No abstract

Centrifugal spinning is a new technique for producing of nano and microfibers that has a great differential: a higher production rate than those presented by traditional methods. Due to a great interest in using nano and microfibers in technological applications along with the environmental interest in polymer recycling, this research had the purpose of production fibers by centrifugal spinning from the expanded poly-styrene recycling and the evaluation of the influence of operational parameters such as the concentration of polymer solution and the speed of rotation in the average diameter and in the distribution of the diameters of fibers formed. The fibers obtained were characterized using the Scanning Electronic Microscopy (SEM) and they had their diameters measured using ImageJ software. The fibers obtained in this research were entangled, woven, fused, with a rough and porous surface, with bead formation and without directional ordering. The results obtained show that the polymer solution concentration was the most influential parameter in the fibers analyzed characteristics and, in general, its increase generates an increase in the average diameter. With the increase in rotation speed, there has been often a reduction in the presence of beads and microparticles due to the better stretching of the fibers. In less concentrated solutions, continuous fibers with more regular surfaces were obtained, however, promoting the higher production of beads. In the most concentrated solutions, we noticed the formation of porous fibers and very rough surfaces, as well as fused and woven fibers. Through the measurement of its diameters, it was possible to observe the obtaining of fibers with average diameters of 407,02 nm to 38113,20 nm, and the smallest value was obtained with the parameters of 5% w/w of polymer concentration and rotation speed of 15000 rpm and the highest value had 15% w/w concentration polymer and 10000 rpm.

The aim of this study was to evaluate the influences of synthesis parameters on the organophilization of a sodium bentonite clay via interlayer cation exchange by organocations. The parameters analyzed were: stirring time, rest time and surfactant concentration. The novelty of this study, when compared to others reported on the literature data, is the evaluation of different stirring and rest times, which is usually used as 20 min and 24 h, respectively. The organoclays obtained were characterized via X-ray diffraction, Fourier transform infrared spectroscopy and Foster swelling test performed in water and hexane. The results allowed to observe the intercalation of the surfactant between the bentonite layers, the low influence of stirring and resting times on basal interplanar distance, and that the increase of the resting time resulted in higher efficiency on the organophilization process. The Foster swelling test evidenced the organophilic character of the obtained clay.

Argila bentonita natural e após modificações superficiais, foram testadas como adsorventes do corante Rodamina B para fins de comparação de eficiência dos tratamentos na remoção do corante. As modificações realizadas na argila foram: organofilização em solução, feita através da intercalação do sal quaternário cloreto de cetil trimetil amônio, organofilização no estado sólido pela intercalação do sal cetil trimetil amônio e tratamento ácido, feito com ácido clorídrico. Soluções de corante na concentração de 10 mg/L para pH diferentes (3,4,9,12) foram feitas e posteriormente as agilas foram dispersas nessas soluções na concentração de 0,4 g/L, sendo o sistema mantido sob agitação manual. Alíquotas em diferentes tempos (10, 20 e 30 min) foram retiradas e levadas para análise de espectrofotometria no UV-Visível, onde pode-se avaliar a variação de corante nas soluções que estiveram em contato com as argilas. As argilas que tiveram contato com a argila ácida foram as que obtiveram melhor resultado de remoção de corante, exceto para o pH 12 onde a argila natural foi mais eficiente. As modificações com sais quaternários não tiveram bons resultados mostrando que não são metodologias adequadas para modificação de adsorventes do corante Rodamina B.