| More and more attention has been paid to the water environment problems caused by emerging pollutants.These pollutants are characterized by low concentrations(usually at the level of ?g/L)and are difficult to biodegrade.Heterogeneous Fenton catalytic oxidation is a water treatment technology that can effectively remove emerging pollutants in water,and has been widely concerned and studied by scholars at home and abroad in recent years.However,the heterogeneous Fenton catalytic technology still has practical problems such as narrow pH range,large ion loss,and low catalytic performance.Therefore,it is necessary to develop more efficient heterogeneous Fenton catalyst to improve these aspects.In this paper,the sol-gel method was used to prepare the Fe/Cu/zeolite heterogeneous Fenton catalyst.Carbamazepine and benzotriazole were selected as the target pollutants,and the catalytic degradation performance of heterogeneous Fenton catalytic system at neutral pH for the two pollutants was investigated.The stability of the catalyst and the catalytic degradation mechanism were analyzed.Firstly,the preparation conditions of the catalyst were optimized.By setting the mass ratio of Fe and Cu bimetals to 1:1,the mass ratio of metals to zeolites to 2:1,and the anaerobic calcination temperature to 900?,the obtained heterogeneous catalysts had the best performance.Characterization results by scanning electron microscope(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)showed that the effective metal oxides in Fe/Cu/zeolite heterogeneous Fenton catalyst could be arranged regularly and stably.The catalyst had less impurities and better crystallinity.Its main components were Fe3O4,Fe2O3 and CuO.The two active metal elements Fe and Cu accounted for 33.92%and 26.91%of the total mass of the main elements of the catalyst,respectively.Secondly,taking 2 mg/L carbamazepine and benzotriazole solution as the research object,the influence of reaction conditions on its degradation effect was investigated.The results show that the heterogeneous catalyst can effectively catalyze the degradation of carbamazepine and benzotriazole.When the initial pH of the solution was 7,the reaction temperature was 25?,the catalyst dosage was 0.5 g/L,and the H2O2 concentration was 0.10 mol/L,the catalyst could almost completely degrade carbamazepine in 3 hours.Optimization of the catalytic degradation experiment of benzotriazole by response surface methodology showed that at a neutral pH,when the reaction temperature was 25?,the H2O2 concentration was 0.08 mol/L,the catalyst dosage was 0.41 g/L,and the reaction time was 43.6 min,Fe/Cu/zeolite could effectively catalyze the degradation of benzotriazole with a removal rate of 99%.Then,repeated recovery experiments showed that when the catalyst material was reused 8 times,the removal rate of carbamazepine can still be stabilized above 95%,indicating that the material had good s reuse performance.By measuring the dissolution of metal ions,it was found that the dissolution of iron ions accounted for 0.1%of the total iron content in the catalyst,and copper ions accounted for 3.2%.The dissolution control of copper ions is the focus of future research.Overall,the catalyst prepared in this study has good stability.Finally,the catalytic mechanism of Fe/Cu/zeolite heterogeneous Fenton catalyst was explored.The result shows that Fe and Cu act as active sites of the catalyst,combine with H2O2 in the solution on the surface of the catalyst,react and produce strong oxidizing radicals such as 'OH and 'HO2,and oxidatively decompose organic pollutants in water.At the same time,Cu+reduces Fe3+to Fe2+,promotes the regeneration of Fe2+,and accelerates the redox cycle of Fe3+/Fe2+and Cu2+/Cu+.In addition,the unique structure of the zeolite increases the dispersion of the material,enabling the material surface to evenly distribute more active sites.Organic pollutants can be accelerated to decompose under the efficient catalysis of heterogeneous catalysts. |
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