bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface and Catalytic Properties of γ-Irradiated Fe2O3/Al2O3 Solids
Authors: El-Shobaky G.A. , Ahmad A.S. , Ghozza A.M. , El-Khouly S.M.
Published: January 2017

Two specimens of Fe2O3/Al2O3 solids were prepared by impregnating a known mass of finely-powdered Al(OH)3 with calculated amounts of ferric nitrate solutions followed by drying at 120°C and calcination in air at 400°C for 4 h. The mixed solids thus prepared had the nominal molar compositions 0.06Fe2O3/Al2O3 and 0.125Fe2O3/Al2O3 (FeAl-I and FeAl-II). The surface and catalytic properties of various irradiated solids (15–200 Mrad) were studied using nitrogen adsorption at −196°C and catalysis of CO oxidation by O2 at 150–280°C using a static method.

The results obtained revealed that γ-irradiation at doses between 15 and 80 Mrad resulted in a progressive decrease (7–22%) in the surface area of the treated solids. Treatment with doses above this limit exerted an opposite effect. γ-Irradiation also resulted in a widening of the pores of the irradiated adsorbents. The catalytic activity of the FeAl-I solid was influenced slightly by γ-rays while the FeAl-II catalyst was significantly modified by this treatment. The reaction rate constant per unit surface area of the catalytic reaction conducted at 280°C over the FeAl-II solid decreased (65%) by exposure to doses up to 120 Mrad, then increased on increasing the dose above this limit. This did not modify the mechanism of the catalytic reaction, but changed the number of catalytically-active sites taking part in chemisorption and catalysis of the CO oxidation reaction without affecting their energetic nature.
Adsorption and Impregnation of Alumina with Molybdenum or Tungsten Solutions
Authors: Pizzio Luis R. , Vázquez Patricia G. , Cáceres Carmen V. , Blanco Mirta N.
Published: January 2017

The equilibrium parameters of molybdenum and tungsten adsorption on alumina were compared. Adsorptions were performed from aqueous solutions of monomeric or polymeric ions of these elements. For all solutions tested, molybdenum showed a greater affinity for alumina than tungsten. Assuming a pore-filling impregnation of alumina spheres, a model that interprets this process was used for the calculation of theoretical profiles which showed a smooth decrease in concentration along the sphere radius. In turn, the experimental profiles were similar to those predicted for impregnations with solutions of heptameric molybdate, monomeric molybdate and monomeric tungstate. For polymeric tungstate, however, the experimental tungsten concentration rapidly fell to zero near the sphere surface. Using diffuse reflectance spectroscopy, it was observed that the molybdenum was in tetrahedral and octahedral coordination in spheres impregnated with polymeric or monomeric molybdenum solutions; in addition, the ratio of the concentrations of these species was approximately the same. The species observed in spheres impregnated with tungsten solutions was monomeric tungstate, indicating a distortion in tetrahedral symmetry as a consequence of interaction with the alumina.
Adsorption Characteristics of Coal-Based Activated Carbons. 1. Adsorption of Nitrogen and Carbon Dioxide
Authors: El-Nabarawy Th. , Petro N.Sh. , El-Aziz S.Abd.
Published: January 2017

Non-activated carbon from coal contains ultrafine pores in which adsorption of nitrogen at 77 K is controlled by activated diffusion. Carbons activated with phosphoric acid or with steam contain a large fraction of microporosity. However, they do not contain ultrafine pores or pore constrictions in which activated diffusion takes place.

The BET equation can be applied to calculate the surface area of microporous carbon when the monolayer capacity lies in the relative pressure range 0.05–0.30, the BET areas in such cases being comparable with those obtained from the αs-method. The Dubinin–Radushkevich (D–R) equation is the most suitable for the interpretation of CO2 adsorption at 298 K.

Chemical and physical activation starts with new pore creation, further activation being associated with pore widening. Microporosity is more predominant in chemically-activated carbons.
Hydrochlorofluorocarbon Adsorption by Granular and Extruded Activated Carbons
Authors: Lin S.H. , Chen Y.W. , Huang J.K.
Published: January 2017

Experiments have been conducted to examine the adsorption/desorption characteristics of 1,1-dichloro-1-fluoroethane (HCFC-141b) by granular activated carbon (GAC) and extruded activated carbon. HCFC-141b is currently deemed an excellent replacement for CFC-11, a foaming agent widely used in the rigid polyurethane foam industries. Experimental results of adsorption and desorption were analyzed in terms of the equilibrium capacity, time to reach equilibrium and desorption efficiency of the adsorbent, and with the aim of assessing the viability of using both adsorbents for possible HCFC-141b recovery. The results have clearly revealed great potential for both adsorbents for this purpose.
Thermodynamics of Steel Corrosion in Acid Media Containing Organophosphorus Derivatives
Authors: Khamis E. , Moussa M.N. , El-Ashry E.S.H. , Ibrahim M. , Ibrahim A.K.
Published: January 2017

