Adsorption of Short-Chain Alcohols by Hydrophobic Silica Aerogels

Abstract

The hydrophobic silica aerogel Cabot Nanogel TLD302 was evaluated as an adsorbent for recovering 2–5 carbon n-alcohols from aqueous solutions. Whereas intraparticle transport limitations restricted adsorption under dilute conditions, at higher concentrations, improved surface wetting resulted in facile “pore intrusion” and ∼5-fold increases in adsorption capacity for all alcohols. To promote surface wetting and pore intrusion at lower concentrations, partial oxidation of TLD302 was performed by heat treatment to create a series of novel aerogel materials with tunable surface hydrophobicities. An optimum surface oxidation state was found to exist wherein pore intrusion under dilute conditions was achieved while still balancing high adsorption affinity. Lastly, the optimized aerogel adsorbent was used to recover n-butanol from a Clostridium acetobutylicum ATCC 824 fermentation broth. Relative to model solutions, no loss of adsorption affinity or capacity was observed, indicating that competitive coadsorption by other media components was not a performance-limiting factor.

Biovalorisation of liquid and gaseous effluents of oil refinery and petrochemical industry

“…This indicates the non-ionic characteristics of the NtBA/AA gel. Therefore, it can be expected that these gels are unable to undergo sufficient dissociation into ions, particularly in the case of relatively polar solvents like methanol and water to produce the necessary osmotic pressure difference that is usually responsible for swelling (Weihn et al, 2013.…”

“…Here, the value of ∆G0 = -4.18 kJ/mol for the Langmuir isotherm. This observation indicates that the adsorption can be readily reversed, a necessity for adsorbent regeneration and ultimate recovery of the alcohol (Weihn et al, 2013) As the negative ∆G0 is not too high (i.e., not too much negative), a strong interaction such as chemisorption does not appear to take place at the interface, i.e. a weak interaction as the Van der Waals interaction is operative at the interface.…”

Quest for sustainable bio-production and recovery of butanol as a promising solution to fossil fuel

“…Accordingly, butanol is first adsorbed by a suitable adsorbent from the fermentation broth and subsequently desorbed by heat treatment or using displacers in order to obtain a more concentrated biobutanol solution (Figure 5b). For example, Wiehn et al (2013) did not observe any difference in biobutanol adsorption capacity when partially oxidized silica aerogel (Cabot Nanogel TLD302 at 330°C for 8 h) performance was tested both in model solutions and complex fermentation broths [219]. For example, Wiehn et al (2013) did not observe any difference in biobutanol adsorption capacity when partially oxidized silica aerogel (Cabot Nanogel TLD302 at 330°C for 8 h) performance was tested both in model solutions and complex fermentation broths [219].…”

“…Main factors affecting adsorption efficiency include selectivity for butanol over other components present in the media, adsorption and desorption rate, adsorption and desorption capacity (which is related to the surface area, pore structure and surface functional groups), adsorbent integrity after long-term application and material cost. For example, Wiehn et al (2013) did not observe any difference in biobutanol adsorption capacity when partially oxidized silica aerogel (Cabot Nanogel TLD302 at 330°C for 8 h) performance was tested both in model solutions and complex fermentation broths [219].…”

Anisotropic Cellulose Nanofibers/Polyvinyl Alcohol/Graphene Aerogels Fabricated by Directional Freeze-drying as Effective Oil Adsorbents

“…Traditional methods for dealing with petroleum pollution include the following methods: physical and mechanical methods [4], direct combustion methods [5], bioremediation methods [6], chemical treatment methods [7] and dosing materials [8], in which the adsorption of adsorbent materials is simple and environmentally friendly. The oil-absorbing materials reported in the literature can be summarized into three categories according to the nature and source of the materials: (1) porous inorganic minerals such as clay [9], silica [10], perlite [11], fly ash [12], etc. These materials come from a wide range of sources, which have low oil absorption, poor oil holding capacity, and difficulty in recycling; (2) synthetic polymers such as polyurethane [13], polystyrene foam [14].…”