearly network structure and the composites had a relatively high specific surface area and mesopore volume. The electrochemical performance of the composite electrodes was studied by cyclic voltammetry, galvanostatic charge/discharge measurements and electrochemical impedance measurements. The results indicated a substantial increase in the specific capacitance of the composite. Moreover, the utilization efficiency of RuO2 · xH2O was greatly improved by loading it on the conductive and porous CA due to a significant improvement in the inter-particle electronic conductivity and the extensive mesoporous network of the composites. [ABSTRACT FROM AUTHOR]

Three nickel-based catalyst systems, Ni/γ–Al2O3, Ni/BaTiO3, and Ni–0.75wt%La–BaTiO3, were investigated for the CO2 reforming of CH4. The temperature of CH4 decomposition on catalyst Ni/γ–Al2O3 is the lowest and the relative content of H2 is the highest; but the temperature of CH4 decomposition on catalyst Ni–0.75 wt%La–BaTiO3 is the highest and the relative content of H2 is the lowest. The amount of carbon deposition via CH4 decomposition decreases with the increase of rare earth La and the temperature of decomposition also declines gradually. Different active coke species were formed on different catalysts. The higher activity of coke species is, the easier the reaction with activated CO2 is. The coke species were investigated by the XPS technique. Several surface coke species existed on catalysts after the reaction. The surface species with the binding energy near 282 and 286 ev are the main coke species. These species resulted in the catalyst deactivation. By analyzing the coke on catalyst, it was found the catalyst Ni–0.75wt% La–BaTiO3 suppressed the formation of coke species whose binding energy is near 282 and 286 ev. [ABSTRACT FROM AUTHOR]

Abstract: An experimental investigation was conducted to study the effect of soaking time and polymerization temperature on the mechanical and physical properties of polymer-impregnated concrete. Soaking time was controlled in 4, 8, 12, 16, 20 and 24h, polymerization temperature was set at 70, 80 and 90°C for 0.5, 1, 2, 4, 6, 12 and 24h in impregnation process, respectively. Cylindrical concrete specimens with water/cement ratios of 0.45 and 0.65 were impregnated with methyl methacrylate (MMA) and benzoyl peroxide (BPO) mixtures. The polymer loading increases as immersion time increases until 12h. Based on compressive strength and surface absorption, optimum polymerization temperature is 70°C for Mix A (high cement content) and 80°C for Mix B (low cement content). Polymer impregnation not only increases concrete strength and resistivity but also greatly decreases surface absorption comparing with normal concrete. SEM and MIP observations indicate that the micro-pores and meso-pores of PIC specimens are filled with PMMA and the total pore volume and maximum pore size are reduced significantly. [Copyright &y& Elsevier]

Several zeolite-based catalysts containing Ce3+ and/or CeO2 were prepared by a variety of catalyst preparation techniques like ion exchange, solid-state ion exchange, impregnation and physical mixing and are characterised. Selective catalytic reduction was evaluated using simulated exhaust gas containing NOx, NH3, O2 and H2O at high space velocities (>180000 h-1) in the temperature window 150–600 °C. The activity and selectivity in NOx reduction was found to strongly depend on the charge compensating ions, crystallite size of the zeolite and CeO2 content in the catalyst. CeO2 mixed with zeolite having H+ or Ce3+ co-cations showed benificial effect and increased the NOx conversion and selectivity. Among the different zeolite materials studied, the structure and the strength and amount of Brønsted acidity did not influence the NOx conversion. [ABSTRACT FROM AUTHOR]

Combustion of two Chinese coals, without and with the impregnation of calcium acetate, was carried out in a drop tube furnace. Coal pyrolysis was first conducted to study the morphology of the resultant chars, the mode of occurrence of calcium, sulfur and their association within char were studied as well. Secondly, combustion of chars was carried out to reveal the emission of sulfur, transformation of char structure and that of calcium- and sulfur-based compounds in this process. The combustibility of two coals was investigated. Yanzhou high sulfur (YZHS) coal combusted quickly and a portion of the emitted sulfur were captured by the inherent calcium oxide during its combustion. Datong coal (DT) combusted relatively slowly and its sulfur emission was continued until all the carbon burnt out. A thin walled porous structure was formed for the pyrolyzing YZHS char while a relatively thick wall was formed for the pyrolyzing DT char. SO2 emission during combustion of impregnated coals was decreased considerably compared to that in the cases of raw coals. More than half the emitted sulfur was captured by added calcium in coal pyrolysis. Sulfur removal in the following char compounds varied with both reaction temperature and coal type. Almost all the emitted sulfur was captured at 1000 °C; increasing temperature to 1200 °C, however, decreased its removal efficiency. During coal pyrolysis, the added calcium, which penetrated into coal due to the impregnation, moved to the surface of porous char, where it met the emitted sulfur, capturing it quickly. Little calcium reacted with the inherent aluminosilicate in this step. In the beginning of char combustion, the reaction of oxygen with volatile and char led to the increase of char temperature, as a result, the sulfation of calcium was inhibited to certain extent, whereas the formation of calcium aluminosilicate was facilitated. With char combustion progressed, a porous calcium network was formed, which reacted with SO2 readily, and hence, the sulfur removal efficiency was increased eventually. [Copyright &y& Elsevier]