A green approach for the extraction of diamondoids from petroleum source rock

Extraction of adamantanes and diamantanes from petroleum source rock using nonionic surfactant was investigated and the optimum conditions for yields of the diamondoids were determined. The conventionally used accelerated solvent extraction method was compared to an innovative microwave-assisted nonionic surfactant extraction (MANSE). A three-level full factorial design of experiment (DoE) was adopted for the optimization of MANSE, involving solvent concentration, extraction temperature as well as extraction time. In-tube extraction (ITEX-2) using TENAX TA as sorbent in combination with gas chromatography-mass spectrometry (GC-MS) was used to determine the diamondoids in the extract. The results revealed that solvent concentration, extraction temperature and time have significant effects on extraction yields of the diamondoids. 0.04 M was the optimum surfactant concentration for extraction of both, adamantane and diamantane. The highest yields of the diamondoids were obtained at extraction temperature of 80 °C. The optimum extraction time for both adamantane and diamantane was 10 min. In comparison with the accelerated solvent extraction method, the results showed that MANSE is more efficient. This study has revealed that MANSE is a robust and efficient environmentally benign sample preparation method for geochemical evaluation of petroleum source rock.