High-efficiency Solar Desalination Evaporator Composite of Corn Stalk, Mcnt and TiO2: Ultra-fast Capillary Water Moisture Transportation and Porous Bio-tissues Multi-layers Filtration
Studies on solar steam evaporations for potential applications of desalinations have attracted many attentions due to unique advantages of low energy consumption and environmental friendliness, etc. However, water molecule transportation in capillaries of solar steam evaporators to develop a high-efficient solar evaporation system is critical but often ignored. This work reports high-yield and low-cost natural corn stalks as solar steam generators with ultra-fast water transportation in capillaries, sea-salts multi-layers self-cleaning, large seawater capacity, long-term anti-corrosion of seawater, low thermal conductivity, and excellent evaporation properties. This solar steam evaporator with the conventional photothermal coating by Multi-walled carbon nanotube and Titanium dioxide (Mcnt-TiO2) behaves outstanding evaporation rate of 2.48 kg m-2 h-1 and evaporation efficiency of 68.2 % under a solar light intensity. These advantages are significantly attributed to natural structural features of stem marrow of corn stalks including scattered vascular bundles with the super-hydrophilic properties achieving high-speed water moisture transportation, and porous basic tissues with layer by layer bio-filtration and porous cavities realizing multi-stage filtration, transportation and storage of seawater, and low moisture enthalpy and heat loss. Meanwhile, an efficient and low-cost solar desalination device via bundling pluralities of corn stalks is developed to collect freshwater, and the average daily freshwater amount per unit area (4.3~5.8 kg m-2 on sunny days and 3.0~3.9 kg m-2 on cloudy days) can meet the daily water needs of more than twenty adults. These findings not only provide the possibility of discovering corn stalks as low-cost, scalable, highly efficient evaporation of heat transfer devices for future efficient desalination, but also present innovative inspiration for the greenhouse effect brought by corn stalks burning, which promotes the efficient use of bio-mass straws.