Breathable honeycomb membranes for water desalination

High degree of sophistication is the rule to get tight control over pore size, shape, geometry and spatial distribution as well as surface membrane properties. Here, we propose an advanced bio-inspired process, which reproduces on lab-scale what happens in nature when water vapor approaches cold surfaces. Based on self-assembly events, honeycomb-packed pores have been obtained in 3D arrays reaching an overall porosity of 85%. Water droplet lattice dynamics have been directed through polymeric solutions under well-established environmental conditions, leading to a long-range order with modular pore size (5 to 0.8 um) over a surface area of around 64 cm2. Further surface modifications have enhanced the membrane resistance to the spreading of salt solution (?>130±3° for NaCl solutions 4M), thereby meeting the basic requirements of the membrane distillation technology. Water vapor transmission rate measurements along with thermal membrane distillation experiments have been executed by using a difference of temperature through the membrane as the driving-force for the process. The membrane performance has been investigated as a function of temperature, flow rate, and salt concentration. The results obtained have been compared to those of commercial membranes, yielding useful indication how about the finest pores geometry of honeycomb membranes causes a higher interfacial area making the polymeric interfaces capable to transport a larger amount of water vapor. The singular architectures of these honeycomb assemblies associated to the interesting structure-transport relationships suggest these membranes as promising interfaces for technologically sophisticated applications in water purification.