A kinetic–thermodynamic model describing the process of adsorption of organic inhibitors on the surface of metals has been applied to ascertain its validity and to determine the number of active sites and the binding constant. Structure–protection correlations for seven organophosphorus compounds have been studied over the temperature range 25–50°C using potentiodynamic polarization and gasometry techniques. Ultraviolet absorption spectra show that the inhibitors are stable in 1 M and 5 M H2SO4 solutions at 50°C. The activation parameters have been determined using the Arrhenius and Eyring equations and it has been shown that Ea and ΔS are increased by a factor of 1.5 in the presence of the inhibitors over the situation in the acid solution, indicating a decrease in the corrosion rate. The adsorption isotherms of vinyl triphenylphosphonium bromide demonstrate the presence of two progressive steps for all temperatures examined due to the formation of multilayers of the adsorbed inhibitor on the steel surface. Additionally, the use of a 0.001 M concentration terminates the effect of temperature on the protection efficiency of vinyl triphenylphosphonium bromide as a result of the strong inhibitor film chemisorbed on the surface. The process of adsorption leads to an increase in the enthalpy of the corrosion process, i.e., it diminishes the number of hydrogen atoms adsorbed on the metal. The values of the thermodynamic parameters, ΔG°ads., ΔH°ads. and ΔS°ads., have also been computed and are discussed.
The Influence of Organic Cosolvent (Methanol) on the Adsorption of Carbofuran on Three Different Types of Indian Soils
Authors: Singh R.P.
Published: January 2017

The adsorption of carbofuran on three different types of uncontaminated Indian soils (loam, silt clay loam, sandy loam) at various volume fractions (0.25, 0.50, 0.75, 1.0) of methanol (fS) has been studied by the batch shake technique. The adsorption of carbofuran was higher on loam soil, followed by silt clay loam and sandy loam soils, and decreased with increasing fS values on all soils. From the adsorption data, adsorption partition coefficients KD (ml/g) were evaluated and the KD values converted to mole-based partition coefficients Km (mol/g). These values were utilised to test the cosolvent theory. The Km values for soils, when normalised on foc, gave values of Kmoc, and a plot of log Kmoc versus fS resulted in a single line whose equation was determined by linear regression analysis as log Kmoc = –1.12 + 2.84; r2 = 0.96. The aqueous phase partition coefficient KDw (mol/g) normalised on f∞ for carbofuran extrapolated from this relationship was 4.1, The slope may be related to the effect of carbofuran solubility and to carbofuran–soil and solvent–soil interactions. The data presented suggested that methanol–soil interaction may not increase the accessibility of carbofuran to soil organic matter to the same extent as reported for less hydrophobic organic solutes.
Adsorption Characteristics of Activated Carbon Obtained from Rice Husks by Treatment with Phosphoric Acid
Authors: Khalil Laila B.
Published: January 2017

Ground rice husks were impregnated with phosphoric acid (30–70 wt.%) followed by carbonization at 673 or 773 K. Analysis of the nitrogen adsorption isotherms was achieved by applying the BET, DR, t- and αS-methods so as to assess the contribution of micropores and mesopores in the products. The washed products showed reasonable surface areas with dimensions in the micropore range. Adsorption of methylene blue from aqueous solution indicated high affinity and high dye removal capacity. Low iodine numbers and methylene blue values were ascribed to the high ash content extending up to 50% of the activated carbon. Pre-impregnation with 50% H3PO4 and carbonization at 400°C proved to be most effective in producing an activated carbon with the highest adsorption capacity from the gas or solution.
Study of Adsorption from Dilute Aqueous Solutions on to Activated Carbon. Part 2. Some Exotic Adsorption Isotherms
Authors: Mészáros R. , Nagy M. , Veress G.
Published: January 2017

Adsorption isotherms for the adsorption of 1-propanol and 2-propanol from dilute aqueous solution on to two types of activated carbon were presented at fixed different initial concentrations. The confidence limits for the specific excess relative to these fixed initial concentrations were also given. The high precision calculation of these error terms was based on the model description of the equilibrium concentration versus sorbent concentration curves discussed previously. The Dubinin–Radushkevich representation of the adsorption data was presented and tested for the same adsorption data. It appears that in some cases the adsorbed amount as expressed by the specific excess depends not only on the equilibrium concentration of the supernatant solution but also on the initial concentration and sorbent concentration. The so-called characteristic isotherms were also calculated in order to compare the various adsorption systems.
The Effect of the Method of Preparation on the Textural, Acidic and Catalytic Properties of Chromia–Alumina Catalysts
Authors: El-Nabarawy Th. , Khalil L.B. , Youssef A. M.
Published: January 2017

Pure alumina 'A' and chromia–alumina catalysts containing 25 mol% Cr2O3 (IAC, IIAC and IIIAC) were prepared by impregnation, coprecipitation and coating techniques, respectively. The adsorption of nitrogen at 77 K and of benzene and water vapour at 308 K was determined. The chemisorption of pyridine at 400 K was measured and the surface acidities calculated. The conversion of 2-propanol and cracking of cumene were investigated using the pulse microcatalytic technique.

Coating alumina with chromia causes considerable changes in the textural and adsorption properties, impregnation of alumina with chromia leads to smaller variations while coprecipitation gives intermediate changes in textural and adsorption properties. The same was found true for the surface acidities as determined by the chemisorption of pyridine. The dehydration of 2-propanol and cracking of cumene follow first-order kinetics. The dehydration of propanol on alumina and chromia–alumina catalysts is a structure-insensitive reaction independent of the surface area but related to the surface acid density. The cracking of cumene is a structure-sensitive reaction depending on both the extent of the surface and the number of acid sites.
The Adsorption of Mixed Dyes (Acidic and Basic) on to Hardwood in a Fixed Bed
Authors: Magdy Yehia H.
Published: January 2017

