Investigation of Alternative Colouration Processing Medium for Textiles and Novel Filtration Media for Recycling of Textile Effluent

Abstract

The aim of this research was to find a suitable alternative medium of scarce freshwater for textile dyeing, and to recycle and reuse the dyebath using a combined coagulation/flocculation and novel filter media. Simulated seawater (SSW) was tested as the alternative dyeing medium with a salt concentration of 3.5% where NaCl was the major component.Fibre/dye systems of wool/acid and metal complex, wool/reactive, polyester/disperse, nylon/acid and metal complex, and acrylic/cationicdyes were tested in simulated seawater and the performances of dyed fabric were compared to conventional dyeing system of distilled water (DSW). The study found that commercial dyeing processes were robust and can be practically transferable into the seawater medium. The dye exhaustions, build-up, colour characteristics, and fastness to wash, cross-staining, rub and light were satisfactory within the dye ranges studied, which covers commercially available monochromatic Red, Yellow and Blue at light, medium and deep shades. Although SEM micrographs didn't show any presence of salt, a typical wash-off process of 1gL-1 with a non-ionic detergent at 70°C was sufficient to remove any salt that could be present on the surface or sub-surface of the dyed fabric.At room temperature, some acid and metal complex dyes were only partially soluble in SSW but this improved with gentle heating and addition of levelling agents. At dyeing temperatures near the boil, these dyes were completely soluble. A saturation limit was found to be existed for acrylic dyeing of cationic dyes over 1.0% o.m.f. depth. Although ionic interaction was the dominant mechanism for dyeing of wool, nylon and acrylic fibre with acid, metal complex and cationic dyes, the adsorption in highly saline dyebath most likely depended on the combined effects of ionic and physical/hydrophobic interaction. The resultant effect was higher dye exhaustion and consequently higher colour difference in SSW for some dyes. Reactive dyes were known to be sensitive to hardness of water but this study confirmed that reactive dye could be an alternative for deep dyeing for wool fibre in SSW. Reactive dyeing of wool followed a similar mechanism of gradual phase transfer as was observed for disperse dyeing of hydrophobic fibres over 3.0% o.m.f. depth. In contrast disperse dyeing of polyester produced consistent results for all dyes but some black dyeings produced superior colour strength in SSW. The build-up of colour in SSW compared to DSW can be different depending on the application level.To improve permeate flux by reducing membrane fouling, a number of surface modification were carried out to introduce fluorine based functional groups. Gaseous fluorination, fluorocarbon finish (FC) and plasma polymerisation were performed to introduce hydrophilic and oleophobic properties on supplied Azurtex membrane. The fluorinated Azurtex media exhibited increased wettability although it was not directly proportional to an increase in the fluorination level and treatment time. The water and oil repellency of FC and plasma treated filter media provided a reasonable level of repellency while the contact angle remained in the range of 130 to 145°. Pre-fluorination of filter media before FC treatment didn't change the water and oil repellency.Surface characterisation of Azurtex media was performed with ATR-FTIR, XPS and SEM. An increased level of fluorination at 10%F2 and prolonged exposure showed a degradation of the surface along with colour change. The fluorinated, FC treated and plasma polymerised membrane showed a typical C-F stretching vibration in the region of 1100-1350 cm-1 and weakly at 400-800cm-1. The XPS study showed a gradual increase in the -CF2 and -CF3 functionality signal intensities that resulted in imparting hydrophobicity The benchmarking of these modified Azurtex filter media against newly developed materials proved that plasma treatment improved the flow, reduced turbidity and provided an easy cake removal co

Date of Award	1 Aug 2014
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Muriel Rigout (Supervisor)