Search

We investigated the effects of the preparation molar ratios (Cs/(H3O)Zr2(PO4)3 and Sr/(H3O)Zr2(PO4)3) on the immobilization of Cs+ and Sr2+ ions in (H3O)Zr2(PO4)3 through heating at 250 °C for 24 h in an aqueous solution using an autoclave. When the preparation molar ratios were 0.4 or lower for Cs and 0.2 or lower for Sr, the immobilization of the corresponding ions occurred almost to completion. On the other hand, for the molar ratios (1.0 for the Cs system and 0.5 for the Sr system) at which all the H3O+ ions in (H3O)Zr2(PO4)3 could be replaced by the Cs+ or Sr2+ ions, the immobilization reaction did not proceed readily.

The effect of three zinc salts (Zn(CH3COO)2, ZnSO4, and Zn(NO3)2) on the size of the precursors of the ZnO nanoparticles that were mass-produced by precipitation in a rotating packed bed was studied. The precursors were formed at a rotational speed of 2000 rpm and flow rates of 0.5 L/min by precipitation using various zinc salts and NaOH as the precipitant. When zinc salts were Zn(CH3COO)2 and ZnSO4, the smallest precursors were obtained at a Zn2+/OH− molar ratio of 1/2. However, when the zinc salt was Zn(NO3)2, the smallest precursors were obtained at a Zn2+/OH− molar ratio of 1/1. Additionally, various zinc salts yielded different effects of the concentrations of Zn2+ and OH− on the size of the precursors. Experimental results indicate that the smallest precursors for various zinc salts were obtained at a Zn(CH3COO)2 concentration of 0.4 mol/L and an NaOH concentration of 0.8 mol/L, a ZnSO4 concentration of 0.1 mol/L and an NaOH concentration of 0.2 mol/L, and a Zn(NO3)2 concentration of 0.2 mol/L and an NaOH concentration of 0.2 mol/L. ZnO nanoparticles were mass-produced by calcining these precursors at sufficient temperatures for 1 h. In this way, the average sizes of the ZnO nanoparticles that were mass-produced using Zn(NO3)2, Zn(CH3COO)2, and ZnSO4 as zinc salts were 98, 136, and 186 nm, respectively.

This study presents the advances in the field of ZnO/Ag catalysts from the synthesis of hierarchical ZnO nanowires (NWs) decorated with Ag nanoparticles, prepared by a facile solvothermal method at 120°C. It evaluates the photocatalytic efficiency from studying the time reaction of Ag/Zn concentration ratio and the presence of cetyltrimethylammonium bromide (CTAB) as an organic dispersant. X-ray diffraction, scanning electron microscopy, and analytical/high-resolution transmission electron microscopy results confirmed the presence of homogeneous cylindrical ZnO nanowires and quasi-spherical Ag crystals. ZnO NWs exhibited hexagonal wurtzite structure and cubic FCC symmetry in Ag nanoparticles (NPS). Two types of nanostructures, including homogeneous cylindrical ZnO NWs in the absence of Ag and simultaneous presence of ZnO NWs and Ag NPs, formed depending on experimental conditions. The photocatalytic activity was evaluated by studying methylene blue (MB) degradation time under UV light excitation. Diffuse reflectance UV–Vis spectrophotometry (UV–Vis DRS) allowed identifying the ZnO absorption band at ~393 nm. Crystal size varied depending on the reaction time and the addition of CTAB. Synthesis time increased bandgap values, getting better photocatalytic performance in samples synthesized in intermediate times (6 h), higher Ag+/Zn2+ molar ratio (0.2/1.0), and CTAB. According to HRTEM observations, the presence of silver nanocrystals with high content of defects (twinning, stacking faults) could play an essential role in the photocatalytic response. In this context, the specific synthesis conditions of Ag/ZnO might be more appropriate for their use in organic dyes degradation in water and the potential use in protective treatments against materials biodeterioration processes. This work has been supported by the Innovation and Education Ministry (ref. MAT2013-47460-C5-5-P and MAT2016-80875-C3-3-R), the Autonomous Region Program of Madrid (ref. S2018/NMT-4411 and S2013/MIT-2862), the Geomateriales 2 program (S2013/MIT_2914), the TOP Heritage (P2018/NMT-4372) of the Community of Madrid, the Innovation and Education Ministry (MAT201347460-C5-5-P) and the Ministry of Education, Science and Technological Development of Serbia (projects No. 172035 and 45020). Besides, we would like to thank the Master of “Materials Science” of Carlos III University (Spain) for providing financial and laboratory equipment support.