The adsorption of mixed dyes, Acid Blue and Basic Red, on to hardwood sawdust has been studied using the fixed bed technique. The influence of various parameters such as bed depth, solution flow rate and dye concentration were studied. The modified bed depth service time (BDST) model has been used to analyze the experimental data. In addition the empty bed residence time (EBRT) technique has been applied to optimize the adsorption process variables for either single or multi-component dyes.
Mixed Micelle Formation and Co-adsorption of Anionic/Non-ionic Surfactant Mixtures on Rutile
Authors: Vanjara Ajay K. , Dixit Sharad G.
Published: January 2017

Mixed micelle formation between the anionic surfactant p-dodecyl benzene sulphonate and the non-ionic surfactants Brij-58, Brij-78 and Brij-99, having the same number of oxyethylene units but a varying number of hydrophobic groups, has been studied using surface tension and NMR spectroscopic measurements. Both hydrophobic–hydrophobic and hydrophilic–hydrophilic interactions play an important role in mixed micelle formation leading to greater non-ideality. The effect of mixed micelle interactions on the adsorption of these surfactants from their mixtures on rutile have been investigated using adsorption and zeta potential measurements. Adsorption above the CMC level is dictated by the relatively higher tendency of mixed micellization over mixed aggregation at the solid/liquid interface.
Surface and Catalytic Properties of NiO–Fe2O3 Solids Supported on Al2O3
Authors: El-Shobaky G.A. , Ghozza A.M. , Deraz N.M.
Published: January 2017

A series of NiO–Fe2O3 catalysts supported on γ-Al2O3 was prepared. The effect of the NiO and Fe2O3 contents and the precalcination temperature on the surface and catalytic properties of the various solids has been investigated. The surface characteristics, viz. SBET, Vp and r, were determined using N2 adsorption conducted at –196°C. The catalytic activities of the various solids were studied using the oxidation of CO by O2 at temperatures in the range between 150°C and 400°C. The prepared solids were preheated in air at various temperatures between 400°C and 1000°C.

The results obtained revealed that the SBET values of the different solids decrease progressively on increasing the precalcination temperature above 400°C due to sintering. The specific surface areas were also found to decrease on increasing both the NiO and Fe2O3 contents. The catalytic activities, expressed as reaction rate constant (k) and reaction rate constant per unit area (k), were found to decrease on increasing the precalcination temperature in the range 400–1000°C. Furthermore, the amounts of NiO and Fe2O3 in the different solids modified their catalytic activities in different manners.
Adsorption of Dodecatungstosilicic Acid on to Activated Carbons from Aqueous and Acidic Media
Authors: Chu Wen-Ling , Yang Xiang-Guang , Ye Xing-Kai , Wu Yue
Published: January 2017

Heteropoly acids (HPAs), such as dodecatungstosilicic acid (SiW12), adsorb strongly on to activated carbons. The surface chemical properties of the activated carbons have a pronounced effect on the adsorption of HPAs. To obtain activated carbons with the desired surface chemical properties, modification with mineral acids has been applied. The adsorption isotherms of SiW12 from aqueous solution and various acidic media on to the various carbons have been studied. On the basis of the results obtained, an adsorption model for HPAs from acidic media is presented.
A Test of the Horvath–Kawazoe Method by Monte Carlo Simulation
Authors: Valladares D. , Zgrablich G.
Published: January 2017

The Horvath–Kawazoe (H–K) method, which is frequently used to obtain the micropore size distributions of microporous materials, has been tested by Monte Carlo Simulation of nitrogen adsorption isotherms. The results show that the H–K method only gives good results when the microporosity is confined to a pore size lower than approximately 13 Å. In this region, although the method can predict the micropore size distribution peak with acceptable precision, it fails for wider distributions.
Adsorption Properties of Native and Modified Forms of the Clay Mineral Saponite
Authors: Shonija N.K. , Detistova A.L.
Published: January 2017

Studies have been made of the surface characteristics of the schistose silicate, saponite, and samples obtained by acid modification of the mineral. The structural characteristics of the samples were determined via the complete adsorption/desorption isotherms of benzene. It was shown that acid modification of saponite generates materials with improved adsorption–structural characteristics and high adsorption capacity towards small non-polar molecules. By mans of the ionogenic adsorption of dye molecules, electro-osmotic data and DTA, it has been shown that saponite could be used for the creation of effective ion-exchange materials.
Heats of Adsorption of Aliphatic Alcohols on α-Al2O3 at 25–200°C. II. Variations with Chain Length
Authors: Rossi Pier Francesco , Rossi Paola
Published: January 2017

The adsorption of the first five members of the aliphatic alcohol series on α-Al2O3 has been studied at 25–200°C by means of a heat-flow Calvet microcalorimeter (moderately high temperature). At very low coverage and at 25°C, the values of the differential heats of adsorption of the different alcohols were very high (250–200 kJ/mol) and were apparently independent of the chain length. However, at average coverage, the chain length of the alcohol began to influence both the values and the trends in the differential heats of adsorption of the various alcohols on α-Al2O3. Finally, at high coverage, it was found that the incorporation of each additional –CH2–group in the homologous series led to a decrease in both the integral heat of adsorption and the amount of alcohol adsorbed according to the series MeOH > EtOH > 1-PrOH > 1-BuOH > 1-PeOH. Increasing the temperature led to an increasing dependence of the differential heat on the chain length of the alcohol.

