bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption Properties of Activated Carbons Prepared from Olive Stones by Chemical and Physical Activation
Authors: Alaya M.N. , Hourieh M.A. , Youssef A.M. , El-Sejariah F. 
Published: October 2002

Activated carbons were prepared from olive stones either by the addition of zinc chloride (25–50 wt%) or by gasifying non-activated carbon with steam to burn-offs between 25% and 49%. The adsorption of nitrogen at 77 K was investigated and the adsorption data interpreted by the application of the Langmuir equation, the BET equation and the αS-method. The adsorption of carbon dioxide at 273 K was also followed and the data analyzed using the DR and DA equations. The adsorption of iodine from aqueous potassium iodide solution, and of Methylene Blue and p-nitrophenol from aqueous solutions at 298 K was also determined. Activation with zinc chloride produced physical and chemical changes which modified the thermal degradation process. Carbonization with zinc chloride restricted the formation of tars with the subsequent formation of solid carbon, the amount of zinc chloride incorporated in the precursor governing the porosity of the resulting carbon. The atmosphere under which activation of samples containing zinc chloride was undertaken was another factor in determining the texture of the carbon. Activation with steam to low burn-offs created new micropores by burning off the more reactive carbon atoms, but at high burn-offs erosion of the pore walls occurred leading to pore widening. Adsorption from solution was determined by the solubility of the solute in the solvent and by competition for this solute between the solvent and the adsorbent. The pore size of the carbon adsorbent and the molecular size of the adsorbate molecule were prominent factors in determining the extent of adsorption from solution.
Effects of Li2O Doping on the Surface and Catalytic Properties of Co3O4–Fe2O3 Solids Precalcined at Different Temperatures
Authors: El-Shobaky G.A. , Shouman M.A. , Alaya M.N. 
Published: October 2002

The effects of Li2O treatment on the solid–solid interactions and the surface and catalytic properties of the Co3O4–Fe2O3 system have been studied using TG, DTA and XRD methods, nitrogen adsorption studies at −196°C and the catalytic oxidation of CO by O2 at 150–350°C. The results obtained showed that Li2O doping followed by precalcination at 500–1000°C enhanced the formation of cobalt ferrite to an extent proportional to the amount of dopant added (0.52–6.0 mol% Li2O). The solid–solid interaction leading to the formation of CoFe2O4 took place at temperatures ≥700°C in the presence of the Li2O dopant. Lithia doping modified the surface characteristics of the Co3O4–Fe2O3 solids, both increasing and decreasing their BET surface areas depending on the amount of dopant added and the precalcination temperature employed for the treated solids. The activation energy of sintering (ΔES) of cobalt/ferric mixed oxides was determined for the pure and doped solids from the variation in their specific surface areas as a function of the precalcination temperature. Both an increase and a decrease in the value of ΔES due to Li2O doping occurred depending on the amount of lithia added. The doping of Co3O4–FeO solids, followed by precalcination at 500°C, effected a significant increase (144%) in their catalytic activity towards CO oxidation by O2. Precalcination at 700–1000°C of the mixed oxide solids doped with Li2O (0.52 and 0.75 mol%) resulted in an increase in their catalytic activity which decreased upon increasing the amount of Li2O added above this limit. The activation energy of the catalyzed reaction was determined for the pure and variously doped solids studied.
Adsorptive and Membrane-Type Separations: A Bibliographical Update (1999)
Authors: Ray Martyn S. 
Published: October 2002

This paper provides a useful and quick reference source to the 1999 journal literature on adsorptive and membrane-type separations (from the 50 most important chemical engineering journals) for researchers in this area. This article continues a series of annual bibliographic updates of the literature published since 1985 (see Ray 1990–1999). The references included here have been divided into the following subject groups: theory; design data; adsorbents; PSA and cyclic systems, and applications; liquid-phase adsorption; ion exchange, chromatography and related separations; membranes; and membrane-type separations. Adsorption and related separations for industrial and environmental applications are described in detail by Dabrowski (1999) which also contains extensive bibliographies prepared by this author. A complete bibliographic listing of the chemical engineering journal literature from 1959 to 1999 (with subsequent six-monthly updates) is available on a CD-ROM database* and full details can be obtained from the author.
Studies of the Kinetic Characteristics of HSA Adsorption by Different Types of Activated Carbon Fibres
Authors: Eretsky Eugene 
Published: October 2002

