Impact of acid hydrolysis on composition, morphology and xylose recovery from almond biomass (skin and shell)

Abstract

The aim of this study is to compare the impact of methane sulphonic and sulfuric acid hydrolysis for xylose recovery from almond industry waste such as shell (ASH) and skin (ASK). A two stage dilute acid hydrolysis (<1 % w/w) was evaluated to improve xylose following arabinose removal in stage 1. Sulfuric acid was observed to yield higher xylose- ASK (3.88 g/L) and ASK (14.01 g/L). Though xylose recovery was lower (38.1 % in ASH and 31.7 % in ASK) with methane sulphonic acid the hydrolyzed fibers showed enhanced delignification resulting in separation of the individual fibers suitable for downstream application in fiber composites. FTIR studies indicate an increased loss of syringyl subunit of lignin along with changes in core lignin structure with methane sulphonic acid responsible for fiber separation.