## 3 Results
### FTIR Analysis  
The chemical structure of blended ratios of torrefied sewage sludge and sugarcane bagasse were analyzed using FTIR. Figures 5 and 6 present the infrared (IR) spectra of the 50:50 and 75:25 blended ratio. This was obtained within the mid-IR range of 4000-500 cm\({}^{-1}\), which is a typical vibration band for organic components. Various peaks corresponding to the characteristic functional groups of the analyzed samples were observed in the spectra. Figure 5: Infrared (IR) spectra for 50:50 mixing ratio of torrefied sewage sludge and sugarcane bagasse. As observed, the IR spectra for 50:50 and 75:25 blended ratio of sewage sludge and sugarcane bagasse only differed slightly; hence Figures 5 and 6 are discussed concurrently. FTIR absorption peaks associated with-OH bond formation in alcohol, phenols and carboxylic acid were observed at 3342.36 cm\({}^{-1}\) in the raw bagasse (BG\({}_{\text{a}}\)) and 3278.21 cm\({}^{-1}\) in the raw sewage sludge (SS\({}_{\text{a}}\)). However, a decrease in intensity of these peaks was noticed in both 50:50 and 75:25 mixed ratio of sewage sludge and sugarcane bagasse samples torrefied at 200 \({}^{\circ}\)C (M\({}_{\text{a200}}\), M\({}_{\text{e200}}\)), 250 \({}^{\circ}\)C (M\({}_{\text{a250}}\), M\({}_{\text{e250}}\)), 300 \({}^{\circ}\)C (M\({}_{\text{a300}}\), M\({}_{\text{e300}}\)) and 350 \({}^{\circ}\)C (M\({}_{\text{a350}}\), M\({}_{\text{e350}}\)). The observed decrease in intensity is associated with the occurrence of the methylation reaction initiated by the torrefaction process, which consequently improves the hydrophobicity of the biomass. The unique double absorption peak characteristics of hemicellulose obtainable within 2930-2850 cm\({}^{-1}\) wavenumber were observed in the SS\({}_{\text{a}}\) and all torrefied blended samples, with the exception of M\({}_{\text{a350}}\). In contrast, the BG\({}_{\text{a}}\) exhibited more of a cellulose characteristic peak within the same IR region. These peaks were ascribed to symmetric and asymmetric vibrations of C-H\({}_{\text{n}}\) stretching CH4 and C2H6 particularly. To further explain, the cracking of methylene (-CH\({}_{\text{2}}\)-) and aromatic rings along with methoxy (-OCH\({}_{\text{3}}\)) and the methyl (-CH\({}_{\text{3}}\)) decomposition gave rise to CH\({}_{\text{4}}\)[43]. The peak at the IR region of 1720-1700 cm\({}^{-1}\) was attributed to the acetyl groups present in hemicellulose. A previous study indicated that the abundance of acetyl groups reduces the uptake of moisture by a biomass material, which is advantageous when subjected to gasification [44]. Peaks between 1650 and 1600 cm\({}^{-1}\) in SS\({}_{\text{a}}\) and BG\({}_{\text{a}}\) were associated with skeletal aromatic vibrations typically seen in lignin structure. These peaks increased in intensity with the blended torrefied samples at higher torrefaction temperature due to insignificant modification of lignin component as well as degradation of hemicellulose and cellulose. Consequently, these degradations yielded chars that were more thermally stable and rich in aromatic groups. Furthermore, the deformation of C-H bonds linked to polysaccharides of lignin was noticed between the wavenumber of 1460-1430 cm\({}^{-1}\)[8]. Most notably, a pronounced peak corresponding to C-O, C=C and C-C-O vibration from hemicellulose, cellulose as well as lignin occurred within the 1035 and 1030 cm\({}^{-1}\) region in all the samples. However, the intensity was higher in the BG\({}_{\text{a}}\), but lesser in blended torrefied samples due to the aromatic nature of lignin that leads to its slower degradation rate compared to cellulose and hemicellulose. The peak within wavenumber 695-660 cm\({}^{-1}\) is ascribed to vibrations of the O-H group stretching outside of the plane and represents a typical cellulose characteristic [28]. Upon torrefaction, this bond was removed through the reaction H + OH \(\rightarrow\) H\({}_{\text{2}}\)O.