Adsorption Properties of ZSM-5 Zeolites

1998 ◽  
Vol 63 (2) ◽  
pp. 141-154 ◽  
Author(s):  
Pavol Hudec ◽  
Agáta Smiešková ◽  
Zdenek Židek ◽  
Milan Zúbek ◽  
Petr Schneider ◽  
...  
Keyword(s):  
Crystal Size ◽  
Physical Adsorption ◽  
Hysteresis Loops ◽  
Low Pressure ◽  
Adsorption Properties ◽  
Relative Pressure ◽  
Small Crystals ◽  
Bet Method ◽  
Adsorption Of Nitrogen ◽  
Microporous Solids

Adsorption properties determined by physical adsorption of nitrogen for a series of ZSM-5 zeolite samples with various Si/Al ratios and different crystal size were compared. In addition to the BET method, the t-plot method was used to determine the microporosity of samples. Very small crystals of ZSM-5 zeolites, generally below 1 μm, with Si/Al ratio between 14 and 21 exhibit adsorption isotherms typical for purely microporous solids. Samples with Si/Al ratios larger than (about) 95 show low-pressure steps and hysteresis loops and, depending on crystal morphology, also high-pressure hysteresis loops. The low-pressure steps were associated with steps on t-plots which showed two linear parts. Small increase of adsorption up to relative pressure 0.2 is characteristic for samples with Si/Al ratios between 25 and 50.

Possibilities of determining the polymodal pore-size distribution from physical adsorption of nitrogen

1987 ◽  
Vol 52 (5) ◽  
pp. 1160-1166
Author(s):  
Dagmar Tomanová ◽  
Petr Schneider
Keyword(s):  
Pore Size ◽  
Size Distribution ◽  
Physical Adsorption ◽  
Relative Pressure ◽  
Size Distributions ◽  
Porous Sample ◽  
Fine Grained ◽  
Mesopore Size Distribution ◽  
Pore Size Distributions ◽  
Adsorption Of Nitrogen

It is shown, on the basis of experimentally determined adsorption isotherms of physical adsorption of nitrogen on two- and three-component mixtures of fine grained porous glasses with narrow pore-size distributions, that the polymodal mesopore-size distribution curves can be evaluated in case that the porous sample contains groups of mesopores differing rather significantly in size. The differentiation of groups of pores gets worse with wider pores where the demands on the accuracy of the relative pressure measurement grow stronger.

Evaluation of Bentonite Clay Type in the Chocobofe Zinc Adsorption in Finite Bath System

2015 ◽  
Vol 820 ◽  
pp. 539-544
Author(s):  
J.V. do N. Silva ◽  
Janaína Rafaella Scheibler ◽  
M.G.F. Rodrigues
Keyword(s):  
Physical Adsorption ◽  
Bentonite Clay ◽  
Exchange Capacity ◽  
X Ray Diffraction ◽  
Promising Alternative ◽  
X Ray ◽  
Smectite Clays ◽  
Bet Method ◽  
Adsorption Of Nitrogen ◽  
Percentage Removal

In this work the smectite clays Chocobofe from the state of Paraíba was investigated to evaluate their affinity and capacity for removal of zinc using a finite bath system. The clay was characterized by means of X-Ray Diffraction (XRD), Infrared Spectroscopy in the Region (IV) and Cation Exchange Capacity (CEC) and Physical Adsorption of Nitrogen (BET method). A 22 factorial design was conducted with three center points in a finite bath system to determine the percentage removal (% Rem) and removability (qeq) of the clay. Values of 83.35 to 98.83% and the percentage removal from 3.83 to 4.24 mg / g removal were achieved in experiments, indicating that the use of clay Chocobofe appears as a promising alternative to remove of Zn2+

scholarly journals Fabrics of Icing-Mound and Pingo Ice in Permafrost

1978 ◽  
Vol 20 (84) ◽  
pp. 563-569 ◽  
Author(s):  
W. Alan Gell
Keyword(s):  
Active Layer ◽  
Crystal Size ◽  
Early Growth ◽  
Bulk Water ◽  
Freezing Rate ◽  
Lattice Orientation ◽  
Small Crystals ◽  
Freezing Direction

Abstract Crystallization histories of some ice layers in permafrost are inferred from crystal size, shape, dimensional and lattice orientation, and inclusion patterns. In an icing mound, formed by injection of water beneath frozen active-layer soil, early growth was rapid, indicated by copious small crystals and bubbles, followed by slower growth giving rise to crystals and bubbles elongate parallel to the freezing direction, c-axes were normal to crystal long axes. In a small pingo, bulk water existed temporarily at the freezing interface and freezing was unidirectional. In a larger pingo, variations in freezing rate were inferred. Later flow of ice modifies growth fabrics.

Crystal size distribution of benzoic acid at its crystallization from the bulk of vapour phase

1979 ◽  
Vol 44 (7) ◽  
pp. 2165-2172 ◽  
Author(s):  
Jaroslav Vítovec ◽  
Jiří Smolík ◽  
Josef Kugler
Keyword(s):  
Benzoic Acid ◽  
Cooling Rate ◽  
Size Distribution ◽  
Crystal Size ◽  
Vapour Phase ◽  
Crystal Size Distribution ◽  
Water Dispersion ◽  
Small Crystals ◽  
Permeable Walls

Crystal size and their distribution were measured in the crystallizer with gas-permeable walls, at crystallization of benzoic acid vapours from the bulk of vapour phase in the mixture with nitrogen in dependence on concentration (in range from 1.1 to 23 vol.%), temperature (401 to 473 K) and velocity of mixture (0.5 to 6.6 cm/s). At small cooling rate of the mixture the vapours of benzoic acid are condensing in the form of droplets which at continuing cooling solidify. At cooling of the mixture by water dispersion create the needle-shaped crystals. The effect of concentration, temperature and velocity is not profound obviously because by evaporation of water is the mixture rapidly cooled and supersaturated. This results in creation of a large amount of crystal nuclei and thus also of small crystals.

