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Impact of supercritical drying and heat treatment on physical properties of titania/silica aerogel monolithic and its applications

Paper ID Volume ID Publish Year Pages File Format Full-Text
43004 45950 2008 6 PDF Available
Title
Impact of supercritical drying and heat treatment on physical properties of titania/silica aerogel monolithic and its applications
Abstract

TiO2–SiO2 monolithic aerogels were homogeneously prepared using sol–gel method. Critical point of drying of TiO2–SiO2 gels with ethanol was studied for 30, 60, 90 and 120 min. Subsequently, the gels were dried with supercritical ethanol, resulting in amorphous aerogels that crystallized following heat treatment at 550 °C from 1 to 5 h. The TiO2–SiO2 aerogels were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface area measurements. The molar ratio of SiO2:TiO2 was 6 and the synthetic strategy revealed that TiO2–SiO2 aerogel, had a surface area ∼868 m2/g, particle size ∼40 nm, density ∼0.17 g/cm3 and 80% porosity. The finding indicated that from economic point of view, TiO2–SiO2 gel should be supercritical dried for 30 min and heat-treated for 5 h. The TiO2–SiO2 aerogel monoliths photocatalyst synthesized using sol–gel method provided insight into the characteristics that make a photocatalyst material well-suited for photodegradation of phenol and cyanide in an industrial waste stream containing Cl−, S2− and NH4+. Interestingly, after multiple reuse cycles (i.e. ≥7), photodegradation systems with regenerated photocatalyst showed a slightly decreasing of photoactivity ∼2–4%. The overall kinetics of photodegradation of either phenol or cyanide using TiO2–SiO2 aerogel photocatalyst was found to be of first order.

Graphical abstractTiO2–SiO2 monolithic aerogels were homogeneously prepared using sol–gel method. Critical point of drying time of TiO2–SiO2 gels with ethanol was studied at 30–120 min. Subsequently, the gels were dried with supercritical ethanol, resulting in amorphous aerogels that crystallized following heat treatment at 550 °C for 1–5 h. TiO2–SiO2 gel should be supercritical dried for 30 min from economic point of view and heat treated for 5 h. SEM images of representative TiO2–SiO2 aerogel morphologies were monolithic aerogel. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
TiO2–SiO2; Aerogels; Monolithic; Photodegradation; Real wastewaters
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 346, Issues 1–2, 31 August 2008, Pages 200–205
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us