Wang Tongshuai, Wu Jingqi, Hu Tao, Wang Congcong, Li Shijia, Li Zhixiong, Chen Jiawei
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China; China Household Electric Appliance Research Institute (CHEARI), Beijing 100053, PR China.
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, PR China.
Sci Total Environ. 2024 Dec 20;957:177668. doi: 10.1016/j.scitotenv.2024.177668. Epub 2024 Nov 23.
Adsorptive removal of the emerging organic pollutant perfluorooctanoic acid (PFOA) from contaminated water using biochar is a promising cost-effective approach. To determine the stability of PFOA adsorption on biochar, the thermodynamic analysis of the adsorption-desorption behavior is essential. This study comprehensively investigated the adsorption and desorption of PFOA on biochars derived from maple sawdust, peanut shells and corn stalks, pyrolyzed at peak temperatures of 400, 600 and 800 °C. The findings indicated that the micropore volume of the biochars was key to PFOA adsorption, with peanut shell biochar produced at 800 °C showing the highest adsorption capacity of 16.75 mg/g, attributed to its larger micropore volume (0.22 m/g). Thermodynamic analysis showed that the negative values of ∆G of PFOA adsorption ranged from -2.24 to -5.38 kJ/mol, confirmed that the process was spontaneous and involved physical pore-filling. However, the close similarity between the adsorption and desorption isotherms, coupled with a low hysteresis coefficient, clarified that the PFOA adsorption was unstable and prone to desorption. The thermodynamic insights from this study highlighted that lignin-rich biochar produced at high temperature with high micropore content was very favorable for the effective adsorptive removal of PFOA, while the long-term adsorption stability should not be overlooked in the remediation applications.
利用生物炭从受污染水中吸附去除新兴有机污染物全氟辛酸（PFOA）是一种很有前景的经济有效方法。为了确定PFOA在生物炭上吸附的稳定性，对吸附-解吸行为进行热力学分析至关重要。本研究全面考察了在400、600和800℃峰值温度下热解得到的枫木锯末、花生壳和玉米秸秆生物炭对PFOA的吸附和解吸情况。研究结果表明，生物炭的微孔体积是PFOA吸附的关键，800℃下制备的花生壳生物炭吸附容量最高，为16.75mg/g，这归因于其较大的微孔体积（0.22m/g）。热力学分析表明，PFOA吸附的∆G负值范围为-2.24至-5.38kJ/mol，证实该过程是自发的，涉及物理孔隙填充。然而，吸附和解吸等温线非常相似，且滞后系数较低，这表明PFOA吸附不稳定，容易解吸。本研究的热力学见解突出表明，高温制备的富含木质素且微孔含量高的生物炭对有效吸附去除PFOA非常有利，而在修复应用中不应忽视长期吸附稳定性。
