## 3 Results and Discussion
### M. sylvestris Biomass Valorization Options
#### 3.5.1 The Textile Dyeing Valorization Chain  
The pretreatment of textile with alum or iron is a current practice, as it improves the dyeing of the textile, but that should be avoided if possible in order to reduce the use of metals in the dyeing process. Therefore, three modalities were compared for the used textiles: without pretreatment or with iron or alum pretreatment. For all dye extracts (area 1, area 2, area 3, 10 \({}^{\circ}\)C and room temperature), the mixture of flower powder and water initially had a purple color. As expected, the purple color faded into a brownish color during the heating process and after several minutes without heating. These brownish extracts were used for the dying test on cotton or silk fabrics for the three pretreatment modalities (without pretreatment or iron or alum pretreatment, Figure 3). The initial colors of the pretreated fabrics are reported in Figure 3. The untreated and the alum-pretreated fabrics were white, while the iron-pretreated fabrics presented a light orange color. For the three pretreatment modalities, the dyeing process with the _M. sylvestris_ flower extract was not impacted by the cultivation area, the heating time, or the extraction temperature (Supplementary Materials Figure S2). The dyeing of the fabrics without pretreatment was unsuccessful, and only a faint color was achieved (Figure 3, Supplementary Materials Figure S2). The orange shade obtained on the iron-pretreated fabrics was mainly due to the pretreatment itself, with the addition of the flower extract only slightly intensifying the color (Figure 3, Supplementary Materials Figure S2). The best dyeing results were achieved on the alum-pretreated silk fabrics, which had a bright yellow shade that could be due to the flavonoid content reported in _M. sylvestris_ flowers [25; 53]. Such shade could also be obtained from other plant species extracts, such as onions [53]. All of these observations emphasize the importance of pretreating the fabric with alum prior to the dyeing test. Moreover, our results suggest better dyeing on silk compared to cotton. This higher affinity of silk with natural colorants has been previously reported [21; 54]. The possible darkening of the yellow shade on the fabrics was investigated using a ratio of 1:40 to increase the extract amount in relation to the textile. The dyeing color result was similar to the 1:100 ratio (results not shown). We assumed that the reason why the shade could not be darkened with the 1:100 ratio was because the dye contained in the extract solution had already saturated the fabrics. This is in line with a previous study [54] that attributed the color strength to the number of functional groups interacting with the natural dye extract. Using a dyeing ratio of 1:100, 0.6 g of silk could be dyed with an extract obtained with 0.3 g of dry flowers. Based on this dyeing capacity, we could assess the quantity of silk that could be dyed with the flowers harvested per hectare. Through the use of the flower yield extrapolation (Table 2), the number of flowers obtained per hectare was able to dye around 290-482 kg of silk. Figure 3: Color of the pretreated fabrics before and after the dyeing with _Malva sylvestris_ L extract. The small fabric squares are cotton, and the large fabric squares are silk. The TE concentrations throughout the textile dyeing process were studied to assess this valorization option when using mallow issued from phytomanagement. TE concentrations were measured in the dyeing extract solution and in the fabrics (cotton and silk) during the three steps of the dyeing process: before pretreatment, after pretreatment, and after dyeing. The TE concentrations measured in the five dye extract solutions (Table 5) were significantly low when compared to the values retrieved in the flowers (Table 3) and were in usual concentrations in the dye (Table 5) [55].