## 3 Results and Discussion
### Photocatalytic Activity Evaluation
#### 3.5.1 Composition of the Rice Husk Extract before the Photocatalytic Reaction
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**RT (min)**} & \multicolumn{2}{c}{**Name of the Compound Found in the Rice Husk Extract**} \\  & & **before the Photocatalytic Reaction** & **Area (\%)** \\ \hline \multicolumn{4}{c}{**Phenols in Rice Husk Extract**} \\ \hline
8 & 9.42 & Phenol & 1.25 \\ \hline
9 & 10.82 & 3-Methyl Phenol & 0.66 \\ \hline
10 & 11.1 & 2-Methoxy Phenol & 1.69 \\ \hline
11 & 12.03 & 4-Ethyl Phenol & 0.3 \\ \hline
12 & 28.45 & Pentametethoxyflavone & 10.26 \\ \hline
13 & 34.95 & Heptamethoxyflavone & 3.3 \\ \hline
14 & 35.27 & Hexamethoxyflavone & 7.07 \\ \hline \multicolumn{4}{c}{**Alcohols in Rice Husk Extract**} \\ \hline
15 & 4.99 & 3-methyl 1-Butanol & 3.94 \\ \hline
16 & 5.07 & 2-methyl 1-Butanol & 1.08 \\ \hline
17 & 7.33 & 2-Furanmethanol & 0.82 \\ \hline
18 & 9.84 & Acetate Tetrahydro 2-Furanmethanol & 0.35 \\ \hline
19 & 28.13 & 2-(6-Ethoxy-4-Methyl-Quinazolin-2-Ylamino)-5-Methyl- & 3.93 \\  & & Pyrimidine-4,6-Diol \\ \hline \multicolumn{4}{c}{**Aldehydes in rice husk extract**} \\ \hline
20 & 6.91 & Furfural & 2.77 \\ \hline
21 & 9.18 & 5-methyl 2-Furancarboxaldehyde & 0.43 \\ \hline \multicolumn{4}{c}{**Ketones in Rice Husk Extract**} \\ \hline
22 & 5.68 & 1-Hydroxy 2-Butanone & 0.29 \\ \hline
23 & 6.41 & Dihydro 2-Methyl 3(2H)-Furanone & 0.30 \\ \hline
24 & 8.24 & 2-Methyl 2-Cyclopenten-1-One & 0.38 \\ \hline
25 & 8.31 & 1-(2-Furanyl) Ethanone & 0.26 \\ \hline
26 & 10.18 & 3-Methyl 1,2-Cyclopentanedione & 0.27 \\ \hline
27 & 21.59 & 3-Carbethoxy-2-Piperidone & 0.43 \\ \hline \multicolumn{4}{c}{**Alkanes in Rice Husk Extract**} \\ \hline
28 & 3.53 & Cyclohexane & 2.30 \\ \hline
29 & 4.90 & 1,1-Diethoxy Ethane & 2.76 \\ \hline \multicolumn{4}{c}{**Other Compounds in Smaller Quantity**} \\ \hline
30 & 3.73 & 1,1-Bis(2,2-Dimethylpropoxy) N,N-Dimethyl Methanamine & 0.20 \\ \hline
31 & 7.54 & Diethyl (3-decyn-1-yl) Amine & 0.21 \\ \hline
32 & 6.54 & Butyl Ester Acetic Acid & 0.44 \\ \hline
33 & 12.50 & Creosol & 0.45 \\ \hline
34 & 25.73 & Glycidyl Palmitate & 1.66 \\ \hline
35 & 27.83 & Glycidyl Palmitate & 0.83 \\ \hline
36 & 27.94 & Glycerol 1-Palmitate & 1.14 \\ \hline
37 & 32.89 & Hexadecamethyl Octasiloxane & 2.30 \\ \hline
38 & 36.35 & N-Methyl-1-Adamantaneacetamide & 0.78 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
**Carboxylic acids in the rice husk extract:** Carboxylic acids derive from cellulosic and hemi-cellulosic components, when these components undergo hydration or dehydration during pyrolysis [34]. The largest peaks that appeared after 24 and 21.84 min with 18.42% and 12.23% area, represent carboxylic acids (9-octadecanoic acid and n-hexadecanoic acid, respectively), which were highly abundant in the rice husk extract, as shown in Table 1.  
**Phenols in the rice husk extract:** The presence of phenolic compounds was indicated by their corresponding peaks, as illustrated in Table 1. Phenolic compounds originated by the degradation of rice husk [35] that contained a large amount of lignin [36]. Phenyl propane group present in lignin is the best source of phenolic compounds, as reported by wood chemistry studies. Phenols are key compounds when checking quality, because the presence of phenols may cause aging during long-term storing in a container e [37; 38]. **Alcohols in the rice husk extract:** Table 1 reports the presence of alcoholic compounds before the photocatalytic reaction. Alcoholic compounds are the most important for the conversion to long-chain alkanes and other important products obtained from rice husk. Rice husk contains sugar molecules, and when it is converted by means of pyrolysis, these sugar molecules are degraded forming different acids, alcohols, and ketones [39]. **Aldehydes in the rice husk extract:** Aldehyde compounds were present in a very small amount in the rice husk extract after pyrolysis.