scholarly journals Water treatment to reduce the porosity of nanowebs

Author(s):  
Sedigheh Aghayari

Abstract Here a way used to reduce the porosity of the electrospun web which removed PVA nanofibers from PVA/PA6 hybrid nanoweb by water treatment. Measuring the porosity of the electrospun web before and after treatment by BET method and image processing, proved this. The specific surface area of the web 70 % reduced after water treatment.

2021 ◽  
Author(s):  
Sedigheh Aghayari

Abstract Here away used to reduce the porosity of the nanofibers, which is removing PVA nanofibers from PVA/PA6 nanofibers by water treatment. Measuring the porosity of the electrospun web before and after treatment by the BET method proved this. The specific surface area of the web was 60 % reduced after water treatment. Surface roughness and pore volume have reduced after water treatment. Also, I introduced BET as the method for measuring the diameters of mesopores (or lower than 100nm). I used BET to prove that the cracks can make mesopores on the nanofibers.


Author(s):  
Sedigheh Aghayari

One of the main properties of nanofiber webs is their porosity, and any application needs its porosity value. There are many applications which they high or low porosities. Electrospinning is a way to get high porosity, but in some applications, higher or lower porosities than electrospun webs are needed. Up to now, removing one part of the nanofiber web has been used to change the porosity. Here, a new way is introducing for reducing the porosity of the nanowebs, which chose a hydrophilic nanofiber as one part. In the past, only hydrophobic one’s use. We can get the visa versa results. Here a way used to reduce the porosity of the electrospun web which removed PVA nanofibers from PVA/PA6 hybrid nanoweb by water treatment. Measuring the porosity of the electrospun web before and after treatment by the BET method, density method, and image processing proved this. The specific surface area of the web was 70 % reduced after water treatment. After water treatment, the surface roughness and pore volume reduce. Also, the best way introduced for measuring the porosity. Image processing introduces as the best method for measuring the porosity of the nanowebs.


2011 ◽  
Vol 197-198 ◽  
pp. 17-20
Author(s):  
Jun Ming Li ◽  
Ai Juan Wang ◽  
Yu Peng Lv ◽  
Bai Ling Jiang

Effect of crystals size, surface area, pore size and porosity of hydroxyapatite microspheres on the loading ability of bovine serum albumin was studied in this paper. The surface morphology, specific surface area and porosity of hydroxyapatite microspheres were characterized by scanning electron microscope, specific surface area and pore size analyzer, respectively. The concentration of BSA in aqueous solutions both before and after adsorption was determined by ultraviolet-visible spectrophotometer. The results indicated that the adsorption behavior of bovine serum albumin appeared to obey the Langmuir-type isotherm model. Fast adsorption appeared at the beginning, and then decreased gradually. Hydroxyapatite microspheres calcined at 600°C had the maximum capacity, and those calcined at 800°C showed lower adsorption ability. The loading ability of hydroxyapatite microspheres depended on its crystal size, specific surface area, pore size and porosity, etc.


2008 ◽  
Vol 8 (12) ◽  
pp. 6445-6450
Author(s):  
F. Paraguay-Delgado ◽  
Y. Verde ◽  
E. Cizniega ◽  
J. A. Lumbreras ◽  
G. Alonso-Nuñez

The present study reports the synthesis method, microstructure characterization, and thermal stability of nanostructured porous mixed oxide (MoO3-WO3) at 550 and 900 °C of annealing. The material was synthesized using a hydrothermal method. The precursor was prepared by aqueous solution using ammonium heptamolibdate and ammonium metatungstate, with an atomic ratio of Mo/W = 1. The pH was adjusted to 5, and then the solution was transferred to a teflon-lined stainless steel autoclave and heated at 200 °C for 48 h. The resultant material was washed using deionized water. The specific surface area, morphology, composition, and microstructure before and after annealing were studied by N2 physisorption, scanning electron microscopy (SEM), analytical transmission electron microscopy (TEM), and X-Ray diffraction (XRD). The initial synthesized materials showed low crystallinity and high specific surface area around (141 m2/g). After thermal annealing the material showed higher crystallinity and diminished its specific surface area drastically.


