The combined pretreatment using ultrasonication with different chemical pretreatments to enhance lignin production and enzymatic hydrolysis efficiencyKitilux Viwatmetawut, Santi Chuetor, Suchata Kirdponpattara and Wanwitoo WanmoleeE3S Web Conf., 679 (2025) 01033DOI: https://doi.org/10.1051/e3sconf/202567901033