554
M. Singh et al.
100 W) and microwave (MW) plasma (2450 MHz, 600 W). Post-plasma treatment
100 °C temperature was sufficient to attach TiO 2 to the fabric in contrast to the
conventional high temperature of 500 °C used for coating of glass and silica. The
degradation of organic stains like coffee, wine or grease on textiles activated by
plasma and TTIP or TiCl 4 colloidal TiO 2 was accompanied with the release of CO 2 .
In case of cotton, a 60 min RF plasma-treated bleached cotton showed the maximum
CO 2 evolution (2000 μl) and a mercerised cotton showed the maximum amount of
CO 2 for just 15 s MW plasma treatment for wine stain after 24 h suntest light irradiation. MW plasma treatment was accompanied by heat so it increased the contact
between cotton tissue and TiO 2 nanoparticle surface, thus increasing dispersion rate
on the fabric with little treatment time. No CO 2 was observed in any of the fabric in
the absence of TiO 2 or absence of any stain. In case of pretreated polyester and wool–
polyamide samples, self-cleaning action was enhanced in 30 min RF plasma-treated
sample coated with colloidal TiO 2 as a basic layer followed by another coating of
Degussa P-25 nanoparticles. The action of nanoparticles was clearly visible with
partial discolouration induced by light and a generous amount of CO 2 gas evolved.
A TiO 2 coating with 150–220 nm thickens was observed in TEM micrograph for
cotton samples and 20–25 nm for synthetic fabric. XRD spectra showed peaks for
rutile form of TiO 2 nanoparticle along with some amorphous TiO 2 . The mechanism
of self-cleaning was explained by a photochemical reaction where coffee or wine
pigments would inject an electron in TiO 2 conduction band to generate highly active
O– radicals (Airoudj et al. 2014), or the excited pigment will react with photo-induced
holes which will react with carboxylic acids through Kolbe-type reaction to generate
CO 2 (Bhatia 2016). The active O– species further generate oxidative radicals like
HO 2 ˙–, OH˙, RO˙, RO 2 ˙ which will eventually degrade the textile stains (Bozzi et al.
2005).
e
−
cb + O 2 −→ O
−
2
(1)
RCOO
−
+ h vb
+ −→ R
•
+ CO 2
(2)
4.4 Dye Adsorption Enhancement
Plasma treatment has been highly successful in etching the hydrophobic layer in
natural polymers. Etching of the surface improves dye and fibre interaction thereby
more dye particles get attached to the treated substrate and penetrate into the bulk.
Plasma pretreatment of any textile thus is effective in enhancing dyeing rate, dye
bath exhaustion and provide more homogenised dyeing (Morent et al. 2008). Rezaei
et al. showed that corona treatment was helpful in increasing the attachment of nanozinc on nylon fabric surface which was visible with SEM studies. The pretreated
sample was dyed with acidic dye. The K/S results demonstrated that with increasing
M. Singh et al.
100 W) and microwave (MW) plasma (2450 MHz, 600 W). Post-plasma treatment
100 °C temperature was sufficient to attach TiO 2 to the fabric in contrast to the
conventional high temperature of 500 °C used for coating of glass and silica. The
degradation of organic stains like coffee, wine or grease on textiles activated by
plasma and TTIP or TiCl 4 colloidal TiO 2 was accompanied with the release of CO 2 .
In case of cotton, a 60 min RF plasma-treated bleached cotton showed the maximum
CO 2 evolution (2000 μl) and a mercerised cotton showed the maximum amount of
CO 2 for just 15 s MW plasma treatment for wine stain after 24 h suntest light irradiation. MW plasma treatment was accompanied by heat so it increased the contact
between cotton tissue and TiO 2 nanoparticle surface, thus increasing dispersion rate
on the fabric with little treatment time. No CO 2 was observed in any of the fabric in
the absence of TiO 2 or absence of any stain. In case of pretreated polyester and wool–
polyamide samples, self-cleaning action was enhanced in 30 min RF plasma-treated
sample coated with colloidal TiO 2 as a basic layer followed by another coating of
Degussa P-25 nanoparticles. The action of nanoparticles was clearly visible with
partial discolouration induced by light and a generous amount of CO 2 gas evolved.
A TiO 2 coating with 150–220 nm thickens was observed in TEM micrograph for
cotton samples and 20–25 nm for synthetic fabric. XRD spectra showed peaks for
rutile form of TiO 2 nanoparticle along with some amorphous TiO 2 . The mechanism
of self-cleaning was explained by a photochemical reaction where coffee or wine
pigments would inject an electron in TiO 2 conduction band to generate highly active
O– radicals (Airoudj et al. 2014), or the excited pigment will react with photo-induced
holes which will react with carboxylic acids through Kolbe-type reaction to generate
CO 2 (Bhatia 2016). The active O– species further generate oxidative radicals like
HO 2 ˙–, OH˙, RO˙, RO 2 ˙ which will eventually degrade the textile stains (Bozzi et al.
2005).
e
−
cb + O 2 −→ O
−
2
(1)
RCOO
−
+ h vb
+ −→ R
•
+ CO 2
(2)
4.4 Dye Adsorption Enhancement
Plasma treatment has been highly successful in etching the hydrophobic layer in
natural polymers. Etching of the surface improves dye and fibre interaction thereby
more dye particles get attached to the treated substrate and penetrate into the bulk.
Plasma pretreatment of any textile thus is effective in enhancing dyeing rate, dye
bath exhaustion and provide more homogenised dyeing (Morent et al. 2008). Rezaei
et al. showed that corona treatment was helpful in increasing the attachment of nanozinc on nylon fabric surface which was visible with SEM studies. The pretreated
sample was dyed with acidic dye. The K/S results demonstrated that with increasing