The hydro-biological parameters such as thermohaline structure, nutrients, and chlorophyll-a (chl-a) during pre-southwest monsoon (PRSWM) and post-southwest monsoon (POSWM) periods of 2017, was investigated and compared along a coastal transect in the western Bay of Bengal (BoB). The impact of cold-core and warm-core eddies on chl-a in the very near coastal waters of the western BoB was analyzed. During PRSWM period, the water column was recharged with phytoplankton growth-promoting nutrients entrained by cold-core eddies that resulted in an increment in chl-a concentration. A three-times increase in chl-a concentration was observed due to the cold-core eddy, whereas the presence of warm-core eddy reduced the chl-a concentration by 87%. However, during POSWM period, despite having higher nitrate concentration and adequate light in the water column, the surface chl-a was substantially lesser than PRSWM. The molar ratio of ambient inorganic macronutrients during POSWM period played a significant role resulting in lower chl-a concentration. Nitrogen to phosphate (N:P) and nitrogen to silicate (N:Si) ratios were less than the Redfield values. The chl-a concentration off Godavari, a biological hotspot, was the lowest during POSWM period. This study highlights phosphate limitation off Godavari during the high river discharge period.

Polyvinyl alcohol (PVA) is widely used in nuclear power plant uniforms, these uniforms are usually sealed with cement after use because they are radioactive, but this will waste land resources. Therefore, to find a simple and effective chemical method to deal with them has become a scientific challenge. Although Fenton process needs further post-treatment, but it has a great advantage on the treatment of PVA fabric, meanwhile, it is one of the most effective methods to dispose organic pollutants at present. In this paper, we investigated the degradation of discarded polyvinyl alcohol (PVA) fabric and PVA (1750) via Fenton process. Several potential factors were evaluated to describe the PVA fabric degrading efficiency and TOC removal rate, such as H2O2 dosage, the molar ratio of H2O2/Fe(NO3)2, initial pH value, reaction temperature, and reaction time. The optimum H2O2 dosage, the molar ratio of H2O2/Fe(NO3)2, initial pH value, reaction temperature, and reaction time were found to be 650 g, 10, 4, 50 °C, and 30 min, respectively. The viscosity-average molecular weight of PVA fabric was degraded from 130,293 to 420. The degrading efficiency and TOC removal rate were 99.96% and 99.97%, respectively. At last, the degradation mechanism and kinetics were studied in this paper.

In circulating fluidized bed combustion (CFBC) boilers, the method of feeding of limestone with fuel into the furnace gives high desulphurization efficiency and avoids the usage of pulverization equipment in the plants. Ca/S molar ratio and bed temperature play an important role in the process of sulphur capture. Generally, Ca/S ratio ranges between 2 and 6 and bed temperature is around 800–900 ​°C in the commercial CFBC boilers. Higher value of Ca/S ratio and optimum value of bed temperature provide higher desulphurization efficiency. The present work focuses on providing the stipulated value of Ca/S molar ratio (1–6), bed temperature (800oC–925 ​°C) which are required to achieve 95% sulphur capture efficiency for Indian lignite based CFBC boiler operating with 210MW steam parameters using simplified sulphur capture model. The work also shows the effect of Ca/S molar ratio and bed temperature on the values of sulphur emissions, reaction rate of sulphation, limestone feed rate and boiler efficiency for three lignite samples which are popularly available and used in commercial operations of Indian CFBC boilers.

The present study aims to investigate the effect of Longan Arillus extract (ELA) on oral absorption of bioactive peptides (cationic P1: VEGNLQVLRPR, anionic P2: HNLDTQTESDV) derived from defatted walnut meal hydrolysates (DWMH). Oral co-delivery of ELA with DWMH led to a significantly higher maximum blood concentration of P2 in rats than delivering DWMH alone. Endocytosis pathway of P2 in intestinal epithelia cells was altered by ELA, probably resulting from formation of uniform microparticles by mixing of P2 and ELA. Results of isothermal calorimetry proved strong binding between molecules of P2 and ELA at a molar ratio of 1:1. On the contrary, the absorption of cationic P1 remained unchanged after co-delivery of ELA, probably resulting from the complicated patterns of binding between ELA and P1 molecules. In conclusion, we found the enhancing effect of polysaccharides on absorption of peptides by formation of microparticles, which could be predicted by molecule binding.

