Density fractionated hollow silica microspheres with high-yield by non-polymeric sol–gel/emulsion route

Author(s):  
R.K. Singh ◽  
A. Garg ◽  
R. Bandyopadhyaya ◽  
B.K. Mishra
2019 ◽  
Vol 64 (2) ◽  
pp. 153-161 ◽  
Author(s):  
László Nagy-Győr ◽  
Emese Farkas ◽  
Mihai Lăcătuș ◽  
Gergő Tóth ◽  
Dániel Incze ◽  
...  

In this study, an efficient and generally applicable 2nd generation sol – gel entrapment method was developed for immobilization of yeastcells. Cells of Lodderomyces elongisporus, Candida norvegica, Debaryomyces fabryi, Pichia carsonii strains in admixture with hollow silica microspheres support were immobilized in sol – gel matrix obtained from polycondensation of tetraethoxysilane. As biocatalysts in theselective acyloin condensation of benzaldehyde catalyzed by pyruvate decarboxylase of the yeast, the novel immobilized whole-cell preparations were compared to other states of the cells such as freshly harvested wet cell paste, lyophilized cells and sol – gel entrapped preparations without hollow silica microspheres support. Reusability and storability studies designated this novel 2nd generation sol – gel method as a promising alternative for solid formulation of whole-cells bypassing expensive and difficult downstream steps while providing easy-to-handle and stable biocatalysts with long-term preservation of the biocatalytic activity.


2012 ◽  
Vol 159 ◽  
pp. 119-125 ◽  
Author(s):  
Pavel Kovačík ◽  
Zuzana Kremláčková ◽  
František Štěpánek

2012 ◽  
Vol 15 (2) ◽  
Author(s):  
Mohammad Hossein Habibi ◽  
Maryam Mikhak

AbstractNanostructured zinc titanate (NZT) was synthesized in high yield via a one-step and template-free sol-gel route. The prepared nanocomposite exhibited good size uniformity and regularity. The enhanced photocatalytic activity of the NZT was evaluated in the degradation and mineralization of Indocorn Brilliant Red (M5B) under metal halide lamp irradiation. The effects of different parameters such as pH of the solution, and initial dye concentration on photodegradation of M5B were analyzed. The degradation of M5B follows pseudo-first order kinetics according to the Langmuir-Hinshelwood model. The experimental results showed that the initial concentration of azo dye in the dye mixture greatly affected the degradation efficiency. At M5B concentrations of 10 mg/L, the optimum conditions for the highest degradation efficiency (94%) of azo dye were a photocatalyst dosage of 0.01 g/L and an initial solution pH of 9. This study provided new insight into the design and preparation of nanomaterial demonstrated an excellent ability to remove organic pollutants in wastewater.


2009 ◽  
Vol 79-82 ◽  
pp. 1511-1514
Author(s):  
Hong Feng Wang ◽  
Zhi Qi Wang ◽  
Ai Ping Wang ◽  
Zhi Bin Zhu ◽  
Yan Sheng Yin

An attempt was made to prepare hollow silica microspheres by an oil-in-water emulsion which proposed to use waste polystyrene organic solution as oil phase. Effects of the kinds and amounts of surfactants and the concentration of waste polystyrene solution on the nanosized hollow silica microspheres were studied. The prepared hollow silica microspheres were characterized by TEM, XRD, TG-DTA and particle size distribution analyzer. The experimental results showed that the waste polystyrene organic solution was successfully treated as oil core and the cores could be removed at about 350°C. Meanwhile, the obtained hollow microspheres were amorphous with an average particle size of 40nm. The hollow silica microspheres could be obtained with the selected surfactant.


2014 ◽  
Vol 617 ◽  
pp. 170-173
Author(s):  
Tetsuo Umegaki ◽  
Shunsuke Imamura ◽  
Naoki Toyama ◽  
Qiang Xu ◽  
Yoshiyuki Kojima

The present study reports a facile and effective approach for fabrication of hollow silica-alumina composite spheres. In this approach, silica-alumina composite walls were coated on polystyrene template by the sol-gel method using L(+)-arginine as a promoter for the reaction followed by calcination procedure. Using L(+)-arginine as a promoter of coating process, homogeneous hollow silica-alumina composite spheres are obtained and the wall thickness is larger than that of the hollow spheres prepared with ammonia. The hollow spheres shows high activity for hydrolytic dehydrogenation of ammonia borane compared with spherical silica-alumina composite particles without hollow structure, the hollow spheres prepared with ammonia, and conventional H-BEA zeolite. The results indicate that hollow structure plays important role to show high activity.


2007 ◽  
Vol 61 (2) ◽  
pp. 363-368 ◽  
Author(s):  
Kun Han ◽  
Zhihui Zhao ◽  
Zheng Xiang ◽  
Chunlei Wang ◽  
Junhu Zhang ◽  
...  

2013 ◽  
Vol 17 (10) ◽  
pp. 1029-1033 ◽  
Author(s):  
Alexandru Mihai Grumezescu ◽  
Ecaterina Andronescu ◽  
Anton Ficai ◽  
Valentina Grumezescu ◽  
Coralia Bleotu ◽  
...  

2006 ◽  
Vol 45 ◽  
pp. 2043-2048
Author(s):  
Undine Aust ◽  
Gerhard Tomandl

TiO2-ZrO2 mixed-oxide membranes were prepared via polymeric sol-gel technique. The final composition is already predefined during the preparation of the sols by using the corresponding quantities of the starting alkoxides. The mixed-oxide membranes were characterized by Xray diffraction, nitrogen sorption, and field emission scanning electron microscopy as well as filtration and corrosion tests. The observed results prove the positive influence on the investigated properties by addition of a second oxide. Depending on the composition of the mixed-oxide membranes, a remarkable increase in the crystallization temperatures is demonstrated. Using mixed-oxide systems, the retardation of grain growth is confirmed.


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