Mesophyll surface area as measured by physical adsorption of nitrogen: the case of wheat

2000 ◽  
Vol 28 (1-2) ◽  
pp. 139-145 ◽  
Author(s):  
Roberto R. Filgueira ◽  
Silvina I. Golik ◽  
Guillermo O. Sarli ◽  
Jaime R. Jatimliansky ◽  
Santiago J. Sarandón
Keyword(s):  
Surface Area ◽  
Physical Adsorption ◽  
Adsorption Of Nitrogen ◽  
Mesophyll Surface Area

scholarly journals Band Engineering and Morphology Control of Oxygen-Incorporated Graphitic Carbon Nitride Porous Nanosheets for Highly Efficient Photocatalytic Hydrogen Evolution

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Yunyan Wu ◽  
Pan Xiong ◽  
Jianchun Wu ◽  
Zengliang Huang ◽  
Jingwen Sun ◽  
...  
Keyword(s):  
Surface Area ◽  
Hydrogen Evolution ◽  
Carbon Nitride ◽  
Separation Efficiency ◽  
Physical Adsorption ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Photocatalytic Hydrogen Evolution ◽  
Band Engineering ◽  
Highly Efficient

AbstractGraphitic carbon nitride (g-C3N4)-based photocatalysts have shown great potential in the splitting of water. However, the intrinsic drawbacks of g-C3N4, such as low surface area, poor diffusion, and charge separation efficiency, remain as the bottleneck to achieve highly efficient hydrogen evolution. Here, a hollow oxygen-incorporated g-C3N4 nanosheet (OCN) with an improved surface area of 148.5 m2 g−1 is fabricated by the multiple thermal treatments under the N2/O2 atmosphere, wherein the C–O bonds are formed through two ways of physical adsorption and doping. The physical characterization and theoretical calculation indicate that the O-adsorption can promote the generation of defects, leading to the formation of hollow morphology, while the O-doping results in reduced band gap of g-C3N4. The optimized OCN shows an excellent photocatalytic hydrogen evolution activity of 3519.6 μmol g−1 h−1 for ~ 20 h, which is over four times higher than that of g-C3N4 (850.1 μmol g−1 h−1) and outperforms most of the reported g-C3N4 catalysts.

scholarly journals Synthesis of Zeolite-A and Zeolite-Y Using Silica Gel Waste as Silica Source and Modifying with Fe

2018 ◽  
Vol 7 (4.38) ◽  
pp. 1376
Author(s):  
Pornnipa Khaosomboon ◽  
Kulyakorn Khuanmar ◽  
Panomchai Weerayutsil
Keyword(s):  
Surface Area ◽  
Silica Gel ◽  
Zeolite Y ◽  
Physical Adsorption ◽  
Lower Surface ◽  
Zeolite A ◽  
Silica Source ◽  
Bet Specific Surface Area ◽  
Silica Gel Waste ◽  
Modified Zeolites

The purpose of this research was to synthesize zeolite-A (Ze-A) and zeolite-Y (Ze-Y) using silica sources from silica gel waste, and also improving adsorption capacity with Fe which was trapped in the synthesized zeolites:  Ze-Fe-A and Ze-Fe-Y. All synthesized zeolites were tested with lead solution of 40 mg/L at pH 5. For BET specific surface area, the parent Ze-A and Ze-Y presented surface area of 27.02 and 211.42 m2/g, respectively, whereas Ze-Fe-A and Ze-Fe-Y presented a lower surface area of 10.90 and 28.22 m2/g, respectively. SEM and TEM image demonstrated the cubic and polygon shapes for Ze-A and Ze-Y, respectively, while their modification with Fe presented more round shape. Additionally, both modified zeolites with Fe presented higher adsorption efficiency than their parents. Although the modified zeolites gave lower surface area, the efficiency removal of lead showed higher capacity than zeolite without Fe. It could be concluded that the adsorption mechanism of modified zeolites did not only rely on physical adsorption, but also on chemical adsorption.      

Studies on the surface area of zeolites, as determined by physical adsorption and X-ray crystallography

1968 ◽  
Vol 46 (10) ◽  
pp. 1695-1701 ◽  
Author(s):  
D. J. C. Yates
Keyword(s):  
Surface Area ◽  
Physical Adsorption ◽  
Independent Method ◽  
Linear Portion ◽  
Adsorbed Molecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Surface Areas

The determination of the surface areas of zeolites is discussed. It is shown that it is incorrect to use the multilayer isotherm method of Brunauer, Emmett, and Teller for solids where only little more than one monolayer can be adsorbed, in cavities little larger than the adsorbed molecules. The areas of such materials can, however, be determined from the beginning of the linear portion of their isotherms (point B). In addition, X-ray spectra can provide an independent method of measuring changes in the surface areas of zeolites.

