Li Shuilian,Zhang Lishan,Zhong Shan,Zhu Jiayan,Wei Zengxian
View large Download slide View large Download slide Close modal This study reports the preparation of granular ternary micro-electrolysis materials and their effectiveness in removing the emerging contaminant PFOA. Al/nZVI/C@F granules were synthesized using a liquid-phase reduction method combined with high-temperature calcination. By comparing the removal of methylene blue dye by granules, the optimum preparation conditions were determined as follows: Fe:C = 5:1, fly ash = 50%, calcination temperature = 800 °C, and holding time = 1 h. Static batch experiments revealed that under optimal conditions (PFOA concentration = 25 mg/L, solid–liquid ratio = 30 g/L, pH = 3, reaction temperature = 15 °C), Al/nZVI/C@F achieved a PFOA removal rate of 97.83%. The removal efficiency of Al/nZVI/C@F (93.90%) was significantly higher than that of commercial iron-carbon (12.75%). After 45 days of dynamic column experiments, the removal efficiency of nZVI/C@F and Al/nZVI/C@F for PFOA (50 mg/L) remained above 60%, demonstrating strong practical application potential. Further adsorption–desorption experiments revealed that nZVI/C@F and Al/nZVI/C@F primarily removed 50 mg/L PFOA through adsorption. For a lower PFOA concentration of 0.5 mg/L, the defluorination rates were 53.2% for nZVI/C@F and 68.9% for Al/nZVI/C@F. High-performance liquid chromatography-tandem mass spectrometry was used to analyze the intermediates formed during PFOA removal, leading to a proposed degradation pathway. Developed Al/nZVI/C via liquid-phase reduction and high-temperature calcination. Proven efficacy in PFOA removal from water using fly ash-Al/nZVI/C@F granules. Identified adsorption as the primary mechanism for over 50% PFOA removal. Degradation of PFOA to form short-chain fluorinated intermediates. The materials hold promise for PFOA removal in water treatment applications.
PFOA has caused enormous environmental risks with recalcitrance, toxicity, and bioaccumulation, while the degradation of PFOA is still a challenging topic related to the high energy of C F bonds. However, the conventional methods such as biological oxidation, electrochemical oxidation and membrane separation have their own drawbacks. Actually, adsorption-photocatalysis is considered a potential treatment due to effectiveness and thoroughness. Instead of preparing the composite material by adding TiO 2 , the method to in-situ grow TiO 2 in the MOF (MIL-125(Ti)) was carried out, which achieved narrowed band gap and improved the photoresponse ability, simultaneously. Furthermore, the surface F-functionalized MOF provided more available special adsorption sites for PFOA enrichment. Linked fluorine groups not only improved the adsorption capacity (185.151 μmol/g) but also enhanced the photocatalytic rate (1.221 E −4 /s) by altering the electronic density of VB and CB. The constructed F-TiO 2 @MIL-125 stepwise degraded PFOA through a dominant ·OH attack pathway and maintained the oxidize ability of h + to PFOA. As a bifunctional material for adsorption and photocatalysis , F-TiO 2 @MIL-125 was able to be applied in various water environments repeatedly, which has unlimited environmental application potential.
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