Adsorption of human serum albumin (HSA) from aqueous solution on to activated carbon fibres (ACF) with different degrees of activation in the range 0–70% has been studied at 293 ± 1K. The various parameters for the porous structure were calculated by different methods on the basis of the low-temperature adsorption isotherms of nitrogen measured at 77 ± 1 K. It was shown that an increase in the degree of ACF activation led to the development of a porous structure which exhibited increasing values of the micropore and mesopore volumes. Relationships between the structure, the physicochemical properties of the surface and the adsorption characteristics of ACF were established. The kinetic curves for HSA adsorption from aqueous solution at an initial concentration of 0.5 mg/ml were characterized by negative adsorption ranges. This phenomenon may be explained, on the one hand, by the energetic heterogeneity of the protein–surface interaction and, on the other hand, by the possibility of alterations in the conformations of the protein molecules at the interface. The latter suggestion was confirmed by the hyperchromous shift observed in the UV spectrum of the HSA solution after protein–surface contact had been established.
Carbons Suitable for Medium Pressure (6.9 MPa) Methane Storage
Authors: Quinn D.F. , Ragan S. 
Published: October 2002

The storage and delivery of natural gas using adsorbent carbon monoliths at 3.4 MPa is only about 75% that of natural gas compressed to 21 MPa on an equal volume basis. One possible way to increase ambient temperature adsorbed natural gas (ANG) storage is to simply increase the storage pressure. However, this will only be beneficial if there is unfilled micropore capacity within the carbon adsorbent. Carbons that have been optimized for storage at 3.4 MPa may not have sufficient micropore capacity to give increased storage at 6.9 MPa. In the present work, carbons have been prepared which are considered to be more useful for storage at 6.9 MPa than at 3.4 MPa due to their having an increased micropore volume fraction per monolith or storage volume. Although the pore wall separation of these carbons may not be ideal for maximum adsorbate density, these carbons showed that more than 180 v/v can be delivered from 6.9 MPa. This value approaches that of delivery from compressed natural gas (CNG) and exceeds it if the rectangular external envelope is considered as the realistic volume of the storage vessel. The results obtained clearly show the diminishing returns for methane adsorption storage with pressure increase. An increase of only about 30% in storage capacity was achieved from a doubling of the storage pressure from 3.4 MPa to 6.9 MPa.
Treatment of Confectionery and Gum Factory Wastewater Effluent
Authors: Diwani Guzine El , Abd Hamman El , Hawash Salwa , Ibiari Nagwa El , Rafei Shadia El 
Published: October 2002

A pilot plant for the treatment of wastewater was designed, constructed and installed for the continuous treatment of 250 l/d wastewater originating from a gum and confectionery factory. The pilot plant consisted of an equalizer, chemical mixing tank, aerator, clarifier, disinfectant tank and sand filter as the main components. In addition, a set of centrifugal and dosing pumps, an air blower and a pH controller were added. The industrial-scale treatment unit could handle a 50 m3/d effluent flow rate composed of combined industrial and municipal wastewater effluents heavily loaded with organic and biologically resistant pollutants (sugars, gums, pesticides and detergents) with a chemical oxygen demand (COD) value extending to 25 000 ppm. House-keeping arrangements and the isolation of some streams were necessary in order to attain an end-pipe effluent capable of treatment by conventional procedures at reasonable cost values. Different operating conditions were tested in order to treat effluent loaded with a COD value reaching 5000 ppm to obtain acceptable limits capable of containment in underground wells or re-use in irrigation.
Decomposition of H2O2 on Pure and ZnO-Treated Co3O4/Al2O3 Solids
Authors: El-Shobaky G.A. , Amin N.H. , Deraz N.M. , El-Molla S.A. 
Published: October 2002

