Near complete valorisation of Hybrid pennisetum to biomethane and lignin nanoparticles based on gamma-valerolactone/water pretreatment

This study is the first to integrate gamma-valerolactone/water (GVL/water) pretreatment with anaerobic digestion (AD) for biogas production and lignin nanoparticles (LNPs) synthesis. The hydrothermal treatment was conducted at 135 to 180 °C with GVL at 0 to 90%. After pretreatment, the compositions of hybrid pennisetum were changed with the removal of lignin, hemicellulose, and cellulose to different extent. Subsequent anaerobic digestion achieved a maximal specific methane yield of 228.00 ± 4.37 mL/g VS, compared with that at 165.11 ± 1.99 mL/g VS for the control. The highest actual methane yield (150 mL/g RM) was achieved by pretreatment with GVL/water (50/50) at 150 °C for 90 min. LNPs at 200 to 2000 nm were synthesized from the liquid waste with a yield at ~4 mg/mL. The mass balance of this integrated method was discussed. In general, the maximal valorisation of hybrid pennisetum was achieved based on a catalyst-free of GVL/water pretreatment.