Response surface optimization, morphological characterization, and thermal analysis of bamboo-based composite biomass pellets

Bamboo-based composite biomass pellets were prepared using bamboo sawdust as the base material and incorporating camphor leaves and maize straw. Maize-straw composition was literature-derived, not experimentally measured. Single-factor tests and a Box–Behnken response surface design assessed how molding temperature, wet-basis moisture content, and blending ratio affected pellet density and compressive strength. SEM supported morphological interpretation; TG/DTG served as supplementary, unreplicated thermal characterization rather than an optimization response. Temperature had the largest statistical effect on density, while temperature and camphor leaf content most strongly influenced compressive strength. Higher temperature and appropriate moisture promoted compactness, reduced pore defects, and improved structural continuity. A process-robust condition of 178°C, 8.3% moisture content, 27% wb camphor leaves, and 21% wb maize straw gave predicted density and compressive strength of 1.28 g·cm−3 and 3.401 MPa, respectively. Experimental validation yielded 1.197 ± 0.027 g·cm−3 and 3.133 ± 0.220 MPa (mean ± SE, n = 3), with relative prediction errors of 6.51% and 7.87%, respectively. TG/DTG descriptively confirmed typical staged lignocellulosic decomposition. These results provide a practical basis for optimizing bamboo-based multi-feedstock pelletization.