Surface characterization and adsorption abilities of cellulose fibers (original) (raw)
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Reactivity and electrokinetical properties of different types of regenerated cellulose fibres
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2001
Natural cellulose fibers (cotton) comprise several noncellulose compounds (hemicellulose, wax and pectin substances) and cationic impurities which cause problems during different adsorption processes such as dying, or final fiber finishing and coating. Therefore the chemical purification (NaOH boiling, enzymatic purification, demineralization, extraction or oxidative bleaching) is the most important step in cellulose textile finishing. Alternative ways to describe the success of different processes in fiber purification which result in distinct surface charge and hydrophilicity are the determination of electrokinetic properties and the water uptake of textile fibers. The zeta-potential (f) was determined by streaming potential measurement as a function of the pH. From the f-pH functions the adsorption potential for all ionic species
Modified cellulose fibres for adsorption of organic compound in aqueous solution
Separation and purification technology, 2006
This paper presents the results of an experimental study of removal of organic contaminant from wastewater using chemically modified cellulose fibres. The adsorption capacities of the modified fibres towards various organic molecules were investigated. The ensuing modified fibres appeared to be efficient absorbent for different dissolved organic molecules in water. The recycling tests revealed that the exhausted substrates could be regenerated without loosing their capacity. The adsorption isotherm related to different solutes follows the Langmuir model in entire range of concentration. To confirm the possibility of using the modified cellulose fibres as a sorbent for the removal of dissolved organic pollutant, adsorption breakthrough curves were established under different operating condition such as concentration, flow rate and the column length. The main advantage of this substrate lies in its relative facile regeneration without a significant loss of its adsorption capacity.
Adsorption of four non-ionic cellulose derivatives on cellulose model surfaces
Cellulose, 2013
The adsorption of four commercial nonionic cellulose derivatives onto two different model surfaces of cellulose fibres has been studied with surface plasmon reflectance. The model surfaces of cellulose were ultrathin films of either nano fibrillated cellulose or regenerated cellulose on Au(s). Partial least squares models were used in the analysis of the data and it was found that the type of cellulose model surface seems to be most important for both the total adsorption and the initial adsorption rate of the studied cellulose derivatives. It is believed that this can be explained by morphological differences between the surfaces, and it was found that the properties of the cellulose derivatives that affect the adsorption of the two types of cellulose surface differ. For adsorption onto a NFC-based model surface, the type of cellulose derivative and the polydispersity index (PDI) of the cellulose derivative seem to be the two most important variables for the observed adsorption of these cellulose derivatives. For the regenerated cellulose surface the three most important variables are the M n of the cellulose derivatives, the DS NMR of the methyl celluloses, and PDI of the cellulose derivatives. Thus the adsorption of cellulose derivatives on the NFCbased cellulose model surface is strongly affected by the type of substituent, while the same cannot be said for a surface regenerated from N-methylmorpholine-N-oxide. Additionally, the DS NMR of methyl celluloses affects their adsorption differently on the investigated cellulose model surfaces.
Studies on the Cellulose-Binding Domains Adsorption to Cellulose
Langmuir, 2004
Cellulose-binding domains (CBD) are modular peptides, present in many glycanases, which anchor these enzymes to the substrate. In this work, the effect of CBD adsorption on the surface properties of a model cellulose, Whatman CF11, was studied. The methods applied include inverse gas chromatography (IGC), ESCA, X-ray diffraction, and scanning electron microscopy (SEM). The CBD partition affinity (0.85 L/g) was calculated from adsorption isotherms. However, true adsorption equilibrium does not exist, since CBDs are apparently irreversibly adsorbed to the fibers. Both IGC and ESCA showed that fibers with adsorbed CBD have a lower acidic character and also a slightly higher affinity toward aliphatic molecules. This may however be a consequence of an increased surface area, a hypothesis that is supported by microscopic observations. The crystallinity index was not affected by CBD treatment.
