Low-temperature highly selective water delignification based on geopolymer materials

Area of Science:

• Biomass Pretreatment
• Green Chemistry
• Materials Science

Background:

• Delignification is a costly and polluting step in biomass processing.
• Current methods often involve harsh chemicals and generate problematic waste streams like black liquor.

Purpose of the Study:

• To develop a simple, cost-effective, and environmentally friendly delignification pretreatment process.
• To utilize geopolymers for highly selective and efficient biomass delignification under mild conditions.

Main Methods:

• A geopolymer catalyst with a SiO2/Al2O3 ratio of 4.4 was synthesized and characterized for its acidic sites and catalytic activity.
• Low-temperature water-cooking pretreatment of woody (eucalyptus) and herbaceous (bagasse) biomass using the geopolymer catalyst.
• Optimization of reaction conditions including geopolymer/fiber ratio, time, and temperature.

Main Results:

• The geopolymer catalyst demonstrated high catalytic activity for delignification.
• Delignification rates increased by up to 38.90% for eucalyptus and 62.20% for bagasse under mild conditions (90°C, 90 min).
• The process generated low-alkali black liquor, simplifying subsequent water treatment and eliminating alkali recovery needs.

Conclusions:

• Geopolymers offer a highly selective and efficient method for biomass delignification.
• The developed low-temperature water-cooking process presents a sustainable alternative for biomass and papermaking industries.
• This geopolymer-based approach has significant potential for widespread application in biomass fiber processing.