Enhanced Oxygen Mass Transfer in Mixing Bioreactor Using Silica Microparticles
Matheus M. Pereira | Ivus Lorenzo Oliveira Matos | Filipe Moreira Mascarenhas Cordeiro | Ana Cristina Morais da Silva | Eliane Bezerra Cavalcanti | Álvaro Silva Lima
This work aimed to improve the oxygen transfer mass coefficient (k<sub>L</sub>a) in mixing reactors, first evaluating the effect of agitation and aeration and then evaluating the influence of the size and concentration of silica microparticles. Silicon dioxide synthesized via the sol-gel technique, commercial sand, and beach sand were characterized by particle size distribution, scanning electron microscopy, XRD, EDS, FTIR, TG/DTA, and BET. The particles presented average values of approximately 9.2, 76.9, 165.1, and 364.4 µm, with irregular surfaces and different roughness. Silica sol-gel is amorphous while beach and commercial sand have a crystalline structure consisting of silicon, oxygen, and carbon residues. Silica sol-gel presents a higher loss of mass and surface area than other silica microparticles, with a shallow mass loss and a smaller surface. Increasing aeration and agitation improves the k<sub>L</sub>a, as well as adding silica microparticles. The best k<sub>L</sub>a was found using silica microparticles with approximately 75 µm concentrations of 1.0 g L<sup>−1</sup> (silica sol-gel) and 2.0 g L<sup>−1</sup> (commercial and treated beach sand). All silica microparticles used in this work improve mass transfer performance in mixing bioreactors.
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