Journal of Textile Science & Engineering

Natural dyes which are known to possess antibacterial properties can be safely used for the purpose of antibacterial finishing of natural fibres like wool. Chitosan is a functional biopolymer which can be utilized for various applications in textiles. In the present work bio-waste chitosan was utilized as a mordant in the printing of wool fabric with natural dyes making it eco-friendly. The efficacy of natural mordant chitosan was studied in comparison with alum as a standard mordant. Both the mordants gave prints of similar color values. The printed fabric showed excellent antibacterial properties against both S. aureus and E. coli. This method hence can be suitable for ecofriendly printing and antibacterial finishing of wool fabrics.

In order to improve their affinity to the cationic dyes, cotton and jute cellulosic fibres were chemically modified using natural compounds such as: Tannic acid, Mimosa and cactus juice and commercialized compounds such as Clarite Com, Albatex and Albaflow. Cellulose modifications were performed using physiochemical analysis such as Bohem titration, spectroscopic analysis (FTIR spectroscopy and UV-Vis), the Point of Zero Charge (pHPZC) and the Cationic Exchange Capacity (CEC) determination.

The dyeing performance were evaluated by controlling the percentage of the dye bath exhaustion (E %), the color yield (k/s), the brightness index BI (%) and the dyeing fastness to light, washing and rubbing.

Two cationic dyes CI Basic Red 46 and CI Basic Blue 3 with a delocalised cationic charge were checked for dyeing properties. The pHPZC of modified samples varied from 2.98 to 5.7. The CEC varied from 43meq/g to 82meq/g. This study showed that the color yield and the dyeing fastness were improved for modified cellulosic fabrics. The Bohem titration and FTIR spectrum showed that the acidic sites number on the fabrics increased after using anionic agents.

Madder (Rubia tinctorum L.) has been used for dyeing textiles since the Stone Age. Common madder produces pigments in its roots, such as alizarin, pseudopurpurin, purpurin, munjistin, rubiadin, xanthopurpurin, purpuroxanthin, lucidin, chinizarin, christofin, and antrhagallol. Madder gives a unique red colour to textiles. The aim of this study is to understand the effect of different mordant concentration on silk dyeing by using madder extract. Degummed and bleached, woven silk fabric was used. Alum [KAl(SO₄)₂.12H₂O] was used as mordant. All reagents were analytical grade. Silk fabrics were scoured by soap (35% w/w) at 90°C for 1.5 hours. Liquor ratio was 100:1. Dyeing was performed at 65°C, 100% owf, for 2 hours. Mordanting procedure was achieved at different mordant ratio, for 2 hours, at 65°C. All color measurements were performed using Minolta 3600D spectrophotometer (D65 illuminant, specular included, 10° observer angle). Colour fastness to washing, light, perspiration and rubbing was performed according to ISO 105 C06, ISO 105 B02, ISO 105 E04 and ISO 105 X12 respectively. Each dyed silk fabrics were analysed RP-HPLC-DAD. Semi-quantities of colouring compounds were determined in the dyed silk fabrics, depending on the amounts of mordant metal.

Iron oxide nanoparticles (Fe₂O₃ NPs) were prepared by mixing iron(II) sulfate (FeSO4) and hydrogen peroxide (H₂O₂) in aqueous solution at pH 3. Fe₂O₃ NPs are used to degrade Reactive Red-84 (RR-84) azo dye in a glass annular photo-reactor using a white light lamp. The presence of Fe₂O₃ NPs was verified by HRTEM analyses. Kinetic studies were made varying the reagents concentration and the reaction rate was controlled increasing the concentration of iron ions in comparison with H₂O₂. Langmuir-Hinshelwood (L-H) kinetic model was performed to analyze heterogeneous catalytic reactions under illumination conditions. The elimination process of azo dye followed the pseudo first-order kinetic according to L-H model. The adsorption process of the azo dye on the catalytic surface was determinant for the dye photodecomposition. The linear expression of the Langmuir adsorption isotherm under darkness was further used to establish the maximum amount of dye adsorbed Q_max=0.80 ± 0.18 mg*mg_catalyst^-1 and the adsorption constant k_ads=0.016 ± 0.004 L*mg-1. The Langmuir-Hinshelwood equilibrium constant for dye adsorption under illumination conditions was K_L-H=0.03 ± 0.02 L*mg-1. This similarity with adsorption constants could depict an evidence which suggest that Fe₂O₃ NPs are presents in Fenton´s reaction (FeSO4/H₂O₂) interacting as catalysts in the degradation of organic substrates.

Pre-treated Cotton/polyester blended fabrics were printed with kayacelon reactive/disperse dyes in one step process using slightly acidic medium (pH 6). The blended fabrics were introduced to enzymatic and alkaline treatment, (each separately). Several factors affecting both treatments were studied in details. The results addressed a remarkable improvement in both color strength and fastness properties for printed blend fabric; as well a comparison was obtained concerning the environmental impact.