scholarly journals Physicochemical and structural characteristics of HEU-type zeolitic tuff treated by hydrochloric acid

2004 ◽  
Vol 69 (4) ◽  
pp. 273-282 ◽  
Author(s):  
Ana Radosavljevic-Mihajlovic ◽  
Vera Dondur ◽  
Aleksandra Dakovic ◽  
Jovan Lemic ◽  
Magdalena Tomasevic-Canovic
Keyword(s):  
Crystal Structure ◽  
Hydrochloric Acid ◽  
Bosnia And Herzegovina ◽  
Acid Treatment ◽  
Structural Characteristics ◽  
Chemical Analyses ◽  
Zeolitic Tuff ◽  
Zeolitic Tuffs ◽  
Before And After

Samples of natural HEU-type zeolites ? clinoptilolite-Ca, from the Novakovici deposit (near Prijedor, Bosnia and Herzegovina) were treated with the hydrochloric acid of various concentrations (from 10-3Mto 2M). Zeolitic tuffs before and after the acid treatment were examined using IR, XRPD, and chemical analyses. The changes in the crystal structure of acid treated samples showed a significant reduction in the crystallinity of zeolitic tuffs (60?70 %), which were effected by hydrochloric acid with concentrations of 1 M and above.

scholarly journals Mineralogy and crystallochemical characteristics of HEU-type minerals from zeolitic tuff deposits of Serbia

2017 ◽  
Vol 71 (1) ◽  
pp. 49-60
Author(s):  
Vladan Kasic ◽  
Vladimir Simic ◽  
Dragana Zivotic ◽  
Ana Radosavljevic-Mihajlovic ◽  
Jovica Stojanovic
Keyword(s):  
Crystal Structure ◽  
Cation Exchange Capacity ◽  
Raw Materials ◽  
Volcanic Glass ◽  
Exchange Capacity ◽  
Exchangeable Cations ◽  
Zeolitic Tuff ◽  
Pyroclastic Rocks ◽  
Zeolitic Tuffs ◽  
Thermal Stability Of

The results of perennial research of several Serbian zeolitic tuffs enriched with HEU-type minerals are presented in this paper. There are several recognized zeolitic tuff deposits containing HEU-type minerals: Zlatokop, Igros, Beocin, Toponica, Slanci, but their comparative mineralogical and crystallochemical features have not been studied in detail so far. These zeolitic tuff deposits are spatially and genetically connected to volcanic and pyroclastic rocks of marine and lake environments of Senonian and Eocene, and Neogene age, respectively. As a result of devitrification and diagenesis process of volcanic glass within zeolitic tuffs hypocrystalline porphiry and vitroclastic textures occur. The studied zeolitic tuffs are mainly composed of heulandite occuring in a form of needle- to plate-like crystals of 0,1 do 100 ?m in length, associated with other silicates. Depending on the type and content of exchangeable cations as well as the thermal stability of these raw materials, 24 clinoptilolite-Ca and heulandite-Ca can be distinguished. The values of cation exchange capacity and surface area capacity range from 96 to 166 meq/100 g, and from 8,0 to 10,5 meq/100 g, respectively. HEU-type minerals can be distinguished either by a Si/Al ratio or arrangement of extra framework cations within the crystal structure of these minerals.

Mixed Acid-Catalyzed Hydrolysis (MACH) of Waste Distiller's Grains (WDG) for Production of Fermentable Sugar

2013 ◽  
Vol 295-298 ◽  
pp. 1768-1775
Author(s):  
Hai Wei Ren ◽  
Jin Ping Li ◽  
Fei Zhang
Keyword(s):  
Acid Treatment ◽  
Structural Characteristics ◽  
Crystallinity Index ◽  
Reducing Sugar ◽  
Brewing Industry ◽  
Structural Modifications ◽  
Distiller's Grains ◽  
Mixed Acid ◽  
Before And After ◽  
Solid Liquid