Modified cellulose fibres for adsorption of dissolved organic solutes
Cellulose, 2006
This paper presents the results of an experimental study of removal of organic contaminant from wastewater using chemically modified cellulose fibres. The adsorption capacities of the modified fibres towards various organic molecules were investigated. The ensuing modified fibres appeared to be efficient absorbent for different dissolved organic molecules in water. The recycling tests revealed that the exhausted substrates could be regenerated without loosing their capacity. The adsorption isotherm related to different solutes follows the Langmuir model in entire range of concentration. To confirm the possibility of using the modified cellulose fibres as a sorbent for the removal of dissolved organic pollutant, adsorption breakthrough curves were established under different operating condition such as concentration, flow rate and the column length. The main advantage of this substrate lies in its relative facile regeneration without a significant loss of its adsorption capacity.
Colloids and Surfaces A-physicochemical and Engineering Aspects, 2004
Adsorption kinetics and equilibrium studies of sodium dodecylbenzenesulfonate (NaDBS) on cellulosic surface are investigated. Modifications in adsorption induced by cationic surfactant cetyltrimethylammonium bromide (CTAB) are studied. It is concluded that the rate of adsorption and the amount of adsorption are increased. Importance of these observations in detergency is indicated.
Anion specific adsorption of carboxymethyl cellulose on cellulose
Integration of fiber modification step with modern pulp mill is a resource efficient way to produce functional fibers. Motivated by the need to integrate polymer adsorption with the current pulping system, anion-specific effects in Carboxymethylcellulose (CMC) adsorption have been studied. The QCM-D adsorption experiments revealed that the CMC adsorption to the cellulose model surface is prone to anion-specific effects. A correlation was observed between the adsorbed CMC and the degree of hydration of the co-ions present in the magnesium salts. The presence of chaotropic co-ion such as nitrate increased the adsorption of CMC on cellulose compared to the presence of the kosmotropic sulfate co-ion. However, anion-specificity was not significant in the case of salts containing zinc cations. The hydration of anions determines the distribution of ions at the interface. Chaotropic ions, such as nitrates, are likely to be distributed near the chaotropic cellulose surface, causing changes i...
Colloid and Polymer Science, 2004
Surfactant adsorption at the solid-liquid interface is a phenomenon of significant importance for many industrial processes, such as selective flotation [1], cosmetic formulation, paint technology, and ceramic processing. The study of the adsorption of ionic surfactants on charged surfaces has led to the concept of aggregation and self-assembly of the surfactant at the solid-liquid interface . Three models for the adsorbed layer structure have been proposed. The reverse orientation model, first proposed by Somasundaran and Fuerstenau [7,, is based on a sequence of four steps for the surfactant adsorption. The first involves the individual surfactant adsorption via an ion-exchange mechanism exclusively; in the second step, the aggregation into hemimicelles takes place as a result of the reorganization, accompanied by an association process, which led to the formation of a surfactant monolayer oriented with the head groups in contact with the solid surface; the third step considers the increase of the density of the aggregated domains through further surfactant adsorption; finally, the fourth step involves the formation of bilayerorganized structures which saturate the surface. The second model, proposed by Harwell et al. , differs slightly from the previous one, in that patches of bilayer structures, termed admicelles, are formed as soon as the concentration of free surfactant attains a critical level, without hemimicelle formation at lower surfactant concentrations. A different model was proposed by Gu and coworkers , according to which the surfactant adsorption proceeds through two phases: the first results from electrostatic interactions between the surfactant head groups and the surface charges and the second involves lateral interactions among the alkyl chains which induce the formation of a bundle of adsorbed surface micelles that become progressively more closely packed as further surfactant is adsorbed.
Adsorption of a Cationic Surfactant onto Cellulosic Fibers I. Surface Charge Effects
Langmuir, 2005
This paper reports on a flowable lignocellulosic thermoplastic prepared from forestry biomass by solvent-free acetylation. The non-solvent approach relies upon a functionalizing agent derived from benzethonium chloride (hyamine) and sulfuric acid, which was chosen for its similar wetting attributes to an ionic liquid for the lignocellulose but was much less inexpensive to use. Besides acetylation, this functionalizing agent became chemically bonded to the lignocellulose by the sulfate group formed in situ, as demonstrated by 13 C NMR, infrared and elemental analysis. This attached species appeared to contribute strongly to the flowable nature of the product. The modified material showed good melt flowability by compression molding, as demonstrated in this study by the production of semi-transparent films and was characterized by differential scanning calorimetry and dynamic mechanical analysis. An experimental investigation of reaction parameters was included in the study, exploring the mechanism by which the cationic functionalizing agent modified the structure of lignocellulose.