Absorption of gas into a wavy falling film

In this work, we present results of a study of gas absorption into a falling film on a vertical substrate. The film flow is accompanied by the formation of nonlinear waves which strongly influence the diffusion layer that develops from the film surface. As a result, significant enhancement of mass transfer has been observed in experiments. We use recent advances in modelling of the hydrodynamics and solve a two-dimensional convective-diffusion equation for the solute concentration. Numerical solutions for the finite-amplitude wave regimes and associated integral absorption rates are obtained for a range of flow conditions. Our results show clearly the influence of waves on the development of the diffusion layer and, in particular, the enhancement of absorption due to the waves; the existence of optimal conditions for maximizing the absorption rate is also demonstrated.     

Composite Nanoarchitectonics of Graphene Oxide for Better Understanding on Structural Effects on Photocatalytic Performance for Methylene Blue Dye

Journal of Inorganic and Organometallic Polymers and Materials - The fabrication of graphene/graphene oxide bounded metal nanostructures, to form hybrid composites, and their utilization for the...     

Polyphenol Oxidase from Coleus forskohlii: Purification,Characterization, and Immobilization Onto Alginate/ZnO Nanocomposite Materials

Catalysis Letters - Herein, polyphenol oxidase (PPO) was purified from Coleus forskohlii via a three-step process involving precipitation by (NH4)2SO4, ion exchange chromatography and gel...     

Production of Methyl Oleate in Reactive‐Separation Systems

The esterification of oleic acid and methanol using sulfuric acid as a homogeneous catalyst is studied in reactive‐separation systems. The conversion of the free fatty acid was investigated in two different experiments with the molar ratio of methanol/oleic acid, amount of catalyst, temperature, and reaction time as variables. The conversion of the free fatty acid was found to depend strongly on the molar ratio of methanol/oleic acid. The reaction time had a direct effect on the conversion of the free fatty acid, and this conversion decreased with higher temperature. These results were valuable for a preliminary study on biodiesel production, using an acid homogeneous catalyst in a reactive dividing‐wall distillation column.     

COSMO-RS:An ionic liquid prescreening tool for gas hydrate mitigation

Recently ionic liquids(ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial error as well as selection based on existing literature are the methods currently employed for selecting and/or tuning ILs. These methods are probabilistic, time consuming, expensive and may not result in selecting high performance ILs for gas hydrate mitigation. In this work, COSMO-RS is considered as a prescreening tool of ILs for gas hydrate mitigation by predicting the hydrogen bonding energies(E_(HB)) of studied IL inhibitors and comparing the predicted E_(HB) to the depression temperature(?) and induction time. Results show that, predicted EHBand chain length of ILs strongly relate and significantly affect the gas hydrate inhibition depression temperature but correlate moderately(R = 0.70) with average induction time in literature. It is deduced from the results that, ? increases with increasing IL EHBand/or decreases with increasing chain length. However, the cation–anion pairing of ILs also affects IL gas hydrate inhibition performance. Furthermore, a visual and better understanding of IL/water behavior for gas hydrate inhibition in terms of hydrogen bond donor and acceptor interaction analysis is also presented by determining the sigma profile and sigma potential of studied IL cations and anions used for gas hydrate mitigation for easy IL selection.     

Crystal Structure–Ionic Conductivity Relationships in Doped Ceria Systems

In the past, it has been suggested that the maximum ionic conductivity is achieved in ceria, when doped with an acceptor cation that causes minimum distortion in the cubic fluorite crystal lattice. In the present work, this hypothesis is tested by measuring both the ionic conductivity and elastic lattice strain of 10 mol% trivalent cation-doped ceria systems at the same temperatures. A consistent set of ionic conductivity data is developed, where the samples are synthesized under similar experimental conditions. On comparing the grain ionic conductivity, Nd_0.10Ce_0.90O_2−δ exhibits the highest ionic conductivity among other doped ceria systems. The grain ionic conductivity is around 17% higher than that of Gd_0.10Ce_0.90O_2−δ at 500°C, in air. X-ray diffraction profiles are collected on the sintered powder of all the compositions, from room temperature to 600°C, in air. From the lattice expansion data at high temperatures, the minimal elastic strain due to the presence of dopant is observed in Dy_0.10Ce_0.90O_2−δ. Nd_0.10Ce_0.90O_2−δ exhibits larger elastic lattice strain than Dy_0.10Ce_0.90O_2−δ with better ionic conductivity at intermediate temperatures. Therefore, it is shown that the previously proposed crystal structure–ionic conductivity relationship based on minimum elastic strain is not sufficient to explain the ionic conductivity behavior in ceria-based system.     

