Self-Healing Hydrogel Membrane Provides a Strategy for the Steady Production of Clean Water from Organic Wastewater

Abstract

When the typical solar-driven hydrogel water evaporator treats the organic sewage, the organic pollutants will be accumulated in the evaporator and affect the evaporation performance. This issue is resolved by using silver–disulfide bonding to fix the silver oxide/silver (Ag2O/Ag) nanoparticles inside the polyacrylamide-acrylic acid hydrogel, resulting in the photocatalytic degradation of methyl orange and solar-driven water evaporation. Ag2O/Ag nanoparticles are a solar–thermal conversion material used to replace the traditional carbon material. On the one hand, the heterojunction structure of Ag2O/Ag enhances the separation ability of the photogenerated carriers, thereby increasing the photocatalytic efficiency. On the other hand, the surface of the nanoparticles is grafted with N, N′-bis(acryloyl) cystamine and becomes the crosslinking agent which is fixed in the hydrogel. Meanwhile, the inverted pyramid structure can be built at the surface of the hydrogel by soft imprinting technology. This kind of structure has excellent light trapping performance, which can increase the efficiency of Ag2O/Ag photocatalysis. Furthermore, the dynamic reversible coordination effect between Fe3+ and carboxyl realizes the self-healing capability of the hydrogel. Here are the properties of hydrogel: the fracture stress is 0.35 MPa, the fracture elongation is 1320%, the evaporation rate is 1.2 kg·m−2·h−1, and the rate of the photocatalytic degradation of methyl orange is 96% in 3 h. This self-healing hydrogel membrane provides a strategy to steadily get clean water from organic sewage.

Keywords

• hydrogel membrane
• photothermal
• photocatalytic
• self-healing
• hydrogel
• light trapping