Double-layered solar evaporator based on polymeric ionic liquid grafted attapulgite and MXene/PPy for efficient desalination and photodegradation

Abstract

Solar-driven interfacial evaporation (SIE) is a promising fresh water acquisition technology to address the global water resource shortage. Therefore, solar evaporators with efficient photothermal conversion efficiency and multifunctional purification capabilities are still in high demand. At present, a variety of photothermal conversion materials have been explored, however, there are few studies on integrating interfacial evaporation and photocatalytic capabilities into one solar steam generation system collaboratively. In this work, a new double-layered solar interfacial evaporator (MXene/PPy-ACA) was fabricated by using polymeric ionic liquid grafted attapulgite (ATP-PIL) as the matrix and modified the upper surface by MXene and polypyrrole (PPy). The evaporator can not only carry out seawater desalination efficiently, but also has good photocatalytic degradation effect on organic dyes. The MXene/PPy-ACA achieves an evaporation rate of 1.53 kg m−2 h−1 and corresponding to an efficiency of 92.17 % under irradiation of 1 sun. In addition, duing to the ionic repulsion effect of ATP-PIL, the MXene/PPy-ACA possesses good salt resistance. When tested in 20 wt% high brine, the evaporation rate is measured to be 1.40 kg m−2 h−1. Moreover, owing to the superb photocatalytic properties of MXene and PPy, the MXene/PPy-ACA exhibits remarkable photocatalytic efficiency towards organic dyes, achieving degradation rates of 94.9 %, 67.49 %, and 65.11 % for methyl orange (MO), rhodamine B (RhB), and methylene blue (MB), respectively. The prepared interfacial evaporation system can also run stably in acid and alkali solution, and has a good practical application prospect. This study may offer an alternative approach in achieving clean water via SIE of seawater and complex wastewater.