Polypyrrole-modified natural eggplant aerogel with high shape recovery for simultaneous efficient clean water generation and heavy metal ion adsorption from wastewater

Solar water evaporation has proven to be one of the most effective approaches to generate clean water. However, simultaneous clean water generation and heavy metal ion removal is challenging and urgent for the treatment of wastewater containing heavy metal ions. Herein, polypyrrole (PPy)-modified natural eggplant (PPy@eggplant) aerogel was developed to effectively address the aforementioned problems. The resultant PPy@eggplant aerogel possessed impressive shape recovery capacity after absorbing water regardless of multiple squeezing and twisting, which contributed to usage stability in long-term applications. Moreover, the PPy@eggplant aerogel achieved solar light absorption of 98.48 % due to PPy uniform distribution and multiple light diffraction/scattering in the porous structure (porosity of 92.16 %), excellent water replenishment capacity (water droplet fully spread within 118 ms), and extremely low thermal conductivity (0.039 W·m −1 ·K −1 ). Thus, the PPy@eggplant aerogel demonstrated a high evaporation rate of 2.05 kg·m −2 ·h −1 and a simultaneous Cr 6+ adsorption capacity of 27.83 mg·g −1 for treating dye water with Cr 6+ ions. Additionally, the PPy@eggplant aerogel preserved the evaporation rate after a 10-h test, indicating long-term stability in practical applications. In conclusion, the impressive shape recovery capacity, high evaporation performance, and satisfactory Cr 6+ adsorption ability make the PPy@eggplant aerogel a good alternative for treating wastewater, especially wastewater with heavy metal ions.