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Use of Limestone Sludge in the Preparation of ɩ-Carrageenan/Alginate-Based Films

2024; Multidisciplinary Digital Publishing Institute; Volume: 17; Issue: 7 Linguagem: Inglês

10.3390/ma17071668

1996-1944

Pedro Adão, Maria da Luz Calado, Wilson Fernandes, Luís G. Alves, Leonor Côrte‐Real, M. Guedes, Ricardo Baptista, Raul Bernardino, Maria M. Gil, Maria Jorge Campos, Susana Bernardino,

Marine and coastal plant biology

The use of processed limestone sludge as a crosslinking agent for films based on Na–alginate and ɩ-carrageenan/Na-alginate blends was studied. Sorbitol was tested as a plasticizer. The produced gel formulations included alginate/sorbitol and carrageenan/alginate/sorbitol mixtures, with tested sorbitol concentrations of 0.0, 0.5 and 1.0 wt%. The limestone sludge waste obtained from the processing of quarried limestone was converted into an aqueous solution of Ca2+ by dissolution with mineral acid. This solution was then diluted in water and used to induce gel crosslinking. The necessity of using sorbitol as a component of the crosslinking solution was also assessed. The resulting films were characterized regarding their dimensional stability, microstructure, chemical structure, mechanical performance and antifungal properties. Alginate/sorbitol films displayed poor dimensional stability and were deemed not viable. Carrageenan/alginate/sorbitol films exhibited higher dimensional stability and smooth and flat surfaces, especially in compositions with 0.5 wt% sorbitol. However, an increasing amount of plasticizer appears to result in severe surface cracking, the development of a segregation phenomenon affecting carrageenan and an overall decrease in films’ mechanical resistance. Although further studies regarding film composition—including plasticizer fraction, film optimal thickness and film/mold material interaction—are mandatory, the attained results show the potential of the reported ɩ-carrageenan/alginate/sorbitol films to be used towards the development of viable films derived from algal polysaccharides.