Fengxia An,Guangyan Wang,Shuyun Wang,Huan Chen,Jingliang Liu
Perfluorooctanoic acid (PFOA) and 2,4,6-trichlorophenol (2,4,6-TCP) were typical POPs (Persistent Organic Pollutants) in water. In this study, fluorine-doped covalent triazine framework (F-CTF) was synthesized using an ionothermal method, and the adsorption behavior for PFOA and 2,4,6-TCP on F-CTF was investigated using batch experiments and adsorption kinetic tests. Characterization results showed that the large surface area and abundant pore structure of F-CTF provide a large number of adsorption sites for PFOA and 2, 4, 6-TCP. Batch adsorption tests showed that F-CTF adsorbent exhibited high adsorption affinity to PFOA and 2,4,6-TCP, and the adsorption ability could be described well by the Langmuir adsorption model. The maximum adsorption capacity ( q max ) of F-CTF for PFOA and 2,4,6-TCP reached 262.5 mg/g and 709.2 mg/g, respectively. The adsorption process obeyed the pseudo-second-order kinetics. The adsorption mechanism including electrostatic attraction, hydrophobic interaction, and ion-dipole interaction was further confirmed by pH and ionic strength experiments. Additionally, the UV/Na 2 SO 3 /KI system achieved 100 % degradation rate of PFOA and 2, 4, 6-TCP within 40 minutes and the influence factors were further studied. The e aq − was the main active species for the high reduction of PFOA and 2,4,6-TCP in the UV/Na 2 SO 3 /KI system.
Pollution caused by per - and polyfluoroalkyl substances (PFASs) has raised global health concerns and there is an urgent need for researchers to find effective treatment methods. The covalent triazine framework (CTF) adsorbent materials with different structures based on various precursors using the ionothermal method were prepared and characterized in this study. Among them, F-doped CTF (F-CTF) is favorable for effective mass transfer in the adsorption process due to its rich microporous structure and large specific surface area. The maximum adsorption capacity (q max ) for PFOA reached 769.2 mg/g under the synergistic effect of electrostatic force and the interaction of F F. After six cycles of adsorption-desorption experiments, the adsorption and desorption rates of the F-CTF 400°C were stable at >90 %. This result indicates that F-CTF 400°C possesses high stability and recyclability. Furthermore, the desorption solution containing a high concentration of PFOA was treated directly by a UV/Na 2 SO 3 system, utilizing the e aq − within the system to decompose PFOA. The reduction and defluorination efficiencies for the desorption solution with high concentrations of PFOA reached 90 % and 40 %, respectively. The study results indicate that by leveraging the high adsorption selectivity and stable recoverability of F-CTF 400°C , the UV/Na 2 SO 3 system can completely remove PFOA. This approach offers a novel solution for the elimination of PFOA pollution in the environment.
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