In addition, from measurements of the thermokinetic parameters for the heat emission peaks for the adsorbed alcohols, it has been deduced that all five aliphatic alcohols studied adsorb on to an α-Al2O3 surface in an open-chain perpendicular fashion.
Intermolecular Interactions in Gas Chromatography on Carbon Black Coated with Monolayers of Hydrocarbons with Different Electronic Structures
Authors: Vlasenko E.V. , Gavrilova T.B. , Daidakova I.V.
Published: January 2017

The adsorption and chromatographic properties of surfaces obtained by the adsorptive modification of thermally graphitized carbon black (TGCB) with hydrocarbons differing in composition and electronic structure (n-dotriacontane and coronene) were studied by gas chromatography (GC). The contributions towards the retention of methylene groups in homologous series of n-alkanes, alkylbenzenes, ethers, esters and n-alcohols were estimated for TGCB coated with monolayers of the above-mentioned hydrocarbons. The thermodynamic characteristics of the adsorption process were also measured for molecules of the various classes of organic compounds described. In addition, differences in the mechanism of chromatographic retention on n-alkane monolayers, when the latter may exist as solid-like, transitional or liquid-like states, and on coronene monolayers were studied. The influence of the electronic configuration of the carbon atoms in the modifier molecules on the adsorption energy of the various organic compounds studied has been demonstrated. The possibility of employing GC methods for demonstrating phase transitions in long-chain alkane monolayers adsorbed on carbon black is discussed. Furthermore, the possibility of controlling the retention selectivity during GC by TGCB modification with adsorbed monolayers of hydrocarbons is presented.
A Non-Analytical Solution of the Description of Single Gas Adsorption on a Microporous Adsorbent
Authors: Garbacz J.K. , Dabrowski M.
Published: January 2017

Two distribution functions for the energy of localization dividing two neighbouring adsorption sites were suggested for the model of partially mobile adsorption on energetically heterogeneous microporous solids. The experimental isotherms of ethane adsorption on NaX-type zeolite derivatives cationized by Li+, K+, Rb+, Ca2+, Sr2+ ions as well as isotherms of ethane, ethene and n-pentane adsorption on NaX-type zeolite were described by the relationships of the proposed adsorption model.
Adsorption Equilibria in Carbon/Hydrocarbon/Water Systems
Authors: Eltekova N.A. , Eltekov Yu.A.
Published: January 2017

Two equations derived from the theory of volume filling of micropores (the DR and DS equations) were used for the description of the liquid-phase adsorption of benzene, toluene and p-xylene from aqueous solution on to two commercial microporous activated carbons.

Comparison of the experimental and calculated adsorption isotherms showed good accord between the theoretical and experimental values. The results of this work indicate that the parameters of these equations can be used for modelling a water purification process based on the activated carbons.
Molecular Modelling in Chromatostructural Analysis: A New Approach to the GC/MS Study of Isomers
Authors: Kulikov Nickolay S.
Published: January 2017

The importance of gas-solid chromatography as a source of additional data for the positive structural elucidation of novel isomers by gas chromatography/mass spectrometry is discussed. As an example, a mixture of 11 isomers of perhydroanthracene and perhydrophenanthrene has been considered. The retention parameters of these isomers on thermally graphitized carbon black (TGCB) were calculated by Kiselev's method to predict the order of their separation on a column packed with TGCB. The molecular models required for these calculations were constructed using a conventional approach and molecular mechanics; the corresponding results obtained are compared. The order of separation predicted by molecular mechanics appeared close to that observed experimentally.
Effect of Cosolvent (Acetone) on the Adsorption and Movement of Cypermethrin in Indian Soils
Authors: Singh R.P. , Singh Dhirendra
Published: January 2017

The adsorption and movement of cypermethrin in different types of uncontaminated soils in acetone-water mixtures at different fs values has been studied by batch shake and soil thin-layer chromatographic techniques, respectively. Higher adsorption and a reduced movement of cypermethrin was observed on silt clay loam soil followed by loam and sandy loam soils and was anticipated by the Freundlich adsorption constants Km and Rf values. The Km and Rf values also confirmed that the adsorption of cypermethrin decreased while its movement increased with increasing fs values. The values of the Freundlich constant Km were used to evaluate the cosolvent theory for describing the adsorption of cypermethrin in acetone–water mixtures. For each soil, the values of the adsorption coefficient Km decreased in a linear logarithmic fashion as fs increased, the slopes of the log Km versus fs plots being essentially the same for all soils. Thus, the cosolvent effects on adsorption could be expressed by a single parameter (σs) which combines the characteristics of the solvent (acetone) and the adsorbate (cypermethrin). For adsorbates with a low solubility in aqueous solutions, the adsorption data from mixed solvents was extrapolated to fs = 0 to estimate the values of the adsorption constant Kw in the aqueous phase.
Dependency of Phenol Hydrogenation Activity on Hydrogen Chemisorption over Supported Palladium Catalysts
Authors: Mahata Nagendranath , Vishwanathan V.
Published: January 2017

A series of catalysts containing 1 wt.% Pd supported on various oxides of commercial origin have been characterised by hydrogen adsorption at 298 K and evaluated for vapour-phase phenol hydrogenation at 473 K employing an H/phenol ratio of 5.4 at atmospheric pressure. The activity of phenol hydrogenation showed a dependence on the irreversible uptake of hydrogen. Among the catalysts studied, Pd/Al2O3 showed a decrease in activity with increasing temperature while Pd/MgO passed through a maximum at 503 K. The Pd/MgO catalysts exhibited a higher dispersion of smaller Pd crystallites leading to higher activity and total selectivity for cyclohexanone. The higher resistance towards deactivation and better stability of the Pd/MgO catalysts suggest that the acidic sites of alumina may be responsible for deactivation, thereby accounting for the lowering of activity with Pd/Al2O3 catalysts.
Application of the Kinetic–Thermodynamic Model to the Adsorption of Organophosphorus Compounds on to a Steel Surface
Authors: Khamis E. , Moussa M.N. , Ibrahim A.K.
Published: January 2017

