Synthesis Design of TiO2 Nanotubes and Nanowires and Photocatalytic Applications in the Degradation of Organic Pollutants in the Presence or not of Microorganisms

2012 ◽  
Vol 1442 ◽  
Author(s):  
Asma Turki ◽  
Pilar Fernández Ibáñez ◽  
Abdelhamid Ghorbel ◽  
Hafedh Kochkar ◽  
Chantal Guillard ◽  
...  
Keyword(s):  
Formic Acid ◽  
Surface Area ◽  
Tio2 Nanotubes ◽  
High Surface ◽  
High Surface Area ◽  
Alkaline Solutions ◽  
Synthesis Design ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Photocatalytic Applications

ABSTRACT1 D TiO2 nanomaterials (nanotubes, nanowires) were synthesized through hydrothermal treatment of TiO2 powder (P25) in concentrated alkaline solutions (NaOH for nanotubes, KOH for nanowires) followed by calcination at varying temperatures between 400°C and 700°C. Samples were characterized by HRTEM, XRD, Raman spectroscopy, and N2 adsorption-desorption isotherms. High surface area nanotubular TiO2 materials can maintain their 1D morphology up to a temperature of calcination of 400°C while changing their phase from hydrogenotitanate to anatase. The use of KOH leads to a retarded formation of anatase. Photocatalytic results showed that TiO2 anatase nanotubes calcined at 400°C can degrade formic acid with a rate constant four times higher than for P25. A direct correlation between surface area and photocatalytic activity explains the much higher activity of TiO2 anatase nanotubes. On the opposite, for the degradation of phenol, P25 remains more active. In the disinfection of water, contrary to P25, the high surface area of TiO2 nanotubes allows the simultaneous degradation of formic acid and the inactivation of pathogen fungus showing the interest of such materials for the treatment of wastewater.

Development of α-Fe2O3 as Adsorbent and its Effect on CO2 Capture

2016 ◽  
Vol 840 ◽  
pp. 421-426 ◽  
Author(s):  
Azizul Hakim ◽  
Tengku Sharifah Marliza ◽  
Maratun Najiha Abu Tahari ◽  
Muhammad Rahimi Yusop ◽  
Mohamed Wahab Mohamed Hisham ◽  
...  
Keyword(s):  
Particle Size ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Co2 Adsorption ◽  
High Surface ◽  
High Surface Area ◽  
N2 Adsorption ◽  
Mixing Method ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Iron oxide (α-Fe2O3) as adsorbent was no longer new in CO2 adsorption studies. However, its contributions in the industry still in limited wherein lack of convincing results of quantifying of adsorbed CO2. This work presents an analysis for α-Fe2O3 was prepared by simple mixing method with identified the adsorption capacity that applied in CO2 capture. The synthesized α-Fe2O3 from different concentrations of precursor were analyzed using XRD, N2 adsorption-desorption isotherms with BET and BJH method, TEM, FTIR, CO2 adsorption at 298 K, CO2-TPD and TGA-DTG. It was noted that 2M concentration of precursor (s2M) with highest crystallite peaks shows highest surface area among all samples which indicative of well generated pores. The different concentration of precursor was found generated more porosity rather than particle size according to TEM micrograph. The sphere shape crystallite particle with high surface area (50.5 m2/g) and porosity were desirable properties in CO2 adsorption. Consequently, physically adsorbed CO2 with adsorption at 298 K was highest with adsorption capacity of at 17.0 mgCO2/gadsorbent. Finally, chemically adsorbed CO2 was successfully identified from CO2–TPD analysis with adsorption capacity of 0.19 mgCO2/gadsorbent and 1.31 mgCO2/gadsorbent at maximum desorption temperature of 375 °C and 749 °C respectively.

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

scholarly journals Enhancement of Photocatalytic Oxidation of Glucose to Value-Added Chemicals on TiO2 Photocatalysts by A Zeolite (Type Y) Support and Metal Loading

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 423 ◽  
Author(s):  
Kamonchanok Roongraung ◽  
Surawut Chuangchote ◽  
Navadol Laosiripojana
Keyword(s):  
Formic Acid ◽  
Surface Area ◽  
Gluconic Acid ◽  
Photocatalytic Oxidation ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Value Added ◽  
Incipient Wetness Impregnation ◽  
Microwave Assisted

