zeolite membrane scale up for desalination

The lack of sufficient available water resources has already affected every continent and thus represents a significant global problem. The concern about the water availability is in continuous growing and now has reached unsustainable levels. In fact, the drought, the water overuse and the pollution and exploitation of groundwater aquifers and surface water have led to a decrease of quantity and/or quality of available natural water resources in many countries [1]. Membrane technology has emerged, in the last years, as the main contributor to solve water shortage problems. In particular, membrane distillation have attracted increasing interest in applications related to the water treatment, such as desalination of seawater or brackish water and drinking water purification [2]. In this field, zeolite membranes, due to their crystalline structure and to their pore diameters close to molecular size of different species, have gained a growing importance. In this work, for the first time, tubular silicalite 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 (VMD) to verify if their performance were comparable respect to those obtained for shorter membranes [3]. Deionized water and NaCl solutions at different concentrationswere used as feed. The obtained results showed that is possible to reach a good reproducibility in the preparation of uncalcined defect-free membranes and aremarkable performance in desalination by VMD up to 50 g/L of NaCl.