Waste distiller's grains (WDG),a co-product of brewing industry, was an abundant source of biomass that could be hydrolyzed to yield fermentation sugar for the production of fuel ethanol. In this study, hydrolysis of WDG using mixed acid as catalysts was examined with the indices of the concentration of reducing sugar and furfural. The structural characteristics of WDG before and after acid treatment were also discussed by means of SEM, FTIR and XRD. The results indicate that there are 59.32gL-1 reducing sugar under the conditions of 100°C, solid-liquid ratio of 1:12 gmL-1, acid concentrations of 2.0% and time of 120 min, with the conversions rate of 77.38% and 62.50% for hemicelluloses and cellulose, respectively. SEM photographs show that the structural modifications after acid treatment are pronounced in comparison to that of WDG, which present a rigid and compact morphology. A lot of large irregular pores with different sizes and shapes are formed and the structures are also severely distorted resulting in the increasing surface exposure and porosity. Instrumental analyses with FTIR and XRD indicate that the strength of characteristic peaks for corresponding typical functional groups of each component are changed compared with the feedstock, and there is an increase of the crystallinity index when WDG is subjected to the MACH treatment.

Child and Adolescent Suicides in Bosnia and Herzegovina Before and After the War (1992–1995)

Crisis ◽  
2010 ◽  
Vol 31 (3) ◽  
pp. 160-164 ◽  
Author(s):  
Almir Fajkic ◽  
Orhan Lepara ◽  
Martin Voracek ◽  
Nestor D. Kapusta ◽  
Thomas Niederkrotenthaler ◽  
...  
Keyword(s):  
Bosnia And Herzegovina ◽  
Age Differences ◽  
Suicide Risk ◽  
Child And Adolescent ◽  
Youth Suicide ◽  
Southeastern Europe ◽  
Suicide Rates ◽  
Before And After ◽  
Sex And Age Differences

Background: Evidence on youth suicides from Southeastern Europe is scarce. We are not aware of previous reports from Bosnia and Herzegovina, which experienced war from 1992 to 1995. Durkheim’s theory of suicide predicts decreased suicide rates in wartime and increased rates afterward. Aims: To compare child and adolescent suicides in Bosnia and Herzegovina before and after the war. Methods: Data on youth suicide for prewar (1986–90) and postwar (2002–06) periods were analyzed with respect to prevalence, sex and age differences, and suicide methods. Suicide data from 1991 through 2001 were not available. Results: Overall youth suicide rates were one-third lower in the postwar than in the prewar period. This effect was most pronounced for girls, whose postwar suicide rates almost halved, and for 15–19-year-old boys, whose rates decreased by about a one-fourth. Suicides increased among boys aged 14 or younger. Firearm suicides almost doubled proportionally and were the predominant postwar method, while the most common prewar method had been hanging. Conclusions: The findings from this study indicate the need for public education in Bosnia and Herzegovina on the role of firearm accessibility in youth suicide and for instructions on safe storage in households. Moreover, raising societal awareness about suicide risk factors and suicide prevention is needed.

The crystal structure of gatehouseite

2011 ◽  
Vol 75 (6) ◽  
pp. 2823-2832
Author(s):  
P. Elliott ◽  
A. Pring
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Three Dimensional ◽  
Direct Methods ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Manganese Phosphate ◽  
Phosphate Mineral ◽  
Unit Formula

AbstractThe crystal structure of the manganese phosphate mineral gatehouseite, ideally Mn52+(PO4)2(OH)4, space group P212121, a = 17.9733(18), b = 5.6916(11), c = 9.130(4) Å, V= 933.9(4) Å3, Z = 4, has been solved by direct methods and refined from single-crystal X-ray diffraction data (T = 293 K) to an R index of 3.76%. Gatehouseite is isostructural with arsenoclasite and with synthetic Mn52+(PO4)2(OH)4. The structure contains five octahedrally coordinated Mn sites, occupied by Mn plus very minor Mg with observed <Mn—O> distances from 2.163 to 2.239 Å. Two tetrahedrally coordinated P sites, occupied by P, Si and As, have <P—O> distances of 1.559 and 1.558 Å. The structure comprises two types of building unit. A strip of edge-sharing Mn(O,OH)6 octahedra, alternately one and two octahedra wide, extends along [010]. Chains of edge- and corner-shared Mn(O,OH)6 octahedra coupled by PO4 tetrahedra extend along [010]. By sharing octahedron and tetrahedron corners, these two units form a dense three-dimensional framework, which is further strengthened by weak hydrogen bonding. Chemical analyses by electron microprobe gave a unit formula of (Mn4.99Mg0.02)Σ5.01(P1.76Si0.07(As0.07)Σ2.03O8(OH)3.97.

