Reduced Red Mud as the Solar Absorber for Solar-Driven Water Evaporation and Vapor–Electricity Generation

Abstract

The emergent solar-driven water evaporation technology provides a reassuring scheme for red mud (RM) utilization in environment and materials science. With fewer restrictions on raw materials, wide availability of sheer quantity, and high complexity in chemical composition, the RM may be a promising candidate for solar absorbers. Here, we developed a novel solar absorber with reduced RM. It features favorable light absorption and photothermal conversion ability using biomass pyrolysis. When added to the polyvinyl alcohol and chitosan gel substrate, the light absorptance can reach 94.65%, while the corresponding evaporation rate is as high as 2.185 kg m–2 h–1 under an illumination density of 1 kW m–2. We further demonstrated its potential as an efficient solar absorber in the solar-driven water evaporation and the thermoelectric device to realize the stable and efficient coproduction of vapor and electricity.

A robust starch–polyacrylamide hydrogel with scavenging energy harvesting capacity for efficient solar thermoelectricity–freshwater cogeneration

“…[1][2][3] It is estimated that by 2025, more than two-thirds of the world's population will face severe imbalances between water requirements and supplies, especially in Asia and Africa. 4 Following the sustainable development, various green energy sources have been researched to produce electricity (piezoelectricity, [5][6][7] wind power generation, 8 hydro power, 9 photovoltaics, [10][11][12] and thermoelectricity [13][14][15][16] ) and freshwater (reverse osmosis, 17 ion exchange, 18 catalytic oxidation, [19][20][21] and solar evaporation [22][23][24][25][26] ). However, separate development inevitably causes high costs, low energy utilization efficiency and a large footprint to achieve both goals.…”

Solar-driven interfacial evaporation for water treatment: advanced research progress and challenges

“…Wang et al 233 developed an SDIE that could coordinate steam and power generation using red mud, with an ER of 2.185 kg m −2 h −1 . This SDIE was applied for the treatment of seriously eutrophicated water, and it was revealed that the chemical oxygen demand (COD) decreased from 250 mg L −1 to 0 mg L −1 and the ammonia nitrogen content decreased from 70–100 ppm to 2 ppm (Fig.…”

Recent developments of hydrogel based solar water purification technology

“…A research group even coated PPy on the real Setaria viridis spike to use the plant's own water transport and evaporation-promoting properties to maximize its potential. 144 Other studies have reported the use of specific solid waste as solar absorbers, including red mud (residue of the aluminum mining industry), 180 semi-coke, 183 and pencil graphite. 178 Besides, reducing the use of solar absorbers by distributing them only around the evaporation interface 35,148 and constructing multilayer-structure with only one layer of them 73,75,83,96,100,141 is also effective.…”