Highlights • First report of degradation of thiamethoxam using cavitation based processes. • Ultrasound cavitation based combined processes leads to synergistic effect. • Ultrasound cavitation + photo-Fenton combined process is the most efficient approach. • Degradation mechanism is proposed based on identified degradation by-products., The present study has investigated the degradation of thiamethoxam using ultrasound cavitation (US) operated at a frequency of 20 kHz and its combination with intensifying additives viz. hydrogen peroxide, Fenton and photo-Fenton reagent. At the outset, the performance of US (20 kHz) has been maximised by the optimization of process parameters. Highest rate of degradation of thiamethoxam was observed at the optimum ultrasonic power density of 0.22 W/mL, thiamethoxam concentration of 10 ppm and the pH of 2. The established optimum values of operating parameters were used further in case of combined treatment approaches. The effect of concentration of H2O2 on the rate of degradation of thiamethoxam in the case of US + H2O2 process has confirmed the existence of optimum concentration of H2O2 with the ratio of thiamethoxam: H2O2 as 1:10. US + Fenton process indicated the optimal molar ratio of FeSO4·7H2O:H2O2 as 1:15. The combined processes of US + H2O2, US + Fenton and US + photo-Fenton have resulted in the extent of degradation of 20.47 ± 0.61%, 34.41 ± 1.03% and 85.17 ± 2.56% respectively after 45 min. of operation. These combined processes lead to the synergistic index of 2.04 ± 0.06, 2.26 ± 0.07 and 2.42 ± 0.07 in case of US + H2O2, US + Fenton and US + photo-Fenton processes respectively over only US/stirring treatment with the additive. Additionally, the extent of mineralization and the energy efficiency of individual and combined processes have been compared. US + photo-Fenton process has been found to be the best strategy for effective degradation of thiamethoxam with a significant intensification benefit. The by-products formed during the ultrasonic degradation of thiamethoxam have been identified by using LC-MS/MS analysis.

Emerging contaminants and, among them, pharmaceutical compounds, have a significant impact on water ecosystems. Layered Double Hydroxides (LDH), being easy to synthesize and cheap materials, have recently gained attention as adsorbents in aqueous solutions. This work describes the latest research performed in the adsorption capacity of LDH towards both antibiotics and Non-Steroidal Anti-Inflammatory Drugs (NSAID) describing and analyzing the synthesis conditions (Me2+:Me3+ molar ratio, calcination temperature, choice of metals for the memory effect), kinetics and isotherm models used, use of support (more practical in a 3D over a 2D form), temperature effect and several techniques for the recovery of the adsorbents. LDH exhibited great performance and potential as clean adsorbents for these emerging contaminants. This work was funded by the Spanish Ministry of Economy, Industry and Competitiveness (AEI/MINECO) and the European Regional Development Fund (ERDF) through project MAT2016-78863-C2-R. LS thanks the Universidad Pública de Navarra for a pre-doctoral grant. AG also thanks Banco Santander for funding through the Research Intensification Program .

In this paper, hybrid silica aerogels were prepared by methltrimethoxysilane (MTMS) and water-glass co-precursor through two-step sol-gel process followed by freeze drying (FD). The characteristics of aerogels were strongly affected by the molar ratio of MTMS/Water-glass. When the molar ratio is 5.1, hybrid aerogel was obtained with good performances, such as low density (0.083 g/cm3), high contact angle (155.1°) and low thermal conductivity (0.0226 W/m·K). The density, contact angle and thermal conductivity of aerogels based on co-precursor are still showing excellent thermal stability with the same performances after 550 °C heat-treatment. Keywords: Silica aerogels, MTMS/Water-glass, Freeze drying, Hydrophobic, Thermal stability

Herein a novel process for CO₂ capture and utilization suitable for small-medium scale applications is presented. The use of potassium and calcium wastes is proposed as an alternative low-energy path to CO₂ capture and waste valorization. In our work, CaCO₃ precipitation studies were performed to corroborate the feasibility of the novel process described. Reaction time, reaction temperature, molar ratio, and K₂CO₃ initial concentration were varied to analyse their effects on the precipitation efficiency. The purity and main characteristics of the obtained product were physicochemically characterized to evaluate the potential cost of the final solid product by means of Raman spectroscopy, X-ray diffraction, FTIR, and scanning electron microscopy. Results show that promising precipitation efficiencies are obtained in comparison with other waste-valorization and CO₂ capture process, even at room temperatures. High quality calcite was obtained as solid product. Overall our work confirms the technical viability of the proposed route to synergize CO₂ capture and saline waste utilization.

This dataset disclose the investigational data on the extraction of bio-oil from seeds of Vitis vinifera through combination of mechanical pressing and soxhlet solvent extractor. Biodiesel is produced through single stage base catalysed transesterification process due to lower free fatty acid content in the Vitis vinifera bio-oil. Independent variable process parameters like molar ratio, reaction time and catalyst concentration are optimized using Artificial Neural Network, Response Surface Methodology and Adaptive Neuro-Fuzzy Interference System to predict the maximum biodiesel yield and the results are compared with the experimental data. Response Surface Methodology predicted a maximum Vitis vinifera biodiesel yield of 97.62% at methanol to oil molar ratio 0.2758 v/v, catalyst concentration 1.045 gm of NaOH and reaction duration of 1.11 hrs which is also confirmed with experimental results. Keywords: Vitis vinifera biodiesel, Transesterification, Molar ratio, ANN, RSM, ANFIS

