scholarly journals Kinetics of proton transfer in the zeolitic tuff

2009 ◽  
Vol 7 (3) ◽  
pp. 508-511
Author(s):  
Fehime Çakıcıoğlu-Özkan ◽  
İlker Polatoğlu
Keyword(s):  
Particle Size ◽  
Proton Transfer ◽  
Size Fraction ◽  
Proton Transfer Reaction ◽  
Reaction Model ◽  
Zeolitic Tuff ◽  
Particle Size Fractions ◽  
Model Equations ◽  
Kinetics Of ◽  
And Diffusion

AbstractThe kinetics of a proton transfer into dilute acid solutions containing natural zeolitic tuff was studied by following the pH evolution of the liquid phase. Four different solutions with tuff contents of 9, 3, 1 and 0.5 (% wt) and three different particle size fractions (≤ 2000 μm) were studied. The proton concentration of the solution was decreased by increasing the zeolite amount and decreasing the particle size fraction. The proton transfer reaction was analyzed with chemical reactions and diffusion model equations. Analysis shows that the adsorption and/or ion exchange are possible mechanisms and are expressed by a second order reaction model.

scholarly journals Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland. III. Distribution and kinetics of soil organic carbon in particle size fractions

Soil Research ◽  
1986 ◽  
Vol 24 (2) ◽  
pp. 293 ◽  
Author(s):  
RC Dalal ◽  
RJ Mayer
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Size Fraction ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Clay Size Fraction ◽  
Sand Size

Distribution of soil organic carbon in sand-, silt- and clay-size fractions during cultivation for periods ranging from 20 to 70 years was studied in six major soils used for cereal cropping in southern Queensland. Particle-size fractions were obtained by dispersion in water using cation exchange resin, sieving and sedimentation. In the soils' virgin state no single particle-size fraction was found to be consistently enriched as compared to the whole soil in organic C in all six soils, although the largest proportion (48%) of organic C was in the clay-size fraction; silt and sand-size fractions contained remaining organic C in equal amounts. Upon cultivation, the amounts of organic C declined from all particle-size fractions in most soils, although the loss rates differed considerably among different fractions and from the whole soil. The proportion of the sand-size fraction declined rapidly (from 26% to 12% overall), whereas that of the clay-size fraction increased from 48% to 61% overall. The proportion of silt-size organic C was least affected by cultivation in most soils. It was inferred, therefore, that the sand-size organic matter is rapidly lost from soil, through mineralization as well as disintegration into silt-size and clay-size fractions, and that the clay fraction provides protection for the soil organic matter against microbial and enzymic degradation.

scholarly journals Effect of Soil Washing Using Oxalic Acid on Arsenic Speciation and Bioaccessibility in Soils

2020 ◽  
Vol 42 (4) ◽  
pp. 218-227
Author(s):  
Yeseul Gwon ◽  
Seong Ryeol Kim ◽  
Eun Jung Kim
Keyword(s):  
Particle Size ◽  
Oxalic Acid ◽  
Contaminated Soil ◽  
Arsenic Speciation ◽  
Arsenic Concentration ◽  
Size Fraction ◽  
Soil Washing ◽  
Large Particle Size ◽  
Amorphous Oxides ◽  
Particle Size Fractions

Objectives : Soil washing process has been widely applied for remediation of contaminated soil with arsenic and heavy metals in Korea. The application of soil washing could change physical and chemical properties of soils and metal speciation in soil, which could affect the risk to the environment and human health. Thus, it is necessary to evaluate metal and arsenic speciation and their mobility in soil after soil remediation in order to evaluate effectiveness of soil remediation process and manage soil quality effectively. The purpose of this study is to evaluate the risk of arsenic in soil after remediation of arsenic contaminated soil via soil washing.Methods : Arsenic contaminated soil collected at the abandoned mine site was washing with oxalic acid. The arsenic contaminated soil was divided into 2,000-500 µm, 500-250 µm, 250-150 µm, 150-75 µm, 75-38 µm, < 38 µm particle size fractions. After soil washing for each soil particle size fraction, arsenic speciation via sequential extraction and bioaccessibility in the soils were evaluated. Results and Discussion : Generally, arsenic and metal concentrations were higher in the soil fractions with smaller particle sizes. But high arsenic concentration was observed at the large particle size fractions (>250 µm), which might be due to the presence of mineral phases containing arsenic such as arsenolite or pyrite in the large particle size fraction soils. Sequential extraction showed that arsenic in mine soils was majorly present as associated with amorphous oxides. After soil washing with oxalic acid, arsenic in soils associated with amorphous oxides was greatly decreased, whereas the arsenic fraction associated sulfide and organic matter was increased. Soil washing decreased the bioaccessible arsenic concentration (mg/kg) in soil, but increased the bioaccessibility (%) depending on the soil characteristics. Conclusions : Soil washing changed arsenic species in soils, which affected mobility and risk of arsenic in soil.

