The Orthogonal Optimization of Process Parameters of Silica Xerogels

2007 ◽  
Vol 121-123 ◽  
pp. 235-238
Author(s):  
Xiao Dong He ◽  
Fei He ◽  
Yao Li
Keyword(s):  
Process Parameters ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Molar Ratio ◽  
Process Conditions ◽  
Silica Xerogels ◽  
Optimization Of Process Parameters ◽  
Acid Catalyzed ◽  
Orthogonal Optimization

Two-step acid-base catalyzed silica xerogels were prepared through sol-gel and ambient pressure drying. Various additive components were main fators which influenced the porosity of silica xerogles. An orthogonal array (OA) design OA9(34) was applied to select the optimum conditions of additives. The effects of the molar ratio of H2O, alcohol, HCl, and ammonia were evaluated on the basis of the other same process parameters. Every experiment was conducted several times under different process conditions which included reactive temperature, the acid catalyzed time, aging, exchanging solvent and drying for assuring gels formed. The porosity was an index which was used to appraise the characteristic of silica xerogels. Two kinds of silica xerogels, prepared by the most optimal molar ratio (OMR) and the best OA experiment respectively, were compared by means of SEM. The results showed that the most OMR of TEOS, H2O, alcohol, HCl and ammonia was 1:4:10:7.5× 10-4:0.0375.

scholarly journals Preparation of Silica Aerogels by Ambient Pressure Drying without Causing Equipment Corrosion

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 1935 ◽  
Author(s):  
Lixiao Zhu ◽  
Yali Wang ◽  
Suping Cui ◽  
Feihua Yang ◽  
Zuoren Nie ◽  
...  
Keyword(s):  
Pore Structure ◽  
Raw Materials ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Molar Ratio ◽  
Insulation Property ◽  
Water Contact ◽  
Thermal Insulation Property

The silica aerogels were prepared via a sol-gel technique and ambient pressure drying by using industrial solid wastes, dislodged sludges, as raw materials. A strategy was put forward to reduce the corrosion of equipment during the drying procedure. The pore structure, hydrophobicity, and thermal insulation property of the obtained samples were investigated in detail. The results show that the corrosion can be effectively avoided by using an equimolar mixture of trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDS) as silylation agents. At a Si:TMCS:HMDS molar ratio of 1:0.375:0.375, the silica aerogels possess a desirable pore structure with a pore volume of 3.3 ± 0.1 cm3/g and a most probable pore size of 18.5 nm, a high hydrophobicity with a water contact angle of 144.2 ± 1.1°, and a low thermal conductivity of 0.031 ± 0.001 W/(m∙K).

The Microwave-Assisted Preparation and Properties of SiO2 Aerogels by Fractional Modification

2010 ◽  
Vol 148-149 ◽  
pp. 1152-1162 ◽  
Author(s):  
Wen Zhi Zheng ◽  
Li Chen ◽  
Xiang Hua Huang ◽  
Lei Fu
Keyword(s):  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Base Catalysis ◽  
Raw Material ◽  
Microwave Method ◽  
Scanning Calorimetry ◽  
Hydrophobic Sio2 ◽  
Water Bath Heating ◽  
Fractional Modification

Under microwave radiation and using trimethyl chlorosilane as modifier, hydrophobic SiO2 aerogel was prepared through fractional hydrophobic modification and ambient pressure drying of the raw material, tetraethoxysilane (TEOS), in the process of sol-gel and acid-base catalysis. Hydrophilic SiO2 aerogels were also prepared using the microwave method and water bath heating method. The SiO2 aerogels prepared using the three methods, including their morphology and chemical composition, were analyzed and compared using scanning electron microscopy, Brunauer-Emmett-Teller analysis method, Fourier transform infrared spectroscopy, X-ray diffraction, and themogravimetric-differential scanning calorimetry. The results indicate that by adopting the microwave reaction, the specific surface area of the SiO2 aerogels was effectively increased and the structure of the internal nanoscale pores of petal-coated shape was found to exist under the dense external surface of the SiO2 aerogels. Thermal stability of the hydrophobic SiO2 aerogels prepared through fractional modification assisted by the microwave method was increased with the hydrophobic angle at153°, which showed super hydrophobicity.

scholarly journals Small-angle scattering investigation of silica xerogels and sonogels prepared with ionic liquid pyridinium tetrafluoroborate

2017 ◽  
Vol 11 (3) ◽  
pp. 229-233 ◽  
Author(s):  
László Almásy ◽  
Ana-Maria Putz ◽  
Adél Len ◽  
Josef Plestil ◽  
Cecilia Savii
Keyword(s):  
Ionic Liquid ◽  
Small Angle ◽  
Sol Gel ◽  
Molar Ratio ◽  
Strong Increase ◽  
Silica Xerogels ◽  
X Ray Scattering ◽  
Angle Scattering ◽  
Gel Processing ◽  
Functionalized Alkoxide

