Self-cleaning surface functionalisation of wool fibres

Photocatalytic purification of organic pollutants, contaminants and hazardous microorganisms is an interesting approach toward pollution control. Using photosensitive catalysts, undesirable organic compounds can be completely mineralised. Among photosensitive catalysts, nanostructured anatase titanium dioxide has long been regarded as excellent catalyst scientifically and commercially for a wide range of applications, especially in sterilisation, disinfection, air purification, water treatment, and deodorisation. Although research work on anatase photocatalyst has been intensively pursued, the development of photocatalytic self-cleaning treatment for fibrous materials with low thermal and chemical resistance, particularly in keratinous fibres, is still at infantile stage. The core motivation for conducting this present study is to investigate and modify the photocatalytic property and compatibility of anatase titanium dioxide on naturally-occurring keratinous fibres. Attempts were successful to produce an innovative photocatalytic self-cleaning keratinous fibrous material, in which environmental-friendly photocatalytic self-cleaning property was conferred on keratin fibers by coating low temperature-synthesised colloid of anatase nanocrystals using the conventional dip-pad-cure surface coating treatment. The synthesis parameters of the photocatalytic self-cleaning colloid formulation in terms of chemicals used, synthesis preparation time, and formulation concentration were studied to advance the photocatalytic efficiency. The anatase adhesion to the surface of keratinous fibers was also improved so as to enhance the photoactivity and its sustainability using surface activation techniques such as wettability pre-treatment, silicone surface modification, and microwave-generated plasma afterglow treatment. On the other hand, the photocatalytic activity of anatase has been limited by its specific excitation source to ultraviolet light. To date, current debate centeres on the limited use of solar energy in triggering advanced oxidation process due to the large photonic band gap (3.2eV) of anatase. In order to take full advantage of the photoreaction, the synergistic effects of chemical doping on the visible-light photocatalysis of anatase were also studied in this investigation. The properties of anatase nanocrystals were modified by doping with metals and non-metal in order to tune the oxidising power of anatase to the visible light region. The spectroscopic and physicochemical characteristics of the modified-anatase have been determined. The findings revealed that the modified-anatase spectral response was extended to the visible light region and concurrently the electron-hole recombination was retarded, resulting in accelerating the visible-light photoactivity. This research provides insights on the structure-property-use relationship of anatase titanium dioxide in biomaterial applications under ultraviolet and visible light conditions. In addition, development of keratin fibers with self-cleaning function helps in preserving our limited natural resources such as water, energy, and petrochemical detergents for a more sustainable environment by reduction of the laundering cycles through exploiting new possibilities of self-cleaning materials in the society.