The effects of Co3O4 loading, precalcination temperature and ZnO treatment on the catalytic properties of the Co3O4/Al2O3 system were investigated. The amounts of Co3O4 were varied between 5.57 wt% and 32.0 wt% and the resulting solids subjected to heat treatment at temperatures in the range 400–600°C. The amounts of ZnO were varied between 0.36 wt% and 2.12 wt%. The results obtained indicated that ZnO treatment of Co3O4/Al2O3 solids followed by precalcination at 400°C resulted in a progressive decrease in the particle size of the Co3O4 crystallites in the resulting samples. The catalytic activity of such solids towards H2O2 decomposition decreased progressively as the precalcination temperature employed was increased in the range 400–600°C. The relationship between the catalytic activity expressed as a plot of the reaction rate constant, k, versus the amount of Co3O4 in the samples showed a progressive increase in the range 5.6–17.7 wt% followed by an abrupt increase when the extent of loading exceeded this limit. Treatment with ZnO effected a measurable increase (42%) in the specific surface area (SBET) of the treated solids. However, such treatment also resulted in a considerable increase in the value of the reaction rate constant for the catalyzed reaction. Thus, the maximum increase in the value of k20°C due to doping with 2.12 wt% ZnO attained a value of 543% while the corresponding increase in the value of the reaction rate constant per unit surface area, k̄20°C, was 331%. Precalcination at 400–600°C of Co3O4/Al2O3 solids subjected to ZnO treatment did not modify the mechanism whereby the catalytically active constituents (surface cobalt species) were involved in the reaction although their concentration was altered without affecting their energetic nature.
Surface and Catalytic Properties of the CuO/Al2O3 System Treated with Different Proportions of ZnO
Authors: El-Shobaky Gamil A. , Amin Nabil H. , El-Molla Sahar A. 
Published: October 2002

The effects of ZnO treatment on the surface and catalytic properties of CuO/Al2O3 were investigated. All the samples studied contained a fixed amount of CuO (13.5 wt%) while the amount of ZnO dopant was varied in the range 0.68–6.46 wt%. The pure and variously doped solids were subjected to heat treatment (precalcination) in the temperature range 400–600°C. The samples obtained were investigated by XRD methods, nitrogen adsorption at −196°C and studies of their catalytic influence on the decomposition of H2O2 at 20–40°C. The results obtained indicated that ZnO treatment of CuO/Al2O3 followed by precalcination at 500°C led to a progressive decrease in the degree of crystallinity of the CuO phase to an extent proportional to the amount of ZnO present in the system. This suggests that such treatment led to a significant decrease in the particle size of the CuO crystallites produced. The BET surface areas of the treated solids increased on increasing the amount of ZnO present in the system. Similarly, the catalytic activity, as expressed in terms of the reaction rate constant for the decomposition of H2O2, increased on increasing the amount of dopant added to reach a maximum value (ca. 67%) when 1.7 wt% ZnO had been added to the system, and then subsequently decreased on further addition of dopant. It was found that ZnO treatment of CuO/Al2O3 did not modify the activation energy of the catalyzed reaction but rather changed the concentration of catalytically active constituents without changing their energetic nature.
Studies of the Effect of Crosslinking in the Strongly Basic Anion Exchanger Dowex 1 and the HNO3 Concentration Employed on the Separation of the SmIII–NdIII Pair in the Polar Organic Solvent–H2O–HNO3 System
Authors: Hubicki Z. , Olszak M. 
Published: October 2002

Because of their specific structure, rare earth elements are used for the modification or structural stabilization of many metallic or ceramic materials employed in modern technology and also in the metallic form, i.e. in alloys and compounds with unique properties. Industrial demand for rare earth metals has increased lately due to their new application possibilities, e.g. in supermagnets of the Nd–Fe–B type or in ceramic high-temperature superconductors. Equally, the application of rare earth elements in metallurgy, catalysis, ceramics, etc. remains of significant importance. The separation and purification of rare earth elements(III) which occur in groups with similar physicochemical properties involve extremely difficult and complex processes. Ion exchange is one method which enables such separation. This paper presents the results of studies of the influence of the extent of crosslinking in the anion exchanger Dowex 1 and the concentration of nitric acid on the separation of the SmIII–NdIII pair by frontal analysis in 90% v/v CH3COCH3– or the CH3OH–10% v/v × M HNO3 systems. The most effective results were obtained in the 90% v/v CH3OH–10% v/v 7 M HNO3 system employing the anion exchanger Dowex 1 × 4 allowing 0.11 kg samarium(III) to be purified on 1 dm3 ion exchanger in the nitrate form and leading to a decrease in the micro-component content to a value below 10−3%.
Analysis of Adsorption Data of Nitrogen and Carbon Dioxide on Chemically-Activated Carbons from Cherry and Wild Cherry Stones by considering Different Approaches Based on Different Models
Authors: Alaya M.N. , Hourieh M.A. , El-Sejariah F. , Youssef A.M. 
Published: October 2002

