Application of hydrophobic coatings on commercially available hydrophilic membranes for direct contact membrane distillation

Membrane distillation (MD) is an emerging separation technology, used for separation of non-volatile components from an aqueous stream. The most known application is desalination. The main advantages of MD are: the possibility to use waste heat, the high recovery rates and the easy scalable modules. In contrast to its great potential, the process has not yet been widely accepted in industry. The main problems are the lack of good performing membranes, adequate module configurations and uncertain energetic and economic costs [2]. One way to improve the performance of the membranes is the synthesis of dual layer hydrophilic/hydrophobic membranes. In this contribution, commercially available hydrophilic membranes are coated with different hydrophobic materials, including cheap commercial coatings. Overall treatment of a hydrophilic membrane with a hydrophobic coating results in a single layer hydrophobic membrane structure, while the treatment of only one side of membrane results in a dual layer hydrophilic/hydrophobic membrane structure. The coated membranes have the same membrane morphology as the commercial hydrophilic membrane enabling a comparison between one layer and dual layer membranes. Additionally, the performance of these membranes in direct contact membrane distillation (DCMD) is compared with the performance of commonly used PTFE-membranes.status: publishe