Spirulina platensis protein extract as an additive to improve the removal capacity of protein hydrogels

D´ORSO, M.; MEIORIN, C.; MARTUCCI, J.

Buenos Aires

Congreso; The WCCE11 - 11th World Congress of Chemical Engineering; 2023

The aim of this work is design eco-friendly chemically cross-linked hydrogels based on bovine gelatin (Ge), microalgal protein from Spirulina platensis (PC) and magnetite (Fe3O4/γFe2O3) with potential aapplication in wastewater treatment, taking advantage of the chelating characteristics of phycobiliproteins, protein adsorbents and the possibility of recovering hydrogels by magnetization.Materials and methods: Protein concentrate (PC) was obtained from commercial lyophilized powder of S. platensis following reported procedure with some modifications [1]. Oxidized sodium alginate (OA) was synthesized [2] and magnetic nanoparticles (magnetite, NPs) were prepared from iron salts by the chemical co-precipitation method.Hydrogels with a total protein content of 20 % were developed, using Ge as base material and PC in different proportions (0 - 1.5 %), glycerol as plasticizer (30 % w/w dry protein basis), OA as chemical crosslinking agent (0 – 5 % w/w dry protein basis) and NPs (0 - 1 % w/w dry protein basis). The system was homogenized by sonication cycles. The hydrogels were stabilized for 48 h at 4°C and then lyophilized for further characterization. The obtained materials were characterized by thermal (DSC and TGA), structural (FTIR, XRD and SEM) and magnetic (VSM) analysis. The absorption capacity of water, model dyes (cationic: methylene blue and anionic: eosin) and lead (as heavy metal model) were analyzed bygravimetric method and UV-vis spectroscopy, respectively.Results: No significant changes were observed in the thermal stability of the hydrogels due to the presence of PC or NPs. All hydrogels with NPs presented superparamagnetic behavior at room temperature. Respecting the swelling behavior, the highest rate of absorption occurs during the first 2 h, reaching 40 % of the equilibrium absorption that is achieved after 24 h of swelling. The crosslinked hydrogels show between 50 to 100 % less swelling capacity than those without OA, being the formulation with PC and NPs that gives the highest reduction. In contrast, the same formulation shows the greatest removal capacity of dyes with methylene blue, due to the ionic interactions generated with the hydroxylated chain of OA and for the chelating activity of phycocyanins. Lead removal capacity is under analysis.