## 2 Materials and Methods
### Harvesting and Delignification Kraft Process  
The four highly invasive arboreous and herbaceous plants (_Arundo donax_, _Phylolaca americana_, _Eucalyptus globulus_, and _Tradescantia fluminensis_) were harvested between March and May of 2023 in the Umia Riverbank area, in a delimited area of 2 km in the walking path after Ribadumia town (Pontevedra, Spain). Before the treatment in laboratory, samples were separated into its parts, shown in Table 1 (leaves, stem, and bark/branches), and then fragmented to 50-20 mm long pieces. Prepared raw matter was dried at 105 \({}^{\circ}\)C until moisture was reduced.  
Once raw matter was dried, delignification of biomass samples was conducted according to kraft process. Delignification processes aim to dissociate lignin from cellulose fibers within lignocellulosic biomass by breaking ester and ether bonds present in the natural lignin structure [37]. Due to the lack of proper digester, dry matter was cooked in 5 L of distilled water within 20% of dry mass weight of NaOH added. Other studies [38] suggested that optimized conditions for the delignification process in a forced circulation digest were: 22% of effective alkali charge (NaOH); 30% sulfidity; a liquor-to-wood ratio of 4:1; a cooking temperature of 165 \({}^{\circ}\)C; and 90 min of cooking time. In this occasion, the liquid/solid mass ratio was 5:1, as stablished in other studies [39]. And, the estimated time of cooking was 120 min at 160 \({}^{\circ}\)C, depending on raw matter type (leaves, stem of bark). _Arundo donax_ and _Phylolaca americana_ stems and _Eucalyptus globulus_ bark were the samples that needed more reaction time. Once the fibers were in optimal condition, and all the lignin was already eliminated, it was possible to separate them without any mechanical means.  
After the kraft process (Figure 5), and once the reaction was finished, the mixture was filtered and rinsed. Back bleaches, the residual liquid obtained after the delignification process, was then stored for posterior neutralization with wood sawdust. By this means, the pH is neutralized, obtaining an organic matter suitable to be used as compost.  
Figure 5: Kraft delignification process developed in the school of Forestry Engineering of the University of Vigo, Galicia.  
The unbleached delignified pulp was further dried at 105 \({}^{\circ}\)C during at least 24 h and divided into portions of 30 g of dried matter. A total of 30 g of dried fibers was left in 1 L of distilled water to rehydrate, and the disintegration process (Figure 6) was performed following UNE-EN ISO 5263-1:2005 instructions and using a Creusot-loire instumenttion--adamen-I homary disintegrator, adding 1 L of distilled water to a previous mixture.  
The refining process was performed in a PFI laboratory beater mill at 600 and 1200 rpm according to UNE-EN ISO 5264-2:2011. Disintegrated fibers, within a consistency of 10% (UNE-EN ISO 4119:1996), were refined running in tests of 30 s, 1 min, and 2 min, depending on material properties.  
Refined fibers were stored for pulp characterization and morphological, mechanical, and optical properties' observation.  
The same time test was performed with IAS plant waste, commercially used pulp of Eucalyptus wood, bleached, and summitted to pulping and characterization processes in order to compare properties. In Figures 7-10, we can observe different delignified matter in different steps of the refining process. Leaves and stem matter from different species can be easily distinguished, due their morphological differences.  
Figure 6: Disintegration process of delignified matter before refining in PFI. Matter from _Phylolacea americana_ stem.  
Figure 8: _Pntolacca americana_ stem matter. Different parts of the plant can be observed, stems and leaves.  
Figure 7: Delignified fibers from _Arundo donax_.