Student name: Margarida Matias

RUN-EU institution: Technological University of the Shannon: Midlands Midwest, Ireland

Abstract

Gelidium corneum, a red seaweed harvested for centuries in the Iberian Peninsula, has traditionally been used for agar extraction and applications in the agri-food sector [1]. However, recent studies have highlighted its broader biotechnological potential beyond agar production [2]. In our previous research, a sequential extraction of a hydroethanolic extract yielded a lipophilic fraction with strong antimicrobial activity against Cutibacterium acnes (IC₅₀ = 16.1 μg/mL). Chemical analysis using Liquid Chromatography-Mass Spectrometry (LC-MS) identified its fatty acid profile, which was rich in palmitic, myristic, oleic, arachidonic, and eicosapentaenoic acids. To further utilise the remaining seaweed biomass after extraction, we converted it into biochars through conventional pyrolysis and advanced processes, including hydrothermal carbonization (HTC) and acid-mediated carbonization (AMC). Among these methods, HTC produced the most developed porous structure (BET surface area = 30 m²/g, total pore volume = 0.07 cm³/g), whereas pyrolysis and AMC resulted in biochars with significantly lower values. The oxygen content of the biochars ranged from 20–27%, with the HTC-derived biochar exhibiting the highest heteroatom content due to its elevated ash content (21% vs. 3% for HTC and <1% for AMC). Additionally, pyrolysis yielded a biochar with a basic surface (pHₚZ₀ = 9.0), while HTC and AMC produced acidic surfaces (pHₚZ₀ = 2.4 and 2.2, respectively). The biochar obtained from the biorefinery processing of G. corneum presents promising characteristics for the development of innovative biotechnological applications, including skin-cleansing products and water filtration systems.

References

1. Gaspar, R., Pereira, L., & Sousa-Pinto, I. (2019). The seaweed resources of Portugal. Botanica Marina, 62(5), 499–525.

2. Mouga, T., & Fernandes, I. B. (2022). The Red Seaweed Giant Gelidium (Gelidium corneum) for New Bio-Based Materials in a Circular Economy Framework. Earth, 3(3), 788–813. https://doi.org/10.3390/earth3030045.