Recovery of Direct Dye and Acid Dye by Adsorption on Chitosan Fiber – Equilibria

Abstract

The recovery of direct dye and acid dye from dilute aqueous solution by adsorption on chitosan fiber, which is cheaper than an activated carbon fiber, appeared technically and economically feasible. The amounts of adsorption of Brilliant Yellow (direct dye) and Acid Orange II (acid dye) on the chitosan fiber were much larger than that for the activated carbon fiber, though these dyes were adsorbed well on the activated carbon fiber too. The experimental equilibrium isotherms were correlated by B.E.T. equation for a finite number of layers. The equilibrium isotherm was affected by the initial concentration of the dye and temperature considerably, but was little affected by coexisting salt NaCl. These dyes were desorbed by dilute aqueous solution of caustic soda, e.g. at 20mol/m3, irreversibly.

Synthesis of chemically modified chitosans with a higher fatty acid glycidyl and their adsorption abilities for anionic and cationic dyes

“…The great dependence of the amount of the bound dye on the pH value of the adsorption bath can be seen, because an acid dye binds to the protonated amino groups 4 in the substrate, and the amounts of the protonated amino group can increase with the drop in the pH of the bath. Therefore, Red 1 was almost adsorbed on the substrate in the buffer solution of pH 7.0, in which the protonated amino groups are only slightly present in the substrate as shown in Figure 4.…”

Degradation of dye solution by an activated carbon fiber electrode electrolysis system

“…However, there are many functional groups on its surface, such as =C=O. This material can greatly adsorb significant amounts of pollutants, such as trihalomethanes, bromoform, atrazine, dyes and natural organic matters [11][12][13][14][15] or react with them chemically or physically [16,17]. It is also reported that pH value and temperature has no significant effect on its adsorptive capacity [13].…”

Preparation and Characterisation of Novel Biodegradable Material Based on Chitosan and Poly(Itaconic Acid) as Adsorbent for Removal of Reactive Orange 16 Dye from Wastewater

“…These results are expected because in the case of chitosan, the pKa value of the amino group (R-NH 2 ) in the structure of chitosan is 6.3 (Uzun 2006), so at lower pH values the deacetylated amino groups in chitosan will be protonated to form -NH 3 + groups and subsequently interact with the sulfonyl groups of acid dye to form the NH 3 + − O 3 SR organic complex. In other words, at acidic pH values protonated amino groups will enhance the electrostatic attractions between dye anions and adsorption sites of chitosan and increase dye adsorption (Guibal 2004;Yoshida et al 1991). The adsorption capacity decreases in alkaline solution because of deprotonating amine groups in chitosan, resulting in poor reaction between adsorbent and dye.…”