2010 ◽  
Vol 4 (2) ◽  
pp. 69-73 ◽  
Author(s):  
Marija Milanovic ◽  
Ivan Stijepovic ◽  
Ljubica Nikolic

Titanate structures were synthesized in highly alkaline solution using hydrothermal procedure. As-prepared powders were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). A specific surface area of the powders was measured by BET method. Results confirmed formation of layered trititanates, already after one hour of hydrothermal synthesis. To examine the photocatalytic activity of the as-prepared layered titanates, methylene blue (MB) was employed as a target compound in response to visible light at ambient temperature. It was observed that the specific surface area, size distribution and crystallinity are important factors to get high photocatalytic activity for the decomposition of MB. .


2015 ◽  
Vol 80 (5) ◽  
pp. 717-729 ◽  
Author(s):  
Jelena Milovanovic ◽  
Ruth Stensrød ◽  
Elisabeth Myhrvold ◽  
Roman Tschentscher ◽  
Michael Stöcker ◽  
...  

In this work, different metal oxides (MO) supported on two types of zeolites: 1) natural clinoptilolite (NZ) and 2) synthetic zeolite, ZSM-5 were prepared and tested as catalysts in the fast pyrolysis of hardwood lignin. NZ was modified with the CaO and MgO by a simple two steps procedure consisting of an ion exchange reaction and a subsequent calcination at 773 K. The synthetic ZSM-5 was modified with several MO species (Ni, Cu, Ca, Mg) by a wet impregnation and calcination at 873 K. ?he prepared catalysts were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS) and measurement of specific surface area (BET method). Acid sites were characterized and quantified by pyridine (py) absorption using Fourier transform infrared spectroscopy (FTIR). The catalysts exhibit catalytic activity depanding on modification, reaction temperature and of the MO contents. The highest yield of useful phenol in bio-oil was obtained with NiO/ZSM-5 (34.8 wt.%) which exhibits the highest specific surface area and the highest concetration of Br?nsted and Lewis acid sites. The studied catalysts did not increase significantly the content of polycyclic aromatic hydrocarbons (PAHs) and heavy compounds compared to non-catalytic experiment.


Jurnal Kimia ◽  
2020 ◽  
pp. 82
Author(s):  
D. A. D. N. Dewi ◽  
I N. Simpen ◽  
I W. Suarsa

A montmorillonite clay modified with semiconductor metal can act as a photocatalyst material. Montmorillonite clays were chosen because of their natural characteristics which are easily to be modified and have high specific surface area. This research aims to modify montmorillonite clay into photocatalyst material. The montmorillonite clay was intercalated using Fe2O3 to produce Fe2O3-pillared montmorillonite clay, then doped with TiO2 to form a photocatalyst material Fe2O3-PILC / TiO2. Modifications were intended to increase the specific surface area and number of active photocatalyst sites and thus increase the ability of photodegradation. The characterization carried out included characterizing the pillar formation using X-ray Diffraction (XRD), specific surface area by the BET method (Bruneau, Emmet, and Teller), a the number of surface acid-base sites by the titration method. Photocatalyst with the best character was Fe2O3-PILC / TiO2 1: 3 with specific surface area, number of acid and base sites respectively 45,947 m2/g, 20,1736 x 1023 sites/gram and 19,0044 x 1023 sites/gram. The result of photodegradation at optimum condition with visible light at pH 3 using 400 mg photocatalyst was 99.84%.   Keywords: photocatalyst, Fe2O3, montmorillonite clay, TiO2, rhodamine B


2021 ◽  
Vol 887 ◽  
pp. 603-609
Author(s):  
A.S. Kondratenko ◽  
S.L. Buyantuev ◽  
S.Yu. Shishulkin

This paper dwells upon finding the specific surface area of cake, a coal enrichment waste, exposed to electroplasma treatment; the goal is to make an organomineral porous material to be used as a sorbent for wastewater treatment. The research team used a monomolecular Langmuir adsorption model and surface tension of the surfactants before and after adsorption at the interface of solution and solid adsorbent. Another process considered herein was thermal activation of substances in the electroplasmic reactor for making organomineral porous materials from coal cakes. The paper presents the resulting specific surfaces area of the organomineral sorbent thus produced. Thus, the waste of flotation, i.e. coal cake, is fundamentally suitable for making porous substances by thermal destruction in an electroplasma reactor.


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