Synthesis and Polymerization of Cationic bis(cyclopentadienyliron)arene Complexes Containing Arylazo Dyes

The synthesis of the title complexes was achieved via the reaction of -p-dichlorobenzene- -cyclopentadienyliron cations with 4,4′-bis(4-hydroxyphenyl)valeric acid to produce the diiron complexes which were then reacted with a number of arylazo dyes to give cationic bis(cyclopentadienyliron)arene complexes containing the arylazo dyes. These iron-containing monomers were subsequently polymerized via nucleophilic aromatic substitution using 1,8-octanedithiol, 4,4′-thiobisbenzenethiol, or bisphenol A to produce the desired coloured cationic organoiron polymers. The weight – average molecular weights were estimated to range from 11,800 to 31,600. UV–vis studies conducted in dimethylformamide (DMF) showed that the metallated polymers exhibited of 412–491 nm. Addition of HCl to the polymer solution caused a bathochromic shift into the range of 515–530 nm. Thermogravimetric analysis (TGA) revealed that the iron moieties were cleaved between 205 and 248 °C while the polyether/thioether backbone degraded between 380 and 613 °C. Differential scanning calorimetry (DSC) showed that the polymers exhibited glass transition temperatures (Tg) ranging from 106 to 184°C.This paper is dedicated to Professor Richard J. Puddephatt in recognition of his outstanding contribution to the field of metal-containing polymers.     

Hyperbranched Polymers Containing Cyclopentadienyliron Complexes

A number of hyperbranched polymers containing cyclopentadienyliron moieties were prepared using the A₂+B₃ method. The A₂ compounds used were common diols, dithiols or dichloroarenecomplexes. B₃ compounds included either prepared star-shaped molecules or a purchased triol. The effect of the reaction conditions on the properties of the products was probed. Analysis of the prepared polymers was conducted using ¹H and ¹³C NMR, viscometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Viscometry values were generally found to be low, in the range of 0.175–0.300 dl/g. TGA showed losses starting at approximately 230°C and ending at 280°C, corresponding to the decomposition of the cyclopentadienyliron moiety. Degradation of the polyether backbone was found to occur starting at 390–567°C. Glass transition temperatures were found to be between 60 and 134°C, whereas melting temperatures ranged from 155 to 190°C.     

Reticular chemistry: occurrence and taxonomy of nets and grammar for the design of frameworks

The structures of all 1127 three-periodic extended metal-organic frameworks (MOFs) reported in the Cambridge Structure Database have been analyzed, and their underlying topology has been determined. It is remarkable that among the almost infinite number of net topologies that are available for MOFs to adopt, only a handful of nets are actually observed. The discovery of this inversion between expected and observed nets led us to deduce a system of classification "taxonomy" for interpreting and rationalizing known MOF structures, as well as those that will be made in future. The origin of this inversion is attributed to the different modes with which MOF synthesis has been approached. Specifically, three levels of complexity are defined that embody rules "grammar" for the design of MOFs and other extended structures. This system accounts for the present proliferation of MOF structures of high symmetry nets, but more importantly, it provides the basis for designing a building block that "codes" for a specific structure and, indeed, only that structure.     

Effects of additives on oxidation characteristics of palm oil‐based trimethylolpropane ester in hydraulics applications

Hydraulic fluids represent one of the most important groups of industrial lubricants. Increasing attention to environmental issues drives the lubricant industry to choose vegetable‐based hydraulic fluids which are biodegradable as compared to mineral‐based fluids. However, the lubricating properties of vegetable oil, such as poor oxidative stability and high pour point, have hindered their use. In this study, trimethylolpropane ester, which was derived from palm‐based methyl ester, was used as the base hydraulic fluid. The purpose of the study was to determine the optimum formulation for palm oil‐based synthetic lubricants by using suitable additives that can improve the oxidative stability and viscosity in accordance with the standard regulations for hydraulic fluid applications. The oxidative stability of the oil was evaluated by total acid number (TAN) and viscosity tests. In general, base oil without additive began to degrade after 200 h. The formulated oil, on the other hand, was quite stable even after 800 h of operation. The best formulation was obtained using 1.0% of either additive A or additive B. Both TAN and viscosity values were found to increase with increasing heating temperature. Meanwhile, the results have also shown that additive A performs better than additive B. After 800 h of exposure, the final TAN value for the formulated oil was only at 0.32 as compared to 4.88 mg KOH/g for the oil without additive. However, the kinematic viscosity of the oil at 40 and 100 °C was almost unchanged as compared to the oil without additive.