The inhibitive action of organophosphorus derivatives on the dissolution rate of steel in H2SO4 has been determined by gasometry and weight loss methods and then compared to rates measured using the potentiodynamic polarization technique. Additionally, UV spectroscopy was used to study the thermal stability of these compounds in different acid concentrations. An empirical kinetic relationship has been presumed correlating the molecular structure of the inhibitors to their inhibition efficiency. The shape of the adsorption isotherms of the compounds shows that some exhibit one S-shaped curve whilst others are characterized by two-consecutive steps. This behaviour was correlated to the proposed skeletal representation of the adsorption mode of the inhibitors on the metal surface. Electrochemical results indicated that all the compounds investigated acted as cathodic-type inhibitors. The data obtained provide a good fit to both the Temkin adsorption isotherm and the kinetic–thermodynamic model recently proposed. Estimated values of the binding constant, lateral interaction, number of active sites and the change in free energy of adsorption are presented.
Equilibrium Studies for the Adsorption of Dyes on Bagasse Pith
Authors: McKay Gordon , El-Geundi Mohammed , Nassar Mamdouh M.
Published: January 2017

The adsorption of four dyes on to bagasse pith has been studied. The equilibrium isotherms have been measured and analyzed using the Langmuir, Freundlich and Jossens equations and the experimental data have been compared with the theoretically predicted data.

The equilibrium saturation adsorption capacities were 21.7. 22.9. 155.4 and 76.6 mg/g for Telon Blue ANL (Acid Blue 25, CI62055), Erionyl Red RS (Acid Red 114, CI23635), Astrazone Blue FRR (Basic Blue 69) and Maxilon Red BL-N (Basic Red 22, CI11055), respectively.

Isotherms were measured at different temperatures and from the data the enthalpies of adsorption were determined to be 11.5, 11.8. 10.3 and 10.7 kJ/mol for Acid Blue 25, Acid Red 114, Basic Blue 60 and Basic Red 22, respectively.
Displacement Transition in CH4/Cyclohexane Adsorbed on Graphite
Authors: Asada Hiromu , Seiyama Hiroshi , Takechi Miho
Published: January 2017

The adsorption of methane on cyclohexane-preplated graphite has been studied volumetrically at 77 K. Methane undergoes a displacement transition as well as layer-by-layer condensation transitions, similarly to Kr studied previously. The isotherm step of the displacement transition is clear and sharp, being indicative of a first-order phase transition. The transition takes place when the adsorbed methane molecules exceed the pre-adsorbed cyclohexane in number. The results support our previous interpretation that the displacement transition is a change from the layer-on-layer mode to the two-phase mode of two-component adsorption.
Adsorption of Lower Alcohols from Water Solutions on High Silica Zeolites, Mesoporous MCM-41 and AlPO4-5
Authors: Dahl Ivar M. , Myhrvold Elisabeth , Slagtern Åse , Stöcker Michael
Published: January 2017

Two dealuminated β-zeolites, zeolite Y and MCM-22 as well as silicalite, MCM-41 and AlPO4-5 have been studied as hydrophobic adsorbents in water solutions. Dealuminated β-zeolite, MCM-22 and silicalite all adsorb alcohols from water solutions. Enhanced adsorption is obtained for alcohols with longer alkyl chains. Adsorption in the practically most interesting 10–80% range of zeolite filling may adequately be described by Langmuir isotherms. The Langmuir adsorption constants are similar for β-zeolite, MCM-22 and silicalite. This indicates that the adsorption is independent of the pore structure for the alcohols tested in this study. The surface silanol density is however important, such that a low SiOH density is required to give lipophilic properties. In line with this, dealuminated zeolite Y, as prepared here, and MCM-41 give only a poor preference for alcohols from water.

For the β-zeolite, the dealumination procedure is important for retaining the micropore volume and adsorption capacity of the zeolite. AlPO4-5 shows no potential as an adsorbent for alcohols from water solutions.
Characterization of Maxsorb Activated Carbons and Their Evaluation for Gas Storage
Authors: Manzi S. , Valladares D. , Marchese J. , Zgrablich G.
Published: January 2017

A series of Maxsorb activated carbons, in powder, pellet and disk form, has been characterized by N2 adsorption, following which CH4 adsorption at high pressures up to 3.5 MPa was studied for the different samples.

The evaluation of these materials for gas storage shows very promising behaviour for Maxsorb disks with a storage capacity of 150 volumes of gas at STP per container volume at 3.5 MPa.
Prediction of Adsorptional Henry Constants Using the Corresponding States Principle
Authors: Kutarov V.V. , Kats B.M.
Published: January 2017

An equation is suggested which allows the prediction of the values of adsorptional Henry constants for a given adsorbent and various adsorptives at any temperature, in terms of the known experimental adsorption isotherm for an adsorptive on the same adsorbent at a given temperature. The potential application of the suggested method has been tested using known experimental data and the conditions for its use in the analysis of adsorption equilibria in different systems are discussed.
Recovery of Glycerol Epichlorohydrin from the Waste Gas by an Adsorption Method
Authors: Milchert Eugeniusz , Goc Waldemar , Paździoch Waldemar , Myszkowski Jerzy
Published: January 2017

Adsorptivity and other parameters describing the adsorptivity of epichlorohydrin from an air stream on active carbon A have been determined. The methods of epichlorohydrin desorption and adsorbent regeneration have been presented.
Surface Characteristics and Cracking Activity of MoO3–AlPO4 Catalysts
Authors: Mostafa M.R.
Published: January 2017

