Criticism on Jäntti's Three Point Method on Curtailing Gas Adsorption Measurements

Jäntti introduced a method to reduce the time required for the stepwise measurement of adsorption isotherms (Jäntti et al., Progress in Vacuum Microbalance Techniques, Vol. 1, Heyden, London, pp. 345–353, 1972). After a pressure change he measured the adsorbed mass three times and calculated its equilibrium value for the new pressure. In the present paper we discuss the applicability of this method in a broader scope (without starting from a single combination of gas and solid adsorbent) and also discuss the influence of measurement inaccuracies. It is shown that the method can serve as an early warning system, which decides whether an improvement of the adsorption model is necessary.     

A New Kinetic Method of Processing TA Data

A new method of investigating the kinetic parameters and mechanism functions of a solid phase reaction is presented. This method is to analyze the data based on the use of these data at the same temperature and the same degree of conversion on a series of TA curves with different heating rates, so that the kinetic triplet--the activation energy E, the pre-exponential factor A and the analytical form of the function of conversionf(α) can be obtained. The main advantage of this method is that the values of E and f(α) are obtained respectively, and the determination of f(α) is not under the influence of the value of E and the calculation of the value of E is not influenced by thef(α) either.     

The Adsorption of NOx on Magnesium Aluminium Hydrotalcite

Magnesium aluminium hydrotalcite (Mg-Al-HT) with molar ratio of Mg-to-Al of 3 to 1 was prepared and characterized by X-ray diffraction (XRD) and infrared spectra (IR). The performances of Mg-Al-HT for the adsorption and desorption of NOx were studied. The results indicated that the adsorption capacity of the hydrotalcite for NOx was 1398.2mg/g, and it was higher than the acticarbon‘s. The adsorption capacities depended on adsorption time and temperature.Mg-Al-HT could be regenerated by thermal decomposition, and the adsorption efficiency had not changed markedly after three cycles.     

The Determination of Dynamic and Equlibrium Solid/Liquid Transformation Data For Sn–Pb Using DSC

Differential Scanning Calorimetric measurements were performed for accurate determination of the solidus and liquidus temperature of Sn–Pb alloys. The difference between onset and end temperature of the melting peak depended clearly on alloy composition. The results obtained were found to be in good agreement with the existing equilibrium phase diagram for the Sn–Pb system, although the data suggested a slight correction of the eutectic composition. Under cooling conditions a large variation in the onset temperature for solidification was found. A large number of heating and cooling cycles were performed in order to investigate the statistical variation of the solid nucleation process. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis, Structure and Adsorption of AIPO-21 Prepared by Cotemplate Method

The phase of AIPO‐21 was hydrothermally synthesized in the reactant system of diethylamine‐RB‐Al₂O₃‐O₅‐H₂O‐C₂H₅OH. The crystals of AIPO‐21 growing in this system crystallizes in monoclinic system, space group P2₁/n with a = 0.8542(4) nm, b = 1.7635(8) nm, c = 0.9082(4) nm, β = 108.234(5)°, V = 1.2993(10) nm³, Z = 4, and the formula is [C₄H₁₀ NH₂]⁺ = [Al₃P₃O₁₂ (OH)]^?. The structure is resolved by the direct method and refined to R1 = 0.0767 and wR₂ = 0.1627 based on 1719 observed reflections with I > 2.0σ (I). An asymmetric unit consists of three PO₄ tetrahedra, one AIO₄ tetrahedron and two AIO₅ trigonal bipyramids. The framework is composed of 3‐D uniform channels along [100], [001] and [101] with eight‐membered oxygen ring windows. The powder sample of the MS was investigated with powder XRD, TG/DTG/DTA and the adsorption of water, methanol, n‐hexane, ethylene, and ethane. The specific property for sieving molecules was observed on the adsorption isotherms, and proves the result of the single crystal structural analysis.     

Novel Method of Preparation of Monolithic Columns for Fast Separation by γ-Ray Irradiation

A porous monolithic sol-gel column with the solution of methacryloxypropyltrimethoxysilane in toluene with an acid catalyst was prepared in the presence and absence of sodium dodecyl sulfate. In situ polymerization was carried out byγ-ray irradiation within the capillary. Theγ-radiation-initiated synthesis could generate radicals directly on the monomer avoiding use of any initiator. The chromatographic behavior of the capillary monolithic columns were studied in the modes of CEC, p-CEC and low pressure-driven separation, all the tests exhibited reversed-phase character. It provided a viable alternative to either thermally initiated or photo polymerization method for the preparation of monolithic columns.     

Synthesis,Structure and Adsorption of AlPO-21 Prepared by Co-template Method

IntroductionAlPO 2 1isatypeofmicroporousaluminophosphatepreparedbyFlanigenandco workersin 1982 ,andthestructurewasresolvedbySmithetal.1in 1984 .AlmostatthesametimePariseetal.2 preparedAlPO 2 1phasebyanotherrouteandresolvedthestructureindependently .Inthenextyear ,GaPO 2 1phasewasobtainedaswell.3Al thoughAl(Ga)PO 2 1phasespreparedindifferentwayspossesssimilarchannelsystem ,amongthemtherearestillsomedifferencesinlatticeconstants ,indicatingthatdiffer enttemplatemoleculescanaffectlocallythe…     

Direct Method for Measuring Adsorption at the Aqueous Solution–Gas Interface Based on the Stabilization of Foam Films in Hydrophobic Tubes. The Adsorption Isotherm of Sodium Dodecyl Sulfate

It was found that the hydrophobization of the inner surface of a tube offers the stabilization of films of nonfoaming aqueous solutions closing the cross section of the tube. Based on this phenomenon, a modification of the known method of determining adsorption at the solution surface based on the separation of foam films from the solution was proposed for extending the potentialities of this method to nonfoaming solutions. Adsorption of sodium dodecyl sulfate on the aqueous solution–air interface was investigated in the range of low concentrations, which earlier was not easily accessible to measurements by known methods.     

