Synergistic adjustment of water channels and light absorption pathways to co-generate salt collection and clean water production

• Published in: The Science of the total environment 2021-11, Vol.797, p.148912-148912, Article 148912
• Main Authors: Kong, Yan, Gao, Yue, Shang, Yanan, Kong, Wenjia, Qi, Yuanfeng, Wang, Shouquan, Yin, Fengjiao, Gao, Baoyu, Wang, Shuguang, Yue, Qinyan
• Format: Article
• Language: English
• Subjects: Cobalt‑nitrogen-rich CNT; Interfacial evaporation; Salt harvesting; Water transport
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.148912

Solar-driven interface evaporation for clean water production has attracted significant concern due to its energy-saving and environmental protection. However, it is still challenging for the evaporator to continuously and efficiently produce clean water in practical applications because of salt particle deposits and insufficient water supply. Here, an improved and easy-to-manufacture solar evaporator device (Co-NCNT-GO system) enhances water supply and light absorption by introducing a water supply layer (melamine sponge) and bamboo-like structure carbon nanotubes embedded with metal cobalt particles (Co-NCNT). The salt accumulation on the edge of the Co-NCNT-GO film is achieved by controlling the concentration gradient of brine in the center area and the edge area of the film. This paper aims to study the photothermal mechanism of the Co-NCNT-GO system through a series of characterization and theoretical calculations (DFT) and discuss the influence of different water supply areas on the salt recovery capacity. The results show that Co-NCNT-GO significantly reduces the band (0.054 au) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUNO) by graphite nitrogen-doped CNTs, which is beneficial to improve the light-to-heat conversion capability. Furthermore, the Co-NCNT-GO film has good water wettability due to the higher adsorption energy of pyridine nitrogen and water molecules in Co-NCNT (−9.33 kcal/mol). Simultaneously, it is found that the water evaporation capacity and water supply capacity significantly affect whether the salt can be continuously crystallized at the edge of the film. When the ratio of water supply area to light and heat area is 4:2.5, the salt recovery rate is 46.54 g m−2 h−1 during 108 h continuous desalination under one sun illumination. This rationally designed structure and adjustable water transport channel can simultaneously meet high-efficiency evaporation and salt recovery, which can have great potential in practical applications. [Display omitted] •A solar adsorbent based on bamboo-shaped carbon nanotubes coated with metal particles is introduced.•The coupling of graphite nitrogen and cobalt nanoparticles is the main reason for efficient photothermal conversion.•The transfer speed of salt can be easily controlled by adjusting the size of the water supply interface.•The photothermal device can efficiently produce water vapor and recover salt particles simultaneously.