Ultra-Thin Ion Exchange Membranes by Low Ionomer Blending for Energy Harvesting.

Exploring the utilization of ion exchange membranes (IEMs) in salinity gradient energy harvesting, a technique that capitalizes on the salinity difference between seawater and freshwater to generate electricity, this study focuses on optimizing PVDF to Nafion ratios to create ultra-thin membranes. Specifically, our investigation aligns with applications such as reverse electrodialysis (RED), where IEMs facilitate selective ion transport across salinity gradients. We demonstrate that membranes with reduced Nafion content, particularly the 50:50 PVDF:Nafion blend, retain high permselectivity comparable to those with higher Nafion content. This challenges traditional understandings of membrane design, highlighting a balance between thinness and durability for energy efficiency. Voltage-current analyses reveal that, despite lower conductivity, the 50:50 blend shows superior short-circuit current density under salinity gradient conditions. This is attributed to effective ion diffusion facilitated by the blend's unique microstructure. These findings suggest that blended membranes are not only cost-effective but also exhibit enhanced performance for energy harvesting, making them promising candidates for sustainable energy solutions. Furthermore, these findings will pave the way for advances in membrane technology, offering new insights into the design and application of ion exchange membranes in renewable energy.

Effect of Internal Pores Formed by a Superabsorbent Polymer on Durability and Drying Shrinkage of Concrete Specimens.

In this study, the effect of internal pores formed by a superabsorbent polymer (SAP) was analyzed by evaluating the compressive strength, chloride penetration depth, drying shrinkage, and pore size distribution of SAP-containing concrete, while securing workability using a water-reducing agent (WRA). The experimental results showed that the amount of WRA necessary increased as the amount of SAP added increased, and that the compressive strength was the highest when the SAP content was 1.5% of the concrete mix. Drying shrinkage tended to decrease as the SAP content increased, and it decreased by approximately 31-41% when the SAP content was 2.0% compared to that of the reference mix. The SAP expanded by approximately three times inside concrete, and it was distributed within the internal pores of air-entrained concrete. The optimal SAP content in concrete mix was 1.5%, and an SAP content of 2.0% or higher adversely affected the workability and compressive strength.