Janus

Salt (chemistry)

Engineering

Materials science

Biochemistry

Chemical engineering

Contact angle

Thermodynamics

Physics

Nanotechnology

Organic chemistry

Membrane

Photothermal therapy

Surface modification

Composite material

Fiber

Evaporation

Chemistry

Wetting

Chemical Engineering Journal

The emerging solar-driven steam generation technology is considered as one of the most promising strategies for purifying seawater and wastewater, while it is still challenging to achieve superior evaporation rate, salt-resistant property and multi-media evaporation applications at the same time. Herein, an ultra-robust Janus PP hollow fiber membrane (PP HFM) with capillary-driven siphon and photothermal properties was fabricated. Dopamine (DA), (3-aminopropyl) triethoxy-silane (KH550), TiO2 nanoparticles were immobilized on the inner surface of PP HFMs for turning from a common hydrophobic state to a hydrophilic state. An outer surface with hydrophobicity is constructed by chemical vapor deposition polymerization (CVDP) of polypyrrole (PPy). The fabricated PP-PDA/KH550/TiO2-PPy HFMs showed an asymmetric wettability (inner and outer water contact angle of 0° and 95°), mechanical strength of 1.2 GPa, and light absorption of 95%. Importantly, the low heat loss through decreasing contact area with water enabled vertically aligned HFMs with a superior solar evaporation rate of 3.65 kg/(m2·h), and a high photothermal conversion efficiency of 229.13% under one-sun irradiation. Furthermore, the Janus PP HFMs showed a superior salt-resistance without salt crystals even in 20 wt% high salinity condition, rejections of ion (<10 ppm salt ions), oil (>99%), and dye (>99%), and excellent stability. The Janus PP HFMs evaporator provide a new paradigm for low heat loss, high evaporation rate, salt-resistant and multi-media purification.

Ultra-robust vertically aligned three-dimensional (3D) Janus hollow fiber membranes for interfacial solar-driven steam generation with salt-resistant and multi-media purification