scholarly journals Preparation of Composite Monolith Supercapacitor Electrode Made from Textile-Grade Polyacrylonitrile Fibers and Phenolic Resin

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 655
Author(s):  
Karim Nabil ◽  
Nabil Abdelmonem ◽  
Masanobu Nogami ◽  
Ibrahim Ismail
Keyword(s):  
Electrical Resistivity ◽  
Surface Area ◽  
Phenolic Resin ◽  
Physical Adsorption ◽  
Chemical Activation ◽  
Specific Capacity ◽  
Physical Activation ◽  
Gravimetric Analysis ◽  
Capacitive Properties

In this work a composite monolith was prepared from widely available and cost effective raw materials, textile-grade polyacrylonitrile (PAN) fibers and phenolic resin. Two activation procedures (physical and chemical) were used to increase the surface area of the produced carbon electrode. Characterization of the thermally stabilized fibers produced was made using differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and Carbon-Hydrogen-Nitrogen(CHN) elemental analysis, in order to choose the optimum conditions of producing the stabilized fibers. Characterization of the produced composite monolith electrode was performed using physical adsorption of nitrogen at 77 °K, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrical resistivity in order to evaluate its performance. All the electrodes prepared had a mixture of micropores and mesopores. Pressing the green monolith during the curing process was found to reduce largely the specific surface area and to some degree the electrical resistivity of the chemically activated composite electrode. Physical activation was more suitable than chemical activation, where it resulted in an electrode with specific capacity 29 F/g, good capacitive behavior and the stability of the electrical resistivity over the temperature range −130 to 80 °C. Chemical activation resulted in a very poor electrode with resistive rather than capacitive properties.

scholarly journals Sorption and Diffusion Properties of H- and Modified Forms of ZSM-5 Zeolites

1996 ◽  
Vol 13 (6) ◽  
pp. 495-508 ◽  
Author(s):  
P. Hudek ◽  
D. Bobok ◽  
A. Smiešková ◽  
Z. Židek
Keyword(s):  
Physical Adsorption ◽  
Gravimetric Method ◽  
Equilibrium Concentration ◽  
Sorption Isotherms ◽  
Effective Diffusivity ◽  
Micropore Volume ◽  
Unit Cell ◽  
Adsorption Of Nitrogen ◽  
Effective Diffusivities ◽  
Modified Forms

The sorption properties of samples of H-ZSM-5 zeolite and their forms modified with P, B and Mg were determined by the physical adsorption of nitrogen and evaluated by BET isotherm and t-plot methods. The diffusivities of the samples were measured using a new flow gravimetric method involving the sorption of p- and o-xylenes. The BET specific surface area decreased from 358 m2/g to 35–90 m2/g mainly because of a decrease in micropore volume as determined by the t-plot method. The rate of sorption of p-xylene on all the samples investigated followed Fick's second law of diffusion, leading to an effective diffusivity of ca. 1.7 × 10−11 m2/s, irrespective of whether the H-form or the modified forms were investigated. The sorption isotherms for o-xylene showed some unusual steps. Values for the effective diffusivities decreased from 2.6 × 10−12 m2/s for the H-form to 2.0–2.3 × 10−12 m2/s for the modified forms. The equilibrium concentration of o-xylene at P/P0 = 0.1 was only 0.38–0.68 mol/unit cell, while that of p-xylene was 4.40–5.98 mol/unit cell.

Potential Evaluation of Gray Clay as Adsorbent of Heavy Metals Zinc (II) and Lead (II)

2014 ◽  
Vol 798-799 ◽  
pp. 622-627
Author(s):  
Wellington Siqueira Lima ◽  
José Vanderley Nascimento Silva ◽  
Aline Cadigna Lima Patrício ◽  
Guilherme Costa Oliveira ◽  
Meiry Glaúcia Freire Rodrigues
Keyword(s):  
Heavy Metals ◽  
Factorial Design ◽  
Metal Removal ◽  
Physical Adsorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Removal Capacity ◽  
Adsorption Of Nitrogen ◽  
Potential Evaluation ◽  
Good Percentage

The problems caused by contamination of heavy metals generate a growing need to implement technologies to reduce or eliminate them. This work aims to evaluate the potential of gray clay, the process of removal of zinc and lead from synthetic effluents in finite bath system. The clay was characterized by: X-ray diffraction, X-ray Spectroscopy Energy Dispersive and Physical Adsorption of Nitrogen. The tests were performed finite bath following a 22 factorial design, with the variables: pH and initial concentrations of metal. The clays were evaluated for their removal capacity and rate of metal removal. After the characterization and evaluation, it was found that the gray clay comprises clay of the groups of kaolinite and mica. The results of the factorial design shown that the adsorption of the metals zinc and lead can be developed with good percentage of removal.

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