Hydrophobic Membrans of Tetrafluoroethylene and 2,2,4, Trifluoro 5 Trifluorometoxy 1,3 Dioxole

Gordano, A.,Clarizia, G.,Tocci, E.,Drioli, E. The Membrane Society of Korea 1999 Korean Membrane Journal Vol.1 No.1

Symmetric asymmetric and composite perfluoropolymer membranes made with HYFLON AD have been prepared and evaluated. Porous and non porous symmetric membranes have been prepared by solvent evaporation with various processing conditions. Non-contact atomic force microscopy (AFM) was used to investigate the membrane morphology in air. Analysis of the images gave quantitative imformation on the surface pore strcture in particular on the pore size distributin. Possible useful uses of porous membranes are envisaged in the field of gas-liquid separations such as membrane contactors (MSc) Molecular Dynamics(MD) simulations structure of HYFLON AD 60X copolymer supporting these results are also reported. Amorphous perfluoropolymer membranes appears to be ideal other than in MCs when separation processes have to be performed in hostile environments i.e. high temperatures and aggressive non-aqueous media such as chemicals and solvents. In these cases HYFLON AD mem-branes can exploit the outstanding resistance of perfluoropolymers.

CO Selox Reaction Using Y-type Zeolite Catalytic Membranes

Bemardo, P.,Algieri, C.,Barbieri, G.,Drioli, E. The Membrane Society of Korea 2006 Korean Membrane Journal Vol.8 No.1

The production of CO-free hydrogen streams for feeding PEM-Fuel Cells using catalytic zeolite membrane reactors was analysed by means of selective oxidation. Tubular FAU (Na-Y) zeolite membranes, prepared by a secondary growth method and Pt-loaded, were used in a flow-through MR configuration. The catalytic tests were carried out at $200^{\circ}C$ and at different pressures with a simulated dry reformate shifted gas mixture ($H_2$ ca. 60%, CO 1 %, plus $O_2,\;N_2,\;CO_2$). The operative $O_2/CO$ stoichiometric equivalent feed ratio was ${\lambda}= 2$. These catalytic tests, reducing the CO concentration down to $10{\sim}50$ ppm, verified the possibility of MR integration after using a low temperature water-gas shift unit of a fuel processor to convert hydrocarbons into hydrogen-rich gas.

Open-source predictive simulators for scale-up of direct contact membrane distillation modules for seawater desalination

Dong, G.,Kim, J.F.,Kim, J.H.,Drioli, E.,Lee, Y.M. Elsevier 2017 Desalination Vol.402 No.-

Proper industrial-scale module design for seawater desalination by means of direct contact membrane distillation (DCMD) can be aided by module simulation. Accordingly, two open-source simulators (of flat sheet membranes and hollow fibre membranes) were developed on the Matlab GUI platform to supplement DCMD module scale-up. A coupled ''tanks-in-series'' and ''black box'' mathematical approach was developed not only to yield accurate simulation, but also to produce profiles of all the key parameters versus membrane length. Using laboratory-scale experimental results in one configuration as simulation inputs, the developed simulators were able to predict large-scale DCMD module performance in both co-current and counter-current configurations. These predictions exhibited good accuracy in both laboratory-scale and large-scale. Design considerations informing appropriate module scale-up for the DCMD process were demonstrated using the simulators. Key design criteria for industrial-scale module design were identified and evaluated. The results presented in this study offer general and practical guidance for proper module scale-up to deliver optimal pure water productivity for industrial-scale seawater desalination using the DCMD process. More importantly, the developed simulators are open-source, available for all researchers to develop specific DCMD module scale-up strategies for their own membranes.

Improvement of ${\beta}-glucosidase$ Activity of Olea europaea Fruit Extracts Processed by Membrane Technology

Mazzei, R.,Giomo, L.,Spadafora, A.,Mazzuca, S.,Drioli, E. The Membrane Society of Korea 2006 Korean Membrane Journal Vol.8 No.1

The ${\beta}-glucosidase$ from olive fruit is of particular interest compared to the ones from other sources because it has shown to have high specifity to convert the oleuropein into dialdehydes, which have antibacterial activity and are of high interest for their application in the food and pharmaceutical fields. The enzyme is not yet commercially available and advanced clean and safe technologies for its purification able to maintain the functional stability are foreseen. The purification of this protein from fruit extracts has been already tempted by electrophoresis but either enzyme deactivation or high background with unclear profiles occurred. In this work, fruit extracts obtained from the ripening stage that showed the highest enzyme activity have been processed by diafiltration and ultrafiltration. Asymmetric membranes made of polyamide or polysulphone having 50 and 30 kDa molecular weight cut-off, respectively, were tested for the diafiltration process. Ultrafiltration membranes made of polyethersulfone with 4 kDa molecular weight cut-off were used to concentrate the dia-filtered permeate solutions. The efficiency of the separation processes was evaluated byenzyme activity tests using the hydrolysis of p-D-nitrophenyl-${\beta}$-D-glucopyranoside (pNPGlc) as reaction model. Qualitative and quantitative electrophoresis were applied to analyze the composition of protein solution before and after the membrane separation; in addition dot blot and western blot analyses were applied to verify the presence of ${\beta}-glucosidase$ in the processed fractions. The overall results showed that the ${\beta}-glucosidase$ functional stability was preserved during the membrane operations and the removal of 20 kDa proteins allowed to increase the specific activity of the enzyme of about 52% compared to the one present in the initial fruit extract.