A New Method For Quick Determination of CODcr Without Hg(Ⅱ)

A new method for determining COD_cr has been developed.     

The Adsorption Effect of Quaternized Chitosan Derivatives on Bile Acid

Chitosan, which is easily derived from chitin by N-deacetylation. It is well known that hypercholesterolemia has been identified as a major risk factor in the development of atherosclerosis and its clinical sequelae like coronary heart disease and myocard…     

Studies on The Adsorption Capacity for Bilirubin of The Adsorbent Chitosan-β-Cyclodextrin

Bilirubin is a metabolite of heme from hemoglobin in the blood. Disorders in its successive metabolism or excretion may cause the accumulation of the unconjugated bilirubin in blood of the patients who suffer from hyperbilirubinemia. The accumulation of bilirubin can cause serious tissue damage1,2. Hyperbilirubinemia may be treated by the removal of bilirubin from body. The ways for its removal include phototherapy, orally administered sorbents3 and adsorbents for hemoperfusion. Successful he…     

The Adsorption of Aqueous—Organic Mixture Components on Cellulose

The isotherms of composition changes were obtained for the cellulose—water—dimethylsulfoxide and cellulose—water—acetonitrile systems. The isotherms of sorption of aqueous—organic mixture components on cellulose were calculated. The heat effects of wetting of cellulose with water—dimethylsulfoxide and water — acetonitrile solutions were measured. The special features of sorption of the components on cellulose were shown to be related to the character of cluster formation in the binary systems under consideration.     

A Novel Method For Synthesis of Titanium Silicalite-2(TS-2)

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Applicability of Parallel μLC for Achiral Method Development and Impurity Profiling in Support of Pharmaceutical Early Development

A comprehensive study has been done to examine the feasibility of applying Eksigent ExpressLC-800 parallel μLC–UV system for the achiral method development and impurity profiling in support of pharmaceutical early development. The system evaluation was performed extensively with respect to linearity, sensitivity and reproducibility. Some real-world applications for method screening and purity assessment are also carried out to demonstrate the instrument’s versatility as well as to address the needs to further improve sensitivity and micro-column packing quality. Some thoughts on future improvement are also discussed.     

On the Calculation of Liquid–Vapor Interfacial Thickness Using Experimental Surface Tension Data

In this paper we investigate the vapor–liquid interfacial thickness of several pure fluids using a new method. In this method, the surface thickness is obtained using experimental surface tension data, and its dependence on the temperature is evaluated. The interfacial width is found to increase with increasing temperature and goes to infinity when the temperature approaches its critical value. Also, we find that a plot of ln δ versus ln {(1−T _r)⁻¹} is linear, in which δ and T _r are the interfacial thickness and reduced temperature, respectively. In this method, the equation of state obtained from the Statistical Associating Fluid Theory (SAFT EOS), which is molecular based, is accepted.     

The Evaluation of Two-Dimensional Madelung Constant For NaCl Crystal Structure

The following documentation is an evaluation of the two-dimensional Madelung constant for the NaCl structure. The infinite series for the structure is formulted asThe first term in the formula converges to 41n2. The series after K =2 in the second term is put together with the third term and a constant- 4/ 2 is left. The combination of the third term and the series after K=2 in the second term is assumed to be 8 Sn. The converging series Sn can be solved on a computer. The seven significant figures of the two-dimensional Madelung constant for the NaCl structure is then determined as 1. 615558.     

The Bond Nature in the AsCl3–POCl3 System According to ab initio Calculation Data

Russian Journal of General Chemistry - To study the nature of the coordination bond in the AsCl3–PОCl3 system, quantum-chemical calculations have been performed using the...     

The Adsorption Behavior of Lithium Cationon Polyacene and Its Influenceon Conductive Property

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The Study of Alcoholysis of 1,2-Thiazetidine-1,1-dioxide with Quantum Chemical Method

The alcoholysis mechanism of 1,2-thiazetidine-1,1-dioxide with methanol, in which the relatively stable product is sulfonate ester, has been investigated by quantum chemical method. Our calculations indicate the reaction for alcoholysis of 1,2-thiazetidine-1,1-dioxide proceeds via two possible mechanisms: concerted and stepwise. In the stepwise mechanism, two possible reaction pathways can be followed while only one possible reaction pathway can be followed in the concerted mechanism.     

The Study of Alcoholysis of 1,2-Thiazetidine-l,l-dioxide with Quantum Chemical Method

The alcoholysis mechanism of 1,2-thiazetidine-1,1-dioxide with methanol, in which the relatively stable product is sulfonate ester, has been investigated by quantum chemical method. Our calculations indicate the reaction for alcoholysis of 1,2-thiazetidine-1,1-dioxide proceeds via two possible mechanisms: concerted and stepwise. In the stepwise mechanism, two possible reaction pathways can be followed while only one possible reaction pathway can be followed in the concerted mechanism.