Diet has an important role in maintaining dental health, and there is a general need for more research to understand the impact of different foods and drinks on dental endpoints. An EU health claim has been authorised for a range of modified, non-alcoholic, fruit juice drinks branded as ‘Toothkind’. The claim relates to the maintenance of healthy teeth when these drinks are used, in the context of a balanced diet, as an alternative to sugar-sweetened beverages and fruit juices. Characteristics of the Toothkind drinks include set parameters for the molar ratio of calcium to acid, pH and fermentable carbohydrate content. The evidence used to substantiate the claim was based on comparisons of Toothkind drinks with soft drinks and fruit juices. The authorised wording of the claim is: ‘Replacing sugar-containing, acidic drinks such as soft drinks (typically 8–12 g sugars/100 mL), with reformulated drinks contributes to the maintenance of tooth mineralisation’. The claim was granted protection of proprietary data for 5 years, until September 2018. However, due to changing market conditions the Toothkind formula is no longer produced and the claim is not in use. Nevertheless, this claim illustrates the type and quality of scientific research that is needed to gain an authorised claim for an innovative product.

Reactive magnesia (MgO) with a high purity and reactivity is used in several high-end applications. This study reports the feasibility of synthesizing high reactivity MgO from reject brine with the use of NH$_{4}$OH. The molar amount of NH$_{4}$OH was optimized at a NH$_{4}$OH/Mg$^{2 +}$ molar ratio of 6 to provide maximum magnesium oxide yield and purity. This led to the synthesis of Mg(OH)$_{2}$ with a purity of 93.5%, which was further calcined at 500 °C for 2 h to produce reactive MgO with a SSA of 78.8 m2/g. This study shed light on the significant potential of reject brine in the recovery of Mg$^{2 +}$ and the synthesis of reactive MgO with a wide range of potential applications.

Thermodynamic analysis of the production of solar syngas (a mixture of H 2 and CO with molar ratio equal to 2:1) via SnO 2 /SnO based thermochemical H 2 O and/or CO 2 splitting redox reactions was investigated and presented. Commercially available HSC Chemistry software and databases were used for the thermodynamic modeling of this process. Thermodynamic analysis was performed in two sections, namely, a) equilibrium thermodynamic calculations, and b) second law thermodynamic modeling of the SnO 2 /SnO based thermochemical H 2 O and/or CO 2 splitting process. Results obtained via the computation thermodynamic modeling are presented.

For direct propene epoxidation with H2/O2, TS-1 with blocked micropores (TS-1-B) is recognized as an attractive support for Au catalysts with enhanced stability and activity by suppressing the deactivation caused by micropore blocking. In this work, as a consecutive effort, effect of Si/Ti molar ratio of TS-1-B on catalytic performance is investigated. It is shown that the optimum Si/Ti molar ratio is 40. In other words, both lower and higher ratios are unfavorable for the formation of propylene oxide, which are possibly attributed to the presence of extra-framework Ti species and the difficult transmission of hydroperoxide species from Au surface to nearby Ti sites, respectively. Based on this, effect of Au loading on catalytic performance is further examined. When the Au loading is 0.13 wt%, the catalyst shows not only high PO formation rate of 158 gPO h−1 kgCat−1 comparable to the reported best activity without adding promoters, but also significantly enhanced stability at 200 °C over 30 h. © 2014. This is the authors’ accepted and refereed manuscript to the article. Locked until 13 October 2016 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

We have synthesized flexible monolithic carbon aerogels by incorporating diatomite as antishrinkage agent during the sol-gel polycondensation of the precursors. The materials displayed elastic properties and preserved their pristine dimensions upon densification by carbonization even after etching of the diatomite, due to the open pore structure of the siliceous additive in the material’s matrix. The aerogels displayed a well-developed porous structure, confirming that the polymerization of the precursors is not impeded; the effect of the additive was independent of the formulation of the aerogels, as evidenced by the behavior of aerogels with varied composition (molar ratio, pH, N-doping)., This work was partially funded by MINECO (grant CTM2014/56770-R, IPT-2011-1450-310000 ADECAR and Feder cofunding). The help of Mr. D.L. García in the preparation of the specimens is greatly appreciated.

Au/TS-1 catalyst prepared by deposition–precipitation method is efficient for propene epoxidation with H2/O2, and its performance is significantly affected by the preparation parameters and the properties of support. In this work, effects of the slurry aging time and Si/Ti ratio of support on the location of Au nanoparticles inside or outside the micropores of TS-1 supports are examined by multi-techniques such as in situ characterization and molecular dynamics simulation, and the as-obtained catalysts are tested for propene epoxidation. It is found that longer slurry aging time facilitates the evolution of Au complex into smaller sized species which is easier to locate inside the micropores. Accordingly, the as-reduced catalyst has more tiny Au nanoparticles that are extremely active inside micropores and shows higher initial PO formation rate (gPO h−1 gAu−1). In addition, high Si/Ti ratio of TS-1 also favors the deposition of Au nanoparticles inside micropores, resulting in higher initial activity but lower stable activity. © 2015. This is the authors’ accepted and refereed manuscript to the article. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

