Processing and Drying Characteristics of Duckweed as a Candidate Bio-Based Material for Composites

Duckweed (Lemnaceae) is a rapidly growing aquatic plant with promising potential as a bio-based feedstock for composite materials due to its high cellulose and biomass productivity. To enable its utilization in material engineering applications, proper preprocessing is essential to ensure stability, uniformity, and compatibility with polymer matrices. Drying represents a critical step in this processing chain, yet the drying behavior of duckweed remains insufficiently characterized. This study investigated convective hot air drying of duckweed at 60 °C for 5–7 h, focusing on thin-layer modeling, effective moisture diffusivity, color stability, and energy efficiency. Six thin-layer models were evaluated, with the Midilli et al. model providing the best fit (R² > 0.998, lowest RMSE). Effective diffusivity increased with drying time, while energy consumption rose only slightly. Color analysis revealed reductions in L* and b* and an increase in a*, with ΔE stabilizing after 6 h, identifying this as the optimal drying duration balancing energy efficiency, product stability, and quality. The results provide essential drying parameters for duckweed processing, thereby supporting its future application as a sustainable candidate material in composite engineering.