Thermodynamic pathway of lignocellulosic acetylation process

Area of Science:

• Materials Science
• Polymer Chemistry
• Green Chemistry

Background:

• Natural cellulosic fibers are explored for polymer composites and oil sorption.
• Acetylation is a key chemical modification for cellulose, yielding hydrophobic and biodegradable cellulose acetate.
• Lignocellulosic biomass offers a sustainable source for acetylation.

Purpose of the Study:

• To investigate the solvent-free acetylation of oil palm empty fruit bunch (OPEFB), pride of Barbados pods (POBP), and cocoa pods (CP).
• To determine the effect of temperature and reaction time on acetylation efficiency (Weight Percent Gain - WPG).
• To conduct thermodynamic studies and analyze the acetylation mechanism and energy efficiency.

Main Methods:

• Solvent-free acetylation of OPEFB, POBP, and CP.
• Analysis of variance (ANOVA) to assess the significance of temperature and time on WPG.
• Fourier-transform infrared spectroscopy (FTIR) for reaction confirmation.
• Thermodynamic analysis including entropy and Gibb's free energy changes.
• Determination of heat capacity and critical temperatures.

Main Results:

• Successful acetylation of OPEFB, POBP, and CP confirmed by FTIR.
• ANOVA showed no statistical difference in WPG variation with temperature and time.
• Optimal acetylation times: 60 min for OPEFB, 30 min for POBP, and 90 min for CP.
• Acetylation is an endothermic and spontaneous process (negative Gibb's free energy) except at 303 K.
• Low critical WPG suggests a diffusion-controlled acetylation mechanism.
• Specific critical temperatures and heat capacities were determined for each material.

Conclusions:

• Acetylation is a successful and energy-efficient method for modifying OPEFB, POBP, and CP.
• The resulting acetylated materials possess desirable hydrophobic and biodegradable characteristics.
• The process is thermodynamically favorable and spontaneous under typical operating conditions.