Direct biodiesel production from wet spent coffee grounds.

Area of Science:

• Biomass Conversion
• Renewable Energy
• Chemical Engineering

Background:

• Waste spent coffee grounds (SCG) present disposal challenges and limited utilization.
• Lipids in SCG are convertible to biodiesel via transesterification.
• Current methods for SCG biodiesel production are energy-intensive due to high temperatures and water effects.

Purpose of the Study:

• To develop a single-step, energy-efficient method for direct biodiesel production from wet SCG.
• To optimize the simultaneous extraction-transesterification process using a soxhlet apparatus.
• To evaluate the catalytic activity and reusability for sustainable biodiesel synthesis.

Main Methods:

• A novel reactive extraction soxhlet (RES) method was employed for simultaneous lipid extraction and transesterification.
• Homogeneous base catalysis (0.75 M) with hexane as a co-solvent was utilized.
• Factorial analysis of methanol to hexane ratio and reaction time was performed to determine optimal conditions.

Main Results:

• The RES method achieved a high fatty acid to fatty acid methyl ester conversion efficiency of 97%.
• Optimal conversion was achieved with a methanol to hexane ratio of 1:2 and a reaction time of 30 minutes.
• The catalyst demonstrated stability and reusability over five cycles without activity loss.
• Significant energy savings of 38-99% were realized compared to existing methods.

Conclusions:

• The developed RES method offers an efficient and sustainable route for biodiesel production from wet SCG.
• This approach addresses environmental concerns associated with SCG waste and reduces energy consumption in biodiesel synthesis.
• The process is cost-effective due to catalyst reusability and substantial energy savings.