7 research outputs found
Phenol biodegradation by immobilized Pseudomonas putida FNCC-0071 cells in alginate beads
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Kinetic Study of Levulinic Acid from Spirulina platensis Residue
No full textMicroalgae have the potential to emerge as renewable feedstocks to replace fossil resources in producing biofuels and chemicals. Levulinic acid is one of the most promising substances which may serve as chemical building blocks. This work investigated the use of Spirulina platensis residue (solid residue after lipids extraction) to produce LA via acid hydrolysis reaction. In this study, Spirulina platensis residue was set to have a solid–liquid ratio of 5 (w/v). The effect of process parameters on the Spirulina platensis residue to levulinic acid hydrolysis reaction was observed at temperatures ranging from 140 to 180 °C under four acid concentrations, i.e., 0.25, 0.5, 0.8, and 1 M. A simplified kinetic model was also developed to describe the behavior of Spirulina platensis residue conversion to levulinic acid, based on the pseudo-homogeneous–irreversible–1st order reaction. The results showed that the proposed model could capture the experimental data well. The reaction network also considered involvement of intermediate products namely glucose and 5-hydroxymethylfurfural. The results showed that Spirulina platensis residue, with acid catalysts, can be used to produce levulinic acid, and the kinetic model can provide useful information for understanding the Spirulina platensis residue to levulinic acid hydrolysis reaction. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature
Nanostructured silica from bagasse ash as reinforcing filler in styrene butadiene rubber: Does the mixing parameters matter?
No full textA study on the effect of mixing process parameters of nanostructured silica/SBR composite on cure characteristics, mechanical properties, morphology, and vulcanization kinetics was performed. The mixing process was carried out in an internal mixer with 3 (three) investigated parameters, namely: initial mixing temperature (70 - 100°C), mixing time (6 - 21 min.), and rotor speed (40 - 100 rpm). At rotor speed 60 rpm, the higher the initial mixing temperature, the lower the percent agglomeration of silica particles, but at 100°C the percent agglomeration is high due to premature crosslinking. Meanwhile, the higher the initial mixing temperature the higher the tensile strength. The longer the mixing time, the lower the percent agglomeration because the silica is more dispersed, but the tensile decreases due to the influence of polymer degradation due to mastication. At initial mixing temperature 80°C, the higher the rotor speed the better the dispersion, the greater the bound rubber, but at 100 rpm the percent agglomeration is high due to premature crosslinking. Meanwhile, the higher the rotor speed the higher the tensile strength. At mixing time 15 min. selection of the rotor speed and initial temperature of the mix can be adjusted according to the desired mechanical properties with a velocity gradient in the range of 7.31-11.47 s-1. The vulcanization kinetics study was then applied to the compounds that were previously mixed at various initial mixing temperature. It was found that the higher the initial mixing temperature of the compound, the lower its activation energy. © 2022 Author(s)
