Nuclear fuel technology. Guidelines on the measurement of the specific surface area of uranium oxide powders by the BET method

2017 ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1979-1988 ◽  
Author(s):  
Xiao Xu ◽  
Hongjun Zhang ◽  
Junxuan Ao ◽  
Lu Xu ◽  
Xiyan Liu ◽  
...  

The development of high specific surface area amidoxime-based polymeric (H-ABP) fibers presents a new technology for the synthesis of highly efficient adsorbents for uranium extraction from seawater (UES), thus opening a whole new means of nuclear fuel production from the ocean.


2006 ◽  
Vol 24 (1) ◽  
pp. 34-38 ◽  
Author(s):  
Yongxiu Li ◽  
Xiaoyun Lin ◽  
Yizheng Wang ◽  
Junming Luo ◽  
Weili Sun

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.


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.


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


2018 ◽  
Vol 12 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Dajana Milovac ◽  
Ivna Weigand ◽  
Marin Kovacic ◽  
Marica Ivankovic ◽  
Hrvoje Ivankovic

Highly porous hydroxyapatite (Ca10(PO4)6(OH)2, HAp) catalyst support was prepared through hydrothermal transformation of aragonitic cuttlefish bone (Sepia Officinalis, L., Adriatic Sea) at 200?C, preserving the natural well interconnected porous structure. To deposit the TiO2 catalyst on the pore walls of the HAp support two methods were used: i) vacuum impregnation of the support with the suspension of a commercial TiO2 nanopowder in isopropanol and ii) in situ synthesis of TiO2 on the support by sol-gel technique. XRD analysis and FTIR spectroscopy were used to determine the phase composition of the material. The morphology and microstructure of the composite samples were studied by scanning electron microscopy (SEM). The presence of TiO2 particles on the HAp surface was determined by SEM/EDX analysis. To determine the specific surface area and pore size, Brunauer-Emmett-Teller (BET) method was used. The results of the BET method showed the increased specific surface area and pore size reduction after impregnation of TiO2 into the HAp carrier. The photocatalytic activity of HAp/TiO2 samples was studied in a batch reactor with an annular UV-A lamp using salicylic acid as a model water pollutant. The results indicated the suitability of prepared HAp supported TiO2 catalysts for photocatalytic applications.


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