Modification of Clinoptilolite by Synthetic Zeolite

1993 ◽  
Vol 58 (8) ◽  
pp. 1782-1790
Author(s):  
Ľubomír Medvecký ◽  
Jaroslav Briančin ◽  
Ján Mihalik
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Methanol Conversion ◽  
Synthetic Zeolite ◽  
Al Content ◽  
Physico Chemical ◽  
Sol Gel Process ◽  
Dta And Tg ◽  
High Al Content ◽  
Selection Of

The sol-gel process allows to modify clinoptilolite by the nucleation of synthetic zeolite. From the viewpoint of methanol conversion, the obtained high Al content nucleation-deposited zeolite decreases the catalytic activity of clinoptilolite. Therefore, it is necessary to optimize the selection of suitable synthetic zeolite as to its composition. Contamination of zeolite surfaces by carbonaceous fragments during catalytic process results from physico-chemical properties of the used and processed zeolite, and according to DTA and TG analysis it significantly affects the readsorption of water vapours and likely also the zeolite activity in methanol conversion.

Preparation and Photocatalytic Activity of Mixed Phase Anatase/rutile TiO2 Nanoparticles for Phenol Degradation

2014 ◽  
Vol 70 (2) ◽  
Author(s):  
Mohamad Azuwa Mohamed ◽  
Wan Norharyati Wan Salleh ◽  
Juhana Jaafar ◽  
Norhaniza Yusof
Keyword(s):  
Photocatalytic Activity ◽  
Tio2 Nanoparticles ◽  
High Performance ◽  
Sol Gel ◽  
Phenol Degradation ◽  
Chemical Properties ◽  
Mixed Phase ◽  
Rutile Tio2 ◽  
Physico Chemical ◽  
Degussa P25

The evolution of desirable physico-chemical properties in high performance photocatalyst materials involves steps that must be carefully designed, controlled, and optimized. This study investigated the role of key parameter in the preparation and photocatalytic activity analysis of the mixed phase of anatase/rutile TiO2 nanoparticles, prepared via sol-gel method containing titanium-n-butoxide Ti(OBu)4 as a precursor material, nitric acid as catalyst, and isopropanol as solvent. The prepared TiO2 nanoparticles were characterized by means of XRD, SEM, and BET analyses, and UV-Vis-NIR spectroscopy. The results indicated that the calcination temperature play an important role in the physico-chemical properties and photocatalytic activity of the resulting TiO2 nanoparticles. Different calcination temperatures would result in different composition of anatase and rutile. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO2 nanoparticles was measured by photodegradation of 50 ppm phenol in an aqueous solution. The commercial anatase from Sigma-Aldrich and Degussa P25 were used for comparison purpose. The mixed phase of anatase/rutile TiO2 nanoparticles (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400°C exhibited the highest photocatalytic activity of 84.88% degradation of phenol. The result was comparable with photocatalytic activity demonstrated by Degussa P25 by 1.54% difference in phenol degradation. The results also suggested that the mixed phase of anatase/rutile TiO2 nanoparticles is a promising candidate for the phenol degradation process. The high performance of photocatalyst materials may be obtained by adopting a judicious combination of anatase/rutile and optimized calcination conditions.

Infrared Characterization of PMMA-SiO2 Hybrid Glasses Obtained by Sol-Gel Process

2010 ◽  
Vol 1278 ◽  
Author(s):  
L.L. Díaz-Flores ◽  
A. S. López Rodríguez ◽  
P. SifuentesGallardo ◽  
M.A. Hernàndez Rivera ◽  
M.a Garnica Romo ◽  
...  
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Hybrid Coatings ◽  
Force Microscopy ◽  
Air Atmosphere ◽  
Atomic Force ◽  
Sol Gel Process ◽  
Traditional Process ◽  
And Chemical Properties

AbstractThis work is about the production of hybrid coatings of the system SiO2-PMMA (PMMA, polymethylmethacrylate). These materials have interesting mechanical and chemical properties useful for anticorrosive and wear resistance applications. SiO2-PMMA hybrids were obtained by the sol-gel traditional process, using tetraethylorthosilicate (TEOS) and methylmethacrylate (MMA) by Aldrich Co, as starting reagents. The SiO2:PMMA ratio was varied from 0:1 to about 1:1 at air atmosphere deposition. The coatings were obtained on acrylic sheets and silicon wafers. A diversity of coatings with chemical composition ranging from SiO2 and PMMA to obtain the SiO2-PMMA hybrids were obtained. Infrared (IR) and atomic force microscopy (AFM), were performed to determinate structural and morphological behavior.

scholarly journals In situ sol-gel synthesis of hyaluronan derivatives bio-nanocomposite hydrogels

