Progressi nel campo dei contattori a membrana: dal materiale al processo

Responsabili di progetto

Lidietta Giorno, Kuo-lun Tung

Accordo

TAIWAN - NSTC - National Science and Technology Council

Bando

CNR-MoST (ex NSC) 2016-2017

Dipartimento

Scienze chimiche e tecnologie dei materiali

Area tematica

Scienze chimiche e tecnologie dei materiali

Stato del progetto

Nuovo

Proposta di ricerca

Membrane contactors are membrane systems that can find application in different fields of industrial interest, covering, for example, gas-liquid operations, liquid-liquid extractions, distillation. In last years, the use of membrane contactors to prepare emulsions (Membrane Emulsification-ME) and to carry out distillation processes (Membrane Distillation-MD) has been subject of many research activity worldwide.
The emulsions prepared by membrane contactors are usually monodispersed, because their size depends on the membrane pore size, and produced in milder conditions with respect to conventional operations.
If compared with traditional distillation columns, membrane distillation units generally work at lower operating temperatures (40°C- 70°C) and have a smaller footprint.
Although the existing advantages, for both membrane operations there are still some drawbacks that are limiting their implementation at industrial scale.
In membrane emulsification, a current technological challenge is the availability of membranes specifically designed for the preparation of emulsions in the range of nano and micron size droplets. The problem is related to the fact that, in membrane emulsification mechanism, a non wetting phase has to permeate through a mesoporous membrane with high interfacial tension. Therefore, high transmembrane pressure as well as high membrane mechanical stability is required. Furthermore, uniform pore size distribution and pore location on the membrane surface is also a challenge in the nanoscale range.
In membrane distillation, open issues are the need of membranes specifically developed for the process, the loss of the hydrophobic properties of the membranes with time, and the high specific thermal energy consumption. Concerning this last point, in membrane distillation the aqueous stream is heated up to the desired temperature to promote the evaporation through the membrane pores, with consequent reduction of temperature. Moreover, some heat is lost by conduction through the membrane material (especially in the Direct Contact Membrane Distillation-DCMD- configuration). Therefore, the feed is cooled along the module and needs to be heated up again before being recycled back to the module-self.
The aim of this proposal is to improve the performance of both membrane operations by developing membranes with tailored properties. Furthermore, modeling and experiments on membrane distillation for crystallization purposes (Membrane Crystallization- MCr) will be carried out.
The project will focus on the development of tuned hydrophobic and asymmetric wettability membranes. All membrane types will be tested for membrane emulsification for the preparation of oil/water and water/oil nano- and micro-emulsions (with droplets size less than 100 nm and 10 micron, respectively). Superhydrophobic and asymmetric wettability membranes will be tested for membrane distillation. Composite membranes containing superparamagnetic nanoparticles will be also prepared and used to promote novel methods to strip droplets at the pore border in ME, as well as to heat uniformly the solution at the membrane pore border in MD. Its is expected that by supplying heat at the membrane-liquid interface, there will be a reduction of the thermal energy needs in MD.
The ME and MD tests will be optimised also in terms of operating conditions. In MD, tests will be performed on water and on salty solutions, to check the rejection values achievable. Prolonged runs will be also carried out to evaluate the membrane stability and performance with time. Concerning the application of MD to crystallization, the use of membranes as a scaffolding for controlled crystal nucleation will be investigated.

Obiettivi della ricerca

- Development of novel hydrophobic membranes;
- Development of membranes with asymmetric wettability;
- Development of composite membranes containing superparamagnetic nanoparticles;
- Identification of the most suitable membranes for membrane emulsification applications;
- Identification of the most suitable membranes for membrane distillation applications;
- Identification of the most suitable membranes for membrane crystallization applications;
- Preparation of oil/water and water/oil nano and micro-emulsions;
- Development of a mathematical model for simulating and optimizing membrane crystallization;
- Improvement of the membrane distillation efficiency, by enhancing the long-term membrane stability and reducing the thermal energy requirements.

Ultimo aggiornamento: 04/09/2025