Water purification by solar power: an update

Water evaporation systems (from Fillet, et al. 2021)

An update to the Solar-powered water harvesting and purification bibliography. The most current version of the bibliography can be seen here — https://sciencebibliographies.strategian.com/solar-powered-water-harvesting-and-purification/.

Featured articles (these articles have been added to the Science Primary Literature database):

*Fillet, R., Nicolas, V., Fierro, V., & Celzard, A. (2021). A review of natural materials for solar evaporation. Solar Energy Materials and Solar Cells, 219, 110814. [Cited by]

One way to harvest solar energy is to produce steam from liquid water. Steam can be used to provide freshwater even in a harsh environment, with extreme temperature and low groundwater supplies. It can also be extracted from polluted soil or water, purifying the water in the process at the same time. Water evaporation systems are energy effective, with efficiencies ranging from 60% to over 90%. Furthermore, they can be cost-effective and have a low environmental impact, using the right materials. In this article, we will review natural materials, mainly of biological origin, proposed for solar evaporation, from wood and plants to algae and other atypical biomass such as fungi or wastes such as pomelo peels, through gels and foams, raw or charred. Their evaporation effectiveness will be presented and discussed, as well as their energy efficiency. This timely review suggests the suitability of natural materials for this application and reports on the progress that has already been achieved, as well as on the advances that remain to be made to improve the performance of these low cost, low environmental impact but high performance systems.”

*Gong, F., Wang, W., Li, H., Xia, D., Dai, Q., Wu, X., . . . Xiao, R. (2020). Solid waste and graphite derived solar steam generator for highly-efficient and cost-effective water purification. Applied Energy, 261. [Cited by]

Utilizing the clean and renewable solar energy to generate steam for wastewater purification or seawater desalination is a promising solution to the worldwide scarcity of fresh water. Herein, we report a highly-efficient, eco-friendly and cost-effective solar steam generator based on ball-milling graphite and cellulose fiber from waste paper. Ball-milling graphite/cellulose fiber composite aerogels are facilely developed via a freeze casting-drying method, endowing a featured vertically aligned porous structure. The fabrication of composite aerogels and the construction of evaporation systems take full advantages of recycled materials, contributing to the low cost and solid waste reclamation. High porosity, strong solar absorption, hydrophilicity and low thermal conductivity of the composite aerogels collectively contribute to a splendid solar evaporation rate of water as high as 1.61 kg m−2 h−1, with photothermal efficiency of ~90% under one sun illumination (1 kW m−2). Quantitative studies reveal the effects of ball-milling graphite/cellulose fiber ratio, ball-milling graphite concentration and thickness of composite aerogels on the solar evaporation rates, suggesting the optimal design of composite aerogels. Furthermore, the cycling stability and the capability for seawater desalination as well as polluted water purification manifest the potential of the composite aerogels to purify diverse water. Outdoor tests show 8–13 L of fresh water could be produced daily by 1 m2 of composite aerogel.”

From Gong, et al. 2020

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