Artificial phytoremediation solar interface evaporator for efficient heavy metal salt separation and saline soil remediation

Solar-driven interfacial evaporation is an efficient, green, and low-carbon footprint way to separate heavy metals from contaminated soil. A biomimetic mushroom-like evaporator based on polypyrrole-modified cotton fabric is designed, which uses the mechanism of evaporative diffusion and gravity to drive the separation of heavy metal salt crystals, achieving sustainable remediation heavy metal contaminated soil (HMCS). This stereo biomimetic evaporator not only achieves excellent evaporation performance under solar energy drive but also enhances evaporation efficiency by capturing environmental energy from the side and then using natural convection. At an air velocity of 6 m s−1, the evaporation rate reaches 2.32 kg m−2 h−1. After continuous operation for 192 h, the biomimetic evaporator maintains stable evaporation performance and successfully separates metal salt pollutants from the washing solution of HMCS. The removal rates of heavy metal ions Pb2+, Cr3+, Cd2+, Zn2+, and Hg2+ in polluted soil are 53 %, 59 %, 60 %, 62 %, and 84 %, respectively. Compared to untreated control soil, the concentrations of Pb2+, Hg2+, Cr3+, Zn2+, and Cd2+ in the roots of pea treated with solar evaporation remediation decreased by 66.4 %, 31.6 %, 31.1 %, 29.0 %, and 8.3 %, respectively. This study provides a potential new approach and method for the sustainable, low-cost, and low-energy remediation of HMCS using solar evaporation technology.