Flexible, affordable and environmentally sustainable solar vapor generation based on ferric tannate/bacterial cellulose composite for efficient desalination solutions

Abstract

Desalination by solar steam generation (SSG) system is a green technology to produce pure water, which can address the issue of water scarcity. A novel photothermal material for the SSG system was fabricated by immersing bacterial cellulose (BC) sequentially into tannic acid (TA) and iron(III) (Fe³⁺) solutions. Surface analysis of the resulting BC–TA–Fe³⁺ (BTF) material showed that coordination nanocomplexes between Fe³⁺ and hydroxyl groups of TA were formed on the surface of cellulose nanofibers. BTF material exhibited high sunlight absorption (∼95%), hydrophilic, self-cleaning properties, and excellent structural stability. SSG systems based on BTF had an evaporation efficiency of 91% and an evaporation rate of 1.56 kg m⁻² h⁻¹ under 1 sun illumination. Then, an efficient desalination device based on the larger-scale BTF material was fabricated to produce freshwater, the amount of freshwater per day was 5.6 kg m⁻² on a sunny day. BTF material, thus, showed great potential in seawater desalination applications along with simple, versatile, scalable, and affordable fabrication methods.