Pure AlPO4 and MoO3–AlPO4 impregnated catalysts of different compositions have been prepared. The catalysts were characterized using XRD and IR techniques. The textural properties were determined from nitrogen adsorption at 77 K. The acidic properties of these catalysts were measured by the amine titration method. The cracking of cumene at flow rates of 20–60 ml/min and at 653–713 K was investigated over these catalysts. Loading AlPO4 with MoO3 leads to a significant change in texture, surface acidity and catalytic activity of the prepared catalysts. The cracking reaction over the investigated catalysts followed first-order kinetics with activation energies of between 8.0 and 20 kcal/mol. The cracking activity has been related to Brönsted acid sites present on the catalyst surface.
Effect of Li2O Doping on the Surface and Catalytic Properties of the Fe2O3–NiO/Al2O3 System
Authors: El-Shobaky G.A. , Ghozza A.M. , Deraz N.M.
Published: January 2017

Ferric–nickel/aluminium mixed oxide solids have the formula Fe2O3–0.42NiO/Al2O3 were treated with Li2O (0.75–3 mol%) and heated in air for 4 h at 500°C and 800°C, respectively. The effects of this treatment on the surface characteristics of these solids and their catalytic properties in relation to CO oxidation by O2 have been investigated.

The results reveal that Li2O doping at 0.75 mol% concentration resulted in an increase of 24% and 18%, respectively, in the value of the specific surface areas, SBET, of the solids precalcined at 500°C and 800°C, while the addition of 3 mol% Li2O led to a slight decrease of ca. 10% in the SBET value of the same solids. In contrast, irrespective of whether the doping process involved solids precalcined at 500°C or 800°C, a significant decrease of 37% and 78%, respectively, was observed in the catalytic activity of these materials. This decrease in catalytic activity was not accompanied by any appreciable change in the magnitude of the activation energy for the catalytic reaction, i.e. Li2O doping brings about a decrease in the concentration of catalytically active sites without changing their energetic nature.
Potential Use of Bagasse Pith for the Treatment of Wastewater Containing Metals
Authors: Aly H.M. , Daifullah A.A.M.
Published: January 2017

Bagasse pith was tested for its ability to remove cadmium and lead ions from aqueous solutions under two modes of operation, i.e. in batch systems and continuous flow systems. Time dependency experiments showed a very rapid adsorption of these cations by bagasse pith. Thus, 62% of cadmium ions and 84% of lead ions were taken up by the bagasse pith at pH 6 and ca. 99% of each cation was recovered by treatment of the pith with 0.1 M HCl. The breakthrough capacity, Q0.5, the number of theoretical plates and the theoretical plate height were calculated. The capacity of bagasse pith was found to be 6.2 and 8.5 mequiv./g for cadmium and lead ions, respectively. The feasibility of using bagasse pith for cadmium and lead ion removal from wastewater streams was addressed.
Kinetics of Heavy Metal Ion Adsorption on to, and Proton Release from, Electrolytic Manganese Dioxide
Authors: Dahal Madhav P. , Lawrance Geoffrey A. , Maeder Marcel
Published: January 2017

The kinetics of adsorption of lead(II), as well as of copper (II), zinc(II) and thallium(I), on commercial electrolytic manganese dioxide (EMD) powder of different size fractions has been followed by a pH-stat method involving the computer-controlled neutralisation of released protons from the EMD at a fixed pH with hydroxide ion. Base uptake versus time profiles in all cases indicated a rapid initial change followed by a slower process. These can be interpreted in terms of either a solution kinetic model or an adsorption kinetic model. In the former analysis, the adsorption-time profile can be interpreted in terms of two, or at most three, exponentials. The contribution of the first fast step increases with decreasing average particle size (or increasing surface area), consistent with its interpretation as being associated with the replacement of accessible protons on the exposed surface of the EMD by metal ions. The slower rate processes can be considered to be associated with adsorption in less accessible clefts or pores in the structure. In the diffusion model, the experimental data were fitted to the equation of diffusion in a sphere, fitting again requiring a first initial step followed by a slower step, with one diffusion coefficient having typically an upper limit of 10-9 and the other a lower limit of 10-11 cm2/s. For the complete reaction, the moles of protons released per mole of metal ion adsorbed were also measured and found to be relatively insensitive with respect to pH, metal ion concentration, electrolyte concentration and EMD size fraction. At pH 4, the H+: Mn+ ratio ranged from 1.4 to 2.1 (±0.1) for divalent transition metal ions, consistent with dominant chelation of the divalent metal ion to two adjacent oxygen sites on the surface; for thallium(I), a low ratio (0.5) indicated a different mode of surface attachment.
Isotherm Studies for the Sorption of Metal Ions on to Peat
Authors: Mckay G. , Vong B. , Porter J.F.
Published: January 2017

The adsorption of five single-component metal ions, namely, copper, cadmium, cobalt, nickel and zinc, on to peat has been studied. Equilibrium isotherms were measured and analysed using three methods: Langmuir, Freundlich and Redlich–Peterson. Overall the Langmuir equation gave the best fit based on a linear correlation coefficient. The Langmuir equation was used to determine the monolayer saturation capacity for each of the metals on peat. These sorption capacities are: cadmium, 99.47 μmol/g (11.18 mg/g) peat; cobalt, 446.93 μmol/g (26.34 mg/g) peat; copper, 198.31 μmol/g (12.60 mg/g) peat; nickel, 113.24 μmol/g (6.65 mg/g) peat; and zinc, 141.93 μmol/g (9.28 mg/g) peat.
Methanation Activity in Relation to the Textural and Catalytic Parameters of Ni/Al2O3 Catalysts
Authors: Samra S.E. , El-Hakam S.A. , Youssef A.M.
Published: January 2017

A range of NiO/Al2O3, solids (4.0–12.0 wt% Ni) was prepared by the impregnation technique. The textural properties of these solids were determined from nitrogen adsorption measurements at 77 K. Reduction of the solids with hydrogen was carried out 650, 675, 700 and 725 K. Some catalytic parameters for these reduced materials were determined from studies of the adsorption of hydrogen at 400 K. The methanation of carbon monoxide over these reduced materials used as catalysts was followed between 550 K and 600 K using a steady-state flow reactor.

