Full tea waste-based photothermal aerogel with vertical water transport channels for steady solar desalination

Abstract

Interfacial solar desalination technology holds immense promise in combatting global freshwater scarcity. However, salt accumulation on solar evaporators poses a significant hurdle in sustaining desalination performance. Therefore, the development of salt-resistance solar evaporators remains a formidable challenge. Herein, we have exploited a full tea waste-based photothermal aerogel (TWPA) to achieve steady desalination performance. This TWPA is fabricated with carbonized tea waste (TWC) and tea waste fiber (TWF) with a simple crosslinking method and liquid nitrogen freeze-drying. The TWPA efficiently absorbs 97% of sunlight, which results in an exceptional evaporation rate of 1.63 kg m–2 h–1 under 1-solar intensity. Moreover, the vertical water transport channels and large pore structure within TWPA expedite solution transport and salt ion backflow diffusion, ensuring stable desalination of 10 wt% brine at a rate of 1.37 kg m–2 h–1. Long-term indoor and outdoor experiments demonstrate that TWPA is durable. Notably, a 1 m2 TWPA can generate about 6.34 kg freshwater per day from 10 wt% brine. This simple waste-to-treasure approach not only demonstrates a sustainable solution but also promises to drive the development of waste-based solar evaporators, addressing freshwater scarcity while mitigating environmental pollution.