## 3 Results  
### Treatment Using ZnCl\({}_{2}\)-4H\({}_{2}\)O  
Inorganic salt hydrates (ISHs) can be dissolved depending on the amount of water in their structure, the state of dissolution, and the variety of salts used [18; 39]. The cellulose dissolution capacity of ISHs depends on the type of salt used, the water content in the preparation of the salt, the temperature, and the dissolution time, as already demonstrated in previous work [18]. The amount of water added revealed that the use of a ratio R = 4 is the optimum option for biomass dissolution [18; 31]. Therefore, the use of different salt hydrates with different cations for the dissolution of pure cellulose was studied, and we established that ZnCl\({}_{2}\)-4H\({}_{2}\)O was an excellent solvent to study due to its chemical characteristics and low price [18]. ISHs are able to dissolve the structural carbohydrates of the lignocellulosic biomass, leaving the lignin undissolved as a solid [33]. Figure 1: Scheme of the process of the fragmentation of lignocellulosic biomass using ZnCl\({}_{2}\)-4H\({}_{2}\)O. The dissolution of cellulose has been studied in several previous reports, where cellulose (1.5g) was dissolved in ZnCl\({}_{2}\).4H\({}_{2}\)O (28.5 g) at 70 \({}^{\circ}\)C in half an hour [10;35]. However, reports about the dissolution of whole biomass in salt hydrates are scarce; for this reason, we started with the study of pruning waste dissolution at different times: 30 min, 1 h, 3 h, 4.5 h, and 24 h at 70 \({}^{\circ}\)C. The use of short dissolution times (30 min, 1 h, 3 h, and 4.5 h) produces a very small biomass dissolution, with only a slight increase with time; in all cases, the recovery of Solid II was very small. However, after 24 h of dissolution at 70 \({}^{\circ}\)C, we detected an evident partial dissolution of the biomass (approximately 40 wt.%) with a significant recovery of Solid II. For this reason, we decided to continue the study using 24 h of dissolution time with different dissolution temperatures (60, 70, 80, and 90 \({}^{\circ}\)C). The results obtained after dissolution and precipitation at different temperatures are shown in Table 2. The recovery data for solid I (mostly lignin) and solid II (mostly structural carbohydrates) are shown along with total solid recovery data. We calculated the degree of biomass recovered for each dissolution temperature. These data were obtained by the difference between the weight of the isolated solids recovered and the amount of the main components in each original biomass according to the NREL analyses shown in Table 1. The loss of biomass can be related to the dissolution and partial hydrolysis of more reactive carbohydrates, mainly hemicellulose, which remains dissolved in the Solid II mother liquor. The results obtained show the following: The dissolution of biomass is very small at 60 \({}^{\circ}\)C, with a high recovery of Solid I and a small recovery of Solid II. The recovery of Solid I is higher at 60 \({}^{\circ}\)C and decreases for higher dissolution temperatures, probably due to the dissolution and partial hydrolysis of soluble oligomers. An increase in temperature increases the dissolution of biomass, with similar values for 70 \({}^{\circ}\)C to 90 \({}^{\circ}\)C. In view of the results (Table 2), at high temperatures (90 \({}^{\circ}\)C) we detected a slight increase in Solid I recovery and total recovered biomass, possibly due to the occurrence of insoluble byproducts such as humins that remained undissolved and were retained in Solid I. At low temperatures (60 \({}^{\circ}\)C), a great separation is not achieved. Therefore, it was decided to use a temperature of 70 \({}^{\circ}\)C because it demonstrated the greatest separation of Solid I and Solid II. A summary of the mass recovered is shown in Table 3, where a third solid (Solid III) is included. After cleaning Solid II with HCl and water, acetone was added assist in drying and we discovered that the mother liquors were colored.