Carbonized sugarcane as interfacial photothermal evaporator for vapor generation

Biochar-based photothermal evaporators are considered to be a promising choice for low energy consumed, cost-effective and sustainable solar-driven interfacial evaporation. Here, a carbonized sugarcane (CSC) evaporator was demonstrated. Benefiting from the microstructure of CSC, the CSC evaporator modified by concentrated nitric acid possesses high solar absorption and good hydrophilicity. And numerical simulation results proved that the hydrophilic surface is more conducive to photothermal water evaporation. Evaporation rate of 1.69 kg m−2 h−1 and evaporation efficiency of 85% were obtained under 1.0 sun irradiation (1 kW m−2) by the carbonized sugarcane with a carbonization temperature of 700 °C (CSC700). In addition, further studies have found that airflow and solar radiation can work synergistically to improve evaporation rate, and the evaporation rate under 1.0 sun irradiation could reach up to 2.24 kg m−2 h−1 for CSC700 with airflow rate of 5.18 m/s. More importantly, CSC700 shows excellent desalination performance and durability, and the average ion rejection in the collected fresh water was 99.32%. This work presents a good strategy which can make fully use of cost-effective biochar-based photothermal evaporators to produce drinking water from seawater and brackish water.