Understanding the non-solvent induced phase separation (NIPS) effect during the fabrication of microporous PVDF membranes via thermally induced phase separation (TIPS)

Jung, J.T.,Kim, J.F.,Wang, H.H.,di Nicolo, E.,Drioli, E.,Lee, Y.M. Elsevier Scientific Pub. Co 2016 Journal of membrane science Vol.514 No.-

The thermally induced phase separation (TIPS) method is regaining momentum as a competitive platform to fabricate highly porous microporous membranes. In membrane technology, there has been an active search for more sustainable ways to fabricate polymeric membranes using green solvents. Rhodiasolv PolarClean® is a recently identified environmentally friendly TIPS solvent that shows high potential for the preparation of microporous PVDF membranes. Interestingly, its high miscibility with water induces a nonsolvent-induced phase separation (NIPS) effect on the membrane surface and this simultaneous NIPS-TIPS effect is referred to as the combined NIPS-TIPS (N-TIPS) method. In this work, a thorough investigation was carried out to understand the underlying phenomena in the membrane formation kinetics during the N-TIPS process. It was found that the NIPS and TIPS morphology can be tailored to control the mechanical properties, pore size distribution, and flux of the prepared membranes. For instance, increasing the coagulation bath solvent concentration facilitated the formation of a spherulitic morphology, whereas increasing the bath temperature induced the formation of a bicontinuous morphology free of macrovoids. It was determined that by controlling the phase separation kinetics, the mechanical properties of the prepared PVDF membranes could be remarkably improved from 0.9MPa to 6.1MPa. Several pore-forming additives including polyvinylpyrrolidone, Pluronics F-127, LiCl, and glycerol were employed to induce surface pores and their effects were thoroughly characterized. The membranes prepared with Pluronic additives exhibited high water permeabilities up to 2800Lm<SUP>-2</SUP>h<SUP>-1</SUP>bar<SUP>-1</SUP> with narrow pore size distributions.

The effect of operating conditions on the performance of hollow fiber membrane modules for CO₂/N₂ separation

Hwang, H.Y.,Nam, S.Y.,Koh, H.C.,Ha, S.Y.,Barbieri, G.,Drioli, E. Korean Society of Industrial and Engineering Chemi 2012 Journal of industrial and engineering chemistry Vol.18 No.1

A commercialized polysulfone (PSf) hollow-fiber membrane module was tested for CO<SUB>2</SUB>/N<SUB>2</SUB> separation performance for application in post-combustion capture. Cost efficiency, easy module manufacturing, and efficiency in gas separation are the main advantages of using PSf hollow-fiber modules for CO<SUB>2</SUB> separation. The effects of operating conditions such as temperature, pressure, and feed composition on separation performance were examined at various stage cuts. A 2-stage system including concentration of feed composition at stage 1 and production of high-purity CO<SUB>2</SUB> at stage 2 was constructed to improve separation efficiency. Higher operating temperature and pressure increased CO<SUB>2</SUB> permeance, but the loss of selectivity and higher energy consumption are a concern. Modules with various membrane areas were also used to test the effect of area on CO<SUB>2</SUB> separation.

A Pd Doped PVDF Hollow Fibre for the Dissolved Oxygen Removal Process

Batbieri G.,Brunetti A.,Scura F.,Lentini F.,Agostino R G.,Kim, M.J.,Formoso V.,Drioli E.,Lee, K.H. The Membrane Society of Korea 2006 Korean Membrane Journal Vol.8 No.1

In semiconductor industries, dissolved oxygen is one of the most undesirable contaminants of ultrapure water. A method for dissolved oxygen removal (DOR) consists in the use of polymeric hollow fibres, loaded with a catalyst and fed with a reducing agent such as hydrogen. In this work, PVDF hollow fibres loaded with Pd were characterized by means of perporometry, scanning electron microscopy (SEM), energy dispersive X-ray (EDX). The hollow fibre analyzed shows a five-layer structure with remarkable morphological differences. An estimation of pore diameters and their distribution was performed giving a mean pore diameter of 100 nm. The permeance and selectivity of the fibres were measured using $H_2,\;N_2,\;O_2$ as single gases, at different operating conditions. An $H_2$ permeance of $37 mmol/m^2s$ was measured and $H_2/O_2$ and $H_2/N_2$ selectivities of ca. 3 were obtained. $H_2$ permeance was 1/3 when a water stream flows in the shell side. Catalytic fibrebehaviour was simulated using a mathematical model for a loop membrane reactor, considering only $O_2$ and $H_2$ diffusive transport inside the membrane and their catalytic reaction. Dimensionless parameters such as the Thiele modulus are employed to describe the system behaviour. The model agrees well with the experimental reaction data.