Silica matrices were prepared via acid catalysed sol-gel processing augmented with sonocatalysis. As silica precursors, a mixture of tetra-functionalized alkoxide (TMOS) and three-functionalized alkoxide methyl-trimethoxysilane (MTMS) were employed. Ionic liquid N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]), was used in various proportions, aiming to catalyse the sol-gel reactions, and to influence the mesoporous silica materials properties, serving as pore template. Small-angle neutron (SANS) and small-angle X-ray scattering (SAXS) techniques were used to explore the xerogels and sonogels microstructure evolution as a function of the IL/Si molar ratio. The results show a strong increase of the primary particle size under the influence of the ionic liquid. Ultrasonic agitation leads to further size increase by ca. 10%.

A silica aerogel as an extractive coating for in-tube solid-phase microextraction to determine polycyclic aromatic hydrocarbons in water samples

2019 ◽  
Vol 11 (45) ◽  
pp. 5784-5792 ◽  
Author(s):  
Xiangping Ji ◽  
Juanjuan Feng ◽  
Chunying Li ◽  
Sen Han ◽  
Jiaqing Feng ◽  
...  
Keyword(s):  
Silica Aerogel ◽  
Solid Phase Microextraction ◽  
Solid Phase ◽  
Ambient Pressure ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Ambient Pressure Drying ◽  
Acid Base ◽  
Polycyclic Aromatic

A silica aerogel with high surface area was prepared by an acid–base two-step catalytic sol–gel method under ambient pressure drying.

Bioactive and Biocompatible Silica/Pseudowollastonite Aerogels

2014 ◽  
Vol 96 ◽  
pp. 21-26 ◽  
Author(s):  
P.J. Reséndiz-Hernández ◽  
D.A. Cortés-Hernández ◽  
Juan Méndez Nonell ◽  
J.C. Escobedo-Bocardo
Keyword(s):  
Bone Tissue ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Bone Tissue Regeneration ◽  
Tissue Formation ◽  
Potential Applications ◽  
Ft Ir ◽  
Bone Tissue Formation

Silica aerogels have attracted increasingly more attention due to their extraordinary properties and their existing and potential applications in a wide variety of technological areas. Materials that promote bone-tissue formation at their surface and bond to osseous tissues when implanted are called bioactive, such as pseudowollastonite particles. In this work, the synthesis of aerogels with pseudowollastonite particles was performed. The synthesis involved the preparation of an alcogel by a two step sol-gel route followed by ambient pressure drying. To promote a higher bioactivity the obtained aerogels were then biomimetically treated using simulated body fluids, SBF and 1.5 SBF. A high bioactivity was demonstrated by FT-IR, SEM, EDS, and XRD. The in vitro biocompatibility was assessed by testing cytotoxicity using rat osteoblasts cultures. The results obtained indicate that these materials are highly potential aerogels for bone tissue regeneration.

Synthesis of Monolithic Macroporous Carbon Xerogels from Phenol, m-Cresol, Furfural and Phosphoric Acid by Sol-Gel Approach

2013 ◽  
Vol 750-752 ◽  
pp. 1804-1811
Author(s):  
Rui Zhang ◽  
Zi Jun Hu ◽  
Shuang Ling Jin ◽  
Xia Shao ◽  
Ming Lin Jin
Keyword(s):  
Phosphoric Acid ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Nitrogen Atmosphere ◽  
Molar Ratio ◽  
Surface Areas ◽  
Carbon Xerogels ◽  
Porous Properties ◽  
Macroporous Carbon

Mixtures of phenol and m-cresol in 1-propanol were first reacted with phosphoric acid and then with furfural to form gels, which were dried under ambient pressure and pyrolyzed under nitrogen atmosphere to form monolithic macroporous carbon xerogels. The molar ratio of m-cresol to phenol (m-C/P), phenol and m-cresol to furfural ((m-C+P)/F), phenol and m-cresol to phosphoric acid ((m-C+P)/H3PO4) was fixed at 1:5, 1:2 and 4.0 respectively while the m-C+P+F in 1-propanol was changed from 18 to 30 g/100ml to investigate the effect of the m-C+P+F concentrations on the porous properties of the monolithic carbon xerogels. It is found that the surface areas of the monolithic carbon xerogels are mainly contributed by micropores and their mesopore volumes are negligible. The monolithic carbon xerogels are rich in macropores whose sizes decrease from 4 to 0.22μm with increasing m-C+P+F concentrations. Moreover, the yields of the monolithic carbon xerogels are around 60%, which is higher than previous ones without phosphoric acid.

scholarly journals Optimization of Process Parameters and Kinetics Analysis of Cd Removal in ZnSO4 Production

