The Synergistic Effect of Hydrothermal and Deep Eutectic Solvent Pretreatment on the Resource Utilization of <i>Spartina alterniflora</i> Straw

ABSTRACT Biomass feedstocks have attracted considerable research attention as promising renewable alternatives amid rising fossil fuel costs and increasing demand for sustainable energy. The invasive plant Spartina alterniflora poses significant ecological threats; however, its straw represents a potential feedstock for bio‐based products, thereby supporting both ecological management and resource utilization. However, the intrinsic recalcitrance of lignocellulosic biomass limits its efficient conversion, necessitating pretreatment strategies to improve enzymatic digestibility. Hydrothermal and deep eutectic solvent (DES) pretreatments have emerged as promising approaches due to their environmental compatibility and cost efficiency. This study investigated the synergistic effect of sequential hydrothermal and DES pretreatment on enhancing the enzymatic saccharification of Spartina alterniflora straw. The DES system consisted of choline chloride and lactic acid at a molar ratio of 1:10. Sequential hydrothermal pretreatment at 180°C was first conducted, followed by DES treatment. This process achieved xylan and lignin removal rates of 83.89% and 72.02%, respectively, while retaining 62.97% of the cellulose fraction, enzymatic hydrolysis efficiency increased by 245.54% relative to untreated substrates. These results demonstrate the potential of this strategy for sustainable biomass valorization.