Efficient separation and production of high-quality rubber, lignin nanoparticles and fermentable sugars from Eucommia ulmoides pericarp via deep eutectic solvent pretreatment

The natural barriers of lignocellulose hinder the separation of Eucommia ulmoides rubber (EUR) from Eucommia ulmoides pericarp (EUP), whereas traditional separation methods normally lead to the waste of Eucommia ulmoides lignocellulose resource and environmental pollution. In this study, an acidic deep eutectic solvent composed of lactic acid and ZnCl2 was developed as a pretreatment medium to reduce the separation barriers of EUR while producing lignin nanoparticles and fermentable sugars. Results showed that DES pretreatment could accelerate the extraction efficiency (91.0 %) and purity (>99 %) of EUR and maintain its chemical structure compared to the traditional alkaline and mechanical methods. Meanwhile, the regenerated nano-lignin showed excellent antioxidant activity (IC50 = 46.3 μg/mL) comparable to commercial antioxidant BHA. Besides, the enzymatic hydrolysis efficiency of EUP with DES pretreatment was significantly enhanced about 9 times than the control groups. Overall, the acidic DES pretreatment could be considered a promising pretreatment method for separation of high-quality EUR and valorization of lignocellulosic components.