Multifunctional Hydrothermal‐Carbonized Sugarcane for Highly Efficient Direct Solar Steam Generation

Abstract

Solar steam generation is an environmentally friendly water treatment method that produces clean water using solar energy. However, it is still a challenge to effectively prevent the performance deterioration when most photothermal conversion materials are used to evaporate high‐concentration salt‐containing wastewater or strong acid/alkali solution. Herein, a stable and effective solar evaporator is designed using natural sugarcane, where sucrose is simply dehydrated into carbon particles by hydrothermal reaction in sulfuric acid. With a honeycomb structure, it not only enables water transport capacity but also promotes sunlight absorption. Sulfuric acid hydrothermal carbonized sugarcane (SHCSC) can reach up to 95.36% solar absorption in a wide wavelength range (200–2500 nm) and a high evaporation rate of 2.32 kg m−2 h−1 under 1 sun illumination. More importantly, SHCSC has an excellent adsorption capacity with ion removal rate of 99.9% even under artificial wastewater containing 1000 mg L−1 of mixed metal ions. SHCSC also can perform efficiently and stably at a high evaporation rate above 2.2 kg m−2 h−1 in strong acidic or alkaline wastewater. These findings suggest that SHCSC can be potentially applied to the efficient harvest of clean water from the high‐concentration wastewater containing acid, alkali, and mixed metal ions.