No abstract

No abstract

A membrane reactor containing an immobilized heterogeneous catalyst is an alternative for traditional homogeneous-based catalyzed transesterification for biodiesel production. Major problems in homogeneous catalysis are related to catalyst recuperation and soap formation, which can be overcome by using heterogeneous catalysts. Conversion can be increased by a combination of reaction and separation, using membranes with a specific pore size. The aim of this work was to study the performance of different membrane reactors combined with heterogeneous catalysis. The main objectives were: to identify a proper catalyst, to choose the proper immobilization technique, to establish the membrane with the adequate pore size, and to control the reaction and separation process. Amberlyst®15 with acid sites and different types of strontium oxide with basic sites were tested as heterogeneous catalysts. Strontium oxide provided the highest sunflower oil conversion (around 93%) and was easy to immobilize. Two catalytic membrane reactor configurations were investigated, thus confirming the production of several types of methyl esters. The configuration comprising the physical immobilization of the catalyst over the membrane reached a methyl ester yield of > 90 wt%.

A strategy to reduce costs in the microalgae dewatering process via membrane cross-flow filtration was investigated in this work. It consisted in assessing the possibilities of reduce membrane material cost. Several membrane materials, from commonly used in membrane technology (ceramic, polysulfone and polyacrylonitrile) to generally employed in packaging industry (acrylonitrile butadiene styrene, glycol-modified polyethylene terephthalate and polylactide) were tested. Where, last ones are considerably cheaper than common ones.Experiments carried out showed interesting results in terms of permeabilities for polysulfonePluronic® F127 blended membranes and polyacrylonitrile membranes, but with high related costs. Polylactide membranes had good price, mechanical properties results and biodegradability, but low permeability values. Glycol-modified polyethylene terephthalate *Corresponding author: +34.977.202.444, ctorras@irec.cat, carlestorrasfont@gmail.com 2 membranes showed attractive results in terms of costs and permeability, but poor mechanical properties. Finally, the polymer that gave the best results altogether was the acrylonitrile butadiene styrene that reached membrane permeabilities of 19 ± 0.9 L/h/m 2 /bar, really close to ceramic membranes performance (21 ± 2.9 L/h/m 2 /bar). Thus, a novel functionality was found for these not common polymers in water membrane filtration. Additionally, the biodegradable polylactide polymer introduces a new concept of cheap and environmental friendly membrane in this application.

One of the challenges in membrane technology is predicting permeability in porous membranes for liquid applications in an easy and inexpensive way. This is the aim of this work. To achieve this objective, several techniques can be considered. In this study, a morphological approach from two‐dimensional scanning electron micrographs is proposed. First, numerical membrane morphological parameters have been determined from micrographs by using the QUANTS tool, which applies a texture recognition process. Second, the obtained data have been fit to the Darcy's and Hagen–Poiseuille models to calculate permeations. The QUANTS results have also been compared with the ones obtained through a mercury porosimeter, which is a classic and well‐known methodology. Each parameter of the Hagen–Poiseuille model has been analyzed. A comparison between experimentally measured permeations and calculated ones has been performed. An even easier approach is proposed to predict flow rate with the only knowledge of membrane surface mean pore size. This method is based on cross‐section pore size interpolation by using function fits from surface mean pore sizes. The obtained results show a reasonable agreement between measured and computed results, making this technique a valid approach for predicting membrane permeability. POLYM. ENG. SCI., 56:118–124, 2016. © 2015 Society of Plastics Engineers

No abstract