2019 ◽  
Vol 6 (5) ◽  
pp. 249-258 ◽  
Author(s):  
U D’Amora ◽  
A Ronca ◽  
M G Raucci ◽  
S M Dozio ◽  
H Lin ◽  
...  
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Filler Concentration ◽  
Similar Degree ◽  
Nanocomposite Hydrogels ◽  
Physico Chemical ◽  
Inorganic Fillers ◽  
Sol Gel Synthesis ◽  
Physical Blending

Abstract The main driving idea of the present study was the comparison between two different chemical modifications of hyaluronic acid (HA) followed by the development of nanocomposite hydrogels directly in situ by biomineralization of photocrosslinkable HA polymers through sol-gel synthesis. In this way, it has been possible to overcome some limitations due to classical approaches based on the physical blending of inorganic fillers into polymer matrix. To this aim, methacrylated and maleated HA, synthesized with similar degree of substitution (DS) were compared in terms of mechanical and physico-chemical properties. The success of in situ biomineralization was highlighted by reflect Fourier transform infrared spectroscopy and thermogravimetric analysis. Furthermore, mechanical characterization demonstrated the reinforcing effect of inorganic fillers evidencing a strong correlation with DS. The swelling behavior resulted to be correlated with filler concentration. Finally, the cytotoxicity tests revealed the absence of toxic components and an increase of cell proliferation over culture time was observed, highlighting these bio-nanocomposite hyaluronan derivatives as biocompatible hydrogel with tunable properties.

scholarly journals Technologies and Formulation Design of Polysaccharide-Based Hydrogels for Drug Delivery

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3156 ◽  
Author(s):  
Giulia Auriemma ◽  
Paola Russo ◽  
Pasquale Del Gaudio ◽  
Carlos A. García-González ◽  
Mariana Landín ◽  
...  
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Drying Methods ◽  
Special Focus ◽  
Porous Network ◽  
Hydrogel Particles ◽  
Physico Chemical ◽  
Droplet Production ◽  
Inflammatory Drugs ◽  
Sol Gel Transition

Polysaccharide-based hydrogel particles (PbHPs) are very promising carriers aiming to control and target the release of drugs with different physico-chemical properties. Such delivery systems can offer benefits through the proper encapsulation of many drugs (non-steroidal and steroidal anti-inflammatory drugs, antibiotics, etc) ensuring their proper release and targeting. This review discusses the different phases involved in the production of PbHPs in pharmaceutical technology, such as droplet formation (SOL phase), sol-gel transition of the droplets (GEL phase) and drying, as well as the different methods available for droplet production with a special focus on prilling technique. In addition, an overview of the various droplet gelation methods with particular emphasis on ionic cross-linking of several polysaccharides enabling the formation of particles with inner highly porous network or nanofibrillar structure is given. Moreover, a detailed survey of the different inner texture, in xerogels, cryogels or aerogels, each with specific arrangement and properties, which can be obtained with different drying methods, is presented. Various case studies are reported to highlight the most appropriate application of such systems in pharmaceutical field. We also describe the challenges to be faced for the breakthrough towards clinic studies and, finally, the market, focusing on the useful approach of safety-by-design (SbD).

Tin Oxide Based Nano Electroceramics Obtained from Sol–Gel Process: The Modified of the Structural and Opto-Electrical Properties with the Al Doping

2018 ◽  
Vol 13 (10) ◽  
pp. 1460-1467
Author(s):  
Cihat Aydin
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Crystallite Size ◽  
Tin Oxide ◽  
Sol Gel ◽  
Control Surface ◽  
Al Doping ◽  
Al Content ◽  
Tauc Plot ◽  
Sol Gel Process

Nano electroceramic samples of undoped and Al doped SnO2 were synthesized by the sol–gel calcination process. The structural, morphological, electrical and optical properties of samples were characterized. X-ray diffraction analysis results confirm that all of the synthesized nanopowders are polycrystalline with a tetragonal structure. The crystallite size values of the prepared nanocomposites were calculated in the range of 21.32–34.33 nm. The values of crystallite size indicate that the prepared powders have nanostructure. The grain size and morphological parameters of the undoped and Al-doped SnO2 nanopowders calculated. AFM measurements suggest that Al dopants ratio could be an effect to control surface parameters of the SnO2 nanomaterials. The optical band gap (Eg) of prepared nanomaterials were calculated using Tauc plot method for the various atomic ratios of Al. The calculated Eg values for samples are found to be in the range from 3.51 to 3.69 eV. The electrical conductivity of undoped and Al doped Tin oxide nanopowders were carried out at the temperature range from 290 to 420 K. It demonstrates that the electrical conductivity at room temperature and the activation energy of samples increase with the Al doping. The obtained results suggest that the structural, morphological, optical and electrical properties of SnO2 based nanomaterials can be controlled and changed with Al content.

