RECOVERY OF SULFURIC ACID FROM LIGNOCELLULOSIC BIOMASS HYDROLYSATE BY ELECTRODIALYSIS PROCESS

Abstract

Lignocellulosic biomass is the source of pentose (xylose) and hexose (glucose) sugars and found abundantly on the earth but the extraction of these sugars is the main concern of today’s researcher. There are mainly two popular methods for extracting these sugars: enzymatic hydrolysis and acid hydrolysis. The enzymatic hydrolysis is the traditional method which uses pretreatment followed by enzymatic treatment but the generation of toxic compounds during pretreatment, half-life of enzyme, enzyme titer value and its production time has limited this process to be scaled-up. On the other hand the acid hydrolysis is a chemical process which can extract these sugars within much lesser time in comparison to enzymatic hydrolysis with negligible or no amount of toxic compounds generated. The only disadvantage of this technology is the need to neutralization of acid before going for fermentation. So if a technology can be developed to recycle this acid then it will be most economical, ecofriendly, easily scalable and zero-waste technology. Here an acid recovery technology called electrodialysis has been attempted for acid removal from acid hydrolysate of lignocellulosic biomass. This technology is an electrically driven process in which ions move from one compartment to another through the ion exchange membrane in the presence of electric field. This technology is able to recover more than 95% of sulfuric acid from the lignocellulosic biomass hydrolysate. Although, this electrodialysis process is a power consuming process, fast acid recovery and proper utilization of the generated gases (hydrogen and oxygen) can overcome this power cost.