Preparation and characterization of a novel silica aerogel as adsorbent for toxic organic compounds

Abstract

a b s t r a c tHydrophobic and hydrophilic silica aerogels were prepared from cheap waterglass precursors via surface modification of wet gels, ambient pressure drying (APD) route and calcination treatment. Xerogel was also synthesized as a comparison to test the influence of microstructure on the adsorption behaviours. Ethanol (EtOH)/chlorotrimethylsilane (TMCS)/hexane solution was employed to replace the surface silanol groups (Si OH) with alkyl, and to prevent the condensation and shrinkage of the gel structure during the APD process. The synthesized silica aerogels, characterized by using Fourier transform infrared spectra (FTIR), nitrogen adsorption/desorption measurement, element analyses and differential scanning calorimeter (DSC), etc., are porous and translucent solids with surface area of 546-907 m 2 /g. The transition temperature from hydrophobic to hydrophilic was tested around 395 • C, which corresponds to the disappearance temperature of the CH 3 peaks in FTIR. The materials were tested for adsorption capacities on rhodamine B (RhB) and dieldrin, which represented soluble and slightly soluble organic compounds, respectively. Results showed that the hydrophobic silica aerogel exhibited strong adsorption capacity on slightly soluble organic compounds while hydrophilic silica aerogel was much more effective on adsorbing soluble compounds from aqueous solution. Adsorption properties of the silica aerogel remain stable after 5 adsorption/desorption cycles.

Preparation, Characterization, and Application of Silica Aerogel for Adsorption of Phenol: An In-Depth Isotherm Study

“…ity (up to 99%), and high modification capability (12)(13)(14). Up to now, this adsorbent has been widely applied to remove various toxic compounds, such as heavy metals (14), Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) compounds (15), dyes (11), and so on. As far as the authors are aware, however, there is a limited knowledge about the adsorptive behavior of silica aerogel for phenol removal under various conditions of operation.…”

Anhydrite/aerogel composites for thermal insulation

“…This type of aerogels have undergone a surface modification, which provides the hydrophobic character [32,41,43,54,61,63,68,69,72,74]. In particular, their contact angle with water droplet depends on the silylating agent (non-polar groups) [43,54,61,69].…”

Granulation of Cobalt-containing Nickel Hydroxide with Polyethylene Terephthalate and its Phosphate Ion Adsorption Capability

“…The techniques for aqueous phosphate removal include chemical precipitation, crystallization, adsorption, and biological processes with denitrifying phosphateaccumulating organisms [8][9][10][11][12][13][14]. Among these techniques, the adsorption method is considered to be superior to other techniques for water reuse in terms of cost, simplicity of design, ease of operation, and insensitivity to toxic substances [3,15,16]. A variety of adsorbents have been developed for phosphate removal [17][18][19].…”