Application of hydrophobic silica based aerogels and xerogels for removal of toxic organic compounds from aqueous solutions

Perdigoto, M.L.N.; Martins, Rui C.; Rocha, Nuno; Quina, Margarida J.; Gando-Ferreira, Licínio M.; Patrício, R.; Durães, Luísa

doi:10.1016/j.jcis.2012.04.062

Cited by 113 publications

(48 citation statements)

References 25 publications

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“…Silica aerogels have also been used for making heat storage devices used in window defrosting and as acoustic barrier materials [5]. Other aerogels have been demonstrated as battery electrodes [6], catalyst supports [7], and oxygen and humidity sensors [8] and adsorbents for environmental clean-up [9] due to their large internal surface areas and facile changing of their surface chemistry. The low values of thermal conductivity and the very low density make silica aerogels attractive materials for a number of aerospace applications.…”

Section: Introductionmentioning

confidence: 99%

An overview on silica aerogels synthesis and different mechanical reinforcing strategies

Maleki

Durães

Portugal

2014

Journal of Non-Crystalline Solids

574

298

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Silica aerogels are lightweight and highly porous materials, with a three-dimensional network of silica particles, which are obtained by extracting the liquid phase of silica gels under supercritical conditions. Due to their outstanding characteristics, such as extremely low thermal conductivity, low density, high porosity and high specific surface area, they have found excellent potential application for thermal insulation systems in aeronautical/aerospace and earthly domains, for environment clean up and protection, heat storage devices, transparent windows systems, thickening agents in paints, etc. However, native silica aerogels are fragile and sensitive at relatively low stresses, which limit their application. More durable aerogels, with higher strength and stiffness, can be obtained by proper selection of the silane precursors, and constructing the silica inorganic networks by compounding them with different organic polymers or different fiber networks. Recent studies showed that adding flexible organic polymers to the hydroxyl groups on the silica gel surface would be an effective mechanical reinforcing method of silica aerogels. More versatile polymer reinforcement approach can be readily achieved if proper functional groups are introduced on the surface of silica aerogels and then copolymerized with appropriate organic monomers. The mechanical reinforced silica aerogels, with their very open texture, can be an outstanding thermal insulator material for different industrial and aerospace applications. This paper presents a review of the literature on the methods for mechanical reinforcing of silica aerogels and discusses the recent achievements in improving the strength and elastic response of native silica aerogels along with cost effectiveness of each methodology.

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Section: Introductionmentioning

confidence: 99%

An overview on silica aerogels synthesis and different mechanical reinforcing strategies

Maleki

Durães

Portugal

2014

Journal of Non-Crystalline Solids

574

298

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“…The low values of thermal conductivity, very low density, extreme porosity and high specific surface area make silica aerogels attractive materials for a number of aerospace and industrial applications [1]. Examples of these applications involve the use of silica aerogels for environment clean up and protection [2][3][4], battery electrodes [5], catalyst supports [6], oxygen and humidity sensors [7], aerosol particle collectors [8], space mirror protectors and others [9,10]. The majority of silica aerogel applications concerned the development of efficient thermal insulator materials, especially for building, aeronautical and aerospace domains [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of lightweight polymer-reinforced silica aerogels with improved mechanical and thermal insulation properties for space applications

Maleki

Durães

Portugal

2014

Microporous and Mesoporous Materials

116

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Cross-linking of silica aerogels with organic polymers is an effective way to overcome their fragility and poor mechanical properties. It has also been shown that adjusting the nanoskeleton of silica aerogels using different silica precursors can lead to improved mechanical properties, mesoporosity and thermal conductivity. In this paper, the effect of the incorporation of 1,6-bis(trimethoxysilyl)hexane (BTMSH) and 1,4-bis(triethoxysilyl)-benzene (BTESB) into the underlying silica structure of tri-methacrylate crosslinked silica aerogels is examined. In order to attain a simple, cost and time effective procedure, the sol-gel process and addition of organic monomers are performed in one single step. The effect of the amount of silicon derived from alkyl-linked and aryl-linked bis-silane precursors as well as the effect of the cross-linker concentration on the mechanical strength, thermal conductivity, porosity and other properties of the synthesized aerogels are studied. Different reinforced silica aerogels with density range from 0.13 to 0.39 g cm À3 , compression strength from 11 to 400 kPa and thermal conductivity of 0.039-0.093 W m À1 K À1 were obtained. The cross-linked aerogels made by replacing 5-10 mol% of total silicon by BTESB showed a drastic improvement in their surface area and thermal insulation properties along with an increase in the mechanical strength. The surface area and thermal insulation improvements obtained for aryl-bridged polysiloxanes were attributed to the aryl spacer within the aerogels body, which leads to aerogel with high extent of porosity or pore volume when compared to the alkyl-bridged polysiloxanes. Therefore, for the first time we were able to show the dependency of thermal conductivity values on the silica structure by proper designing the mesoporosity of the resulting aerogels.

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“…The removal of phenolic compounds from wastewaters is also crucial to comply with the International Legislation, being their adsorption a conventional and effective route for industrial effluents, usually using activated carbon [1][2][3]. Adsorbents with high selectivity and adsorption capacity are needed, and the silica-based aerogels are promising materials and have attracted great interest for this purpose due to their extremely high porosity/surface area, chemical versatility and possibility of reutilization [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…The literature results described above allow concluding that the hydrophobic/hydrophilic interactions between the silica-based adsorbent and the phenolic compounds are complex and very important to the adsorption capacity of the adsorbents. In an earlier work [4], we had tested MTMS-derived aerogels and xerogels, which were highly porous, flexible and hydrophobic [21][22][23], to the adsorption of the aromatic solvents benzene, toluene and phenol from water. The higher adsorption capacities were obtained for the aerogel in the cases of toluene (173 mg g −1 ) and benzene (192 mg g −1 ), which were remarkably high when compared to the available literature data.…”

Section: Introductionmentioning

confidence: 99%

Silica-based aerogels as adsorbents for phenol-derivative compounds

Matias

Marques

Quina

et al. 2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Application of hydrophobic silica based aerogels and xerogels for removal of toxic organic compounds from aqueous solutions

Cited by 113 publications

References 25 publications

An overview on silica aerogels synthesis and different mechanical reinforcing strategies

An overview on silica aerogels synthesis and different mechanical reinforcing strategies

Synthesis of lightweight polymer-reinforced silica aerogels with improved mechanical and thermal insulation properties for space applications

Silica-based aerogels as adsorbents for phenol-derivative compounds

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