A thermodynamic analysis and experimental validation of bioglycerol catalytic steam reforming process using Ni/Al 2 O 3 catalyst for hydrogen production is presented in this article. The thermodynamic study was performed by developing a mathematical model of the process using ChemCAD process simulator a well-known and widely used CAPE tool. All major reactions and major products (H 2 , CO, CO 2 , CH 4 , C) obtained in the steam reforming of glycerol were considered in the thermodynamic analysis. For the validation of the simulation results, the results were compared with experimental data reported by literature. Following thermodynamic study the most important factors which influence the steam reforming of bioglycerol are the water/bioglycerol molar ratio and the temperature. The concentrations of the main product (H 2 ) at lower temperature are smaller than the ones at higher temperature due to by-products formation (methane). The maximum concentration of H 2 was obtained at 650 – 700 °C, 1 bar and molar ratio water/glycerol 10 : 1. The main by-products concentration (expressed in dry concentrations) where H 2 concentration is maximum, are the following: 0 % mol CH 4 , 21.2 % mol CO, 9.7 % mol CO 2 . The minimum formation of CH 4 and C was obtained at 1 bar, 1,000 °C and molar ratio water/glycerol 10 : 1.

In the research the various ways of increasing the selectivity of the dehydrogenation process and reducing the intensity of coke formation have been studied. All results were received by means of the mathematical model of the dehydrogenation process with the calculating technique of optimal water flow. The main conclusion consists in the fact that the decrease in molar ratio H2/feed leads to increasing the catalyst deactivation by coke. It can be partially compensated by increasing the supplied water flow to the reactor to 13-14 l/h instead of 9-10 l/h at the end of cycle. Reducing the life of the catalyst to 270-290 days even at an increased water flow is determined by the intensity of the coking reactions. However, the economic feasibility of operating in such condition causes a considerable increase in production of LAB to 181-186 t/day.

In the case of electrochemically reversible systems, it is possible to determine the redox state of the dissolved depolariser with the help of cyclic voltammetry. This can be done by measuring the currents at the lower and upper limits of the potential range, i.e., the cathodic and anodic currents iλ,c and iλ,a. The difference I=|iλ,a|−|iλ,c| is a reliable parameter for distinguishing solutions of the reduced and oxidised forms of the depolariser. When background currents are of appreciable size, the value of I has to be compared with that of a solution without the depolariser. When the solution simultaneously contains the oxidised and reduced forms of the depolariser, I is a linear function of their molar ratio. Hence, it is possible to follow a coulometric titration using cyclic voltammetry. Keywords: Cyclic voltammetry, Redox state, Coulometry

Amino acid analysis was performed on four Lp[a] preparations to evaluate whether or not the amino acid data was consistent with Lp[a] containing one molecule of apolipoprotein[a] [apo(a)] linked to one molecule of apoB-100. Amino acid analysis was carried out in duplicate on a Beckman model 121 amino acid analyzer. Apo[a] size was determined by a high-resolution agarose gel electrophoretic method that provides an estimate of apo[a] kringle 4 repeats. When Lp[a] was assumed to contain one apo[a] and one apoB molecule per particle, the average absolute bias between the expected molar percentage of each amino acid, as based on the known sequence of apo[a] and apoB, and the obtained molar percentage ranged from 2 to 3.5%. In contrast, by assuming two molecules of apo[a] and one of apoB per Lp[a] particle, the bias between the expected and observed molar percentage ranged from 8.5% to 10%, and by assuming one apo[a] and two apoB the bias ranged from 8.8% to 11.4%. Comparison of Lp[a] concentrations, calculated from six stable amino acids and the Lp[a] composition predicted from the known sequence, was in excellent agreement (bias ranging from 0.3% to 0.9%) with the Lp[a] concentration calculated from the sum of the amino acid concentrations, when Lp[a] was assumed to contain one molecule of apo[a] and one molecule of apoB. However, there was poor agreement (7.4% to 8.4% bias) when it was assumed that Lp[a] contains two molecules of apo[a] and one molecule of apoB. These results indicate that the evaluated Lp[a] preparations contain one apo[a] per Lp[a] particle. Evaluation of amino acid analysis data provides a relatively simple approach to determine the molar ratio of apoB to apo[a] in Lp[a] and provides evidence that Lp[a] contains one molecule of apo[a] and one molecule of apoB.

