# Enhanced multi step solvent extraction for fractionated bio oil production from sugarcane bagasse via hydrothermal liquefaction

## TL;DR

This study improves bio-oil production from sugarcane bagasse using a multi-step solvent extraction method after hydrothermal liquefaction, resulting in higher separation efficiency and targeted recovery of useful compounds.

## Contribution

The study introduces a novel sequential solvent extraction method for hydrothermal liquefaction bio-oil, enabling efficient and selective recovery of compounds based on polarity.

## Key findings

- Sequential extraction using THF, EAC, and n-hexane achieved yields of 74.6%, 44.6%, and 17.5%, respectively, under optimal conditions.
- The method improved separation efficiency by 25% compared to traditional single-solvent extraction.
- Fractionated bio-oils contained alkanes, ketones, and phenolic compounds suitable for various applications.

## Abstract

Hydrothermal liquefaction (HTL) is a promising thermochemical conversion process for lignocellulosic biomass, which is a sustainable feedstock for the production of renewable fuels. For agricultural residues, systematic multi-step solvent fractionation is still understudied, despite the fact that traditional single-solvent extraction after HTL produces mixed bio-oil fractions with heterogeneous properties. Tetrahydrofuran (THF), ethyl acetate (EAC), and n-hexane are used in this study’s sequential extraction methodology to separate HTL bio-oil from sugarcane bagasse according to polarity. The method overcomes the drawbacks of single-solvent systems for the selective recovery of organic compounds with low and mid-polarity. Sequential extraction produced differential yields of 74.6 ± 2.4% (THF), 44.6 ± 1.9% (EAC), and 17.5 ± 1.2% (n-hexane) under optimal conditions (280–340 °C, 72–175 bar, 20–60 min), indicating a 25% increase in separation efficiency over traditional methods. The systematic characterization of polarity-based fractionation after HTL is novel because it allows for the targeted recovery of aliphatic hydrocarbons, ketones, and phenolic compounds for various uses.

The experiment was done with sugarcane bagasse. First the sugarcane bagasse was. Then ground into a powder. After that it went through a process called liquefaction. This was done in a Parr reactor. The temperatures used were between 280 and 340 degrees. The pressure was between 72 and 175 bar. The process took between 20 and 60 min. They used three solvents to get the bio-oils out of the sugarcane bagasse. These solvents were tetrahydrofuran, ethyl acetate and n-hexane. The sugarcane bagasse produced types of bio-oils, like heavy bio-oils, mid bio-oils and light bio-oils. The resultant oils were analyzed through techniques such as gas chromatography and mass spectrometry to assess their composition, energy production potential, and properties upon heating.

The experiment was carried out using sugarcane bagasse. What was first was the sugarcane bagasse. Then ground into a powder. Subsequently it passed through a liquification process. This occurred in a Parr reactor. Ranging between 280 and 340 degrees were used. The pressure ranged between 72 and 175 bar. It was done 20 to 60 min. The sugarcane bagasse was extracting the bio-oils in three solvents. These were tetrahydrofuran, ethyl acetate and n-hexane. The sugarcane bagasse generated forms of bio-oils, such as heavy bio-oils, mid bio-oils and light bio-oils. The resulting oils were examined using methods like gas chromatography and mass spectrometry to determine their composition, potential of energy production and their properties when heated. Using three solvents—tetrahydrofuran (THF), ethyl acetate (EAC), and n hexane (n H) sequential extraction achieved yields of 74.6 ± 2.4%, 44.6 ± 1.9%, and 17.5 ± 1.2%, respectively. Experiments were performed in triplicate at 280–340 °C and 72–175 bar. The multi-step process improved separation efficiency by 25% over conventional methods. Limitations include solvent recovery losses (~ 8%) and scale up challenges. The results demonstrate a reproducible and sustainable route for valorizing sugarcane bagasse into liquid fuels. Upon examining the bio oils with a tool, we identified several significant chemical groups, including alkanes, ketones, and phenolic compounds. The dense portion of the oil contained many alkanes. The central section contained phenols and ketones, which is intriguing because it implies this oil might potentially serve as an alternative to certain petroleum-derived asphalt.

Multi-step hydrothermal liquefaction and solvent extraction of sugarcane bagasse was able to improve the quality and recovery of bio-oil. THF was the best solvent to use in the extraction and longer reaction time and increased temperature favored more yield and deoxygenation. Hydrothermal liquefaction is one of the feasible and viable thermal aptitude transformation methods that can be used to convert sugarcane bagasse into renewable biofuels and chemical intermediates. The end products of the bio-oils were found to be combustible with similar properties compared to the petroleum crude oil.