X-ray diffraction measurement of the quartz content of clay and silt fractions in soils

Clay Minerals ◽  
1992 ◽  
Vol 27 (1) ◽  
pp. 47-55 ◽  
Author(s):  
M. Hardy
Keyword(s):  
Particle Size ◽  
Size Fraction ◽  
Internal Standard ◽  
Diffraction Measurement ◽  
Particle Sizes ◽  
Quartz Content ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Calibration Curves ◽  
Fine Quartz

AbstractAn XRD method for measurement of quartz content using ZnO as the internal standard was tested on different particle sizes between 0 and 20 µm. Calibration curves showed a good correlation coefficient for particle-size fractions up to 20 µm; the slope increased for the fractions from 0·7 to 5 µm and was relatively constant for coarser particle sizes. Fine quartz fractions were etched with hydrofluoric acid to remove the surface layer damaged during dry grinding. The use of such etched quartz increased the slopes of the calibration curves for small particle-size fractions and approximated the natural fine quartz fraction much better than the original dry-ground material. The mean of six measurements gave good accuracy provided that the slope of the calibration curve was adjusted for the particular particle-size fraction. This method was used on 0–2 µm, 0–0·2µm and 0·2–2 µm fractions of French silty soils and the results are in agreement with the data from chemical analysis and with the mineralogical interpretation.

ÉTUDE COMPARATIVE DE L'AGRÉGATION ET DE LA MATIÈRE ORGANIQUE ASSOCIÉE AUX FRACTIONS GRANULOMÉTRIQUES DE SEPT SOLS SOUS CULTURE DE MAÏS OU EN PRAIRIE

1990 ◽  
Vol 70 (3) ◽  
pp. 395-402 ◽  
Author(s):  
J. ELUSTONDO ◽  
M. R. LAVERDIÈRE ◽  
D. A. ANGERS ◽  
A. N'DAYEGAMIYE
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Size Fraction ◽  
Cropping System ◽  
Clay Content ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Carbon And Nitrogen ◽  
Water Stable Aggregates ◽  
Continuous Corn

Water-stable aggregation and organic matter associated with particle-size fractions were compared for seven pairs of soils that were either under meadow or continuous corn cropping for more than 5 yr. Soils that have remained under meadow contained 25 and 29% more carbon and nitrogen than those under continuous corn. Carbon contents of the sand- and silt-size fractions were also 61 and 15% higher, respectively, under meadow than under continuous corn. The cropping system had no significant effect on the carbon and nitrogen contents of the clay-size fractions. The amount of water-stable aggregates (> 1 mm) was on average 34% higher in soils under meadow than in soils under corn cropping. Significant correlations were found between water-stable aggregates and total C (r = 0.77) and C in sand-size fraction (r = 0.79). The results also indicate that the beneficial effect of meadow over continuous corn on soil aggregation increases as soil clay content increases. Key words: Aggregation, organic matter, particle-size fractions, corn, meadow

Crystallization kinetics of cerium oxide nanoparticles formed by spontaneous, room-temperature hydrolysis of cerium(iv) ammonium nitrate in light and heavy water

2017 ◽  
Vol 19 (5) ◽  
pp. 3523-3531 ◽  
Author(s):  
Natasha W. Pettinger ◽  
Robert E. A. Williams ◽  
Jinquan Chen ◽  
Bern Kohler
Keyword(s):  
Proton Transfer ◽  
Heavy Water ◽  
Room Temperature ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Cerium Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Cerium Iv Ammonium Nitrate

Ceria nanocrystals form tenfold more slowly in D2O vs. H2O, revealing a rate-determining proton transfer reaction and a non-classical crystallization mechanism.

scholarly journals Influence mechanism of excipients on drug crystallization: experimental investigation and model analysis and prediction

