Modified cellulose fibres for adsorption of dissolved organic solutes

Abstract

Cellulose fibres were grafted with aliphatic anhydrides having C6, C8, C12 and C16 chain length using a heterogeneous solvent exchange acylation procedure. The ensuing materials were fully characterised by FTIR, solid state 13 C-NMR, Wide-angle X-ray scattering and contact angle measurements. These techniques showed that the chemical coupling has indeed occurred. The prepared modified fibres appeared to be efficient to trap different organic molecules dissolved in water. Recycling tests revealed that the saturated substrates could be regenerated tens of times without loosing their capacity of absorption of organic contaminants.

Surface Photochemistry: Benzophenone as a Probe for the Study of Modified Cellulose Fibres

“…Indeed, as we have shown previously [15,16], grafting of linear alkyl chains on the fibre's surface boosts its capacity to uptake organic solutes from aqueous solution. By ensuring grafted alkyl chains, one gives rise to hydrophobic domains on which organic solutes can be accumulated.…”

“…remained into the powdered substrate (i.e., an increase in the retention capacity of the powdered substrate of about twelve times when compared to previous reported results) was obtained with nonmodified cellulose [15]. In both cases, the final solvent removal was performed for about two hours in an acrylic chamber with an electrically heated shelf (Heto, Model FD 1.0-110) with temperature control (30 ± 1…”

“…Benzophenone (Koch-Light, Scintillation grade) and ethanol (Merck, LiChrosolv grade) were also used as received. The preparation of the modified cellulose fibres started with the use of microcrystalline cellulose and involved an acylation reaction based on a solvent exchange procedure, as described in detail in [15]. The aliphatic anhydrides have 12 carbon atoms (C12) per alkyl chain and the final modified cellulose has 1500 (C12-1500) or 1700 (C12-1700) micromoles of alkyl chains per gram of cellulose [15].…”

“…The modification consists in grafting with alkyl chains, bearing 12 carbon atoms, by surface esterification with a high density of alkyl chains [15], therefore, transforming the polar surface of the normal cellulose into surfaces with a certain degree of nonpolar character. A comparison of the photochemical behaviour of BZP in modified and nonmodified celluloses was made.…”

“…Benzophenone adsorption on samples was performed using two methods: the solvent evaporation method for the case of ethanol [14], and, also, adsorption from water [15]. The former method consists in the addition of an ethanolic solution containing the probe to the previously dried powdered solid substrate, followed by solvent evaporation from the stirred slurry in a fume cupboard.…”