The surface area of the NiO/Al2O3 solids decreased and their mean pore radius increased with increasing content of NiO. Increasing the temperature employed for their reduction led to increased diffusion of Ni atoms to the surface with a consequent increase in their catalytic activity. A direct relationship was found between % methanation and the surface area of the reduced catalytic material expressed as m2/g (catalyst).
Column Removal of Some Dyestuffs by Activated Carbons Derived from Apricot Stone Shells
Authors: Khalil Laila B. , Girgis Badie S.
Published: January 2017

Activated carbons (ACs) were prepared from apricot stone shells impregnated with H3PO4, followed by carbonization at 400–500°C. Fixed-bed removal of two dyestuffs, i.e. Direct Red 99 (DR) and Reactive Orange 11 (RO) was followed at constant bed height and flow rate. Several column characteristics were evaluated from the breakthrough curves obtained including: the volume and loading at breakpoint, the height of the mass transfer zone, the bed service time, the time and loading at exhaustion, and the fractional bed loadings at various stages. The bed performance with RO was better than for DR, which was ascribed to a screening effect towards the larger DR molecules and to enhanced adsorption arising from the polyhalogenated nature of the RO molecule. The removal of colour was favoured as the porosity of the AC developed, being particularly related to its mesoporosity and total pore volume.
Adsorption Studies of Cu11 from Aqueous/Acidic Solutions on to Bentonite
Authors: Terzyk Artur P.
Published: January 2017

The influence of temperature on the adsorption of 4-hydroxyacetanilide (paracetamol) from aqueous solution (pH = 7) on to de-ashed, commercial activated carbons is described. Three carbon samples, D43/1 (Carbo-Tech. Essen, Germany), WD-extra and AHD (Hajnówka, Poland), were investigated. They were de-ashed and characterised using low-temperature nitrogen adsorption, porosimetry and Bachmann's method, as well as by different theoretical approaches. Carbon surface properties were characterised by the method of Boehm and the enthalpy of immersion in water. The adsorption/desorption isotherms of paracetamol in the temperature range 300–320 K were measured together with the enthalpy of immersion in paracetamol solution. The carbon adsorption properties towards paracetamol are discussed. Relationships describing the dependence of adsorbability on the temperature are proposed as well as the dependence of the relative enthalpy of adsorption on the concentration of basic carbon surface groups.
Surface Modification of Silica Gel by Interfacial Polyelectrolyte Complexes
Authors: Zhang Yongjun , Cao Weixiao
Published: January 2017

Two types of modified silica gel have been prepared by constructing layers of a thermolabile interfacial polyelectrolyte complex on the surface of silica gel using diazo resin (DR) as the polycation and poly(sodium styrene sulphonate) (PSS) as the polyanion. Dye adsorption from aqueous solution was employed to estimate the surface properties of the silica gels. It is believed that the diazo resin is anchored on the surface of the silica gel after thermal treatment through covalent bond formation. The adsorption ability of the surface for cationic dyes increases after such modification. Anionic dyes, which cannot be adsorbed by the unmodified silica gel, can be adsorbed by the modified ones. This indicates that a hydrophobic surface has been built up on the silica gel.
Comparison of Four Adsorption Equations Used for the Description of the Systems: Porous Solid/Binary Liquid Non-Electrolyte Solution
Authors: Ziólkowska D.
Published: January 2017

The solution analogues of four single gas adsorption equations have been examined. The derived expressions have been applied to the description of the experimental adsorption isotherms on to microporous active carbons from binary liquid solutions with limited component miscibility. Statistical analyses of the individual adsorption equations, as well as comparisons of the optimized results obtained from different adsorption equations, have been undertaken.
Immobilized Pt Complex Compounds as Catalysts for the Oxidation Reactions of Small Molecules
Authors: Oleksenko Ludmila P. , Yatsimirsky Vitaly K. , Belyakova Ludmila A. , Yu Ol'ga , Boldyreva Ol'ga
Published: January 2017

A heterogeneous catalyst for the oxidation of small molecules has been prepared by the immobilization of PtII and PtIV complex compounds on the surface of amorphous macroporous silica. The structure of the surface platinum complex compounds has been established by means of vibrational and electronic spectroscopy while the catalytic activity of the catalyst was investigated for the hydrogen (or carbon monoxide) oxidation reaction by molecular oxygen under mild conditions.
Changes in Textural Properties of Precalcined Silicas Induced by Adsorption of Some Low Molecular Weight Polymers
Authors: Youssef A.M. , El-Nabarawy Th.
Published: January 2017

The adsorption of low molecular weight poly(methacrylic acid n-butyl ester) (PBMA) and poly(ethylene glycol) (PEG) on silicas precalcined at 673–1473 K was studied. The changes brought about in the textural properties (total surface area and pore volume distribution) by the adsorption of these polymers were determined.

