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.

Development of chitosan/Spirulina sp. blend films as biosorbents for Cr6+ and Pb2+ removal.

Chitosan film, Spirulina sp. film and its blend were developed as biosorbents to remove Cr6+ and Pb2+ ions from aqueous solutions. The kinetic study and the pH effect on biosorption efficiency were evaluated to comprehend the interactions between the ions and biosorbents. The characterization analyses pointed out that occurred interaction between both biomaterials, which resulted in structural alterations through the blend. The Spirulina sp. film exhibited the highest biosorption capacities for Cr6+ (43.2 mg g-1) and Pb2+ (35.6 mg g-1) ions, however, its physical integrity was not kept in acid medium. The blend film showed results slightly lower (35.8 mg g-1 for Cr6+ and 31.6 mg g-1 for Pb2+), but its physical integrity remained intact in all assays. Chitosan film presented the lower biosorption capacities (15.4 mg g-1 for Cr6+ and 20.9 mg g-1 for Pb2+). Elovich and pseudo-second order models were the most suitable to express the kinetic behaviors for Cr6+ and Pb2+, respectively. Therefore, chitosan/Spirulina sp. blend could be a green alternative for Cr6+ and Pb2+ removal, because this biosorbent showed high biosorption capacity obtained from Spirulina sp. and great physical integrity obtained of chitosan.

Removal of fluoride from fertilizer industry effluent using carbon nanotubes stabilized in chitosan sponge.

Adsorption of fluoride from fertilizer industry effluent using carbon nanotubes stabilized in chitosan sponge as adsorbent was evaluated. The effluent was produced in the washing of acid gases during the reaction in fertilizer production and all assays were performed using this hazardous material. Adsorbent characterization and ions interactions were elucidated from differential scanning calorimetry, thermal gravimetric analyses, X-ray diffraction, scanning electron microscopy dispersive energy X-ray spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The effluent presented pH 3 and its value not changed in the adsorption assays, maintaining the conditions of the process. The kinetics assays of fluoride from industry effluent were performed in different stirring rates from 100 to 300 rpm. It was observed that adsorption was initially fast reaching the equilibrium at 300 rpm in 20 min. The adsorption capacity was around 975.4 mg g-1, showing the potential of the hybrid material to remove fluoride from a real matrix. The high adsorption capacity was attributed to the chitosan functional groups and the high interaction area promoted by sponge form and the carbon nanotube. Reuse and regeneration of the CNT-CS were investigated and 5 cycles were obtained. The adsorption capacity kept similar values in all cycles.

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.

Separation of anthocyanins extracted from red cabbage by adsorption onto chitosan films.

Anthocyanin pigments are suitable as natural dyes for food, cosmetics and dietary supplements, due to the demand for healthier products and their antioxidant properties. This work aimed to extract the anthocyanin pigments from red cabbage and its separation of the solution by adsorption operation onto chitosan films. The anthocyanin was extracted from red cabbage in water hot at 90 °C by 15 min. Chitosan was obtained from shrimp waste, and its films were produced by casting technique (tensile strength of 25.1 ±â€¯1.9 MPa, elongation of 10.5 ±â€¯3.5% and thicknesses of 103.1 ±â€¯1.3 µm). The anthocyanin adsorption assays were performed in batch, and the highest adsorption capacity was around 140 mg g-1. The equilibrium experimental data were adjusted by Henry, Langmuir and Freundlich models, and all models showed a good fitting (R2 ≥ 0.96 and ARE ≤ 6.5%). The thermodynamic parameters represented endothermic and physical adsorption. The kinetic behavior was evaluated by empirical models, being the pseudo-first order model that showed the best fitting (R2 ≥ 0.97 and ARE ≤ 8.5%). This work presented suitable information about the anthocyanin molecules immobilization onto chitosan films and, these results could be important to the use these pigments with chitosan in different areas.

Synthesis of a bio-based polyurethane/chitosan composite foam using ricinoleic acid for the adsorption of Food Red 17 dye.

A novel bio-based polyurethane/chitosan foam (PU/chitosan) was synthesized using a polyol derived from castor oil and applied to remove Food Red 17 dye (FR17) from aqueous solutions. PU/chitosan foam presented better characteristics and adsorption potential than polyurethane foam (PU). PU/chitosan foam showed a semi-crystalline structure, with several functional groups, high porosity and good mechanical properties. These characteristics are adequate for adsorptive separations. Using identical adsorption conditions, PU/chitosan was able to remove >98% of FR17 dye from the solution, while, PU removed only 40%. The adsorption of FR17 on PU/chitosan composite foam was favored at pH 2. Pseudo-second order model was the most adequate to represent the kinetic data. The equilibrium data followed the Sips model, with a maximum adsorption capacity of 267.24 mg g-1. The adsorption process was spontaneous, favorable and endothermic. The results showed that polyurethane foams are capable to support chitosan, generating an adsorbent with better mechanical characteristics and high potential to remove anionic dyes from aqueous media.

Spirulina sp. biomass dried/disrupted by different methods and their application in biofilms production.

Arthrospira Spirulina biomass is a source of intracellular compounds with great commercial interest, such as phycocyanin and phenolic compounds. In this work, different cell disruption methods of the microalgae biomass dried in spouted bed and in conventional tray were performed, aiming lead to the better extraction yields of these compounds. The samples of both drying techniques with the most suitable cell disruption were used to biofilms production. FTIR, DSC, and SEM for all samples were performed. The samples dried in spouted bed with cell disruption by milling and by microwave showed the best results for the powder products, with phycocyanin contents of 75.0 and 85.4 mg g-1, and total phenolic compounds of 41.6 and 41.9 mg g-1, respectively. However, the tray drying/milling produced the biofilms with the best characteristics (tensile strength of 3.69 MPa and water vapor permeability of 1.67 × 10-11 g m s-1 m-2 Pa-1) and the highest thermal stability.