Working Fluids Used for Drilling Deep Boreholes

2014 ◽  
Vol 508 ◽  
pp. 150-155 ◽  
Author(s):  
Marian Šofranko ◽  
Erika Škvareková ◽  
Gabriel Wittenberger
Keyword(s):  
Chemical Composition ◽  
Drilling Fluid ◽  
Chemical Properties ◽  
Proper Function ◽  
Working Fluids ◽  
Physico Chemical ◽  
Geological Conditions ◽  
Deep Boreholes ◽  
Selection Of

Particularly important is the use of drilling fluid in carrying out drilling works to great depths and especially in difficult geological conditions. Proper function of the drilling fluid is governed by the selection of their physico-chemical properties. Drilling works of hydrogeological survey require circulation of borehole with such rinses, which at a minimum pollute water-bearing horizons and their chemical composition meets hygiene requirements.

scholarly journals Wet Oxidation of High-Al-Content III–V Semiconductors: Important Materials Considerations for Device Applications

1999 ◽  
Vol 573 ◽  
Author(s):  
Carol I. H. Ashby
Keyword(s):  
Chemical Properties ◽  
Cavity Surface ◽  
Wet Oxidation ◽  
Device Structure ◽  
Al Content ◽  
Vertical Cavity Surface ◽  
Device Applications ◽  
Emitting Lasers ◽  
And Performance ◽  
High Al Content

ABSTRACTWet oxidation of high-Al-content AIGaAs semiconductor layers in vertical cavity surface emitting lasers (VCSELs) has produced devices with record low threshold currents and voltages and with wall-plug efficiencies greater than 50%. Wet oxidation of buried AlGaAs layers has been employed to reduce the problems associated with substrate current leakage in GaAs-on-insulator (GOL) MESFETs. Wet oxidation has also been considered as a route to the long-sought goal of a III-V MIS technology. To continue improving device designs for even higher performance and to establish a truly manufacturable technology based on wet oxidation, the effect of oxidation of a given layer on the properties of the entire device structure must be understood. The oxidation of a given layer can strongly affect the electrical and chemical properties of adjacent layers. Many of these effects are derived from the production of large amounts of elemental As during the oxidation reaction, the resultant generation of point defects, and the diffusion of these defects into adjacent regions. This can modify the chemical and electrical properties of these regions in ways that can impact device design, fabrication, and performance. Current understanding of the problem is discussed here

Physico-Chemical Properties of Silica Coated Superparamagnetic Magnetite Nanoparticles Synthesized by Non-Seeded Process

2015 ◽  
Vol 1107 ◽  
pp. 267-271
Author(s):  
Sodipo Bashiru Kayode ◽  
Azlan Abdul Aziz
Keyword(s):  
Silica Nanoparticles ◽  
Magnetite Nanoparticles ◽  
Colloidal Suspension ◽  
Sol Gel ◽  
Chemical Properties ◽  
Colloidal Suspensions ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Physico Chemical ◽  
Physical And Chemical

The science of core-shell nanoparticles requires investigation into several physical and chemical properties of the composite nanoparticles. Unlike the conventional sol-gel or the reverse microemulsion micelle method, we presented here a non-seeded process of encapsulating superparamagnetic magnetite nanoparticles (SPMN) with silica. Physico-chemical analysis of the product was used to confirm the result of the coating procedure. Colloidal suspension of SPMN and silica nanoparticles were synthesised through coprecipitation method and modified Stöber method respectively. Afterwards, both colloidal suspensions of SPMN and silica nanoparticles were sonicated to encapsulate the SPMN with silica. Elemental mapping of the composite particles with electron spectroscopy imaging (ESI) confirmed the core-shell micrograph of the SPMN and silica. The X-ray diffraction pattern (XRD) showed the silica shell to be in amorphous form. FTIR analysis further confirmed the chemical properties of the product to be silica coated SPMN.

Influence of gelation time on the morphological and physico-chemical properties of the sol–gel entrapped lipase

2008 ◽  
Vol 52-53 ◽  
pp. 27-33 ◽  
Author(s):  
Rubiane C. Pinheiro ◽  
Cleide M.F. Soares ◽  
Onélia A.A. dos Santos ◽  
Heizir F. de Castro ◽  
Flavio F. de Moraes ◽  
...  
Keyword(s):  
Sol Gel ◽  
Gelation Time ◽  
Chemical Properties ◽  
Physico Chemical
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