scholarly journals Improvement of the Modified Dry-Cup Method for Determination of the Diffusion Coefficients of Gaseous Pollutants in Building Materials

2010 ◽  
Vol 305-306 ◽  
pp. 109-114 ◽  
Author(s):  
José J. Gonçalves ◽  
Gabriela V. Silva ◽  
Armando S. Santos ◽  
Eduardo O. Fernandes
Keyword(s):  
Diffusion Coefficients ◽  
Air Pollutants ◽  
Partition Coefficients ◽  
Passive Sampling ◽  
Building Materials ◽  
Sources And Sinks ◽  
Set Up ◽  
Made In

Diffusion and partition coefficients are key parameters for the characterization of building materials as sources and sinks of air pollutants indoors. A simple and rapid experimental method for direct measurement of the diffusion coefficient (D) was presented in a previous article [1]: the modified dry cup method. This method was based upon two existent methodologies, the passive sampling on Tenax TA and the dry cup method, proposed by Haghighat et al. [2]. In the present article, some improvements were made in the experimental set-up in order to obtain more precise results. The previous cup was modified by increasing the number of Tenax tubes, connected to the bottom of the cup, from one to five. The results obtained with both cups were compared. Measurements with single compounds and with three compounds simultaneously were compared in order to evaluate the influence of competition between molecules of different compounds.

scholarly journals Presentation of a New Method for Determination of Diffusion Coefficients of Gaseous Pollutants in Cladding Wall Materials Indoors

2010 ◽  
Vol 297-301 ◽  
pp. 881-886 ◽  
Author(s):  
José J. Gonçalves ◽  
Armando S. Santos ◽  
Gabriela V. Silva ◽  
Eduardo O. Fernandes
Keyword(s):  
Building Materials ◽  
New Method ◽  
Material Surface ◽  
Indoor Environments ◽  
Gypsum Board ◽  
Sources And Sinks ◽  
Compound Material ◽  
Order Of Magnitude

Diffusion and partition coefficients are two key parameters of importance for the characterization of building materials as sources and sinks of air pollutants indoors. The number of coefficients for each pair ‘chemical compound – material surface’ available in the literature are still scarce and with a high discrepancy in the results obtained by different methods, even for the same method [1]. The objectives of this study were (1) to develop a simple and rapid experimental method for directly measuring the diffusion coefficient (D), and (2) to perform determinations with both the new and the cup method comparing the results obtained. The new method is based on two existent methodologies, the passive sampling on Tenax TA and the dry cup method, proposed by Haghighat et al. [1] and also developed by this research team [2]. The experiments were carried for three different building materials (cork based material, gypsum board and PVC) and three different compounds (cyclohexane, n-octane and m-xylene). The discussion of the results obtained for D by the two methods is presented in this paper. Observed differences were not of the same order of magnitude for the pairs compound/material studied, varying from the order of 101 in the case of PVC to 102 in the gypsum and in the cork. However some facts were the same: the gypsum board presents the higher values of D and PVC the lower values of D for the three compounds studied in both methods. One of the causes of these marked differences could be high difference of the concentration of the compound in the air between the methods, saturation value in cup method (dozens g/m3) and low values typical from indoor environments (few mg/m3) in the proposed method.

scholarly journals Determination of Catalyst Surface Acidity in Liquids by a Pulse Liquid Chromatographic Technique

2005 ◽  
Vol 23 (9) ◽  
pp. 739-749 ◽  
Author(s):  
Paolo Carniti ◽  
Antonella Gervasini ◽  
Serena Biella
Keyword(s):  
Surface Acidity ◽  
Lower Amount ◽  
Chromatographic Technique ◽  
Solvent Flow Rate ◽  
Acidic Sites ◽  
Catalyst Acidity ◽  
Set Up ◽  
Liquid Chromatographic

A pulse liquid chromatographic technique, set up by using an HPLC apparatus, is proposed for the characterization of the surface acidity of solid acids in liquids in view of their use as catalysts in liquid–solid reactions. Dosed amounts of solutions of two different basic probe molecules (2-phenylethylamine, pKa = 9.84 and aniline, pKa = 4.63) in solvents of different polarity were injected onto solid samples (acidic resins, Amberlites and a mixed silica–zirconia oxide) at a constant solvent flow rate. Titration with the weakest basic probe (aniline) rather than 2-phenylethylamine generally led to a lower amount of acidic sites. The amount of acidic sites determined at the surface was greatly affected by the solvent. With silica–zirconia, a higher amount of acidic sites was established by titration in apolar rather than polar solvents. The results have been compared with those obtained by conventional methods, i.e. ion exchange employing salts and, for silica–zirconia, Hammett titrations. The quite satisfactory results obtained are of some importance in establishing valuable relationships between catalyst acidity and catalytic activity in various solvents.