TiO2-based photocatalysts synthesized by the microwave-assisted sol-gel method was tested in the photocatalytic glucose conversion. Modifications of TiO2 with type-Y zeolite (ZeY) and metals (Ag, Cu, and Ag-Cu) were developed for increasing the dispersion of TiO2 nanoparticles and increasing the photocatalytic activity. Effects of the TiO2 dosage to zeolite ratio (i.e., TiO2/ZeY of 10, 20, 40, and 50 mol %) and the silica to alumina ratio in ZeY (i.e., SiO2:Al2O3 of 10, 100, and 500) were firstly studied. It was found that the specific surface area of TiO2/ZeY was 400–590 m2g−1, which was higher than that of pristine TiO2 (34.38 m2g−1). The good properties of 20%TiO2/ZeY photocatalyst, including smaller particles (13.27 nm) and high surface area, could achieve the highest photocatalytic glucose conversion (75%). Yields of gluconic acid, arabinose, xylitol, and formic acid obtained from 20%TiO2/ZeY were 9%, 26%, 4%, and 35%, respectively. For the effect of the silica to alumina ratio, the highest glucose conversion was obtained from SiO2:Al2O3 ratio of 100. Interestingly, it was found that the SiO2:Al2O3 ratio affected the selectivity of carboxylic products (gluconic acid and formic acid). At a low ratio of silica to alumina (SiO2:Al2O3 = 10), higher selectivity of the carboxylic products (gluconic acid = 29% and formic acid = 32%) was obtained (compared with other higher ratios). TiO2/ZeY was further loaded by metals using the microwave-assisted incipient wetness impregnation technique. The highest glucose conversion of 96.9 % was obtained from 1 wt. % Ag-TiO2 (40%)/ZeY. Furthermore, the bimetallic Ag-Cu-loaded TiO2/ZeY presented the highest xylitol yield of 12.93%.

Tuning of Titanium Oxide Morphology at Micro and Nano Scale by Alternating Current Anodising

2009 ◽  
Vol 6 ◽  
pp. 61-66 ◽  
Author(s):  
Maria Vittoria Diamanti ◽  
Marco Ormellese ◽  
Maria Pia Pedeferri
Keyword(s):  
Surface Area ◽  
Electrolyte Concentration ◽  
High Surface ◽  
High Surface Area ◽  
Alternating Current ◽  
Oxide Surface ◽  
Alternative Technique ◽  
Oxide Morphology ◽  
Morphology And Structure ◽  
Photocatalytic Applications

High surface area TiO2 layers are particularly attractive for photocatalytic applications; suitable anodising processes can be used to produce the oxides and to tune their morphology and structure. In the presented research, an alternative technique to enhance the surface area of anodic oxides was identified. This was achieved with the implementation of an anodising treatment performed by supplying alternating current in diluted hydrochloric acid (feeding voltage ranging from 5 V to 10 V). Alternating current anodising caused the formation of a double texture of pits on the oxide surface, the bigger ones being some micrometres wide and formed by smaller pits hundreds of nanometres large; these holes distribution and dimensions can be modulated by varying electrolyte concentration, feeding voltage and anodising time.

scholarly journals Synthesis and characterization of mesoporous materials with SBA and MCM structure types

Cerâmica ◽  
2019 ◽  
Vol 65 (376) ◽  
pp. 585-591
Author(s):  
R. A. Sacramento ◽  
O. M. S. Cysneiros ◽  
B. J. B. Silva ◽  
A. O. S. Silva
Keyword(s):  
Surface Area ◽  
Mesoporous Materials ◽  
High Surface ◽  
High Surface Area ◽  
Textural Properties ◽  
N2 Adsorption ◽  
Structure Directing Agent ◽  
Type Iv ◽  
Xrd Patterns ◽  
Adsorption Desorption

Abstract Mesoporous materials are promising structures for application in catalysis and adsorption due to high surface area and large pore size. Mesoporous materials were synthesized by the hydrothermal method with novel surfactants, distinct from those observed in the literature, in order to carry out a study of its structure and to obtain materials with better textural properties. The structures synthesized with the surfactants Igepal CO630 and Brij O20 presented the best results of specific surface area, 1074 and 1075 m2.g-1, respectively. The obtained materials were characterized by XRD, TG/DTG, N2 adsorption-desorption, and FTIR techniques. XRD patterns indicated that the highly ordered mesoporous silica structures, such as MCM-41 and MCM-48, using CTMABr as the structure-directing agent and the SBA-15, SBA-16 and other SBA structures using different block copolymers were obtained. Through N2 adsorption-desorption isotherms, it was observed type IV isotherms, attributed to mesoporous materials. The FTIR spectra presented similar behaviors with characteristic vibrational bands of MCM and SBA type materials.

Effects of Li+, K+, and Ba2+ Cations on the ORR at Model and High Surface Area Pt and Au Surfaces in Alkaline Solutions

2011 ◽  
Vol 2 (21) ◽  
pp. 2733-2736 ◽  
Author(s):  
D. Strmcnik ◽  
D. F. van der Vliet ◽  
K.-C. Chang ◽  
V. Komanicky ◽  
K. Kodama ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Alkaline Solutions

Rapid and Efficient Synthesis of Platinum Nanodendrites with High Surface Area by Chemical Reduction with Formic Acid

2010 ◽  
Vol 22 (9) ◽  
pp. 2835-2841 ◽  
Author(s):  
Liang Wang ◽  
Hongjing Wang ◽  
Yoshihiro Nemoto ◽  
Yusuke Yamauchi
Keyword(s):  
Formic Acid ◽  
Surface Area ◽  
Chemical Reduction ◽  
High Surface ◽  
High Surface Area ◽  
Efficient Synthesis
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