# Green Extraction of Valuable Compounds from Rubber Seed Trees: A Path to Sustainability
## 7 Green Extraction of Rubber Seed Oil
### Supercritical Fluid Extraction (SFE)
#### 7.1.2 Current Studies on Rubber Seed Trees by SC-CO\({}_{2}\)
These studies aim to showcase the utility and adaptability of these compounds in various situations. In their study, [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [87] explored various extraction methods to obtain seed oil. They utilized both traditional and environmentally friendly techniques. One such eco-friendly method was SC-CO\({}_{2}\) extraction, which employed carbon dioxide in its supercritical state as a solvent. Under optimized conditions of a 30 MPa pressure and a 60 \({}^{\circ}\)C temperature, SC-CO\({}_{2}\) extraction yielded the highest oil yield at approximately 33.562% grams of oil per sample. This method showcased its effectiveness in obtaining a significant amount of rubber seed oil while maintaining environmental sustainability. In contrast, the traditional Soxhlet extraction method was employed using petroleum ether as the solvent. Based on their studies, this method yielded a relatively higher percentage of oil per sample, with an oil yield of 56%. The efficiency of Soxhlet extraction in extracting rubber seed oil was evident, making it a potent technique for obtaining substantial oil yields. On the other hand, the use of a mixture of water and ethanol as a solvent in the extraction process resulted in a considerably lower oil yield, ranging from 7% to 12%. This indicated that the water and ethanol mixture was less effective compared to the other extraction methods. In summary, the study of [PERSON] et al. presented a comparative analysis of extraction methods for rubber seed oil, showcasing the potential of SC-CO\({}_{2}\) extraction as a green and efficient technique and the efficiency of Soxhlet extraction with petroleum ether. These findings underscored the importance of selecting appropriate extraction methods based on both their effectiveness and their environmental impact. \begin{table}
\begin{tabular}{c c c} \hline
**Parameters** & **Outcomes** & **Ref** \\ \hline T = 60 \({}^{\circ}\)C & & \\ P = 30 MPa & The highest oil yield is 33.56\% (w) oil/sample, & [87] \\ \hline T = 60 \({}^{\circ}\)C & the maximum oil recovery (34.71\%), the diffusivity & \\ P = 300 bar & coefficient (5.13 \(\times\) 10\({}^{-12}\) m\({}^{2}\)/s) and extraction rate & [66] \\ Particle size = 425–500 \(\upmu\)m & (0.6 mg/s). & \\ \hline T = 60 \({}^{\circ}\)C & & \\ P = 30 MPa & Rubber seed trees contain 19.22 \(\pm\) 0.21\% of alpha & \\ Flow rate = 4 mL/min & linolenic acid (ALA). & [88] \\ \hline T = 60 \({}^{\circ}\)C & Total carotenoids (as astaxanthin) extracted in this & \\ P = 50 MPa & method were 30.26 \(\pm\) 0.06 mg/kg dry weight & [56] \\  & waste rubber seed trees. & \\ \hline \end{tabular}
\end{table} 
Table 2: Previous study of rubber seed tree extract by SC-CO\({}_{2}\) extraction. In their study, [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [66] conducted a comprehensive investigation into the impact of particle sizes on the supercritical carbon dioxide extraction process of rubber seed oil. Under the experimental conditions of a 30 MPa pressure and a 60 \({}^{\circ}\)C temperature, utilizing rubber seed particles with an average size of 500 \(\upmu\)m yielded remarkable results. The maximum oil recovery rate achieved was 34.71%, showcasing the pivotal role played by this specific particle size in optimizing oil yield. Additionally, the study revealed a diffusivity coefficient of 5.13 \(\times\) 10\({}^{-12}\) m\({}^{2}\)/s, indicating efficient mass transfer during extraction, and an extraction rate of 0.6 mg/sec, denoting the speed at which oil was extracted. Morphological characterization using scanning electron microscopy (SEM) aligned with the particle size results, highlighting the importance of particle size control. Furthermore, gas chromatography mass spectrometry (GC-MS) analysis unveiled the presence of essential fatty acids and valuable chemical constituents within the extracted rubber seed oil, underscoring its potential beyond yield.