Synthesis And Water Sorption Properties Of Aluminophosphate (AlPO4) And Silicoaluminophosphate (Sapo) Molecular Sieves

1991 ◽  
Vol 233 ◽  
Author(s):  
P. B. Malla ◽  
S. Komarneni
Keyword(s):  
Molecular Sieves ◽  
Water Sorption ◽  
Hysteresis Loops ◽  
Sorption Isotherms ◽  
Cooperative Interaction ◽  
Type I ◽  
Relative Pressure ◽  
Micropore Filling ◽  
General Expectation ◽  
Initial Adsorption

ABSTRACTAluminophosphate (AlPO4–5, AlPO4–11, AlPO4–17, AlPO4–20) and silicoaluminophosphate (SAPO-5, SAPO- 11, SAPO-17, SAPO-20) molecular sieves of varying pore sizes (3–8 Å) were synthesized and their water adsorption and desorption properties were studied. Water sorption isotherms of AlPO4 molecular sieves were characterized by unusual isotherm shapes, that is, little or no initial adsorption followed by extreme adsorption leading to volume filling by hydrogen bonding and cooperative interaction in micropores, apparently due to the nonpolar nature of pore surfaces coupled with weak (reversible upon evacuation) chemisorption of water, and hysteresis loops extending to very low pressures. Although micropore filling in AlPO2's and isostructural SAPO's was completed almost at the same relative pressure (p/po), SAPO's exhibited less extreme adsorption isotherms as a result of their slightly more polar nature of pore surfaces compared to AlPO4's. Neither AlPO4apos;s nor SAPO's exhibited Brunauer Type I isotherms with water, contrary to a general expectation of the hydrophilic microporous solids.

Study on Adsorption Characteristics of Klebsiella Biological Adsorbent to Leaded Wastewater

2014 ◽  
Vol 926-930 ◽  
pp. 4353-4356
Author(s):  
Jing Zhao ◽  
Xiao Jun Xu ◽  
Qiang Zhan ◽  
Xuan Li ◽  
Shu Li Liu ◽  
...  
Keyword(s):  
Physical Adsorption ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Adsorption Properties ◽  
Amide Group ◽  
Langmuir Isotherm Model ◽  
Ft Ir ◽  
Resistant Strains ◽  
Main Component

A lead-resistant strains was isolated from activated sludge of the sewage treatment plant in Chenggong County, Kunming, which was identified as Klebsiella by 16 SrDNA. The wet microbial cells were used as adsorbent, we studied adsorption properties for water Pb (II) ions in water of sorbent. The results showed that when the adsorbent treated the waste water with Pb (II) ions, the pH was 5, the time was 60min, the temperature was 30°C, the equilibrium adsorption amount was 73.45mg/g; Adsorbent’s adsorption of Pb (II) ions can better fit Langmuir isotherm model. The FT-IR result presented that the main component of adsorbent was polysaccharide, the physical adsorption and chemisorption occurred between the adsorbent and the Pb (II) ions in the solution, adsorption mainly involved with hydroxyl functional groups, the amide group and the carboxyl group, etc.

RELATION OF pH TO DRIP FORMATION IN MEAT

1938 ◽  
Vol 16d (9) ◽  
pp. 255-267 ◽  
Author(s):  
L. Sair ◽  
W. H. Cook
Keyword(s):  
Crystal Size ◽  
Protein Denaturation ◽  
Maximum Amount ◽  
The Other ◽  
Absorptive Power ◽  
Small Crystals ◽  
Constant Rate ◽  
Quick Freezing ◽  
Frozen Tissue ◽  
Two Factors

The quantity of drip obtained from meat frozen at a constant rate is affected by the period between slaughter and freezing, and the pH of the tissue. These two factors appear to act independently, and only the latter was studied extensively. In precooled meats the maximum amount of drip was obtained at about pH 5.2, and as the pH increased the net drip decreased to zero at about pH 6.4. Pork, beef and mutton behave similarly both with respect to the form of the drip-pH relation and the quantity of drip exuded at a given acidity. Beef is normally more acid than the other meats tested, and this can account for its greater tendency to drip in commercial practice.Microscopic studies showed that large crystals were always produced by slow-freezing, regardless of the pH of the material. The absence of drip from slowly frozen tissue at pH 6.4 is therefore not due to crystal size, but must be attributed to the greater re-absorbing power of the proteins in this region. Protein denaturation does not affect the quantity of drip obtained when meat is slowly frozen or stored for periods up to three days in the freezing zone. The weak re-absorptive power of the proteins at pH 5.2 must be attributed to their isoelectric condition in this region, rather than to their denaturation. It is only in this isoelectric region that the production of small crystals by quick-freezing will reduce the quantity of drip.

Sign in / Sign up

Export Citation Format

Share Document