Construction of a Three-Dimensional Interpenetrating Network Sponge for High-Efficiency and Cavity-Enhanced Solar-Driven Wastewater Treatment

Abstract

It is well known that the photothermal conversion performance of solar-driven interfacial water evaporation systems is known to have a stronger photothermal conversion performance than suspended water evaporation systems due to their relatively strong ability to suppress overall heat loss. Natural polymer chitosan and gelatin can form a three-dimensional interpenetrating network (IPN) sponge to provide an interface for water evaporation due to strong hydrogen bonding and electrostatic attraction interaction. However, the lack of effective light absorption, the intrinsic short lifetime, and the poor photothermal conversion greatly compromise their steam generation performance. Here, we fabricated a chitosan/gelatin-based IPN sponge incorporated with melanin-coated titania hollow nanospheres (CG@MPT-h) as a solar thermal converter, which is designed to exhibit a unique cavity structure and vertical channels. The cavity structure of melanin-coated titania acts as a solar thermal transducer, while the chitosan/gelatin-based IPN sponge acts as a single-pass water pump. A water hyacinth-inspired evaporation system shows outstanding steam generation performance, and the highest steam generation rate was 3.17 kg m −2 h −1 under a 2.5 sun illumination because of the cavity enhancement effect, far above TiO 2 particles and reported photo-thermal conversion materials. More importantly, the embedding of MPT-h nanoparticles in the IPN sponge effectively inhibits the growth of bacteria in the vertical channels, resulting in an antibacterial solar-driven water evaporator. This advanced sponge provides a cost-effective and practical sustainable energy technique for solar-driven wastewater treatment.

Recent advances in structural regulation and optimization of high-performance solar-driven interfacial evaporation systems

“…A chitosan/gelatin-based sponge incorporating melanin-coated titania hollow nanospheres exhibited an evaporation rate of 3.17 kg m À2 h À1 under 2.5 kW m À2 solar irradiation and had an antibacterial rate of 100% against Salmonella. 161 As a low-cost, hydrophilic and 3D porous material with low thermal conductivity, melamine foam (MF) is oen used as a support for photothermal materials. PPy-coated MF could yield evaporation efficiency of up to 87.7%.…”

“…A chitosan/gelatin-based sponge incorporating melanin-coated titania hollow nanospheres exhibited an evaporation rate of 3.17 kg m −2 h −1 under 2.5 kW m −2 solar irradiation and had an antibacterial rate of 100% against Salmonella . 161…”

Recent developments of hydrogel based solar water purification technology

“…39 For instance, as a widely used light-harvesting semiconductor, TiO2 has been used as solar absorbers for preparing hydrogel materials. [42][43][44][45] However, under 1 sun, these hydrogels showed a low evaporation rate of <1.5 kg m -2 h -1 and a low energy conversion efficiency of <80%. This can be attributed to the wide intrinsic band-gap of TiO2 of ca.…”

“…The anti-bacterial performance can be achieved by adding CTS. 43,112 Guo et al 184 recently attached catechol groups to the CTS hydrogel for hydrogen peroxide (a broad-acting antibacterial agent) generation, combining with the synergistic effect of quinone-modified AC, to enhance the anti-fouling properties and guarantee 3 months of performance maintenance. There are numerous methods to improve the anti-crystalline fouling ability, including the construction of the Janus structure 130,165 and the umbrella-shaped platform, 91 the use of ions rejection polymer, 85,152,169 the introduction of bubbles in the middle section, 140 the weight imbalance sensitive spherical platform capable of rotating and renewing the evaporation surface, 163 the millineedle array on the surface for site-specific salt crystallization without salt clogging 155 and so on.…”

High-Performance Solar Steam Generator Based on Polypyrrole-Coated Fabric via 3D Macro- and Microstructure Design

“…One of the most pressing global issues puzzling people is insufficient access to freshwater due to the rapid population growth and increasing water pollution. − Solar-driven water evaporation has been regarded as a highly promising technology to generate clean water due to the abundance and environmental friendliness of solar energy resources. − Therefore, significant attention has been paid to the development of high-efficiency solar vapor generators through designing smart structures and choosing advanced materials. , Consequently, it is necessary to enhance the solar absorption and conversion and heat localization and management of photothermal materials. Over the past several years, solar steam generation has achieved major breakthroughs in improving the energy utilization efficiency, depending on managing the heat loss and improving the solar absorption and conversion. − …”