Preparation of a biopolymer chitosan-polypropylene imine (CS-PPI) as a biocompatible adsorbent and its reactive textile dyes removal potential were performed. Chemical specifications of CS-PPI were determined using Fourier transform infrared, 1 H-NMR, and 13 C-NMR. The surface morphology of the CS-PPI surface was characterized by scanning electron microscopy. Results confirmed that the linkages between the NH 2 groups of PPI dendrimer and carboxylic groups of modified Chitosan were accomplished chemically. Two textile reactive dyes, reactive black 5 (RB5) and reactive red 198 (RR198), were used as model compounds. A response surface methodology was applied to estimate the simple and combined effects of the operating variables, including pH, dye concentration, time contact, and temperature. Under the optimal values of process parameters, the dye removal performance of 97 and 99% was achieved for RB5 and RR198, respectively. Furthermore, the isotherm and kinetic models of dyes adsorption were performed. Adsorption data represented that both examined dye followed the Langmuir isotherm. The adsorption kinetics of both reactive dyes were satisfied by pseudo-second order equation. Based on this study, CS-PPI due to having high adsorption capacity (6250 mg/g for RB5 and 5882.35 mg/g for RR198), biocompatibility and ecofriendly properties might be a suitable adsorbent for removal of reactive dyes from colored solutions.

Cotton fabric was successfully modified by chitosan-poly(propylene imine) dendrimer hybrid (CS-PPI). Cationization of cotton was conformed through zeta potential test. The effects of grafting variables, CS-PPI concentration, pH, time, and temperature on grafting yield were investigated using both salt-free and conventional reactive dyeing processes. Optimal grafting parameters were found to be CS-PPI concentration of 20 % owf, pH 6, grafting reaction temperature of 50 o C, and time of 18 h. Color strength of dyed modified cotton was markedly enhanced in absence of electrolyte or alkali. Dye build-up of modified cotton in salt-free dyeing was higher than that of raw cotton dyed by conventional method. Moreover, the amount of dye fixed on modified cotton was markedly higher than that of virgin cotton. Wash, light, and rubbing fastness and mechanical properties of dyed modified cotton were satisfactory. The results clearly demonstrated high potential of CS-PPI hybrid as a promising bio-compatible compound for eco-benign modification and salt free reactive dyeing of cotton fabrics with satisfactory properties.

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The solubility of naphthalimide-based monoazo dyes containing N-ethyl and N-ethanoic acid groups was investigated in the presence of a conventional monomeric counterpart (DTAB) and two cationic gemini surfactants (12-4-12 or 14-4-14) individually. The effective parameters on dye solubility such as temperature, time and concentration of surfactants were investigated by UVVisible spectrophotometry. The results demonstrate that the solubility of both dyes was considerably increased at concentrations above the surfactant CMC. The wavelength for the maximum absorbance of dyes in the aqueous solution shifts toward longer wavelengths with changes in the concentration of the cationic surfactants. A kinetic study of solubilization of dyes in cationic surfactants solution showed that the rate of solubilization follows the pseudo-first-order reactions. Rates of solubilization were in the range of 0.5 9 10 -3 to 6.8 9 10 -3 min -1 for both dyes. The disperse dye containing a carboxylic acid group (dye 2) has a higher solubility rate than the dye containing an alkyl group (dye 1). The type of surfactant has a very low effect on adsorption of dye 1 onto the polyester fibers, whereas changing the surfactant type from DTAB to 12-4-12 or 14-4-14 causes adsorption of dye 2 on polyester to decrease.

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