Lignocellulosic residue from 2G ethanol production as an effective binder for enhancing the quality of pine sawdust briquettes

This study investigated how binder type and concentration influence the performance of pine sawdust briquettes. Two binders were assessed, cassava starch (CS) and a lignocellulosic residue (LR) from second-generation (2G) ethanol production. Briquettes were formed at 127 MPa at room temperature, with 0–20 % binder by mass and were characterized for proximate and ultimate analysis, higher heating value, apparent density, compressive strength and longitudinal expansion. Analysis of variance showed a significant effect of binder concentration on mechanical performance. Compressive strength followed a quadratic pattern with minima at about 8 % cassava starch and 4 % lignocellulosic residue, decreasing at low concentrations and increasing at higher concentrations. Apparent density increased steadily with concentration. Relative to the briquette without binder, apparent density increased from 869 to 1061 kg m −3 at 20 % lignocellulosic residue and energy density rose from 17.55 to 21.77 GJ m −3 . The lignocellulosic residue increased the higher heating value relative to the briquette without binder and reduced short-term longitudinal expansion compared with cassava starch at matched concentrations. Durability tests showed that briquettes using LR had better durability (∼99 %). Taken together, the results indicate that between 10 and 20 % lignocellulosic residue delivers the best overall balance of mechanical densification, lower longitudinal expansion, energy density, compressive strength and durability for producing high-quality solid biofuel. • Lignocellulosic residue from 2G ethanol was assessed as binder for briquettes production. • The use of LR as a binder resulted in higher compressive strength. • Apparent density reached 1061 kg m −3 at 20 % LR (869 kg m −3 at 0 %). • LR raised higher heating value compared with briquettes without binder. • Briquettes produced with LR exhibited good durability.