Solar-Driven Soil Remediation along with the Generation of Water Vapor and Electricity

Abstract

As a renewable energy source, solar energy has become an important part of human energy use. However, facilities utilizing solar energy are often complex and technically difficult, and preparation equipment and materials are expensive, while these equipment and materials often cause new environmental pollution. Soil, which exists in large quantities on the earth’s surface, is an inexhaustible natural material with loose and stable properties. Due to the specificity of its composition and microscopic form, the soil has an inherent advantage as a medium for solar thermal and photovoltaic conversion. Here, we built an integrated solar energy utilization system, the Integrated Soil Utilization Module (ISUM), integrating multi-functions into one hybrid system, which enables solar-driven water vapor and electricity generation and soil remediation. The evaporation rate of the soil represented by the rocky land was 1.2 kg·m−2·h−1 under 1-sun irradiation with evaporation induced voltage of 0.3 V. With only seven days of continuous exposure to sunlight, the removal of heavy metal ions from the soil reached 90%, while the pH was raised to near neutral. The combined application of readily available natural soil with solar energy not only demonstrates the potential of a soil for solar desalination and power generation, but in addition, solar-driven interfacial evaporation provides an energy-efficient, environmentally friendly, and sustainable method for purifying heavy metal and acid-contaminated soil.