Oil spill remediation and valorization of oil-soaked peat sorbent to biofuel by hydrothermal liquefaction

Environmentally benign oil spill clean-up, remediation of water bodies, and valorization of extracted spill oil waste and used sorbent are some key research areas that are studied to address safe solutions to oil spill disasters. In the present research work, sorption experiments using natural Sphagnum peat moss on various petroleum-based oil samples such as crude oil, diesel, and engine oil were studied to determine the oil sorption capacity. The oil-soaked peat sorbent, being a secondary pollutant, is further valorized by hydrothermal liquefaction (HTL) to yield bio-oil. Experimental results indicated peat sorbent achieved saturate sorption at optimum time of 40 min under controlled experiment conditions with a swelling efficiency of 11 times its self-weight. The sorption capacity was 11.25 g of crude oil per gram of peat sorbent. The sorption results were similar for different oil samples such as diesel and engine oil, with an observed higher sorption affinity towards more viscous oil. No significant improvement in adsorption after 50 min observed due to saturation. Characterization of Sphagnum peat moss indicated it be naturally an excellent oil sorbent, proximate analysis of peat moss gave only 1% of ash content, 66.7% VOC, and 15.3% moisture content. The contact angle (Theta) 102 degrees demonstrated the hydrophobic nature of peat sorbent. Spectral analysis by Fourier-transform infrared spectroscopy (FTIR) indicated distinct peaks in three major regions between 400 and 4000 cm(-1) giving the presence of hydroxylic, phenolic, and carboxylic groups making it a good source for bio-oil feedstock. Thermogravimetry differential thermal analysis (TGDTA) of peat moss showed, the decomposition happened between 250 and 550 degrees C and this was useful in determining the HTL reaction temperature. The HTL of dry peat moss gave a bio-oil yield of 29% wt and that of the oil-soaked peat moss gave a bio-oil yield of 34.47% wt at operating conditions of 280 degrees C, 15 g/200 mL biomass loading rate, and holding time of 60 min. The gas chromatography-mass spectroscopy (GC-MS) characterization of bio-oil detected products in (C8-C12) petrol-diesel range, which conforms that oil-soaked peat to be a good source of bio-oil feedstock and as potential source of biofuel.

Automated summary

The research focused on the use of natural Sphagnum peat moss as an effective oil sorbent and valorized the oil-soaked peat to produce bio-oil through hydrothermal liquefaction. Experimental results showed high sorption capacity of peat sorbent for various oil samples, indicating its potential as a source of bio-oil feedstock and biofuel.