Combustion Synthesis and Infrared Characterization of TiB2

2014 ◽  
Vol 602-603 ◽  
pp. 142-145
Author(s):  
Su Li ◽  
Jun Shou Li ◽  
Fang Zhao ◽  
Ming Yuan Wang ◽  
Xiao Juan Wu
Keyword(s):  
Hydrochloric Acid ◽  
Wave Band ◽  
Qualitative And Quantitative Analysis ◽  
Qualitative And Quantitative ◽  
High Temperature Synthesis ◽  
Hexagonal Shape ◽  
Before And After ◽  
Infrared Spectral ◽  
Middle Infrared

On the basis of magnesiothermy, with Mg powder, TiO2 powder and B2O3 powder as mixed reactants, relatively pure TiB2 powder was prepared by self-propagating high temperature synthesis (SHS) after leached in diluted hydrochloric acid with the suitable concentration. The product after leached was examined by XRD for qualitative and quantitative analysis, SEM for morphology analysis and infrared spectroscopy for transmittance analysis. It was found that diluted hydrochloric acid could decrease most of the impurities, and the proportion of TiB2 phase in the product is more than 99%, which was hexagonal shape crystal with the grain size of 200-300 nm. Compare with the infrared spectrogram of the middle infrared spectral region of the product of before and after acid pickling, it was found that the transmittance of TiB2 is extremely low in the range of 2000-4000 cm-1, which can be excellent infrared absorption material in the corresponding wave band.

Application of a Novel Collector DXS in Cassiterite Flotation

2013 ◽  
Vol 826 ◽  
pp. 14-19
Author(s):  
Yi Min Zhu ◽  
Yan Ping Yang ◽  
Wen Dan Wang ◽  
Yan Feng Li ◽  
Duo Zhen Ren ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Carboxylic Acid ◽  
Comparative Study ◽  
Hydroxamic Acid ◽  
Spectroscopy Analysis ◽  
Adsorption Mechanisms ◽  
Before And After ◽  
The Relationship

A comparative study on the collecting effect to cassiterite was studied using a new carboxylic acid modified collector DXS and traditional collector salicylaldehyde hydroxamic acid as collectors, respectively. In addition, the relationship between floatability of DXS and crystal structure of cassiterite was investigated. By means of infrared spectroscopy analysis of the cassiterite surface before and after adsorbing DXS molecules, the adsorption mechanisms of DXS on the surface of cassiterite were analyzed.Keywords: carboxylic acid modified collector DXS; cassiterite; flotation mechanism

THE USE OF POLYSTYRENE–ALLERGEN CONJUGATES FOR THE REMOVAL OF ANTIBODIES FROM SERA OF ALLERGIC INDIVIDUALS

1960 ◽  
Vol 38 (1) ◽  
pp. 1249-1253
Author(s):  
L. Gyenes ◽  
A. H. Sehon
Keyword(s):  
Hydrochloric Acid ◽  
Protein Concentration ◽  
Complete Removal ◽  
Experimental Conditions ◽  
Comparative Analyses ◽  
Before And After

Polystyrene–ragweed conjugates were shown to remove specifically antibodies from sera of individuals allergic to ragweed. This observation is considered evidence that firm combination occurs in vitro between allergic antibodies and the homologous allergens. Comparative analyses of allergic sera before and after exposure to immunosorbents indicated that complete removal of skin-sensitizing, blocking, and hemagglutinating antibodies did not result in a measurable decrease in protein concentration, thus demonstrating that these factors are present only in minute amounts.Attempts to eîute allergic antibodies from the homologous immunosorbents under various experimental conditions did not lead to their recovery in significant yields; these antibodies could be recovered in small amounts by dissociation with hydrochloric acid at pH 3.

Sign in / Sign up

Export Citation Format

Share Document