Adsorption of PBMA and PEG resulted in a decrease in the specific surface area as determined by nitrogen adsorption at 77 K since the fraction of the surface located in the micropores was covered by the polymer. Adsorption of polymers reduced the water adsorption capacities of the silicas, particularly those precalcined at ≤ 1073 K, as a result of a decrease in the number of surface OH groups. Polymer adsorption on the precalcined silicas made the contribution of mesopores more prominent, the changes in the textural properties of the silicas depending on the stage at which the polymer was added during the course of silica preparation.
Dependence of the Ice Formation Activity of Dioxynaphthalenes, Fluoroglucin and Silver Iodide on the Structure of the Hydrate Shells of Their Crystals
Authors: Turov V.V. , Turov A.V. , Arkharov A.V.
Published: January 2017

The 1H NMR spectroscopy of frozen suspensions has been used to investigate the hydrate shells of Agl, fluoroglucin (FG) and dioxynaphthalenes (DON). It has been shown that the ice formation activity (IFA) of the above compounds may be correlated with the inverse thickness of their associated adsorbed water layer and with the free energy of the strongly bound water film. All the compounds studied formed an ice layer at the substance/ice interface in which the mobility of the water molecules has a value which is intermediate between that for water molecules in ice and for adsorbed water molecules. The ratio between the thickness of the layer of ‘mobile’ ice and that of the layer of adsorbed water increased as a function of IFA.
Metal-Containing Pd and Cu and Bimetallic Pd—Cu Catalytic Systems Based on HZSM-5 Zeolite
Authors: Oleksenko Ludmila P. , Telbiz German M. , Yatsimirsky Vitaly K. , Kuzmich Irina V.
Published: January 2017

Palladium- and copper-containing HZSM-5 zeolites with different metal loadings, together with Pd–Cu and Cu–Pd bimetallic zeolite systems, were prepared by ion-exchanging HZSM-5 zeolite with metal–ammine complex cations. The catalytic activity of such materials in CO oxidation was investigated under flowing conditions using various gas mixtures (0.5–2% CO, 20% O2 and 78–79.5% He). The dependence of the activity of the Cu–Pd system on the CO content in the gaseous mixture was observed. The influence of the catalytic properties on the reduction conditions employed for the metal-containing zeolites was investigated. Correlations between the catalytic activity and the intensity of the N–H band in the IR spectra characteristic of the various Pd/Cu–ammine complexes incorporated in the zeolite matrix were demonstrated.
Prevention of Sapheno-Femoral and Sapheno-Popliteal Recurrence of Varicose Veins by Forming a Partition to Contain Neovascularization
Authors: Glass G. M.
Published: January 2017

Objective:

To test the hypothesis that sapheno-femoral recurrence of varicose veins may be prevented by containment of neovascularization.

Design:

Prospective minimum 4-year follow-up by surgical exploration and morphological examination of recurrent vessels in all limbs with clinical or phlebographic evidence of sapheno-femoral recurrence.

Setting:

Varicose vein clinic of a teaching hospital.

Interventions:

Sapheno-femoral ligation and multiple ligation (group 1); sapheno-femoral ligation, interposition of cribriform fascia and multiple ligation (group 2); sapheno-femoral ligation, interposition of artificial implant and stripping (group 3).

Main outcome measures:

Incidence of sapheno-femoral recurrence.

Results:

The incidence of sapheno-femoral recurrence through neovascularization was lower ( p < 0.001) in groups 2 and 3 after containment of neovascularization at the sapheno-femoral junction by cribriform fascia or artificial implant than in group 1 after ligation alone (3% and 1% vs 25%, respectively). The incidence of recurrent or persistent varices distal to the groin was lower ( p < 0.001) after stripping (group 3, 57%) than after multiple ligation (group 1, 93%; group 2, 81%).

Conclusions:

Sapheno-femoral ligation, interposition of cribriform fascia or artificial implant at the sapheno-femoral junction, and stripping is a more effective treatment of varicose veins than sapheno-femoral ligation and multiple ligation.
Venous Leg Ulcers: Is Pain a Problem?
Authors: Noonan L. , Burge S. M.
Published: January 2017

Objective:

To employ standardized techniques to measure and characterize the pain associated with leg ulcers of defined causes.

Methods:

Patients attending leg ulcer clinics were interviewed by one research nurse using a structured questionnaire. Ulcers were classified as venous, arterial or mixed depending on the clinical assessment and ankle–brachial systolic pressure index. Pain was assessed objectively using two validated instruments for scoring pain: a verbal rating scale and a pain-intensity visual analogue scale. The significance of the observations was tested using either the Mann-Whitney U-test (unpaired observations) or the Wilcoxon signed-rank test (paired observations). A profile of the quality of pain was obtained using the short-form McGill Pain Questionnaire (SF-MPQ). Quality of life was assessed using the COOP Chart System.

Patients:

We assessed 38 patients with venous ulcers, three patients with mixed arterial/venous ulceration and 10 patients with arterial disease.

Main outcome measures:

Pain scores on verbal rating scales and visual analogue scales.

Results:

Venous leg ulcers are painful. Although pain scores are greater in arterial ulcers, most patients with venous ulceration suffer at least moderate pain. Night pain disturbed sleep in 73% of all patients and pain affected mood in more than 50%. Dressing changes exacerbated pain.

Conclusions:

Pain reduces the quality of life in most patients with leg ulcers. Pain control is an essential consideration in all patients with leg ulcers.