Atmospheric kraft pulping in glycerol

Area of Science:

• Wood Chemistry
• Pulping Technology
• Sustainable Materials

Background:

• Kraft pulping is the dominant industrial method for chemical pulp production from wood.
• The conventional process necessitates high pressure and expensive equipment, limiting accessibility.
• Water is the standard solvent, but alternative solvents are explored for process modification.

Purpose of the Study:

• To investigate the feasibility of kraft pulping at atmospheric pressure using glycerol as a water substitute.
• To evaluate the influence of process parameters (temperature, chemical charge, chip size) on glycerol-based kraft pulping.
• To assess the impact of these parameters on lignin dissolution in hardwood and softwood.

Main Methods:

• Atmospheric pressure kraft pulping experiments were conducted using glycerol instead of water.
• The study systematically varied temperature, chemical charge (alkali concentration), and wood chip size.
• Lignin dissolution was quantified as a measure of pulping efficiency for both hardwood and softwood sapwood.

Main Results:

• Reduced chip size significantly accelerated lignin dissolution for both hardwood and softwood.
• Lowering the chemical charge detrimentally affected the rate and extent of lignin dissolution.
• Increasing the pulping temperature markedly enhanced lignin removal from the wood matrix.

Conclusions:

• Glycerol-based kraft pulping at atmospheric pressure is a viable alternative, potentially reducing equipment costs.
• Optimizing chip size and temperature are critical for efficient lignin removal in this novel process.
• Further research is needed to address glycerol's viscosity limitations on impregnation and overall process economics.