Reactions between boron and clays

Soil Research ◽  
1964 ◽  
Vol 2 (1) ◽  
pp. 83 ◽  
Author(s):  
FJ Hingston
Keyword(s):  
Boric Acid ◽  
Surface Area ◽  
Total Surface Area ◽  
Langmuir Equation ◽  
Adsorbed Species ◽  
Mannitol Solution ◽  
Clay Surface ◽  
Ph Values ◽  
Area Basis ◽  
Surface Area Basis

Sorption of boron by Kent sand kaolinite, WilIalooka illite, and Marchagee montmorillonite in 0.01M CaCl2 is consistent with a mechanism described by the Langmuir equation, except that deviations occur at solution concentrations greater than about 10 �g B/ml. The quantity of boron adsorbed increases markedly with pH, and is rapid, reversible, and unaffected by the concentration of calcium chloride present. Complete desorption of surface boron, without significant solution of lattice boron, is achieved with 0.01M mannitol solution. Comparing the three clays at pH 7.5 on a surface area basis, the illite is most reactive (1.18 �g B/m2), followed by the kaolinite (0.28 �g B/m2) and the montmorillonite (0.02 �g B/m2). For illite, which is the most reactive of the three minerals, the magnitude of the above values emphasizes the small proportion (less than 1.4%) of the total surface area occupied by boron. Consideration of the reaction between boron and clays suggests that either boric acid molecules or borate ions could be the adsorbed species. Increasing sorption with pH could be explained either by the increasing proportion of borate ions to boric acid with pH or by a greater number of sites on the clay surface at higher pH values.

STUDIES ON THE ADSORPTION OF BORON ON HUMIC ACIDS

1990 ◽  
Vol 70 (3) ◽  
pp. 305-311 ◽  
Author(s):  
BAOHUA GU ◽  
L. E. LOWE
Keyword(s):  
Boric Acid ◽  
Humic Acids ◽  
Organic Matter Content ◽  
Langmuir Adsorption Isotherm ◽  
Matter Content ◽  
Langmuir Equation ◽  
Langmuir Adsorption ◽  
Ph Values ◽  
Ph Range

The adsorption of B, in the form of boric acid, was studied on three precipitated humic acids (HA), representing three distinct soil types. B adsorption by HA was strongly pH-dependent, being low and relatively constant in the pH range 3.0–6.5, increasing markedly up to a peak at near pH 9.5, and then decreasing at still higher pH values. Adsorption isotherms for pH values near 6.7 and 8.8 conformed well to the Langmuir equation. The adsorption maxima (b values), as calculated with the Langmuir equation, ranged from 73 to 207 mmol kg−1 HA at a pH near 8.8, and from 10 to 42 mmol kg−1 at a pH near 6.7. The considerable variation in B adsorption by these HA samples was attributed to "Fe + Al" contents present as contaminants in the HA. The role of HA in B adsorption is expected to be minor in most acid and near neutral soils, but may be of greater significance in soils of high pH and above average organic matter content. Key words: Boron adsorption, boric acid, humic acid, Langmuir adsorption isotherm.

Catalytic Activity and Surface Characterization Study of Pd Supported on Nanocrystalline and Polycrystalline CeO2

1999 ◽  
Vol 581 ◽  
Author(s):  
Gar B. Hoflund ◽  
Zhenhua Li ◽  
Timothy J. Campbell ◽  
William S. Epling ◽  
Horst W. Hahn
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Surface Concentration ◽  
Slow Step ◽  
Activity Increase ◽  
Area Basis ◽  
Surface Area Basis ◽  
Supported Pd

ABSTRACTThe catalytic activity of polycrystalline and nanocrystalline CeO2-supported Pd (Pd/pCeO2 and Pd/nCeO2) has been determined as a function of temperature and Pd loading. While the untreated nCeO2 support gives 50% methane conversion at 420°C, the untreated pCeO2 support exhibits little activity under the conditions examined due to its low surface area. A Pd loading of 5 wt% increases the activity of pCeO2 to 50% conversion at 260°C, while a 40 wt% Pd loading on nCeO2 exhibits a relatively smaller activity increase, yielding 50% conversion at 240°C. On a mass basis the 40 wt% Pd/nCeO2 catalyst is the most active tested in this study, but it is less active than the 5 wt% Pd/pCeO2 catalyst on a surface-area basis. Furthermore, the activity of the 40 wt% Pd/nCeO2 catalyst does not decrease during 100 hrs of exposure to CH4 and O2 at 250°C.X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS) have been used to characterize the surfaces of both bare supports and Pd-containing catalysts before and after exposure to reactor conditions. The XPS results reveal that the Pd surface concentration is more than an order of magnitude higher for 5 wt% Pd/pCeO2 than for 5 wt% Pd/nCeO2 due to the larger surface area of nCeO2 and that the 40 wt% Pd/nCeO2 catalyst has a lower Pd loading on a surface-area basis than the 5 wt% Pd/pCeO2 catalyst. Most of the supported Pd is in the form of PdO, but higher PdO2/PdO ratios are observed for both CeO2 supports compared to Pd supported on ZrO2 or CO3O4. Furthermore, a significant amount of metallic Pd forms on Pd/nCeO2 but not on Pd/pCeO2 during reaction. The nanocrystalline and polycrystalline CeO2 behave differently chemically which is consistent with the fact that the nanocrystalline catalysts are less active on a surface-area basis. Accumulation of H20 on the Pd/pCeO2 surface during reaction is significant but not on the Pd/nCeO2 surface. This suggests that the rate limiting step may be H2O desorption on Pd/pCeO2 while for Pd on nCeO2 adsorption of methane appears to be the slow step. The ISS data indicate that the outermost atomic layer of Pd/nCeO2 consists mostly of O and C, which is not the case for Pd/pCeO2. Site blockage by these species may also contribute to the lower activity on a surface-area basis of Pd/nCeO2 compared to Pd/pCeO2.

