Revealing the influence of metallic chlorides pretreatment on chemical structures of lignin and enzymatic hydrolysis of waste wheat straw

Abstract

The addition of various metallic chlorides in pretreatment of lignocellulose have been widely reported to improve cellulose conversion via cellulolytic processing. However, the interaction mechanism between lignin and metallic cations is not well known. In this work, pretreatment with different concentrations of FeCl3 and AlCl3 were performed upon waste wheat straw to enhance enzymatic hydrolysis efficiency. Results showed that pretreatment with FeCl3 and AlCl3 could facilitate the enzymatic hydrolysis efficiency increasing from 50.4% to 82.9% and 76.6%, which was attributed to the enhancement of xylan removal by 33.8% (FeCl3) and 36.5% (AlCl3), respectively. Meanwhile, the surface charge, hydrophobicity, and protein adsorption capacity of lignin from waste wheat straw can be decreased by 3.3 mV, 0.6 L/g, 7.6 mg/g (FeCl3). This was due to the depolymerization of lignin in metallic chlorides pretreatment. These findings will be used to further evaluate the effect of metallic chlorides in biorefinery pretreatment.