Development of adsorbent rigid structure based on Spirulina sp./chitosan bioblends coatings for dye adsorption in fixed bed column.

The glass particles were coated with Spirulina sp. LEB-18 and bioblends of Spirulina sp. LEB-18/chitosan by casting technique and, afterward, it was verified its potential as adsorbents for basic and acid dyes. Nine Spirulina sp. suspensions with different components were used to coat the glass particles, and in the best condition of coating were prepared the bioblends with chitosan. The coated glass particles with Spirulina sp. and its bioblends with chitosan were applied in adsorption of the allura red (acid) and methylene blue (basic) dyes in a batch operation evaluate the pH effect, and a fixed bed column operation, being evaluated to the removal percentage and adsorption capacity of the column. The glass particles coated with Spirulina sp. applied in batch adsorption showed the highest removal percentages for allura red dye (35 to 45%) at pH 4.0, and for methylene blue dye (35 to 80%) at pH 6.0 and 8.0. In fixed bed column using glass particles coated with bioblends were reached the amount dye of 54.2 mg of adsorbed allura red dye and 60.2 mg of the of adsorbed methylene blue dye, respectively. Moreover, it was found good dye adsorption capacities, around 89 mg g-1, for both dyes, in acidic and basic pH values. Based on these results, these bioblends coated glass particles can be applied as an adsorbent for different types of dyes in adsorption column.

Anthocyanins concentration by adsorption onto chitosan and alginate beads: Isotherms, kinetics and thermodynamics parameters.

The anthocyanins health benefits are diverse, but numerous factors affect the anthocyanins stability, thus, this work aimed to extract anthocyanins from Pinot Noir grape skins and, afterward, to concentrate them onto edible and safety adsorbents, chitosan and alginate beads, by adsorption operation. Chitosan was obtained from shrimp waste, and alginate was purchased. Batch adsorption experiments were carried out as pH function, and the highest adsorption capacities and removal percentages were, respectively, 216 mg g-1 and 65% for chitosan beads at pH 8, and 126.4 mg g-1 and 38% for alginate beads at pH 4. All equilibrium isotherms models were suitable for chitosan beads, while for alginate beads only Langmuir and Freundlich models showed fitting. The thermodynamic parameters demonstrated physical adsorption and endothermic behavior for the chitosan and alginate beads. The pseudo-first order model best described the kinetic behavior for both beads. It was demonstrated that is possible to concentrate the different molecular structures of anthocyanins onto chitosan and alginate beads with high yields.

Chitosan-coated different particles in spouted bed and their use in dye continuous adsorption system.

In this work, three polymer suspensions were used for coating glass beads (GB), porcelain beads (PB), and polyethylene pellets (PP) in spouted bed. Subsequently, the continuous adsorption assays of the food dye Brilliant Blue FCF in a fixed bed column were performed, which was packed with the covered particles. Also, the static adsorption assays were carried out. The adsorption equilibrium isotherms were fitted by Freundlich, Langmuir, and Temkin models, being that the Temkin model was the most suitable to represent the equilibrium data. The particle coating in the spouted bed showed promising results due to the high efficiency of the process. The PB, GB, and PP obtained coating efficiency values in the range to 92-96% when using the suspension of chitosan and hydroxyethyl cellulose. However, only the polyethylene particles coated with the chitosan suspension maintained its coating efficiency (95%). The maximum adsorption capacities at equilibrium of the coated particles of PP and GB were achieved with the chitosan suspension, being the values of around 800 mg g-1. Thus, the chitosan-coated polyethylene particles showed to be a promising adsorbent for fixed bed column. Graphical abstract.