Biobleaching of Eucalyptus globulus kraft pulps: comparison between pulps obtained from exploded and non-exploded...

Area of Science:

• Pulp and Paper Chemistry
• Biotechnology
• Environmental Science

Background:

• Kraft pulping generates lignocellulosic materials requiring bleaching for enhanced properties.
• Steam explosion is a pre-treatment method that modifies pulp structure.
• Biobleaching offers a potentially eco-friendlier alternative to conventional chemical bleaching.

Purpose of the Study:

• To assess the efficacy of a laccase-mediator system (LMS) for biobleaching steam-exploded kraft pulps.
• To compare the biobleaching performance against control pulps.
• To evaluate the impact of LMS and steam explosion on pulp properties and chemical consumption.

Main Methods:

• Steam explosion pre-treatment of kraft pulps.
• Laccase-mediator treatment using commercial laccase and acetosyringone.
• Alkaline extraction and hydrogen peroxide bleaching stages.
• Assessment of pulp kappa number, optical properties, and accelerated aging.

Main Results:

• Biobleached steam-exploded pulps exhibited lower kappa numbers and superior optical properties compared to controls.
• The combined steam explosion and biobleaching process led to a reduction in hydrogen peroxide consumption.
• Accelerated aging did not significantly degrade the improved properties of the biobleached pulps.
• The laccase-mediator system had a less pronounced effect on pulp properties and chemical usage than steam explosion.

Conclusions:

• Steam explosion followed by laccase-mediator biobleaching is an effective strategy for producing high-quality pulps.
• This integrated approach reduces the environmental impact by lowering chemical demand, particularly hydrogen peroxide.
• The method yields pulps with enhanced stability and optical characteristics, suitable for various applications.