2019 journal article
Comparison of Structural Characteristics of Straw Lignins by Alkaline and Enzymatic Hydrolysis
BIORESOURCES, 14(3), 5615–5629.
Lignin was separated from wheat straw by NaOH cooking and enzymatic hydrolysis, obtaining yields of 86.2% and 78.6%, respectively. Fourier transform infrared spectrometry (FT-IR) and two-dimensional nuclear magnetic resonance (2D-HSQC) analyses indicated that the H units (p-hydroxyphenyl units) of the Enzymatic Hydrolysis Lignin (EHL) did not suffer much damage. The number-average molecular weight (Mn) of the EHL measured by gel permeation chromatography (GPC) was 3348 g/mol, which was higher than that (3047 g/mol) of Alkali Lignin (AL). The Cr(VI) adsorption experiments demonstrated that the maximum removal percentages and maximum adsorption amount of the EHL and AL were 31.5%, 88.9%, 135.1 mg/g, and 271.7 mg/g, respectively. In addition, the adsorption kinetics, adsorption isotherm and thermodynamics of Cr(VI) on these two lignins were reported in detail.