2022 ◽  
Author(s):  
Qiao Chen ◽  
Jingyun Weng ◽  
Gabriele Sadowski ◽  
Yuanhui Ji
Keyword(s):  
Crystal Growth ◽  
Growth Kinetics ◽  
Surface Reaction ◽  
Chemical Potential ◽  
Potential Gradient ◽  
Reaction Model ◽  
Reaction Rate Constant ◽  
Crystal Growth Kinetics ◽  
Kinetics Of ◽  
And Diffusion

The influence of temperature, stirring speed, and excipients on crystal growth kinetics of mesalazine and allopurinol was investigated through experiment and chemical potential gradient model. The results indicated that the Diffusion-Surface Reaction model (DSR (1,2)) showed good performance in modeling API crystal growth kinetics within the ARDs of 4%. Excipients played a crucial role in inhibiting crystal growth in all the systems. It can not only improve the API solubility, but also reduce the crystal growth rate. By comparing diffusion rate and surface-reaction rate constant within the DSR (1,2) model, it was found that the controlling step of mesalazine crystallization was surface-reaction. Allopurinol crystallization was dominated by both surface-reaction and diffusion. Meanwhile, the crystal growth kinetics of mesalazine and allopurinol were predicted successfully with the ARDs of 2.53% and 4.78%. This work provided a mechanistic understanding of polymer influence on the inhibition of API crystal growth.

Sorption Kinetics of Non-Ionic Organic Pollutants Onto Suspended Sediments

1991 ◽  
Vol 23 (1-3) ◽  
pp. 447-454 ◽  
Author(s):  
H. M. Liljestrand ◽  
Y. D. Lee
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Experimental Studies ◽  
Size Fraction ◽  
Organic Matter Content ◽  
Suspended Sediments ◽  
Spherical Particles ◽  
Particle Model ◽  
Desorption Kinetics ◽  
Kinetics Of

The results of controlled batch experimental studies of the adsorption and desorption kinetics of dichlorobenzene to 1) size fractionated, washed sediments, 2) aggregate, washed sediment, 3) dissolved/colloidal sediment materials, and 4) bulk sediments,are used to determine the effect of inhomogeneous mixtures on the overall sorption rates. The size-segregated sediments are modeled as spherical particles with a porous outer shell of organic matter for sorption and an inert, inorganic core. The characteristic times of intraparticle diffusive transport are found to vary with particle size by about two orders of magnitude. The distribution of natural organic matter content with particle size results in sorption rates which differ greatly from that predicted by the monodisperse, homogeneous particle model. Coupled, reversible reactions between the solute and each solid size fraction are presented as a conceptual model for the interpretation of the empirical results of batch experiments.

Picosecond kinetics of the excited-state, proton-transfer reaction of 1-naphthol in water

1986 ◽  
Vol 90 (21) ◽  
pp. 5154-5164 ◽  
Author(s):  
S. P. Webb ◽  
Laura A. Philips ◽  
Sheila W. Yeh ◽  
Laren M. Tolbert ◽  
J. H. Clark
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Excited State Proton Transfer ◽  
Kinetics Of

Potential for using soil particle-size data to infer geological parent material in the Sydney Region

Soil Research ◽  
2013 ◽  
Vol 51 (4) ◽  
pp. 301 ◽  
Author(s):  
Margaret R. Donald ◽  
Pamela A. Hazelton ◽  
AnneMarie Clements
Keyword(s):  
Particle Size ◽  
Soil Sample ◽  
Soil Texture ◽  
Compositional Data ◽  
Size Fraction ◽  
Parent Material ◽  
Ecological Communities ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Statistical Classifiers

Ecological communities are more than assemblages of species. In assessing the presence of many ecological communities, interpretation of soil properties and associated parent material has become a definitive component under environmental legislation worldwide, and particularly in Australia. The hypothesis tested here is that the geological parent material of a soil sample can be determined from particle size fraction data of the Marshall soil texture diagram. Supervised statistical classifiers were built from data for four particle-size fractions from four soil landscape publications. These methods were modified by taking into account possible autocorrelation between samples from the same site. The soil samples could not be classified with certainty as being derived from Wianamatta Group Shale or Hawkesbury Sandstone parent material. The classification of alluvial/fluvial-derived soils was no better than chance alone. A good classifier using four-fraction compositional data could not be built to determine geological parent material. Hence, the three size fractions of the Marshall soil texture diagram are insufficient to determine the geological parent material of a soil sample.

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