The optimization of neutralization conditions on wheat straw hydrolyzate by orthogonal method

Wheat straw, the second largest agricultural residues after rice straw in the world, has long been considered as one of the abundant feedstocks for bioethanol production, a promising and renewable alternative to fossil fuel. Among various processes, dilute acid pretreatment by H2SO4, which is most widely used, is more efficient in hemicellulose and cellulose solubilization. The wheat straw hydrolyzate pretreated by 1.1% H2SO4 contains many impurities such as sulfates and other acid components, which may inhibit the following fermentation steps when producing bioethanol. In this study, different neutralization conditions, including reaction temperature, soaking time and pH value are investigated and optimized using orthogonal design by comparing three variables of transmittance, sulfate concentration and sugar loss in the hydrolyzate. The optimal condition for higher transmittance and less sugar loss in the acid treated hydrolyzate from wheat straw is obtained as: 60 °C, 45 minutes and pH 3.0–3.3.