A Novel Solid Acid Pretreatment Enhancing Volatile Fatty Acid Production From Biomass

With the reduction of the serious environmental pollution and global fossil energy in the development process of the world,people have shown great concern to the development and utilization of green,renewable and clean energy.Lignocellulosic biomass is a renewable energy source,with the characteristics of low pollution,low cost and variety;therefore,the active development and utilization of biomass can reduce environmental pollution by fossil energy,and then alleviate the greenhouse effect and energy effect.However,the characteristics of lignocellulosic biomass such as compact structure,stable performance and strong biodegradation resistance make it difficult to hydrolysis.In this study,carbon based solid acid was prepared by biomass and it was used to promote volatile fatty acids(VFAs)production,which will improve transformation of agriculture and forestry waste into green and clean energy chemicals.In this study,rice husk and concentrated sulfuric acid were used as materials to prepare carbon-based solid acid by one-step carbonization-sulfonation method.Then the pretreated corn cob was anaerobic fermented to produce VFAs.The results showed that solid acid pretreatment could significantly increase the acid production of corn cob by anaerobic fermentation.The final VFAS content in the system could reach 4050 mg/L,followed by the dilute sulfuric acid pretreatment group,which reached 2869.87 mg/L.The acid production in the solid acid pretreatment group was41.34% and 26.45% higher than that in the control group,respectively.The anaerobic fermentation of corn cob after solid acid pretreatment was dominated by acetic acid fermentation,which was the most important VFAs in all groups,accounting for more than 60% of the total acid production.The feasibility,process optimization and mechanism of membrane absorption technology for the separation and recovery of VFAs were studied by taking the hydrolytic acidizing liquid of corn cob as the original liquid.The hydrophobic hollow fiber membrane was used as the material to construct the membrane absorption system,and NaOH was used as the absorption liquid.VFAs separation and recovery could be realized through membrane absorption.The optimal conditions for the membrane absorption process were p H=1,concentration of the absorption solution was 0.1mol /L and flow rate of 30 rpm.Under this process condition,the recovery of VFAs by membrane system is 4278 mg/L,which indicates that this system can realize efficient recovery of VFAs.This study provides a new idea for the preparation of high-catalytic activated carbon based solid acid from biomass.Solid acid pretreatment can promote the anaerobic fermentation of biomass to produce VFAs,which provides a new method to promote the economic,pollution-free and high-efficiency acid production from biomass.