Effect of Alkali and 1,4-Butanediol Contents on the Extraction of Lignin and Lignin-Based Activated Carbon.

In the process of lignin extraction by the organic solvent method, the amount of alkali and the content of 1,4-butanediol are important conditions that affect lignin yield. The effects of alkali and alcohol contents on lignin recovery, removal rate, and structure were studied. In this reaction system, the removal rate of lignin increased with the increase of alkali content but decreased with the increase of alcohol content. Fourier transform infrared (FT-IR) analysis showed that the phenol hydroxyl group and the ether bond in lignin had different trends in different alkali and 1,4-butanediol environments, and four different infrared parameters in lignin had an obvious linear relationship. Gel permeation chromatography (GPC) results showed that high alkali content and high 1,4-butanediol content could lead to the fragmentation of lignin. In addition, lignin extracted from alkali-quantity factor series was selected to prepare activated carbon, CaCl2 was selected as the activator, and its effects were studied. Results showed that in the process of extracting lignin, on the one hand, NaOH content affects the functional groups of activated carbon by affecting the aromatic structure of lignin; on the other hand, the NaOH content affects the graphitization degree and specific surface area of activated carbon by affecting the removal rate and the molecular weight of lignin.

Investigating desorption during ethanol elution to improve the quality and antioxidant activity of xylo-oligosaccharides from corn stalk.

As the most representative of lignocellulosic materials, corn stalk (CS) will be a great candidate to produce xylo-oligosaccharides (XOS). Owing to the high impurity content of the XOS produced by directly enzymatic hydrolysis of xylan extracted from CS, subsequent refining steps are essential. The present study was aimed to investigate desorption during ethanol elution to improve the quality and antioxidant activity of XOS from CS. The desorption was systematically investigated after optimizing the elution conditions. The results showed that it had an elution watershed when the volume ratio was 2:1. More interestingly, XOS had a obvious priorities of desorption during ethanol gradient elution. The highest purity of XOS was 98.12% from 30% ethanol eluate. Antioxidant activity assay showed that the highest radical scavenging activity of XOS was 89.89% obtained from 70% ethanol eluate at a concentration of 3 mg/mL, which could be used in antioxidant food, feed additives.