## 3 Results
### Experimental Values
#### 3.1.1 Effect of Particle Size, Acid, and Reaction Time on Obtaining TRS  
From the results obtained from the experimental design (Table 1), it was observed that, under the conditions studied, minimum amounts of TRS were present in the treatments without acid and at reaction times of 10 min (experiments 6, 7, and 8). On the other hand, maximum values of TRS were obtained with the highest acid concentration (0.5) and high values for particle size and time (experiments 5 and 14).  
The analysis of the evaluated factors indicated that the particle size obtained with a #50 mesh positively affected the release of reducing sugars during pretreatment, increasing from 3.19 to 17.49 g/L as the reaction time increased from 10 to 30 min, while the experiments with a #30 mesh size released from 5.45 g/L to 15.96 g/L of TRS during the 10 and 30 min treatments, respectively. The particle size of lignocellulosic biomass is known to play an important role in the efficiency of the hydrolysis process because particle size reduction increases the ratio between the effective surface area and the volume [30,31]. In the present work, it was observed that, with a reaction time of 20 min, a TRS amount of 17.64 (+2.17) g/L was found, which was the same as that obtained during a 30 min reaction for the #50 mesh (\(17.49+2.2\) g/L). Therefore, the best results observed in terms of TRS increase were obtained when using a smaller particle size. In the study reported in [32], the authors evaluated three particle sizes and determined that the order of hemicellulose and lignin degradation was 400 > 850 > 1300 \(\mu\)m, confirming that treatment efficiency improves with finer particle sizes in sesame plant residues.  
A positive effect of the sulfuric acid concentration on the amount of TRS released during pretreatment was observed. By increasing the acid concentration from 0.25 to 0.5 N for the particle size obtained from the #16 mesh, it was found that the TRS concentration increased from 5 to 15 g/L as a result. Meanwhile, the treatments without acid did not show an increase in the amount of TRS, remaining at an average of 1.8 g/L. This might have been because the pressure and temperature conditions were not conducive to observing an effect on the lignocellulosic material. In another work, it is mentioned that water used in a liquid form for physicochemical pretreatment should be between 170 and 230 \({}^{\circ}\)C with pressures up to 10 MPa to achieve hemicellulose hydrolysis, rendering the cellulose more accessible [33].  
The results obtained with a #30 mesh size showed an increase in TRS concentration from 8.11 g/L to 15 g/L. Similar results indicated that the solubilization of glucan and xylan decreased from 17.7 to 8.5% and from 89.7 to 73.9%, respectively, with biomass particle sizes from 5 to 20 mm. This could be attributed to the decreased susceptibility to dilute-acid hydrolysis with an increase in biomass particle size, as the diffusion of acid into biomass could be reduced with an increasing particle size [34].  
The effect of acid concentration on the reaction time was mainly observed at a 0.25 N concentration and a 20 min treatment duration, increasing from 3.5 g/L to 14.7 g/L at a #16 mesh size. For a #30 mesh size, a TRS increase of 8.11 g/L was found for the treatment lasting 30 min and employing a 0.25 N concentration, while the 20 min treatment with a 0.5 N acid concentration obtained 9.9 g/L TRS. Previous studies have shown that sugar yield is highly dependent on temperature, acid concentration, and reaction time: for instance, hydrolysis processes utilizing corn with yields greater than 10% solids should be conducted at temperatures below 200 \({}^{\circ}\)C to avoid the degradation of pentoses to 5-hydroxymethylfurfual [7].