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Browsing by Author "Gil, Guilherme Andreoli"

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  • Development of functional biobased microencapsulation systems for textile applications
    Publication . Gil, Guilherme Andreoli; Barreiro, M.F.; Sipoli, Caroline Casagrande; Fernandes, Isabel P.
    Essential oils have been widely used in the textile sector due to their numerous properties and health benefits. Terpenes are the main components of essential oils being limonene one of the most abundant one in nature. Microencapsulation systems based on natural products have emerged as an important tool for the preservation and controlled release of essential oils. In this context, the present work was devoted to the increase of scale of a previously studied microencapsulation process of limonene by complex coacervation method. Chitosan (CH) and gum Arabic (GA) were used as shell materials and (R)-(+)-limonene as the core material. The complex coacervation is based on the formation of a colloidal system in which oppositely charged biopolymers complex and coat oil droplets. After this initial step, the formed microcapsules are hardened through crosslinking of chitosan with tannic acid. The study was divided in the following three different sections: (i) optimization of the process variables and analysis of their influence on the microcapsule’s morphology, where the influence of the homogenization stage (emulsion formation), stirring rate, geometry of the stirring impeller, volume and concentration of tannic acid solution, emulsifier type and the final washing step, was studied leading to an optimized and reproducible process; (ii) study of the biopolymers concentration and oil amount effect on process productivity; and (iii) characterization of the microcapsules produced in the last assays. The microcapsules obtained by inserting 4 mL of tannic acid solution 10% (w/v) showed spherical morphology. The reactor stirring using an impeller with two plane and vertical blades at 150 rpm promoted efficient fluid dynamic flow and thermal exchange. The emulsifier PGPR 4125 (polyglycerol polyricinoleate) was chosen due to its non-toxicity and biodegradability, guaranteeing the stability of the emulsion and uniform dispersion of the oil droplets. The analysis by optical microscopy proved the effectiveness of inserting a final washing step to remove unreacted raw materials. The analysis of the solids content revealed a possible excess of the shell materials or dragging of the microcapsules in the washing step, due to the low values attained, even when the limonene amount was increased. In all assays, microcapsules with perfectly spherical morphologies were identified. The microcapsules had a small mean particle size, between 1.92 and 2.42 μm, which is in accordance with the size range given in the literature (1 to 500 μm) for microcapsules produced by the complex coacervation method. A high encapsulation efficiency was attained, ranging from 99.2% to 99.7%. From the overall analysis of the performed study, it can be considered that the production of limonene CH-GA microcapsules using a laboratorial scale reactor (capacity 1L) was successfully achieved. Thus, the production of limonene microcapsules by the complex coacervation method, using natural raw materials offer the possibility to be scalable, increasing their potential application in the textile industry.
    2020Master thesis Open access Show more