Per- and polyfluoroalkyl substances (PFASs) are commonly used in many consumer and industrial products. However, their resulting widespread release into aqueous environments and their potential toxicities to organisms have raised significant environmental concern. Among the various approaches to the removal of PFAS contaminants, adsorption has proven to be highly effective, especially when carbonaceous nanomaterials (CNMs) are used as the adsorbent. Nonetheless, the interfacial adsorption of PFASs on CNMs is affected by many factors. In this work, the adsorption behaviors of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), two highly representative PFASs, on different CNMs are reviewed. We also examine the mechanisms of PFOA and PFOS adsorption on CNMs, including electrostatic and hydrophobic interactions, ligand exchange and hydrogen bonding. Due to the significant influence of hydrophobic interactions on adsorption, CNMs rich in oxygen-containing functional groups will result in weaker PFAS adsorption than achieved using pristine materials. The important contribution of nanobubbles to hydrophobic interactions is considered herein. Overall, this work contributes to a better understanding of the adsorption affinity of PFASs on CNMs in water environments. Moreover, it provides the systematic theoretical support that is needed for the more effective use of CNMs in the removal of PFASs from aqueous systems.

Biochar application as a soil amendment has been proposed as a strategy to improve soil fertility and increase crop yields. However, the effects of successive biochar applications on cotton yields and nutrient distribution in soil are not well documented. A three-year field study was conducted to investigate the effects of successive biochar applications at different rates on cotton yield and on the soil nutrient distribution in the 0–100 cm soil profile. Biochar was applied at 0, 5, 10, and 20 t ha^-1 (expressed as Control, BC5, BC10, and BC20, respectively) for each cotton season, with identical doses of chemical fertilizers. Biochar enhanced the cotton lint yield by 8.0–15.8%, 9.3–13.9%, and 9.2–21.9% in 2013, 2014, and 2015, respectively, and high levels of biochar application achieved high cotton yields each year. Leaching of soil nitrate was reduced, while the pH values, soil organic carbon, total nitrogen (N), and available K content of the 0–20 cm soil layer were increased in 2014 and 2015. However, the changes in the soil available P content were less substantial. This study suggests that successive biochar amendments have the potential to enhance cotton productivity and soil fertility while reducing nitrate leaching.