Optimization of heterogeneous Fenton-like process with Cu-Fe@CTS as catalyst for degradation of organic matter in leachate concentrate and degradation mechanism research

The heterogeneous Fenton-like process with bimetallic chelated magnetic chitosan aerogel (Cu-Fe@CTS) as catalyst was applied to treat pre-coagulated leachate nanofiltration concentrate. The process conditions were optimized by Box-Behnken Design (BBD) and the maximum UV254 removal reached 96.06% under the conditions of temperature 87.62 degrees C, oxidant dosage 0.2395 mol/L and catalyst dosage 1 g/L. The TOC concentration was reduced from 847.5 to 99.7 mg/L and COD concentration was reduced from 1625 to 464 mg/L. The threedimensional (3D) fluorescence analysis showed that most of Fulvic acid-like (FA-like) was removed. The adsorption experiment showed that the catalyst reached the adsorption balanced after 60 min and the corresponding FA adsorption removal reached 14.1%. The addition of Tert-butanol (TBA) reduced the FA removal by 59.4%, indicating that the hydroxyl radicals (center dot OH) was the main active species. Experiments of the center dot OH capture at different pH showed that the Fenton-like system produced more center dot OH at pH of 4, at which the maximum FA removal was 96.61%, while the FA removal still reached 94.26% at pH of 7. The center dot OH capture at different temperature showed that the Fenton-like system produced more center dot OH at 90 degrees C. KI and TBA shielding experiments showed that center dot OH was produced on the catalyst surface rather than being produced by catalysis of free metal ions in the solution.

Automated summary

In this study, the heterogeneous Fenton-like process using Cu-Fe@CTS as catalyst was applied to treat pre-coagulated leachate nanofiltration concentrate, achieving high removal efficiency of organic compounds. The results showed that the catalyst effectively removed Fulvic acid-like substances in water, with hydroxyl radicals (•OH) as the main active species.