Polysaccharide hydrolysis accelerated by adding carbon dioxide under hydrothermal conditions

Area of Science:

• Biomass Conversion
• Green Chemistry
• Carbohydrate Chemistry

Background:

• Polysaccharides are abundant biopolymers requiring efficient hydrolysis for value-added product generation.
• Conventional hydrolysis methods often involve harsh chemicals, leading to environmental concerns and complex separation processes.
• Developing sustainable and efficient methods for polysaccharide breakdown is crucial for biorefining.

Purpose of the Study:

• To investigate the hydrolysis of various polysaccharides (agar, guar gum, starch, xylan) into mono- and oligosaccharides.
• To evaluate the impact of carbon dioxide under hydrothermal conditions on polysaccharide hydrolysis efficiency.
• To establish an environmentally benign alternative to conventional acid/base hydrolysis.

Main Methods:

• Hydrothermal treatment of polysaccharides (agar, guar gum, starch, xylan) in a batch reactor.
• Varying carbon dioxide loads to achieve different pressures.
• Analysis of molecular weight distribution and product yields (e.g., glucose).

Main Results:

• Hydrolysis under hydrothermal conditions with carbon dioxide significantly reduced molecular weight.
• Increased carbon dioxide load led to higher yields of mono- and oligosaccharides.
• Glucose yield from starch hydrolysis increased from 3.7% to 53.0% within 15 minutes at 200°C with elevated CO2.
• Carbonic acid formation lowered the pH, facilitating hydrolysis.

Conclusions:

• Hydrothermal treatment of polysaccharides in the presence of carbon dioxide is an effective and green method for producing mono- and oligosaccharides.
• This process offers a sustainable alternative to conventional hydrolysis, eliminating the need for neutralization and separation steps.
• The use of carbon dioxide enhances hydrolysis efficiency and product yields, making it a promising technology for biomass valorization.