**4. Conclusion**

**Sample description Ag quantity (ppm) on**

and plasma-treated cotton samples functionalized with synthetized colloidal silver

the dye on the fabric [91] such that silver ions (Ag+

area to volume ratio of these particles [43].

Corona plasma-treated, dyed and functionalized

Corona plasma-treated and functionalized with a

Corona plasma-treated, dyed and functionalized with a half of concentration of colloidal silver

half of concentration of colloidal silver

22 Eco-Friendly Textile Dyeing and Finishing

no bacterial reduction

with colloidal silver

—a

**cotton**

Dyed and functionalized with colloidal silver 24 100 (*E.coli, S.aureus, S.faecalis* and

**Table 4.** The quantity of silver (ppm) and antimicrobial efficiency, expressed as a bacterial reduction (%), of untreated

The results summarized in Table 4 show that atmospheric air corona treatment enhanced the quantity of silver onto dyed cotton up to 1.8 times comparing to the untreated dyed cot‐ ton. In addition to the morphological changes induced by plasma (seen by SEM), XPS analy‐ sis showed the increase of C-O and C=O bonds and formation of O-C=O bonds on the surface of treated cotton. The increased concentration of oxygen and newly formed bonds contributed to a better adhesion of Ag+ ions from the colloidal solution onto cellulosic fibers. In addition to the increased number of functional groups containing oxygen, the dyed cot‐ ton fabric contains additional anionic sites due to the partial ionization of the molecules of insoluble vat dye. Colloidal silver is produced in a water solution using AgNO3 reduced by NaBH4. NaBH4 also slightly reduces the water insoluble vat dye on the dyed fabric into a slightly soluble form. Although NaBH4 is not a sufficiently strong reducing agent for dyeing cotton with a vat dye [90], it is nevertheless strong enough to enhance the negative charge of

electrostatically attracted to the dyed cotton surface. It was reported that while Ag+

from a colloidal silver solution are exhausted to the anionic cotton fibers to a high degree because of the attractive electrostatic interactions, the high increase of the adsorption ability of silver nanoparticles caused by the van der Walls forces resulted from the high surface

The important goal of our research was to use minimal concentrations, initially, of silver nanoparticles for loading onto textiles and to achieve a maximum quantity on the material, and thus to achieve functionalized cotton textile with an excellent antimicrobial efficiency. Since the cotton fabrics already had an excellent antimicrobial efficiency when functional‐ ized with rather low concentration of silver, the decision was made to verify the possibility in achieving good antibacterial efficiency of a cotton fabric with the use of half of the initial

1.6 —a

**Bacterial reduction (%)**

) from a silver colloidal solution can be

ions

*P.aeruginosa*)

43 100 (*E.coli, S.aureus, S.faecalis* and *P.aeruginosa*)

4.6 100 (*E.coli, S.aureus, S.faecalis* and *P.aeruginosa*)

> Our research shows that plasma treatment is an effective method to be used in achieving surface changes on the textile material by changing the functional groups on the textile sur‐ face and by changing the morphology of the fibers. The results of adsorption of different forms of silver nanoparticles on untreated and plasma-treated surfaces of fabrics confirm the fact that, for nanotechnological processes, the surface of the material has to be properly pre‐ pared. The adsorption of metal nanoparticles on textile materials depends on specific chemi‐ cal and morphological properties of fibers. Plasma modification of cotton had a positive influence on the increased adsorption of silver nanoparticles loaded during exhaust dyeing process. From the bath, which contained a low concentration of silver nanoparticles, we have successfully applied a greater quantity of silver onto plasma modified cotton (up to four times). In some cases using plasma the dyeability of cotton was also improved. We suc‐ ceeded to create a cotton fabric containing minimal quantity of silver with an excellent anti‐ microbial efficiency. This is very interesting from the technological point of view since by this method the quantity of silver in wastewater can be dramatically reduced. Another im‐ portant result of the research was that plasma modification did not impair the mechanical properties of textiles. By using plasma technology new and improved properties of materi‐ als can be created that cannot be achieved by standard procedures, where nanostructuring of natural and synthetic fibers is emphasized. The use of plasma for modification of textiles brings to the textile industry many novelties, since plasma technology can be used as a sub‐ stitute or as a support to the existing technologies, and by that positively influences the economy and ecology of the industrial processes. The knowledge of using plasma technolo‐ gy enables an introduction of contemporary (state-of-the-art) and ecological process of a tex‐ tile modification into the textile industry and a development of highly technological products with improved or new properties.
