scale-up of zeolite membranes for desalination

The lack of sufficient available water resources has already affected every continent and thus represents a significant global problem. In the last years, desalination of sea- and brackish water to obtain sweet water in arid regions has gained a growing interest [1]. In this context, membrane distillation is able to efficiently treat also high concentrated brines, allowing to increase the overall fresh water production with respect to actual reverse osmosis plants [2]. For desalination purposes the MFI zeolite topology is appropriate having a pore size (about 5.5 Å) lower than the major kinetic diameters of different hydrated ions. In this work, for the first time, tubular silicalite (MFI) membranes with a length of 30 cm were prepared using the secondary growth method coupled with the cross flow seeding procedure. Subsequently, the prepared membranes were characterized and then applied in desalination process by vacuum membrane distillation to verify if their performance was comparable to that of shorter membranes [3]. The obtained results showed that it is possible to reach a good reproducibility in the preparation of uncalcined defect-free membranes and a remarkable performance in desalination by VMD for feed salt concentrations in the range of 0.2 M-0.9 M