Refining spent cotton gin trash following essential oil extraction for value added cellulosic sugars

Abstract

The effectiveness of high temperature, dilute H2SO4 and NaOH pretreatments for the conversion of a post extracted cotton gin trash (ECGT) biomass was investigated. Whole acidified ECGT slurries were pretreated at various temperatures (180–230 °C) with or without the addition of extra catalyst. Compositional analysis of recovered ECGT fibre revealed xylan removal increased with pretreatment temperature under low pH conditions. Alkaline pretreatment (20 wt% NaOH) selectively delignified the ECGT fibre by as much as 80%. Characterisation of structural features identified an increase in cellulose crystallinity and surface area for all pretreated fibres and positively correlated to increasing pretreatment severity. Pretreatment of acidified ECGT slurries at 230 °C resulted in the highest glucan digestibility (66%) and glucose yields (51%). Glucan digestibility showed a strong positive correlation to xylan removal and surface area but weaker to delignification and total crystallinity for all dilute acid pretreated fibres.