Activated carbons were prepared by activation of cherry and wild cherry stones with phosphoric acid and zinc chloride. The adsorption of nitrogen at −196°C and of carbon dioxide at 0°C was followed and the data obtained analyzed through the use of models based on theories of surface coverage and micropore filling. Chemically-activated carbons obtained from cherry and wild cherry stones exhibited high surface areas and large total pore volumes. Most of the pores lay in the micropore region while a small fraction of the total surface area was located in non-micropores. Fair agreement was established on comparing the textural parameters derived from models based on the theory of surface coverage with those derived from the micropore filling theory. Micropores should be classified into ultrafine pores, micropores and super-micropores, such sub-division helping in the prediction of the adsorption behaviour and in the interpretation of the data derived therefrom.
Adsorption Properties of Zeolite-Containing Microspheres and FCC Catalysts Based on Ukrainian Kaolin
Authors: Patrylak L. , Likhnyovskyi R. , Vypyraylenko V. , Leboda R. , Skubiszewska-Zięba J. , Patrylak K. 
Published: October 2002

A series of samples of zeolite-containing microspheres (ZCMS) and fluid catalytic cracking (FCC) catalysts based on Prosyana (Ukraine) kaolin were synthesized in situ. Their adsorption and chemisorption characteristics were recorded using a nitrogen low-temperature adsorption/desorption method and temperature programmed desorption (TPD) of ammonia, respectively. It was shown that changes in the synthesis conditions had a considerable impact on the micro- and meso-porosity of the samples. A low-temperature band dominated the ammonia TPD spectra of the ZCMS samples, reflecting the retention of ammonia by the sodium cations of the zeolite acting as weak Lewis acid sites. ZCMS was found to display an appreciable activity in cumene cracking at 723 K. It was shown that during the conversion of ZCMS to FCC catalysts through the decationization and ultra-stabilization of the zeolite phase, the latter is appreciably destroyed giving rise to a considerable increase in the mesoporosity of the samples without any change in the average diameters of such mesopores. It was concluded that the catalyst stability is characterized by pores of an intermediate (20–30 Å) diameter, thereby demonstrating the strength of the linkage between the zeolite and matrix phases. The zeolite phase content and adsorption characteristics of catalysts prepared on the basis of Prosyana kaolin meet the demands of modern FCC catalysts.
Measurement and Prediction of the Adsorption of Binary Mixtures of Organic Vapours on Activated Carbon
Authors: Wu Jufang , Xie Zili , Guo Kunmin , Claesson Ola 
Published: October 2002

This paper describes a modified headspace method for measuring the adsorption equilibrium of mixtures of organic vapours. The advantage of the method relative to the ordinary headspace method is the shorter time needed to reach adsorption equilibrium. The adsorption isotherms of benzene, hexane and pentane on activated carbons were acquired quickly and easily using this method. The method has also been used to measure the binary equilibrium data of benzene–hexane, benzene–pentane and hexane–pentane mixtures on three types of activated carbon. The ‘Ideal Adsorbed Solution Theory’ (IAST) was used to predict the binary adsorption equilibria from the adsorption isotherms for the single components. Good agreement was obtained between prediction and measurement for the total amount of components adsorbed, as well as for the ratio of compounds in the adsorbed phase. The small deviation noted was probably a result of using the Freundlich adsorption isotherm in IAST modelling.
Surface and Catalytic Properties of the CuO/Al2O3 System as Influenced by Doping with CeO2 or ZrO2 and by γ-Irradiation
Authors: El-Shobaky Gamil A. , Radwan Farouk M. , Turky Abd. El-Mohsen M. , El-Moemen Ayman Abd. 
Published: October 2002

