Salt-blocking three-dimensional Janus evaporator with superwettability gradient for efficient and stable solar desalination

Xiao-Jing Guo; Xing Wang; Chao-Hua Xue; Bing-Ying Liu; Yong-Gang Wu; Duo Zhang; Fu-Quan Deng; Qiu-Feng An; Yong-Ping Pu

doi:10.1016/j.jcis.2023.04.073

Salt-blocking three-dimensional Janus evaporator with superwettability gradient for efficient and stable solar desalination

J Colloid Interface Sci. 2023 Aug 15:644:157-166. doi: 10.1016/j.jcis.2023.04.073. Epub 2023 Apr 21.

Authors

Xiao-Jing Guo¹, Xing Wang², Chao-Hua Xue³, Bing-Ying Liu⁴, Yong-Gang Wu², Duo Zhang⁵, Fu-Quan Deng², Qiu-Feng An⁵, Yong-Ping Pu¹

Affiliations

¹ College of Materials Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
² College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
³ College of Materials Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China; College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China. Electronic address: xuech@sust.edu.cn.
⁴ College of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, China.
⁵ College of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.

PMID: 37105039
DOI: 10.1016/j.jcis.2023.04.073

Abstract

Solar interfacial steam power generation is a prospective method for seawater desalination. In this work, a salt-blocking three-dimensional (3D) Janus evaporator with a superhydrophobic to superhydrophilic gradient was fabricated by spraying a composite dispersion of multi-walled carbon nanotubes/polydimethylsiloxane (CNTs/PDMS) onto the top side of a polyurethane (PU) foam and polyvinyl alcohol (PVA) solution onto the bottom side. The CNTs/PDMS composite dispersion with nanostructured CNTs and low surface energy PDMS combined with the porous structure of the PU foam rendered the top side superhydrophobic. Therefore, a layer suitable for photothermal conversion was obtained. The hydrophilic PVA combined with the porous structure of the foam rendered the bottom side superhydrophilic, facilitating water absorption and transportation. The asymmetric wettability gradient of the CNTs/PDMS-PU-PVA as a 3D evaporator caused the evaporation rate and transportation speed of water to reach a balance, and the salt was quickly dissolved at the superhydrophilic interface. This 3D salt-resistant Janus evaporator achieved an evaporation rate of 2.26 kg m^-2 h^-1 under 1 kW m^-2 illumination.

Keywords: 3D Janus evaporator; Photothermal conversion; Salt-blocking; Superwettability gradient.