Hybrid electrolytes produced by the sol-gel process were obtained by doping a di-urea cross-linked POE/siloxane hybrid host framework (d-U(2000)) with lithium hexafluoroantimonate (LiSbF6). Flexible, transparent xerogel films with ∞ > n ≥ 2.5 (where n, composition, represents the molar ratio of oxyethylene units OCH2CH2 per Li+ ion), thermally stable to at least 200 ºC, were prepared. At 30 ºC the highest ionic conductivity of all the electrolytes prepared was 1.32x10-5 Scm-1 for n = 30. The electrochemical stability windows of these materials span at least 6.0 V. Samples with n < 200 are amorphous, homogeneous and non-porous. Crystallites of POE are formed in the most dilute electrolyte (n = 200). The guest Li+ ions were shown to coordinate to the oxygen atoms of the urea carbonyl groups over the entire range of salt concentration. The great majority of the SbF6- ions interact with the Li+ ions. Contact ion pairs were detected only at n = 200. Trace amounts of “free” anions exist in all electrolyte samples., Fundação para a Ciência e Tecnologia (FCT)

The highest molecular weight polymers are obtained under strictly controlled stoichiometric conditions, that is to say, an exact 1:1 molar ratio of two functional groups is necessary according to the classical theory of polycondensation. It has been found that an excess of one functional group yields high-molecular-weight polymers comparable to those prepared under stoichiometrically balanced conditions. In this chapter, nonstoichiometric polycondensation is described by categorizing polycondensation into that caused by the change in reactivity, and that caused by the change in the structures of polymers. That is, nonstoichiometric polycondensations are categorized based on the chemical effect and the physical effect.

Beta zeolite with Si/Al ratio equal to 40 was synthesised and used as solid catalyst in acetoxylation of camphene. The main product of camphene acetoxylation was isobornyl acetate being also formed bornyl acetate and fenchyl acetate. Effects of various parameters, such as reactant molar ratio, reaction temperature, catalysts loading and reusability of the catalyst were studied to optimise the reaction conditions. The catalytic stability of beta zeolite in the acetoxylation of camphene was studied by performing consecutive batch runs with the same catalyst sample. After the third run, it was observed similar values of the catalytic activity.

The reaction of AgOTf in dichloromethane with bis(2-(diphenylphosphino)phenyl) ether (DPEphos) in an equimolar ratio afforded a dinuclear complex [Ag2(κ2-P,P′-DPEphos)2(μ-OTf)2] (1), whereas the similar reaction in a 1:2 molar ratio resulted in the formation of a bis-chelating complex [Ag(κ2-P,P′-DPEphos)2][OTf] (2). The silver(I) complex 1 was obtained as a dimer, in which two silver atoms are bridged by two triflate groups to form three adjacent eight-membered spirocyclic rings. The mixed-ligand complex [Ag(κ2-P,P′-DPEphos)(2,2′-bpy)][OTf] (3) was obtained in the reaction of 1 in dichloromethane with 2,2′-bipyridine. The crystal structures of complexes 1–3 were determined by single crystal X-ray analyses., © Elsevier

The effect of the synthesis procedure and variables on the resulting chemical and structural properties of molecular sieves of the MWW family was investigated in detail. In addition, dealumination procedure was optimized to decrease the concentration of framework aluminum, which might lead to the connectivity of both originally independent channel systems. MCM-22 was successfully synthesized with Si/Al ratios higher than 12, while at lower ratios MCM-56 was obtained. The molar ratio of organic templates to inorganic cations forwarded the synthesis towards MCM-22 or MCM-49. Much higher stability of MCM-22 was found against steam treatment compared to alkali treatment.

For ADM catalyst, Ni was an effective promoter for the activity, in particular C2+-OH selectivity. At a Ni/Mo molar ratio of 0.5, the highest ratio of C2+-OH/C1-OH (8.75) was obtained, which was about 10 times that of ADM catalyst in the absence of Ni (0.87). The modification of Ni showed remarkable structural effects and the great deviation of methanol from the linear A-S-F distribution indicated a different reaction route, which might be caused by the bi-functionality of nickel species, namely, the formation of corresponding precursor of alcohol and the strong ability of CO insertion.

6-azonia-spiro-[5,5]-undecane and some mono- and di-substituted compounds were prepared and used as structure directing agents (SDAs) in the hydrothermal syntheses of zeolites. Their relatively low selectivity was demonstrated by the various zeolite structures synthesized, including MTW, MOR, Beta, ERS-10 and defect-free MEL. MOR was obtained with all the SDAs and its formation was favored by the low SiO 2 /Al 2 O 3 molar ratio in the reaction mixture. With the exception of the 1-ethyl-substituted azonia-spiro compound, which selectively gave defect-free MEL, MTW was the main product observed when the SiO 2 /Al 2 O 3 was kept >50 or in the absence of trivalent metal ions. Molecular mechanics and dynamics calculations provided evidences about the different templating properties of the azonia-spiro compounds and predicted MEL as the most stabilized by 1-ethyl-substituted SDA, in agreement with the experimental results.