Synthesis and Structural Characterization of Ca14NbxIn1-xAs11 (x ≈ 0.85)

2016 ◽  
Vol 257 ◽  
pp. 147-151 ◽  
Author(s):  
Yi Wang ◽  
Svilen Bobev
Keyword(s):  
Physical Properties ◽  
Side Reaction ◽  
Structure Type ◽  
Major Product ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ongoing Work ◽  
Set Up

Single-crystals of the new compound Ca14NbxIn1–xAs11 have been obtained from a solid-state reaction in a sealed Nb ampoule. The initial experiment had been set up with the aim to investigate the effect of electron doping (via In) on the crystal structure and physical properties of Ca14MnAs11. Subsequent single-crystal X-ray diffraction and elemental analysis work suggested that instead of Ca14MnxIn1–xAs11, the major product of the reaction is the phase Ca14NbxIn1–xAs11. This supposition was corroborated when the title compound was synthesized from a reaction of Ca, In and As in a sealed Nb ampoule, proving that, 1) Mn metal is not included in the structure, and 2) that the inadvertent side reaction of As with the walls of the Nb container is the source of the niobium. The overall structure is isotypic with the tetragonal Ca14AlSb11 structure type (space group I41/acd), although some marked differences between the two must be noted. Current ongoing work is focused on the synthesis of phase pure polycrystalline samples and determination of the physical properties of this unusual transition metal Zintl phase.

STUDY PORE CHARACTERIZATION OF γ-ALUMINA – ACTIVATED CARBON COMPOSITE MADE OF CASSAVA PEELS (Manihot esculenta Cranz)

2015 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Hartini Hartini ◽  
Yuniawan Hidayat ◽  
Mudjijono Mudjijono
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Total Pore Volume ◽  
Carbon Composite ◽  
Bet Method ◽  
Industrial Standards ◽  
Cassava Peels ◽  
Made In

<p>A composite of γ-alumina and activated carbon made of cassava peels was studied in terms of its pore structures and its properties. The objective of this study was to determine the interaction and structure, as well as the character and pore size of γ-alumina – activated carbon composite.</p><p>Carbon made of cassava peels was activated by H<sub>2</sub>SO<sub>4</sub> and its activities were tested according to the Indonesian Industrial Standards (SII). The addition of activated carbon into γ-alumina made in variations of 10, 20, 30, 40 and 50 % w/w, of the total weight of 10 grams. The composite of γ-alumina - activated carbon was characterized by FTIR, SAA (Surface Area Analyzer), XRD, and determination of Hysteresis Loop composites.</p>The greater addition of activated carbon to γ-alumina causes intermolecular interactions between –O-H groups form rehydrated hydrogen bonds in the composite is greater. The structure of γ-alumina in the composites remain intact although the percentage of activated carbon in composite is large. The total pore volume and surface area using the BET method of the composite decreases with increasing activated carbon percentage. The greater addition of activated carbon to γ-alumina causes size of mesoporous composites decreased with the characteristic of a composite formed is closer to the activated carbon.

scholarly journals The Use of SEM and Other Complimentary Techniques for the Determination of Properties of Cementitious Materials

1992 ◽  
Vol 00 (8) ◽  
pp. 4-4 ◽  
Author(s):  
Eric A. Draper ◽  
Jan Skalny
Keyword(s):  
Building Materials ◽  
State Of The Art ◽  
Raw Materials ◽  
Cementitious Materials ◽  
Modern State ◽  
Microscopic Evaluation ◽  
The World ◽  
Cost Effect

The need for continued rehabilitation of our concrete infrastructure has lead to the adaptation of modern “state-of-the-art” analytical methods for the characterization of concrete and other cementitious materials. Some of these techniques have not, until relatively recently, been commonly associated with the evaluation of concrete but are very useful both as tools for quality assurance and in the determination of the extent of existing damage. The technique of interest here is the coordinated electron-optical microscopic evaluation of concrete.Concrete is the most widely used building material in the world. Contrary to popular belief, concrete is not inert but chemically very complex and dynamic. While it is true that, pound for pound, concrete and its raw materials (cement, aggregate and water} are the most inexpensive building materials available for construction, it is also true that it responds to its environment in numerous and sometimes very subtle ways. These responses may sometimes result in a loss of durability and tremendous amounts of time and money being expended while searching for the cause(s) of the problem and providing a cost-effect solution A quick survey of any large metropolitan area and the on-going construction repairs to highways and bridge decks there will quickly confirm this.

scholarly journals Tide prediction machines at the Liverpool Tidal Institute

2020 ◽  
Vol 11 (1) ◽  
pp. 15-29
Author(s):  
Philip L. Woodworth
Keyword(s):  
Tide Gauge ◽  
100Th Anniversary ◽  
Tide Gauge Data ◽  
Basic Principles ◽  
The World ◽  
Gauge Data ◽  
Set Up ◽  
The Uk ◽  
Made In

