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Dyeing and printing are important steps in textile manufacturing. After the process completion, these dyes are released in the effluent. These dyes impart an unacceptable appearance but are also toxic to the soil and water bodies. The present research has been carried out to study the rate of photocatalytic degradation of an azo dye, namely, CI Direct Green 26, using titania nanoparticles under ultra violet (UV) irradiation as a function of temperature and time. Azo dyes account for the majority of all dyestuffs are produced and extensively used in the textile, paper, food, leather, cosmetics and pharmaceutical industries. Titania nanoparticles have been found to successfully degrade these dyes in the presence of UV light. The purpose of the present paper was to study the photodegradation of azo dyes using titania nanoparticles at different temperatures and time periods.

Titania nanoparticle concentration of 0.1% (w/v) was dispersed in distilled water by sonication for 1 h in sonication bath. The of rate of degradation of Direct Green 26 dye in the titania nanoparticle dispersion, under UV-A exposure was studied at different temperatures ranging from 25°C to 65 °C for time periods ranging from 1 h to 6 h. Photocatalytic degradation tests were performed in a specially designed UV reactor chamber. Raman spectroscopy of Titania nanoparticles, dye and titania/dye mixture before and after UV exposure was carried out using Confocal Laser Dispersion Raman Microscope (Renishaw, UK) with 785 nm excitation laser.

Titanium dioxide is an efficient photocatalyst for decolourisation of direct dye. The photodegradation of the direct Green dye was found to follow the pseudo first-order reaction. The Arrhenius activation energy was found to be 24.8 kJ/mol with A value of 0.0013 for the photocatalytic degradation of the dye. Raman spectroscopy also confirmed the adsorption of dye on titania nanoparticle and its complete degradation on exposure to UV light.

This research highlights the application of titania nanoparticles for the effective degradation of dye in the effluent from textiles, clothing, paper and any kind of dyeing process. Azo dyes account for the majority of all dyestuffs are produced and extensively used in the textile, paper, food, leather, cosmetics and pharmaceutical industries. Titania nanoparticles have been found to successfully degrade these dyes in the presence of UV light which can be very beneficial for the effluent treatment plants in textile and other industries.

Azo dyes are one of the harmful pollutants released in textile waste water. The degradation and removal of the coloured waste in the textile effluent is an important environmental concern and needs to be investigated. The research is one of the first to investigate and understand the mechanism of the degradation of an azo dye in the presence of titania nanoparticles by Raman spectroscopy.

Efficacy of selected commercially available fluorocarbon-based finish agents, such as Oleophobol (Huntsman) Fluoroguard SX and Fluoroguard VOX (Britacel Silicones) Nuva HPU (Clariant) TG-581 (Resil) Aquaphobe-SNT (Akkshata), on cotton and polyester fabrics was studied with respect to water and oil repellency. All the finish agents exhibited excellent water- and oil-repellent properties on both kinds of fabrics. The contact angle of water on the finished cotton and polyester fabrics was found to be ≥ 140° Nuva HPU and Oleophobol gave cotton very good protection against rain. Except Aquaphobe SNT, all other finishes imparted excellent oil-repellent property to cotton. In the case of polyester, maximum oil repellency was achieved with Aquaphobe SNT and Fluorogard SX. The finished polyester fabric showed minimal absorption and better resistance to penetration of water as compared to cotton when subject to the Bundesmann water repellency test. There was a slight yellowing of the cotton fabric after the application of Oleophobol finish. There was no effect on the strength of the fabrics. The effect of these finishes on the crease recovery angle and the bending length of cotton was not significant, However, the polyester fabric became slightly stiffer after the application of the finishes. The crease recovery angle of polyester also increased after the application of these finishes. The finished fabrics showed good water repellency up to 15 washes. Oil repellency showed deterioration after only 5 washes and was partially retained up to 15 washes. Both water and oil repellency became negligible after 30 washes.

Nanoparticles of TiO₂ and ZnO were chemically synthesized by different routes and were characterized using Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM), X ray diffraction (XRD) and Scanning electron microscopy (SEM). These particles were applied to cotton fabric using 1-10 wt% acrylic binder and cured. The photocatalytic activity of the finished fabric was investigated and a comparison was drawn between the synthesized and commercially available TiO₂ (Degussa P25) sample. Experiments were carried out by exposing the coffee stained samples to solar light. The self-cleaning leading to stain discolouration was quantified from the residual concentration of stain to assess the photoactivity of TiO₂ and ZnO nanoparticles. An attempt was also made to study the effect of concentration of nanoparticles (0.5-1.0 wt% on weight of fabric (owf) and acrylic binder concentration (1, 2, 10 wt% owf) on the self cleaning action. TiO₂ particles with smaller particle size of <10 nm was able to show significantly better activity than the commercial sample. At the same time, finish with nano ZnO though showed a bit lower activity; the self cleaning effect was significant and similar to the commercial TiO₂.

Polymeric fibres that have a unique capability to change their structure in response to small environmental changes such as pH, electrolyte and electric field are an attractive alternative for artificial muscles. Stimuli sensitive fibres were prepared by the modification of commercial polyacrylonitrile (PAN) fibres. The modification was carried out in two steps: thermo-oxidation and hydrolysis. During the thermo-oxidation step, the crosslinks imparted through the pendant nitrile groups provided a stable structure. While in the subsequent saponification step, the uncrosslinked nitrile groups were converted to responsive carboxylic acid groups. The effect of stabilization parameters and saponification conditions on the structure, properties and swelling behaviour of these fibres was investigated. The fibres showed muscle like expanding and contracting behaviour stimulated by changes in pH of the environment.