Thermosensitive Hydrogel PNIPAAm-Alg-PEDOT for Sustainable and Efficient Water Purification Powered by Solar Energy

Unrestricted access to clean drinking water is essential for the well-being of the global population, yet this necessary resource is not universally guaranteed, particularly amidst the escalating climate crisis that accentuates disparities across regions. Harnessing solar energy in conjunction with advanced synthetic solar absorbent hydrogels (SAHs) is increasingly recognized as a promising solution and a significant challenge in addressing the purification of brackish water sustainably. This work outlines the development of a SAH using the thermosensitive polymer poly(N-isopropylacrylamide) (PNIPAAm) in combination with alginate (Alg), enriched with poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles (NPs). Through solar evaporation tests using different conducting polymer (CP) concentrations, a discernible relationship between the ratio of free water to intermediate water (FW/IW) within the hydrogel structure and its performance is observed. The hydrogel's remarkable evaporation rate for synthetic seawater (2.82 kg m-2 h-1) aligns with the lowest FW/IW, which is directly related to a reduction in water vaporization enthalpy. Characterization of intermediate water enables easy adjustment of the optimal conductive polymer content within the hydrogel. This technology, based on thermosensitive materials, not only introduces innovative methodologies for designing and customizing functional composite materials but also aligns with global objectives by addressing challenges in sustainable drinking water supply without additional energy inputs. A novel solar absorber hydrogel made of PNIPAAm-Alg enhanced with PEDOT NPs exhibited a remarkable evaporation rate of 2.82 kg m-2 h-1 for synthetic seawater, corresponding with the lowest free water to intermediate water ratio within the hydrogel. This highlights the potential of advanced synthetic SAHs in sustainably purifying brackish water, addressing global drinking water challenges without extra energy inputs. image