Abstract. The 100th anniversary of the Liverpool Tidal Institute (LTI) was celebrated during 2019. One aspect of tidal science for which the LTI acquired a worldwide reputation was the development and use of tide prediction machines (TPMs). The TPM was invented in the late 19th century, but most of them were made in the first half of the 20th century, up until the time that the advent of digital computers consigned them to museums. This paper describes the basic principles of a TPM, reviews how many were constructed around the world and discusses the method devised by Arthur Doodson at the LTI for the determination of harmonic tidal constants from tide gauge data. These constants were required in order to set up the TPMs for predicting the heights and times of the tides. Although only 3 of the 30-odd TPMs constructed were employed in operational tidal prediction at the LTI, Doodson was responsible for the design and oversight of the manufacture of several others. The paper demonstrates how the UK, and the LTI and Doodson in particular, played a central role in this area of tidal science.

scholarly journals Characterization of Environmental Impact of Building Materials for the Purpose of Ecodesign

2011 ◽  
Vol 6 (-1) ◽  
pp. 106-111
Author(s):  
Agnese Skele ◽  
Mara Repele ◽  
Gatis Bazbauers
Keyword(s):  
Environmental Impact ◽  
Building Materials ◽  
Manufacturing Sector ◽  
Impact Indicator ◽  
Life Cycle Inventory Data ◽  
Cradle To Gate ◽  
Total Impact ◽  
Factory Site ◽  
Made In

Characterization of Environmental Impact of Building Materials for the Purpose of Ecodesign -The building material manufacturing sector is one of the sectors with the highest consumption of fossil fuel resources. The "cradle-to-gate" study of the ceramic bricks made in the Āne plant of JSC Lode, Latvia, is performed according to ISO standards 14044:2006. Life cycle inventory data have been collected at the factory site. Three different perspectives of the "Eco-Indicator'99" method are used to conduct an environmental characterization of the building materials to obtain the total impact indicator.

Methods for Source Characterization of Organic Air Pollutants

1990 ◽  
Vol 6 (5) ◽  
pp. 67-80
Author(s):  
H. J. Th. Bloemen ◽  
J. J. G. Kliest
Keyword(s):  
Air Pollution ◽  
Organic Compounds ◽  
Air Pollutants ◽  
Source Characterization ◽  
Mathematical Methods ◽  
Remedial Actions ◽  
Exposure Evaluation

Organic compounds are becoming increasingly more of interest as air pollutants, indoor as well as outdoor. Sources emitting such compounds are numerous and of various origin. For toxicological and epidemiological examination and for deciding on remedial actions information is required on the occurrences of compounds as well as on the emitting sources. For this purpose a number of investigations have been carried out with only limited success. To increase the quality of the description of air pollution related to complaints of dwellers and to exposure evaluation analytical and mathematical methods have tested in our laboratory. Analytical methods for the determination of different groups of organic compounds and mathematical methods for defining minimum sampling strategies and for the characterization of sources are discussed and illustrated with applications dealt with in the passed years. It is concluded that the application of a combination of these methods offers a manner to better describe and understand air pollution with organic compounds.

scholarly journals Micellar Liquid Chromatography for the Determination of Some Less Prescribed Benzodiazepines

2012 ◽  
Vol 9 (1) ◽  
pp. 443-450 ◽  
Author(s):  
Hoonka Subhra ◽  
Bose Devasish ◽  
Esteve-Romero Josep ◽  
Durgbanshi Abhilasha
Keyword(s):  
Analytical Chemistry ◽  
Mobile Phase ◽  
Partition Coefficients ◽  
Sodium Dodecyl ◽  
Micellar Liquid Chromatography ◽  
Serum Samples ◽  
Intermediate Precision ◽  
Chromatographic Procedure ◽  
Made In

A simple chromatographic procedure is reported for the determination of some less prescribed but equally important benzodiazepines (Clotiazepam, clozapine and pinazepam) in serum. The optimization studies have been made in CN, C18and C8columns, using mobile phase containing sodium dodecyl sulphate (SDS) modified with either propanol, butanol or pentanol. The method proposed for the determination of the three benzodiazepines using a mobile phase of 0.13 M SDS, 2.4% pentanol-0.01 M phosphate buffer- 0.1% triethylamine (pH 7) at 25°C and UV detection (240 nm) in a C8column. The serum samples was injected directly, without any pretreatment, eluted in less than 8 min, in accordance to their relative polarities, as indicated by their octanol-water partition coefficients. The limits of detection (ng/mL) was in the 1.6 to 5.6 and 7 to 87 range, for aqueous and serum samples, respectively. Repeatability and intermediate precision was tested for three different concentrations of the drugs, resulting in the 0.1 to 2 range. The results obtained here for the separation of the three benzodiazepines in serum were also counter checked at Department of Bio-analytical Chemistry, Universitat Jaume I, Castelló, Spain.

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