Zinc dialkyldithiophosphate (ZnDTP) is a well-known multi-functional additive for lubricating oils that has superior oxidation inhibition and antiwear performance. All the engine oils for four-stroke automotive engines contain ZnDTP because no additive has been found to have better performance. However, since it was pointed out that ZnDTP poisons the exhaust catalyst, reducing ZnDTP concentrations in engine oil without losing the superior antiwear performance has become an important priority. The friction and wear characteristics of intentionally deteriorated ZnDTP, which can simulate used engine-oil, were studied using a four-ball tribometer. Both see-C6 and prim-C8 ZnDTP were degraded by reacting with cumenehydroperoxide (CHP), which modeled the hydroperoxide present in combustion gas. Several simulated used oils with different degrees of degradation were prepared by changing the molar ratio of [CHP]/[ZnDTP]. Hydro-refined mineral oil was used as a base oil without other additives. Changing the degree of degradation simulated the gradual change in deterioration during actual use. Fresh ZnDTP-containing oil showed lower wear and higher friction than the base oil. However, the anti-wear performance gradually decreased with increasig ZnDTP degradation, and an appreciable wear increase was observed after dissipation of ZnDTP. Beyond this point, further degraded oils showed larger wear and lower friction than those with the additive-free base oil. In other words, simulated used-oils were found to accelerate wear but to decrease friction. ZnDTP production various kinds of accelerated what appeared to be corrosive wear that might have been due to the excess reaction of surfaces with sulfur in the degraded compounds.

Publisher Summary This chapter reviews the calcium orthophosphate family to which hydroxyapatite belongs. Besides hydroxyapatite, the chapter list many kinds of calcium orthophosphate salts. The calcium orthophosphates are conventionally classified according to their Ca/P molar ratio that varies from 0.5 to 2. An important aspect of hydroxyapatite growth in modern technology is that, in many cases, the nucleation and subsequent growth of hydroxyapatite on the surface of biomaterials implanted in body tissues determine the performance and even lifetime of biomaterials. The growth of apatite crystals on the surface of biomaterials determines the characteristics and performance of a number of biomaterials. The chapter also reviews the mechanism and kinetics of hydroxyapatite growth in solution, in addition to the aspect of hydroxyapatite growth associated with hardening of calcium phosphate cements, and the fabrication of hydroxyapatite ceramics and single crystals. Most information about kinetics of hydroxyapatite crystal growth has been obtained from the constant pH method or the constant composition method.

The formation of cubic phase SBA-1 is strongly influenced by the synthesis condition. In-situ XRD experiments showed that SBA-1 crystallized more quickly in higher acidic conditions, and no phase transformation was observed in the synthesis gel when varying either the reaction period or the acidity (HC1: TEOS molar ratio = 2≈5). Moreover, the cubic phase was less stable when the solid was separated from the mother liquid. A phase transformation from cubic to hexagonal was observed on the precipitates formed in short crystallization period when they were dried at room temperature. To the best of our knowledge, it was the first time in the literature to report that the phase transformation was correlated to the removing of the solvent from the precipitate. The stability of SBA-1 crystal structure was greatly improved by post-treatment of the wet products with ammonia solution.

Publisher Summary This chapter presents the determination of the silicon/aluminium (Si/Al) ratio of faujasite-type zeolites. Zeolites Y dealuminated by Si/Al substitution using tetrachlorosilane (SiCl4) (DAY-S) and dealuminated thermochemically in steam (DAY-T) are investigated by X-ray powder diffraction, infrared spectroscopy, and wet chemical methods. The dependence of lattice constants (a) on the molar ratio x = (1+Si/A1)-1 show nonideal solid solution behavior. In a first approximation, the change in a (in nm) can be described as a = 0.187x+2.412, for 0.1

The paper describes the study of HPW, using conditions simulating as close as possible to a real car exhaust. The amounts of NO absorbed and desorbed prove very high with NO and NO 2 in molar ratio. XRD suggests that the structure is conserved following complete saturation by NO x . The adsorption mechanism proceeds via a substitution of the water molecules by NO x to form an [H + (NO 2 - ,NO + )] complex.

Refractory gold-arsenic concentrates of ores from six deposits, their biooxidation (BO) solid residues and residual bacterial solutions were analyzed for chemical composition and Fe/As molar ratio. The effect of the Fe/As ratio on As solubility was examined in two solid BO product types: (I) BO solid residues obtained in the course of biooxidation, and (II) precipitates that formed upon the completion of the BO procedure as a result of As precipitation from the bacterial solutions through the jarosite process. Stable arsenic-containing products can be formed provided that the Fe/As molar ratio is greater than 4. The pH governing the BO process and the iron concentration in the bacterial solutions can be varied in order to provide for a controlled increase in Fe/As. Mineragraphic, X-raying and X-ray photoelectron spectroscopic techniques were used to determine the composition arsenic-containing compounds incorporated in insoluble BO residues FeAsO 4 ·2H 2 O and Fe 2 (AsO 4 )·SO 4 ·OH·7H 2 O.

