High value-added lignin extracts from sugarcane by-products

Area of Science:

• Biomass Valorization
• Green Chemistry
• Biopolymer Extraction

Background:

• Sugarcane bagasse (SCB) and straw (SCS) are abundant agricultural byproducts.
• Alkaline pulping generates black liquors containing valuable lignin.
• Conventional lignin extraction uses sulfuric acid (SA), prompting research into sustainable alternatives.

Purpose of the Study:

• To evaluate greener organic acids (methane sulfonic acid (MSA), formic acid (FA), lactic acid (LA)) as alternatives to SA for precipitating lignin bioactive extracts.
• To compare the yield and composition of lignin extracts obtained using different precipitating agents.
• To assess the radical scavenging activity of the extracted lignin bioactive compounds.

Main Methods:

• Alkaline black liquors from SCB and SCS were treated with MSA, FA, and LA.
• Precipitation yields were measured.
• Lignin extract composition (carbohydrates, lignin, inorganics) was analyzed.
• Radical scavenging activity (ABTS radical) was evaluated.

Main Results:

• Lactic acid (LA) achieved the highest precipitation yield from SCB (14.5 g/100 g SCB).
• SCB extracts showed consistent composition across agents; SCS extracts varied in sugar content.
• All extracts demonstrated radical scavenging activity, with effectiveness against the ABTS radical.

Conclusions:

• Organic acids, particularly FA, are promising alternatives to SA for recovering bioactive lignin extracts from SCB and SCS.
• This approach enhances the valorization of agricultural residues through green chemistry principles.
• The study highlights the potential for producing valuable bioactive compounds from pulping byproducts.