Role of polymeric calcium-alginate particles to enhance the performance capabilities of composite membranes for water vapor separation

We synthesized polymeric calcium-alginate (CA) particles with an "egg box" structure using an emulsification additive process to enhance the performance of the thin film composite (TFC) membranes for water vapor separation. The appealing feature of CA particles is that they have a variety of hydrophilic groups, such as hydroxyl and carboxyl groups, which allow them to absorb more water vapor at a relatively rapid rate. Moreover, CA particles are readily available, inexpensive, and biocompatible. Moreover, they can be obtained by one-pot synthesis, which is a relatively simple and convenient method. These particles can be characterized with different techniques. Transmission electron microscopy (TEM) mapping data and X-ray photoelectron spectroscopy (XPS) data illustrate fundamentally that CA particles consist of mostly calcium and oxygen. Energy dispersive X-ray (EDX) data show that the calcium rises from 0 to 0.41 atomic percent when CA content increases from 0.0 to 0.35 wt%. Water vapor/nitrogen gas permeation results show that relatively more CA particles in the polyamide (PA) layer increases the water vapor permeation due to the increased number of sorption sites and greater surface area provided by the particles with their many hydrophilic functional groups. The TFC membrane with 0.1 wt% CA loading shows the best performance such as water vapor permeance of 2143 GPU and selectivity of 706. Thus, adding a small amount of polymeric CA particles to a PA layer can enhance the performance of TFC membranes, making them a viable candidate for water vapor separation membranes.