The synthesis of micro-mesoporous aluminosilicates via gelation of a reaction mixture containing Si(OC 2 H 5 ) 4 , Al(OC 3 H 7 ) 3 , C 2 H 5 OH, H 2 O and alkali-free NR 4 -OH (R=C 3 H 7 , C 4 H 9 , C 5 H 11 , C 6 H 13 ) is described. X-ray amorphous mesoporous aluminosilicates (MSA) or microporous aluminosilicates, characterized by a broad peak in the low angle region of XRD pattern (ERS-8), are obtained, depending on the NR 4 -OH/SiO 2 molar ratio and on the number of C atoms in the R groups. A structural model is proposed concerning the arrangement of the NR 4 + cations within the gel, which accounts for the experimental data.

Tetraphenylporphinetetrasulfonic acid (TPPS), which is well known as a photochemical hole burning (PHB) dye, was incorporated in silica gels obtained by the sol-gel process from tetraethoxysilane (TEOS). The form of TPPS must be free base (H 2 P), which exists in basic condition, to be active in PHB. To obtain transparent silica gels doped with free-base TPPS, two-step hydrolysis processes using solutions containing NaOH were developed, by the spectroscopic investigation, it was found that in the silica gels almost all the TPPS retained free-base form at the molar ratio of NaOH/TEOS above 10 −3 , and that the dimerization of TPPS incorporated in the TEOS gels did not occur higher NaOH concentration than that in the TMOS gels.

Calcium-deficient fluoridated apatite (DAp) containing HPO42− and Na+ ions was deposited on stainless steel by electrolyzing an acidic calcium phosphate solution added with NaF and NaNO3. The calcium-deficiency was 1.44 + 0.02 in Ca/P molar ratio. The deposited layers on the substrate were composed of single, twined or aggregated DAp crystals with an ellipsoidal, hexagonal pyramidal or hexagonal prismatic form elongated to the [001] direction and surrounded by the (100) planes of the apatite structure. Comparatively large single DAp crystals with a hexagonal bipyramidal form were observed in size of 50μm in major axis and 10μm in minor axis.

1. Summary The influence of surfactant/silica molar ratio(Sur/Si) in M41S syntheses was studied in the simple synthesis system consisting of tetraethylorthosilicate(TEOS), water, and the cetyltrimethylammonium(CTMA) cation at 100°C. As the Sur/Si increased from 0.5 to 2, the siliceous products obtained were identified and could be classified into four separate groups: MCM-4 1(hexagonal), MCM-48(cubic), thermally unstable M4 1 S, and a molecular species, the organic octamer [(CTMA)SiO2, 5]8. One of the thermally unstable structures has been identified as a lamellar phase. These results are consistent with micellar phase transformations that occur at various surfactant concentrations and reinforce the concept that micelle structures serve as templating agents for the formation of M41S type materials.

Stable peroxides, TS-1 (O2-)n, are produced by the reaction of titanium silicalite with hydrogen peroxide, in basic media. These have been characterized by physical chemical methods (XRD, IR, UV, TGA, TPD) and activity tests. The molar ratio n = Oact/Ti increases with the strength and the concentration of the base (0

The vapor-phase reaction of methyl acetate with methylal was examined over vanadium-phosphorus-based catalysts. The best performance was obtained with a V/Ti/P atomic ratio = 1/2/6 catalyst. The sum of yields of methyl acrylate and acrylic acid reached almost 100 mol% on the methylal basis at a methyl acetate/methylal molar ratio of 2. By the addition of oxygen to the feed, the formation of acrylic acid was markedly enhanced; the sum of yields of methyl acrylate and acrylic acid reached 148 mol% on the methylal basis (74 mol% on the methyl acetate basis).

Zeolites of different structural types and chemical compositions have been investigated in aniline alkylation with methanol in a wide range of reaction temperatures. The results obtained have been correlated with IRS investigations of zeolites studied. It is shown that wide-pore zeolites with low molar ratio Si02/A1203 are the most suitable catalytic systems to obtain both N,N-dimethylaniline and C-alkylated anilines.

The low sulphur fuels burned in Athens and the high photochemical activity (high [NOs≥]/[NO] ratios, but low Q 3 concentrations because of a 20 hour per day traffic peak) could mean that the molar ratio of [NO 3 - /[SO 4 - ] in the atmosphere of Athens is often greater than one. This in turn, could mean that the adverse effects of HNO 3 and NO 3 - on marble monuments are relatively important. Nitric acid, nitrates, sulphates, chlorides etc. in the atiiAjtsphere of the Acropolis were sampled with a transition flow reactor and analysed by ion chromatography. Their effects on Pentelic marble are being investigated by drawing air through a bed of coarse and graded Pentelic marble powder, washing the marble with deionized water, analyzing the ions in the wash by ion chromatography and using thermodynamic data from the literature