Intensification of Biodiesel Processing from Waste Cooking Oil, Exploiting Cooperative Microbubble and Bifunctional Metallic Heterogeneous Catalysis.

Waste resources are an attractive option for economical the production of biodiesel; however, oil derived from waste resource contains free fatty acids (FFA). The concentration of FFAs must be reduced to below 1 wt.% before it can be converted to biodiesel using transesterification. FFAs are converted to fatty acid methyl esters (FAMEs) using acid catalysis, which is the rate-limiting reaction (~4000 times slower than transesterification), with a low conversion as well, in the over biodiesel production process. The study is focused on synthesizing and using a bifunctional catalyst (7% Sr/ZrO2) to carry out esterification and transesterification simultaneously to convert waste cooking oil (WCO) into biodiesel using microbubble-mediated mass transfer technology. The results reveal that a higher conversion of 85% is achieved in 20 min using 7% Sr/ZrO2 for biodiesel production. A comprehensive kinetic model is developed for the conversion of WCO in the presence of a 7% Sr/ZrO2 catalyst. The model indicates that the current reaction is pseudo-first-order, controlled by the vapor-liquid interface, which also indicates the complex role of microbubble interfaces due to the presence of the bifunctional catalyst. The catalyst could be recycled seven times, indicating its high stability during biodiesel production. The heterogeneous bifunctional catalyst is integrated with microbubble-mediated mass transfer technology for the first time. The results are unprecedented; furthermore, this study might be the first to use microbubble interfaces to "host" bifunctional metallic catalysts. The resulting one-step process of esterification and transesterification makes the process less energy-intensive and more cost-efficient, while also reducing process complexity.

Separation of Aeruginosin-865 from Cultivated Soil Cyanobacterium (Nostoc sp.) by Centrifugal Partition Chromatography combined with Gel Permeation Chromatography.

Aeruginosin-865 was isolated from cultivated soil cyanobacteria using a combination of centrifugal partition chromatography (CPC) and gel permeation chromatography. The solubility of Aer-865 in different solvents was evaluated using the conductor-like screening model for real solvents (COSMO-RS). The CPC separation was performed in descending mode with a biphasic solvent system composed of water-n-BuOH-acetic acid (5:4:1, v/v/v). The upper phase was used as a stationary phase, whereas the lower phase was employed as a mobile phase at a flow rate of 10 mL/min. The revolution speed and temperature of the separation column were 1700 rpm and 25 degrees C, respectively. Preparative CPC separation followed by gel permeation chromatography was performed on 50 mg of crude extract yielding Aer-865 (3.5 mg), with a purity over 95% as determined by HPLC. The chemical identity of the isolated compound was confirmed by comparing its spectroscopic data (UV, HRESI-MS, HRESI-MS/MS) with those of an authentic standard and data available in the literature.