Reactive and basic dyes removal by sorption onto chitosan derivatives.
ABSTRACT In this study, the removal of a reactive (Remazol Yellow Gelb 3RS) and a basic (Basic Yellow 37) dye from aqueous solutions was investigated using cross-linked chitosan derivatives as sorbents (either powder or beads), which have been grafted with carboxyl and amide groups. The sorption behavior of the materials was examined through equilibrium, kinetic and pH-edges experiments. The reuse of sorbents was affirmed by sequential sorption-desorption cycles. Three isotherms (Langmuir, Freundlich, and Langmuir-Freundlich) were used to fit the equilibrium data, while the pseudo-second order equation for the kinetic data. Chitosan powder presented higher sorption capacity than beads. Chitosan grafted with amide groups was found superior sorbent for reactive dye at pH 2 (Q(max)=1211 mg/g), while chitosan grafted with carboxyl groups for basic dye at pH 10 (Q(max)=595 mg/g). For both cases the optimum contact time was 4 h using 1 g/L sorbent. The characterization of sorbents was achieved by scanning electron microscopy, particle size analysis and FTIR spectroscopy.
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ABSTRACT: Functionalized silica hybrid materials are extensively studied and applied materials in the field of science and technology. Functionalization is an approach, which allows for the application of organic components in the improvement of the design, properties and potential application of silicate materials. Silica hybrid materials, functionalized via incorporation of organic components (chitosan and methacrylic acid) were synthesized by the sol-gel method. The base silica structure of the hybrids was obtained via hydrolysis and condensation of the silicate precursor, tetraethyl orthosilicate. The investigations of synthesized hybrids are focused on the influence of the nature and quantity of functional organic components on their final structures and properties. The structural characteristics of obtained hybrid materials were investigated using XRD, FTIR, SEM and DTA/TG analysis. The obtained results presented the formation of amorphous porous structure and the organic components are evenly distributed into the silica network. The functional radicals of chitosan and methacrylic acid (amine, hydroxyl groups) exist in the hybrid structure as free reactive centers, as their quantity increases with increasing the organic amount. The swelling behavior in acidic and neutral solutions of the synthesized materials is investigated and the results presented, that the silicate materials exhibit hydrophilic character.Open Journal of Inorganic Non-metallic Materials 07/2014; 4(3):35-43.
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ABSTRACT: Chitosan based adsorbents have received a lot of attention for adsorption of dyes. Various modifications of this polysaccharide have been investigated to improve the adsorption properties as well as mechanical and physical characteristics of chitosan. This review paper discusses major research topics related to chitosan and its derivatives for application in the removal of dyes from water. Modification of chitosan changes the original properties of this material so that it can be more suitable for adsorption of different types of dye. Many chitosan derivatives have been obtained through chemical and physical modifications of raw chitosan that include cross-linking, grafting and impregnation of the chitosan backbone. Better understanding of these varieties and their affinity towards different types of dye can help future research to be properly oriented to address knowledge gaps in this area. This review provides better opportunity for researchers to better explore the potential of chitosan-derived adsorbents for removal of a great variety of dyes.Carbohydrate Polymers 07/2014; · 3.92 Impact Factor
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ABSTRACT: In this work, a grafted (with carboxylic groups) chitosan material was synthesized and the adsorption mechanism of a basic dye (Remarcyl Red TGL denoted as CR) and a heavy metal (Zn) was investigated both in single-component and binary solutions. The reaction of succinic anhydride (SUC) with chitosan (CS) inserted a large number of carboxylic groups and the final chitosan-grafted material (abbreviated as CSUC) presented improved adsorption properties. A common phenomenon in the wastewater treatment science is the simultaneous existence of different-type pollutants (dyes, heavy metals etc). The adsorption behavior of the material prepared (CSUC) was tested as multi-adsorbent for the simultaneous removal of Zn and CR from simulated wastewaters. CSUC was characterized using various techniques as SEM, XRD, and TGA, while the variety of adsorption interactions dominated in different pH-conditions (electrostatic forces, hydrogen bonding, chelation etc) were confirmed with FTIR spectroscopy. The calculation of adsorption rate and maximum adsorption capacity were done using kinetic tests (pseudo-second order equation) and isotherms curves (Langmuir-Freundlich model), respectively. The antagonistic adsorption of CR or/and Zn was confirmed with selectivity experiments in binary mixtures. The reuse of this super-adsorbent was also proved with a series of 40 cycles of sequential adsorption and desorption modules.Chemical Engineering Journal 01/2015; 259:438-448. · 3.47 Impact Factor