## 4 Qualitative Discussion
### Development of New LBAs and Their Influence on Workability  
The development of new LBAs from unmodified technical lignins and black liquors can reduce production costs, enabling large-scale commercialization. [PERSON] et al. [27] evaluated the black liquor obtained from the Soda pulping of rice straw in a pulp and paper mill. The replacement of 15% of water volume by black liquor in concrete with a water/cement ratio of 0.4 contributed to an increase of 105 mm in the Slump Test. In another study, [PERSON] and [PERSON] [82] evaluated a lignin extracted from sugarcane bagasse by deep eutectic solvents (a mixture of formic acid and choline chloride was used in the study). The authors observed that a lignin incorporation of 0.3 wt.% contributed to an increase of approximately 50% in the mini-slump spread of a cement paste with a water/cement ratio of 0.47. Studies conducted by [PERSON] and collaborators also demonstrated that unmodified lignins could replace commercial lignocellulosic to develop hybrid (organic-inorganic) admixtures for cement-based composites [84; 85; 86; 87]. In addition, these authors observed that a 1.0 wt.% incorporation of hybrid admixture with an alumina/l lignin ratio of 0.2 increased the spread of the cement paste by 21% [85]. Using the same dosage for the hybrid admixture but with a silica/l lignin ratio of 0.2, the spread of the cement paste enhanced by 7% [86]. In both studies, the pastes containing only lignin showed even better workability. In addition to applying unmodified technical lignins and black liquors, different lignin modification processes for LBAs production have been reported in the literature. As synthesized by [PERSON] and [PERSON] [88], hydrophilic functional groups can be introduced into the hydrophobic tail of lignin to form: (1) anionic polymers, by introducing carboxylates, sulfates, and sulfonates [19; 58]; (2) cationic polymers, by reacting with ammonium salts [20]; and (3) non-ionic polymers, by reacting with alcohols (polyoxyethylened chains) [74]. Sulfonation and sulfomethylation processes were studied by different researchers [68; 62; 31; 69; 62]. These processes usually involve the addition of sodium sulfite and formaldehyde [89], which are responsible for introducing sulfonate and methyl groups into the lignin structure, respectively [62]. The plasticizing ability of sulfonated and sulfomethylated lignins is attributed to their molecular weight and anionic charge density [34]. The introduction of sulfonic groups increases these parameters (molecular weight and anionic charge density) and improves the adsorption capacity of the modified lignins in the cement particles [31]. Thus, the Zeta potential of the system enhances, indicating a higher electrostatic repulsion between the cement particles [24]. Complementary processes of oxidation by peracetic acid [22], hydrogen peroxide [14], and nitric acid [12] to increase the efficiency of sulfomethylation have been reported in the literature. In summary, oxidation processes enhance the reactivity of lignins by favoring the introduction of more sulfonic groups into their polymeric structures during sulfomethylation [34]. [PERSON] and [PERSON] [12] evaluated the performance of a softwood kraft lignin modified by oxidation and sulfomethylation in pastes with a water/cement ratio of 0.35. The incorporation of 0.4 wt.% of oxidized and sulfomethylated lignin increased the spread of the cement paste by 167% compared to the unmodified Kraft lignin and 40% compared to a commercial sodium lignocellulosic [12]. In another study, [PERSON] et al. [22] evaluated the performance of a commercial sodium lignocellulosic modified by oxidation and sulfomethylation in pastes with a water/cement ratio of 0.4. As a result, adding 0.3 wt.% of the oxidized and sulfomethylated lignocellulosiconate, the spread of the cement paste increased by 15% compared to the paste containing the unmodified lignosulfonate [22]. Inboth studies, the molecular weight and the degree of sulfonation of the lignins enhanced due to the modification processes adopted.