An adsorption and kinetic study of lac dyeing on silk

ผลงานวิชาการคณาจารย์มหาวิทยาลัยเทคโนโลยีสุรนาร

Biosorption of lac dye by the red marine alga Gracilaria tenuistipitata: biosorption kinetics, isotherms, and thermodynamic parameters

The hypothesis that the dried, ground biomass of the red marine alga Gracilaria tenuistipitata could be used for the efficient removal of lac dye from aqueous solution was assessed in this work. The effects of parameters such as initial pH, biosorbent dosage, contact time, initial dye concentration, and temperature on the biosorption capacity of the dye were investigated. Equilibrium data were analysed using Langmuir, Freundlich, and Temkin isotherm models, and the Freundlich model provided the highest coefficient of determination values. Biosorption kinetic data were successfully described with a pseudo-second-order model at initial dye concentrations of 50, 80, 100, and 120 mg l−1. The thermodynamic parameters of biosorption - enthalpy change (∆H° = −30.64 kJ mol−1), free energy change (∆G° = 4.32 kJ mol−1 at 303 K to 7.78 kJ mol−1 at 333 K), and entropy change (∆S° = −115.38 J mol−1 K−1) - were determined. The negative value of the enthalpy change and positive values of the free energy change indicate that the biosorption process is exothermic and non-spontaneous. The negative value of the entropy change is consistent with decreased randomness at the solid-liquid interface with dye biosorption. Attenuated total reflectance-Fourier transform infrared spectroscopic analysis confirmed the presence of lac dye on the G. tenuistipitata material. The efficiency of lac dye removal by this biomass material at 20 g l−1 and with an initial dye concentration of 50 mg l−1 in acidic solution was 71%, which indicated its potential usefulness as a new dye biosorbent

Additive effects on cotton dyeing with dye extract from achiote seeds

466-474Cotton yarns have been pretreated with the additives, such as chitosan, microcrystalline chitosan, quaternized chitosan & aqueous extract from the fruit of Diospyros mollis Griff, as well as with the commercial formaldehyde-free cationic fixing agent (Sera® Fast C-NC) & alum (post-mordanting), and their dyeing fastness properties are studied. These treated cotton yarns are then dyed with the annatto dye extract from Bixa orellana L. (Achiote) seeds and tested for different properties including K/S value, light fastness, and wash fastness. Pre-treatment of cotton yarn with chitosan or microcrystalline chitosan solution (together with glyoxal cross-linking) or quaternized chitosan, or Sera® Fast C-NC before dyeing, shows a better color depth (K/S) and improved wash fastness properties in comparison to yarn with alum post-mordanting and the untreated cotton yarn. Improved light fastness is also obtained on inclusion of the anti-oxidant ascorbic acid in the post-treatment protocol. These additive treatments thus offer considerable potential for the improved annatto dyeing of cotton

Additive effects on cotton dyeing with dye extract from achiote seeds

Cotton yarns have been pretreated with the additives, such as chitosan, microcrystalline chitosan, quaternized chitosan &aqueous extract from the fruit of Diospyros mollis Griff, as well as with the commercial formaldehyde-free cationic fixingagent (Sera® Fast C-NC) & alum (post-mordanting), and their dyeing fastness properties are studied. These treated cottonyarns are then dyed with the annatto dye extract from Bixa orellana L. (Achiote) seeds and tested for different propertiesincluding K/S value, light fastness, and wash fastness. Pre-treatment of cotton yarn with chitosan or microcrystallinechitosan solution (together with glyoxal cross-linking) or quaternized chitosan, or Sera® Fast C-NC before dyeing, shows abetter color depth (K/S) and improved wash fastness properties in comparison to yarn with alum post-mordanting and theuntreated cotton yarn. Improved light fastness is also obtained on inclusion of the anti-oxidant ascorbic acid in the posttreatmentprotocol. These additive treatments thus offer considerable potential for the improved annatto dyeing of cotton

An absorption spectroscopic investigation of the interaction of lac dyes with metal ions.

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