Abstract
Nanoparticles (NPs) of titanium dioxide (TiO2) are promising for the photocatalytic degradation of organic compounds, arising as an excellent alternative to conventional bleaching processes. Within this background, aqueous suspensions of TiO2 NPs were impregnated by the pad-dry method in raw cotton. The hydrophilic properties and whiteness index (WI) of Berger were the main parameters examined before and after the TiO2 treatment. In the absence of water, using a UV-Vis lamp, high hydrophilicity was found for raw cotton. Diversely, under UV-LED radiation, the presence of water molecules in the coated cotton was revealed to be a crucial parameter in enhancing its whiteness. A comparable WI of Berger with conventional bleaching methods was obtained using 0.5 g L-1 TiO2 suspension under UV-LED radiation, suggesting that the impregnation of TiO2 NPs can be a promising alternative for the industrial bleaching methods, as it proves to be more sustainable and with low operating costs.
Highlights
In the textile industry, there are different processes to remove impurities from raw cotton, making it more hydrophilic and whiter
Different TiO2 loads were impregnated at the surface of raw cotton in order to study its photocatalytic efficiency for the degradation of hydrophobic compounds and natural cotton pigments
Fabrics characterization Raw cotton is mainly composed of α-cellulose and contains impurities such as waxes and pectins which give it a yellow colour and a hydrophobic nature (Hsieh 2007)
Summary
There are different processes to remove impurities from raw cotton, making it more hydrophilic and whiter. Mercerization and bleaching are the main pre-treatments, so that the resulting cotton has the necessary conditions for the following finishing and dyeing treatments. All these treatments are major water consumers in the industrial textile processes, spending between 250-350 kgwater/kgtextile, and, spending the highest amount of energy, between 55-60 % (Karmakar 1999). During these treatments, different types of waste can be generated being harmful to the environment. With the increasing cost of chemical products, equipment, workers, effluent control and chemicals recovering, there has been an increasing need to find alternatives to these conventional textile treatment processes
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