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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Mesoporous Adsorbents for Perfluorinated Compounds

Kuvayskaya, Anastasia, Lotsi, Bertha, Mohseni, Ray, Vasiliev, Aleksey 01 October 2020 (has links)
Effective adsorbents for polyfluorinated compounds (PFCs) were obtained and successfully tested in adsorption of perfluorooctanoic and perfluorooctanesulfonic acids. Bridged silsesquioxanes containing secondary and tertiary amino groups were synthesized by sol-gel condensation of bis[3-(trimethoxysilyl)propyl]amine and N-methyl-3,3′-bis(trimethoxysilyl)dipropylamine in acidic media in the presence of surfactants. Obtained materials were mesoporous with high BET surface area. They combine high structural stability with high concentration of surface amino groups serving as adsorption sites. Batch adsorption tests demonstrated their high adsorption capacity on PFCs: in some experiments it reached up to 88% of the adsorbent weight. Adsorption of PFCs changed the surfaces of the adsorbent nanoparticles from hydrophilic to hydrophobic thus providing their agglomeration and floatability. Column tests showed fast adsorption of PFCs even at high concentrations and high flow rates. Obtained results can be used in the development of an effective filtration device for clean-up of water contaminated by PFCs.
2

Polycondensation of Bridged Amino-Functionalized Trialkoxysilanes.

Zhou, Guannan 07 May 2011 (has links) (PDF)
The reduction of CO2 emission has been a worldwide mission to resolve global warming predicament. Mesoporous silsesquioxanes, which stabilized by organobridges and has high content aminon absorption site, can serve as a potential CO2 adsorbent. Synthesis of such material is done by hydrolysis and polycondensation of trialkoxysilane. The fastest gelation was observed at reaction in the absence of acids or bases. However, addition of surfactant to the reaction mixture catalyzed formation of silsesquioxanes in acidic media. Obtained materials are strongly hydrophilic and possess a high thermostability. Study of particle size distributions showed that in all cases it was bimodal. The largest particles formed in basic media. Mesoporous silsesquioxanes were obtained from bridged alkyltrimethoxysilanes in the presence of surfactants.
3

Mesoporous Adsorbents for Perfluorinated Compounds

Lotsi, Bertha 01 May 2020 (has links)
Effective adsorbents for polyfluorinated compounds (PFCs) were successfully prepared. And they were tested in the adsorption of perfluorooctanoic and perfluorooctanesulfonic acids. Bridged silsesquioxanes containing secondary and tertiary amino groups were synthesized by sol-gel condensation of bis[3-(trimethoxysilyl)propyl]amine and bis[3-(methylamino)propyl]-trimethoxysilane in acidic media with surfactants. Obtained materials are mesoporous with a high BET surface area. They combine high structural stability with a high concentration of surface amino groups serving as adsorption sites. Batch adsorption tests demonstrated their extremely high adsorption capacity on PFCs: in some experiments, it reached up to 88% of the adsorbent weight. Adsorption of PFCs changed the surfaces of the adsorbent nanoparticles from hydrophilic to hydrophobic thus providing their agglomeration and floatability. Column tests showed fast adsorption of PFCs even at high concentrations and high flow rates. Obtained results can be used in the development of an effective filtration device for clean-up of water contaminated by PFCs.

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