Protein content maximization of vegetable paste by incorporation of whey through the linear programming: drying and rehydration evaluation.

The vegetable paste was optimized by the protein content maximization through incorporation of whey using the linear programming, with linear restrictions functions. The enriched paste was dried in a spouted bed of cone-cylindrical geometry, at different conditions, and the dried powder products were analyzed by the functional, nutritional, bioactive, chemical, thermal and morphological properties and, also its rehydration characteristics were evaluated. The best results were found in the assay performed at inlet drying air temperature of 100 °C and in paste solids concentration of 10% (w/w). In these drying conditions, the values were of protein solubility of 26.5 ± 0.1% (w/w), water holding capacity 10.8 ± 0.1 g g-1, protein digestibility of 84.9 ± 2.2% (w/w), total phenolic compounds 7.72 ± 0.1 mgEAG gsample-1, antioxidant activity of 75.7 ± 0.2% of DPPH inhibition. The glass transition temperature was in range of 97.3 °C, due to the lactose non-caramelization, this fact aided in the functionality of the bed. The powder morphology presented irregular and rough structure, with particles size lower than 100 µm and, with a low crystallinity index (12.8%). The rehydration constant value was found as 16.5 min-1, showing the rapidity with that the water diffused into the powder in the most suitable condition.

Cu(II) adsorption from copper mine water by chitosan films and the matrix effects.

Adsorption of copper ions onto chitosan films was studied, and the matrix effect was evaluated using a synthetic solution and a real effluent from closed copper mine. Chitosan films were prepared by casting technique and characterized. The adsorption study was carried out by equilibrium isotherms, thermodynamics, and kinetics. The thermodynamic parameters indicated that the copper adsorption onto chitosan film was favorable, spontaneous, and exothermic, suggesting an increased randomness at the solid/solution interface. The matrix effect was evaluated in kinetic assays, where a synthetic solution and a real system were carried out at different stirring rates. The highest values of adsorption capacity reached in all stirring rates were about 20% lower in the real effluent, and this reduction in the competitiveness was due to the presence of other ions in the matrix of the real effluent. The maximum adsorption capacity of copper ions onto chitosan films for the synthetic solution was of 450 mg g-1, and the removal percentage was in the range from 78 to 96%, and these values for the real effluent were of 360 mg g-1 and removal ranging from 62 to 76%. The mapping done of ions present in the water adsorbed of the mine in the films showed that the same was homogeneously distributed in the films' surfaces.

Comparison of Spirulina platensis microalgae and commercial activated carbon as adsorbents for the removal of Reactive Red 120 dye from aqueous effluents.

Spirulina platensis microalgae (SP) and commercial activated carbon (AC) were compared as adsorbents to remove Reactive Red 120 (RR-120) textile dye from aqueous effluents. The batch adsorption system was evaluated in relation to the initial pH, contact time, initial dye concentration and temperature. An alternative kinetic model (general order kinetic model) was compared with the traditional pseudo-first order and pseudo-second order kinetic models. The equilibrium data were fitted to the Langmuir, Freundlich and Liu isotherm models, and the thermodynamic parameters were also estimated. Finally, the adsorbents were employed to treat a simulated dye-house effluent. The general order kinetic model was more appropriate to explain RR-120 adsorption by SP and AC. The equilibrium data were best fitted to the Liu isotherm model. The maximum adsorption capacities of RR-120 dye were found at pH 2 and 298 K, and the values were 482.2 and 267.2 mg g(-1) for the SP and AC adsorbents, respectively. The thermodynamic study showed that the adsorption was exothermic, spontaneous and favourable. The SP and AC adsorbents presented good performance for the treatment of simulated industrial textile effluents, removing 94.4-99.0% and 93.6-97.7%, respectively, of the dye mixtures containing high saline concentrations.

Refino de óleos de corvina (Micropogonias furnieri) provenientes dos processos de ensilagem ácida e termomecânico de farinha / Refinement of corvine (Micropogonias furnieri) oil manufactured by means of acid ensilage procedure and thermo treatment processing formeal production

O óleo de pescado constitui importante fonte de ácidos graxos poliinsaturados ômega-3 (PUFA) benéficos à saúde humana. No entanto, há presença de impurezas que afetam suas características. Esse óleo pode ser obtido a partir do processo de ensilagem ácida e pelo processo termomecânico tradicional de produção de farinha. Para o consumo humano, o óleo deve passar pelo processo de refino. No presente trabalho realizou-se o refino dos óleos de resíduos de corvina (Micropogonias furnieri), provenientes dos processos de ensilagem ácida e de tratamento termomecânico, e comparou-se a qualidade final dos óleos refinados. O óleo refinado por meio de ambos processos apresentou características semelhantes. A etapa de“winterização”, em ambos os processos, resultou no ganho de ácidos eicosapentaenóico mais docosahexaenóico (EPA+DHA) em torno de 8,5% e redução de ácidos graxos saturados na faixa de 12,5%. Outrossim, os óleos refinados apresentaram teores de ácidos graxos insaturados na faixa de 62%, o que os tornam favoráveis como fonte de ácidos graxos poliinsaturados.