Hydrochars from industrial macroalgae "Gelidium Sesquipedale" biomass wastes

Area of Science:

• Biomass conversion
• Renewable energy sources
• Materials science

Background:

• Macroalgae waste from the agar-agar industry presents a significant disposal challenge.
• Valorization of algal biomass into value-added products is crucial for sustainable resource management.

Purpose of the Study:

• To investigate the production of hydrochars from macroalgae waste via hydrothermal carbonization (HTC).
• To evaluate the impact of HTC temperature and time on hydrochar yield, energy content, and physicochemical properties.

Main Methods:

• Hydrothermal carbonization of macroalgae waste at varying temperatures (200°C, 230°C) and durations (2h, 6h).
• Characterization of hydrochars, including yield, higher heating value (HHV), elemental analysis (H/C, O/C ratios), and pore structure analysis (meso-macroporous, average pore size up to 110.5 nm).

Main Results:

• Hydrochar yields reached up to 60%, significantly exceeding conventional char yields (27.5-33.5%).
• Carbon content and HHV increased with HTC, with a hydrochar at 230°C for 6h exhibiting an HHV of 23.25 MJ/kg, comparable to lignite.
• Dehydration and decarboxylation reactions reduced H/C and O/C ratios, while the vegetal structure remained largely intact.

Conclusions:

• Hydrothermal carbonization is an effective method for converting macroalgae waste into high-yield hydrochars with improved energy density.
• The resulting hydrochars possess favorable properties for potential use as solid biofuels or in other energy applications.
• Optimizing HTC conditions can maximize hydrochar quality and yield, contributing to a circular economy approach for algal biomass.