In this study, nano zero-valent iron (nZVI) was used as the Fe source in the Fenton reaction, and a UV-nZVI-HO system was constructed to efficiently degrade and mineralize refractory organic matter in landfill leachate. The results showed that under the optimal conditions (initial pH = 3, UV = 14 W, nZVI = 0.5 g/L, and [HO] = 30 mM), the removal efficiencies of total organic carbon, absorbance at 254 nm, and color number were 61.38%, 83.89%, and 85.79%, respectively. Control experiments show that the UV-nZVI-HO system has the highest removal rate and mineralization rate of refractory organic matter. The excellent performance of the UV-nZVI-HO system is related to a higher HO utilization rate. The HO residue in the UV-nZVI-HO system was the lowest, and the effective utilization rate of HO was as high as 98.80%. Alcohol quenching experiments and hydroxyl radical quantitative experiments showed that the dominant reactive oxygen species in the UV-nZVI-HO system was HO and the yield of HO was as high as 2007.80 μM, which was much higher than that in other systems. The results of spectra analysis showed that the low molecular weight, high fluorescence frequency organic matter, and relatively stable aromatic organic matter were significantly degraded after treatment with the UV-nZVI-HO system and the aromatic degree, humification degree, molecular weight, and molecular polymerization degree of refractory organic matter were also significantly decreased. The mechanism of the UV-nZVI-HO reaction includes homogeneous and heterogeneous Fenton reactions and adsorption and precipitation of organic matter by iron-based colloids. This study can provide theoretical and technical support for the advanced treatment of refractory organic matter in landfill leachate.
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http://dx.doi.org/10.1007/s11356-023-25756-5 | DOI Listing |
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