scholarly journals The Surface-Area/Body-Weight Relationship in Mice

1967 ◽  
Vol 20 (3) ◽  
pp. 687 ◽  
Author(s):  
NJ Dawson
Keyword(s):  
Body Weight ◽  
Metabolic Rate ◽  
Recent Work ◽  
Surface Area ◽  
Clinical Studies ◽  
Weight Basis ◽  
Weight Relationship ◽  
Area Basis ◽  
History Of ◽  
Surface Area Basis

Since Sarrus and Remeaux (see Kleiber 1961, p. 180) first proposed a "surface law", the measured or calculated surface area of animals has been used by many workers as a basis for comparison between individuals and between species in studies of metabolic rate. The history of the surface law has been discussed by Kayser (1951) and by Kleiber (1961). The DuBois standards for determining the surface area of humans have served for many years as a valuable basis for comparison between individuals in physiological and clinical studies of metabolic rate. However, standards similar to the DuBois standards for humans do not exist for other species. The trend in recent work on metabolic rate of animals appears to be to make comparisons on a body-weight basis rather than on a surface-area basis. The work reported in this paper was designed to investigate the usefulness of surface area as a basis for comparison in some studies on metabolic rate of mice.

scholarly journals A Facile One-Pot Approach to the Synthesis of Gd-Eu Based Metal-Organic Frameworks and Applications to Sensing of Fe3+ and Cr2O72− Ions

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1679
Author(s):  
Roberta Puglisi ◽  
Anna L. Pellegrino ◽  
Roberto Fiorenza ◽  
Salvatore Scirè ◽  
Graziella Malandrino
Keyword(s):  
Surface Area ◽  
Metal Organic Frameworks ◽  
3D Structure ◽  
Inorganic Ions ◽  
Total Surface Area ◽  
One Pot ◽  
Green Approach ◽  
Metal Organic ◽  
Ft Ir ◽  
Xrd Patterns

Gadolinium metal-organic frameworks (Gd-MOFs) and Eu-doped Gd-MOFs have been synthesized through a one-pot green approach using commercially available reagents. The 1,4-benzenedicarboxylic acid (H2-BDC) and 2,6-naphthalenedicarboxylic acid (H2-NDC) were chosen as ditopic organic linkers to build the 3D structure of the network. The Gd-MOFs were characterized using powder X-ray diffraction (XRD), FT-IR spectroscopy, field emission scanning electron microscopy (FE-SEM) and N2 adsorption–desorption analysis. The Gd-MOF structures were attributed comparing the XRD patterns, supported by the FT-IR spectra, with data reported in the literature for Ln-MOFs of similar lanthanide ionic radius. FE-SEM characterization points to the effect of the duration of the synthesis to a more crystalline and organized structure, with grain dimensions increasing upon increasing reaction time. The total surface area of the MOFs has been determined from the application of the Brunauer–Emmett–Teller method. The study allowed us to correlate the processing conditions and ditopic linker dimension to the network surface area. Both Gd-MOF and Eu-doped Gd-MOF have been tested for sensing of the inorganic ions such as Fe3+ and Cr2O72−.

The disposition of benzo(a)pyrene in the periphyton communities of two South Carolina streams: uptake and biotransformation

1982 ◽  
Vol 60 (10) ◽  
pp. 2084-2091 ◽  
Author(s):  
Mary G. Bruno ◽  
Timothy E. Fannin ◽  
Gordon J. Leversee
Keyword(s):  
South Carolina ◽  
Slide Surface ◽  
Uptake Rates ◽  
Area Basis ◽  
Autoradiographic Analysis ◽  
Colonization Time ◽  
Microscope Slides ◽  
Surface Area Basis ◽  
Glass Microscope ◽  
Sheath Material

The effect of periphyton community composition and colonization time on the uptake and biotransformation of benzo(a)pyrene (BaP) was determined in laboratory studies. Naturally colonized glass microscope slides were collected after 3 and 6 weeks from Castor Creek, which has a predominantly desmid flora, and after 3 and 5 weeks from diatom-dominated Upper Three Runs Creek. When expressed on a slide surface-area basis, the Castor Creek periphyton showed significantly greater BaP uptake rates at both colonization periods. Within streams, uptake rates increased significantly with colonization time. Autoradiographic analysis suggests that BaP was accumulated by surface sorption, especially to gelatinous sheath material. Active biotransformation as measured by the percentage extractable non-BaP 14C was not detected in either community.