The effects of doping the CuO/Al2O3 system with CeO2 or ZrO2, or alternatively treatment with γ-irradiation, on its surface and catalytic properties were investigated using nitrogen adsorption at −196°C, the decomposition of H2O2 at 20–40°C and the oxidation of CO by O2 at 175°C. The pure solids were prepared by wet impregnation with copper nitrate dissolved in the least amount of distilled water of finely powdered solid Al(OH)3 precalcined at 400°C, followed by drying the resulting product and subjecting the same to calcination at 500°C. The doped solids were prepared by treating Al(OH)3 precalcined at 400°C with a known amount of dopant, i.e. cerium or zirconyl nitrate dissolved in the least amount of distilled water, prior to impregnation with the copper nitrate solution. The amount of copper oxide thus introduced was fixed at 13.5 wt% while the amounts of dopants were varied between 1 wt% and 10 wt% CeO2 or ZrO2. The results obtained indicated that ZrO2 doping increased the degree of dispersion of the CuO phase, while CeO2 treatment had the reverse effect. Doping the CuO/Al2O3 system with CeO2 or ZrO2 led to an increase of 15.4% or 8.1%, respectively, in its BET surface area. The catalytic activity of the system towards the decomposition of H2O2 decreased on doping with ZrO2 but increased when CeO2 was used as a dopant. γ-Irradiation (at 20–160 Mrad) of CuO/Al2O3 solids resulted in a measurable and progressive decrease in their catalytic activity towards H2O2 decomposition. In CO oxidation with O2, ZrO2 treatment of the CuO/Al2O3 solids brought about a progressive increase in their catalytic activity with the maximum value (a 31% increase) being observed in the presence of 3 wt% ZrO2 but then decreasing with further increases in the amount of dopant present until the final value attained with 10 wt% ZrO2 was smaller than that measured for the pure CuO/Al2O3 catalyst sample. In contrast, the addition of the smallest amount of CeO2 (1 wt%) led to an effective increase of 69% in the catalytic activity of the CuO/Al2O3 system towards the O2 oxidation of CO, which then decreased when further amounts of CeO2 were added to the system although still exhibiting a catalytic activity greater than that of the undoped catalyst sample. Doping or γ-irradiation of the CuO/Al2O3 system had no influence on the activation energy for the decomposition of H2O2 in the presence of the resulting solid catalysts although the concentrations of catalytically active sites present on the surfaces of the solids investigated were modified by such treatment.
Evolution of Natural Frequencies in Tensegrity Systems: A Case Study
Authors: Moussa B. , Kahla N. Ben , Pons J. C. 
Published: October 2002

In this study, a dynamic analysis of self-stress levels of tensegrity systems is proposed. A direct relation between the first natural frequency of these systems and the levels of self-stress in the elements is established. It constitutes a first step toward the study of the adaptability of tensegrity systems to external loads; this adaptability could be realized by adjusting the levels of self-stress of one or several cable elements. The study is carried out using continuous struts tensegrity systems made of linear associations of simplex type modules. When subjected to static loading, tensegrity systems show an evolution of their frequencies with respect to the tension levels in the elements. The frequencies are computed assuming the structure oscillates linearly about its static equilibrium position. This evolution can be used, to associate the level of self-stress to a desired resonant frequency of the system. The harmonic dynamic loading of these systems, confirms their non linear characters and show a particular evolution of the tension-frequency relation.
A Static Synchronous Converter for Power Conditioning in Network Distribution with High Wind Energy Share
Authors: Beck Hans-Peter , Wenske Jan , Wolf Albrecht 
Published: October 2002

The integration of renewable energy sources, e. g. wind energy in weak or isolated power systems produces disturbances. Such disturbances are due to the power fluctuations caused by the stochastic fluctuating wind energy, current harmonics in the power system, switching operations, tower effects and reactive power consumption of the wind energy installations. These decrease the power quality at the point of common coupling (PCC). This paper introduces a concept to compensate the disturbances by the use of a static synchronous converter with an active damping circuit. This new concept is based on the principle of the static reactive power converter, and was extended by means of system integration of largely standardized components of the drive-converter technology. In combination with an active intervention in the pulse-pattern generator of the main converter, it is possible to balance asymmetrical loads and compensate the harmonics. The pulse pattern generator was realized through an assembler-programmed PC.