Dilute formic acid and alkaline oxidation relay treatment for the whole-fraction efficient gradient separation of space Arundo donax

When attempting to replace fossil feedstocks with biomass, the available options suffer from single-component utilization, low efficiency of full-component separation, and high costs. Here, a thermochemical formic acid (TFA) treatment relayed alkaline oxidation (AO) process was developed for efficient whole-component gradient separation of space Arundo donax. Benefiting from thermochemical action of formic acid, space Arundo donax achieved 93.43% hemicellulose separation and 68.59% selectivity when the product of hemicellulose separation and selectivity was innovatively defined as a benchmark. Similarly, alkaline oxidative separation of lignin achieved about 90% lignin separation and about 80% selectivity. In addition, the solid and liquid products obtained under the most optimal process conditions were characterized. This work contributes to the enhancement of a systematic understanding of whole-component gradient separation of biomass, and it provides a promising approach to realize the clean, low-cost and efficient gradient separation of biomass and the scale-up of the separation process, thereby realizing the high-value utilization of the whole components of biomass. • A dilute formic acid treatment relay alkaline oxidation process was constructed. • Space Arundo donax whole components were efficiently and cleanly gradient separated. • Use the product of separation rate and selectivity as a overall evaluation index. • The dilute formic acid treatment achieved 93.43% hemicellulose removal. • The alkaline oxidation treatment achieved ∼90% lignin removal.