NSAM-derived total surface area versus SMPS-derived “mobility equivalent” surface area for different environmentally relevant aerosols

2013 ◽  
Vol 66 ◽  
pp. 1-11 ◽  
Author(s):  
Megat-Azman Mokhtar ◽  
Rohan Jayaratne ◽  
Lidia Morawska ◽  
Mandana Mazaheri ◽  
Nic Surawski ◽  
...  
Keyword(s):  
Surface Area ◽  
Total Surface Area

In-situ Mössbauer effect spectroscopy of adsorbed species on high surface area electrodes

1982 ◽  
Vol 10 (3) ◽  
pp. 325-332 ◽  
Author(s):  
D. Scherson ◽  
S.B. Yao ◽  
E.B. Yeager ◽  
J. Eldridge ◽  
M.E. Kordesch ◽  
...  
Keyword(s):  
Surface Area ◽  
Mössbauer Effect ◽  
High Surface ◽  
High Surface Area ◽  
Mossbauer Effect ◽  
Adsorbed Species ◽  
Mössbauer Effect Spectroscopy

scholarly journals Regularities of Variation of the Red Blood Indices Characterizing the Respiratory Function of Blood in Selected Fish

2011 ◽  
Vol 56 (1-4) ◽  
pp. 35-48 ◽  
Author(s):  
Sebastian Maciak ◽  
Alina Kostelecka-Myrcha
Keyword(s):  
Surface Area ◽  
Oxygen Transport ◽  
Respiratory Function ◽  
Hemoglobin Concentration ◽  
Total Surface Area ◽  
Great Variability ◽  
Blood Indices ◽  
Erythrocyte Surface ◽  
Area Unit ◽  
Counter Current

Regularities of Variation of the Red Blood Indices Characterizing the Respiratory Function of Blood in Selected FishThere is a large diversity of red blood indices determining oxygen transport ability in vertebrates. In fish this diversity is particularly large, probably due to the great variability in water environments, which impedes the possibility of finding and understanding general patterns. It has been assumed that in mammals, the measure determining the ability of a blood unit to transport oxygen is the ratio of hemoglobin concentration (HB) and total erythrocyte surface area (TSAE). It was also shown that both in mammals and birds the amount of hemoglobin per total surface area unit (Hb/TSAE) conditions maximum use of respiratory pigment in oxygen transport, in different physiological and environmental conditions. In order to check whether this regularity occurs in fish, red blood indices were analyzed in seven species of freshwater fish, differing noticeably in their biology and body mass in two seasons of the year. Notwithstanding this marked seasonal variability to the component variables together determining the total surface area of erythrocytes, the value for TSAE was found to differ in proportion to the higher or lower concentrations of HB. In consequence, the HB/TSAE ratio indicative of the maximal use of haemoglobin in the transport of oxygen was constant in all of the fish studied between analyzed seasons. This constancy - resembling that to be noted in birds - is most probably related to the counter-current gaseous exchange ongoing in the gills of fish.

Transport of Particle-Laden Fluids Through Fixed-Valve Micropumps

1999 ◽  
Author(s):  
Ling-Sheng Jang ◽  
Christopher J. Morris ◽  
Nigel R. Sharma ◽  
Ron L. Bardell ◽  
Fred K. Forster
Keyword(s):  
Surface Charge ◽  
Surface Area ◽  
Flow Rate ◽  
Pure Water ◽  
Maximum Flow ◽  
Total Surface Area ◽  
Maximum Flow Rate ◽  
Number Density ◽  
Polystyrene Microspheres ◽  
Negative Surface

Abstract Micropumps designed for the flow-rate range of 100–1000μl/min have been developed by a number of research groups. However, little data is available regarding the ability of various designs to directly transport liquids containing particles such as cells, microspheres utilized for bead chemistry, or contaminants. In this study the ability of pumps with no-moving-parts valves (NMPV) to transport particles was investigated. The results showed that a NMPV micropump was able to directly pump suspensions of polystyrene microspheres from 3.1 to 20.3μm in diameter. The pump functioned without clogging at microsphere number densities as high as 9000 particles/μl of suspension, which corresponded to over 90,000 particles per second passing through the pump at a flow rate of 600μl/min. Performance with polystyrene microspheres was the same as pure water up to the point of cavitation. Microspheres manufactured with negative surface charge cavitated less readily that other microspheres studied that were manufactured without surface charge. However, cavitation did not appear to be a function of microsphere size, total surface area or number density. Thus pumping polystyrene microspheres was found to be more affected by surface effects than by size, surface area or number density within the range of parameters considered. In the case of charged microspheres, the maximum flow rate was reduced by 30% compared to pure water whereas for uncharged microspheres the maximum flow rate was reduced by approximately 80%.

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