Kinetic study of liquid lipase-catalyzed glycerolysis of olive oil using Lipozyme TL 100L

Monoacylglycerol (MAG) and diacylglycerol (DAG) are two natural components found in most edible oils and fats. Conventional synthesis of MAG and DAG is usually conducted by glycerolysis of triacylglycerol (TAG) at high temperatures (above 200°C) in the presence of an alkaline catalyst. In this work, the synthesis of MAG and DAG using enzymatic glycerolysis of olive oil was investigated using Tween 80 as surfactant, n-butanol as co-surfactant and the novel lipase in free/liquid formulation Lipozyme TL 100L as catalyst. Experimental design was used to evaluate the effect of enzyme load and reaction temperature on the feedstock conversion. Enzyme load and system temperature were significant variables in the statistical design and the best condition was found at 35°C, 7.5 vol% of Lipozyme TL 100L and glycerol to oil volumetric ratio of 2:1 with conversion of TAG at approximately 98% after 2 h of process. A mathematical model based on the Ping-Pong Bi-Bi mechanism was used to describe the reaction kinetics. The model adequately described the behavior of the system and can be a useful tool for the design of reactors in larger scales.     

Composites based on high-density polyethylene,polylactide and calcium carbonate: effect of calcium carbonate nanoparticles as co-compatibilizers

Polymer Bulletin - Investigating the compatibility mechanism of hybrid composites based on two polymers and one mineral nanofiller is a challenge that needs to be better understood. This study...     

Characterization and corrosion protection properties of polypyrrole / montmorillonite electropolymerized onto aluminium alloy 1100

Films of Polypyrrole/Montmorillonite (PPy/MT) clays were electropolymerized potentiostatically on aluminium alloy 1100, using sodium dodecylbenzenesulfonate (SDBS) as a dopant. Two clay species were used: Na⁺-Montmorillonite (MT-Na) and modified-Montmorillonite (MT-M). The characterization of the PPy/MT films performed by XRD and TEM shows that the exfoliation method employed, as well the electrochemical polymerization method used in this work, allow nanocomposite materials to be obtained. The PPy/MT films were found to have less electrical conductivity than pure PPy. The corrosion protection of aluminium alloy 1100 covering PPy/MT was evaluated by electrochemical techniques in 0.05 mol L⁻¹ NaCl medium. The electrochemical parameters derived from the polarization curves, together with the EIS data, revealed that the corrosion resistance of PPy/clay coatings depends on the type and concentration of Montmorillonite employed. The best performance in the corrosion protection of the aluminum was achieved with PPy/MT films containing 1% of clay.     

Monoolein–Water Liquid Crystalline Gels of Gentamicin as Bioresorbable Implants for the Local Treatment of Chronic Osteomyelitis: In Vitro Characterization

To maximize the efficacy of chronic osteomyelitis antibiotherapy while reducing antibiotic systemic toxicity, as well as time and costs of hospitalizations, it has been thought that monoolein–water gels incorporating gentamicin sulfate could be used as local, bioresorbable, and sustained-release implants. For this purpose, four formulations were examined with regard to their physicochemical and in vitro drug release characteristics. Hot stage microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction showed cubic liquid crystalline and eutectic structures. The more suitable formulation consisting of 80–15–5% wt/wt monoolein–water–gentamicin sulfate progressively released the antibiotic for a period of 3 weeks without burst effect. Moreover, the content and the release profile of gentamicin sulfate were not significantly changed after storage at 2–6°C for a period of 10 months.     

Oxidative dehydrogenation of isobutane on phosphorous-modified graphitic mesoporous carbon

Graphitic mesoporous carbon was modified with phosphorous heteroatoms in order to tune the catalytic selectivity and to investigate the roles of different oxygen species for the oxidative dehydrogenation reaction of isobutane to isobutene. Small changes in the isobutane apparent activation energy are consistent with the notion that the phosphorous groups do not change the nature of the active sites but they interfere with the availability of the sites. Our results show that the improvement on selectivity is not proportional to the amount of phosphorous added. Small phosphorous content improved the selectivity by suppressing the combustion of isobutane. However, a higher amount of phosphorous groups lead to coverage of selective quinone sites and/or creation of active sites favorable to total oxidation.