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1437
Author(s):  
Xiaoling Ren ◽  
Xinqian Shu ◽  
Haisheng Li ◽  
Jiushuai Deng ◽  
Peng Li ◽  
...  
Keyword(s):  
Reaction Time ◽  
Process Parameters ◽  
Reaction Temperature ◽  
Zinc Powder ◽  
Diffusion Control ◽  
Process Conditions ◽  
Optimization Of Process Parameters ◽  
Removal Experiments ◽  
Main Effects ◽  
Cd Removal

In order to optimize the process parameters of Cd removal in the ZnSO4 production process and study the mechanism of Cd removal reaction, the response surface methodology was used to arrange Cd removal experiments and analyze the optimal production conditions, and the mechanism of Cd removal was studied using kinetics. The results show that the optimal process conditions for Cd removal are as follows: reaction temperature 55 °C, reaction time 13.43 min, and the zinc powder dosage should be 2.14 times that of Cd; the main effects of the three variables from large to small are zinc powder dosage, reaction temperature and reaction time; Cd removal is a second-order reaction, and the activation energy of the reaction is 29.6986 kJ/mol, so the reaction conforms to the diffusion control mechanism.

scholarly journals A Combined Experimental and Optimization Model to Improve the Machinability of Nimonic C-263 Superalloy

2020 ◽  
Author(s):  
Prashant Jadhav ◽  
Chinmaya Prasad Mohanty
Keyword(s):  
Process Parameters ◽  
Cutting Speed ◽  
Sem Analysis ◽  
Depth Of Cut ◽  
Process Conditions ◽  
Optimization Of Process Parameters ◽  
Excellent Mechanical Property ◽  
Single Response ◽  
Optimal Set ◽  
Super Alloy

Nickel based superalloys finds extensive usage in manufacturing of intricate part shapes in gas turbine, aircraft, submarine, and chemical industries owing their excellent mechanical property and heat resistant abilities. However, machining of such difficult-to-machine alloys up to the desired accuracy and preciseness is a complex task owing to a rapid tool wear and failure. In view of this, present work proposes an experimental investigation and optimization of process parameters of the cryogenic assisted turning process during machining of Nimonic C-263 super alloy with a multilayer CVD insert. Taguchi’s L-27 orthogonal array is used plan the experiments. Effect of input parameters viz. cutting speed (N), cutting feed (f), depth of cut (d) are studied on responses viz. surface roughness (SR), nose wear (NW) and cutting forces (F) under hybrid cryogenic (direct+indirect) machining environment. A scanning electron microscope (SEM) analysis is carried out to explore the post-machining outcomes on the performance measures. The multiple responses are converted in to single response and ranked according to Taguchi based gray relational grade (TGRG). Feed rate (f) is found to be the most influential parameter from the analysis of variance of GRG. The means of GRG for each level of process parameters are used to improve the optimal process parameters further. Finally, the confirmative experiment is performed with these optimal set of process parameters which showed an improvement of 9.34% in the value of GRG. The proposed work can be beneficial to choose ideal process conditions to enhance the performance of turning operation.

Synthesis and Characterization of Amine Impregnated Silica Aerogel from Rice Husk for CO2 Adsorption

2020 ◽  
Vol 13 ◽  
Author(s):  
A.R. Hidayu ◽  
N.F. Mohammad ◽  
S.I.S. Jamaludin ◽  
N.F.M.K. Teo ◽  
N.S.M. Sah ◽  
...  
Keyword(s):  
Rice Husk ◽  
Silica Aerogel ◽  
Co2 Adsorption ◽  
Sodium Hydroxide Solution ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Modified Silica ◽  
Rice Husk Silica ◽  
Wide Range

Abstract: Rice husk has attracted considerable attention in the recent years due to its chemical component that are beneficial to a wide range of application. . In this paper, silica aerogel from rice husk ash (RHA) was prepared through sol-gel processing and ambient pressure drying. The silica RHA was extracted with sodium hydroxide solution to produce sodium silicate solution and neutralized with sulphuric acid to form silica gel. Then, the silica aerogel was further modified with amine, which is 3-(aminopropyl) triethoxysilane (APTES) because amine groups provide specific adsorption sides for CO2 adsorption. The functional group, surface morphology and elemental composition of rice husk, silica aerogel and modified silica aerogel were characterized by Fourier transform infrared spectroscopy (FTIR), Scanning Electronic Microscopy (SEM) and Elemental analyser (EA). For amine modified silica aerogel, it was found that the sample consists of N-H band at a certain peak. FTIR and SEM analysis revealed the synthesized silica aerogel has fibrous morphology and indicates similar trend with previous researches. The amine modified silica aerogel (AMSA) is able to adsorb 0.88 mol CO2/kg AMSA. This study shows that the rice husk silica aerogel modified with APTES could enhance the CO2 adsorption performance due to the physisorption and chemisorption

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