Search

Solar energy used to evaporate seawater and purify fresh water is regarded as an innovative way to address water scarcity. In this paper, high-performance porous wood-carbonized solar steam evaporation (SSE) is proposed by regulating the surface carbonization process, and the evaporation performance of the SSE under different carbonization degrees is studied. The results show that the variation in carbonization degree treatment can significantly affect the photothermal conversion characteristics, which in turn affect the evaporation efficiency of solar steam evaporation. Surprisingly, at 1 sun equivalent input, this evaporator exhibits a low thermal conductivity (0.17 W m−1 K−1), high solar energy absorption rate (92.5%), high surface temperature (49.5 °C) and evaporation efficiency (78%). When the surface carbonization degree of the SSE is 20%, an excellent thermal conductivity coefficient (0.33 W m−1 K−1) is available by the efficient water conduction ability. Additionally, an outstanding evaporation rate (1.8 kg m−2 h−1) of the SSE can be obtained, which is significantly superior to that of the reported wood-based evaporators. Due to its simple preparation, wood-based SSE with recyclability, low-cost and extraordinary performance can be expected to provide potential fresh water for commercial and renewable applications.

Solar steam evaporation is regarded as a green and efficient method to achieve desalination and purification. However, the low-efficiency photothermal conversion of its evaporator is an obstacle to widespread application. Focusing on the interface evaporation method through photothermal conversion, the current bottleneck of the technology is that it is impossible to achieve in-depth interface control of the incident light path to obtain higher water evaporation efficiency. We propose a mesoporous cellulose-based hydrogel for the manufacture of a high-efficiency solar steam evaporator. This type of solar evaporator achieves an enhanced capillary force and optical path extension to increase the photothermal conversion efficiency and evaporation rate. These evaporation performance advantages can all be attributed to the dense mesoporous structure, low thermal conductivity, and high light absorption efficiency. The results showed that under a solar light intensity of 1.5 kW m−2, the mesoporous structure of the MCNT–TiO2–SiO2–TiN hydrogel-based evaporator has an excellent evaporation rate (1.853 kg m−2 h−1) and high solar energy conversion efficiency (77.39%) due to the low thermal conductivity (0.71997 W m−1 k−1), high light absorption efficiency (98.3%, wavelength 190–3000 nm) and good hydrophilic properties (XRD and FT-IR tests). Our results demonstrate a new full-hydrogel solar steam evaporation method by using a simple, easily obtained, reusable, and low-cost solar desalination and purification system based on evaporation can yield fresh water from seawater and sewage. The evaporation technique can be used to produce a simple, easily obtained, reusable, and low-cost solar desalination and purification system for pure freshwater resources from seawater and sewage.