Optimisation of dilute-acid pretreatment conditions for enhancement sugar recovery and enzymatic hydrolysis of wheat straw

In order to produce bioethanol from agricultural residues such as wheat straw, the decomposition lignocellulosic materials into soluble sugars is necessary. This work focused on the influence of dilute sulphuric acid pretreatment conditions on sugar removal and the enzymatic saccharification of wheat straw. Response surface methodology (RSM) based on rotatable central composite design (RCCD) was used to optimise H2SO4-catalysed hydrothermal pretreatment of wheat straw, in respect to acid concentration (0.75–2.25%), treatment time (10–30 min) and temperature (120–160 °C). The pretreated wheat straw was hydrolysed by a standard blend of Cellusoft CR®. Enzymatic hydrolysis was also measured to evaluate the optimal pretreatment conditions for maximising sugar recovery. The optimum values of factors for enhancing sugar recovery in pretreatment, and consequently enzyme hydrolysis, were: retention time 30 min, acid concentration 1.6% and temperature 147 °C. The results showed that temperature was more significant than acid concentration and treatment time for enhancement of xylose release and cellulose digestion.

► Experimental design procedure considers interaction of parameters as a whole domain.
► Retention time, acid concentration and temperature investigated using CCD.
► Evaluating criteria based on high xylose yield and high cellulose recovery.
► Obtained from the solid residues obtained after filtration of pretreated materials.