## 3 Results and Discussion
### Surface Morphology of Saccharum officinarum  
SEM analysis was carried out to investigate changes in surface morphology of bagasse before and after extraction under optimum NaOH extractant concentration, temperature, and mixing duration. Figure 5a shows the SEM image of raw bagasse while Figure 5b shows the image of extracted bagasse. Based on Figure 5a, raw bagasse has a smooth surface with no pores. The rough surface of agro-waste is due to the presence of porous properties on its surface. According to [PERSON] & [PERSON] [43], the presence of pores on the surface of coagulants reveals good coagulation-flocculation properties. The small pores can adsorb small-sized pollutants into pores and cover the surface [44]. After the coagulation process, the surface of the coagulant becomes smoother as the small pollutants filled the pores [45]. Besides, agro-wastes with rougher and porous surfaces have a larger surface area [46]. Coagulants with a larger surface area are preferable because they can increase the capability of bridging mechanisms as it has a higher density of adsorption sites [47].  
Commonly studied natural coagulants such as _Moringa oleifera_[48] and _Opuntia ficus indica_[49] have rough and porous surfaces, unlike bagasse. Despite not having a rough and porous surface area, bagasse has a large surface area that can enhance the interparticle bridging mechanism. In addition, according to [PERSON] et al. [22], bagasse can still become a good natural coagulant by removing significantly high turbidity content.  
Figure 5b shows the SEM image of extracted bagasse. Before extraction, a smooth surface can be observed indicating an undisturbed cell wall surface. After extraction, the original smooth cell wall surface has become irregular from the apparent deposition of relocalized cell wall matrix material [50]. Upon the extraction process, an increase in fragmentation can be observed indicating the fibre cells are loosened and segregated from the larger particles. An increase in fragmentation is also attributed to depolymerisation and removal of lignin from the shared compound middle lamella which facilitates the fragmentation of individual cells from larger tissue culture [51]. The extraction process weakens the mechanical properties of the cell wall which deform the structure of the particles and as shown in Figure 5, major cracking on the surface of the bagasse. As a result  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Wavenumber Range (cm\({}^{-1}\))** & **Peak Wavenumber (cm\({}^{-1}\))** & **Group** & **Indicator** \\ \hline \multicolumn{4}{c}{Raw Bagasse} \\ \hline
3500–3200 & 3338.1 & O-H stretching & Intramolecular hydrogen bonds for cellulose \\ \(\sim\)1730 & 1728.7 & C-O stretching & Acetyl and ester linkage in lignin and hemicellulose \\ \(\sim\)1369 & 1371.8 & C-H stretching & Ionic carboxylic groups that usually present in cellulose. \\ \multicolumn{4}{c}{1243.4} \\
1300–950 & 1160.3 & C-O stretching & Stretching of hemicellulose and lignin \\  & 1034.8 & & \\ \hline \multicolumn{4}{c}{Extracted Bagasse} \\ \hline
3500–3200 & 3339.0 & O-H stretching & Intramolecular hydrogen bonds for cellulose \\
1649–1620 & 1638.0 & C=C stretching & Aromatic ring present in lignin \\ \hline \hline \end{tabular}
\end{table}
Table 4: Bagasse functional groups based on FT-IR analysis.  
of the degradation of hemicellulose and deformation of lignin from the extraction process, an optimum polysaccharide was extracted that can be later used as a natural coagulant.