Persulfate assisted hydrothermal processing of spirulina for enhanced deoxidation carbonization

Area of Science:

• Biomass conversion
• Renewable energy
• Materials science

Background:

• Hydrothermal carbonization (HTC) is a thermochemical process for converting biomass into hydrochar.
• Spirulina is a promising feedstock for biofuel production due to its high content of organic matter.
• Optimizing HTC conditions is crucial for enhancing hydrochar yield and quality.

Purpose of the Study:

• To investigate the effect of persulfate on spirulina hydrothermal carbonization.
• To evaluate the impact of persulfate on hydrochar properties, including carbonization degree, fuel characteristics, and thermal stability.
• To determine the optimal conditions for producing high-quality hydrochar biofuel.

Main Methods:

• Spirulina biomass was subjected to hydrothermal carbonization (HTC) at temperatures ranging from 160°C to 220°C.
• Persulfate was used as an additive to assist the HTC process.
• Hydrochar properties were analyzed using elementary composition, proximate analysis, surface functional group analysis, morphological characterization, and thermal stability tests.

Main Results:

• Persulfate addition enhanced the carbonization degree of hydrochar, evidenced by oxygen reduction (1.53%-2.74%) and increased carbon ratio.
• Higher heating values (HHVs) of hydrochar increased by 0.81-1.39 MJ/kg at temperatures above 180°C.
• Persulfate significantly reduced surface functional groups (-OH, CO) and weakened C-(C, H) and C-(O, N) bonds, forming more C-H peaks, and improved thermal stability by lowering the maximum mass loss rate.

Conclusions:

• Persulfate-assisted HTC is an effective method for improving hydrochar properties for biofuel production.
• The process enhances carbonization and thermal stability, allowing for efficient hydrochar production at lower temperatures.
• This approach offers a viable pathway for sustainable biofuel generation from spirulina biomass.