探究制备工艺对材料吸湿性能的影响

Exploring the Influence of Preparation Method on Material’s Water Sorption Capacity

对于空气取水,理想的吸附剂材料需具备高吸湿性能、优越的传热传质能力等。本文主要以聚丙烯酰胺(PAM)水凝胶为基质,采用不同的制备工艺合成几类凝胶填盐吸附剂。利用扫描电镜、红外光谱等多种表征手段和动态、静态吸湿实验,分析了制备工艺对吸附剂形貌结构、化学组成以及实际吸湿性能的影响。找出最优的制备工艺:先冻干水凝胶,使其内部生成有序的孔道结构;再填盐,优化吸湿时盐溶液的扩散过程;在RH60%下可获得高达1.7 g·g^(-1)的吸附量。

As for atmospheric water harvesting(AWH), desirable sorbent material requires to possess high water sorption capacity and desirable heat and mass transfer properties. In this paper,several sorbents based on polyacrylamide(PAM) hydrogel have been prepared via different kinds of synthetic methods. Their morphologies, physical and chemical structures, and static and dynamic sorption performances have been explored through Scanning Electron Microscopy(SEM), Fourier Infrared Spectroscopy(FTIR), and practical sorption experiments, respectively. Through the above theoretic and experimental analysis, it suggests that freeze-drying pure PAM hydrogel to form the ordered porous structure and then impregnating hygroscopic salts into these pores to enhance subsequent diffusion properties is the optimal preparation method to obtain promising sorbent with superior static and dynamic sorption capacities. Corresponding experiments have demonstrated that the selected sorbent presents up to 1.7 g·g^(-1)of water uptake at 60% relative humidity(RH).