Degradation Of Antibiotics In Water By WS₂/Bernalite Heterogeneous Fenton-like System

Fluoroquinolones(FQs)are one of the most commonly used antibiotics in the world to treat a variety of bacterial infections in humans.Due to the wide use of FQs,it often appears in the water environment detection,and the residual drugs in the water will cause many adverse effects on human health.Therefore,it is urgent to find a feasible technology to effectively remove refractory FQs.Fenton reaction(Fenton)in advanced oxidation technology is an effective method to remove FQs from water.Compared with traditional homogeneous Fenton,heterogeneous Fenton has a wider p H range and can avoid the generation of large amounts of sludge.Therefore,it has received more and more attention in wastewater treatment.For heterogeneous Fenton reaction of Fe(II)/Fe(III)redox cycle is relatively slow and H₂O₂ decomposition efficiency is low,low the number of·OH,deal with the issue of FQs effect is not ideal,considering metal sulfide as cocatalyst can greatly accelerate the heterogeneous Fenton reaction of Fe(II)/Fe(III)the redox cycle,this article first synthesized by the precipitation method were used respectively to iron base materials burr mines(Bernalite,Bn)and tungsten disulfide was synthesized by hydrothermal method(WS₂),a composite of both together,A heterogeneous Fenton catalyst of WS₂/Bn was successfully synthesized.A series of studies were carried out on the removal of levofloxacin(LEV)from FQs in water under the condition of non-light and visible light respectively.The specific results are as follows:Firstly,WS₂ and Bn were prepared by precipitation method and hydrothermal method respectively.Then,WS₂/Bn heterogeneous Fenton catalyst was obtained by combining the two together by blending method.The heterogeneous Fenton catalyst of WS₂/Bn prepared was characterized by SEM,XRD,etc.It was verified that WS₂ and Bn were successfully combined together.XPS characterization showed that the valence states of the main elements in WS₂/Bn were Fe³⁺,W⁴⁺,S^2-.The effect of heterogeneous Fenton catalyst of WS₂/Bn on LEV removal was investigated under different conditions.The optimal removal conditions were as follows:WS₂/Bn-5,H₂O₂ dosage of 20 m M,catalyst dosage of 0.5 g/L,and p H value of 5.0.Under these conditions,the apparent rate constant(Kobs)of LEV removal was 3.79 times that of homogeneous Fenton.The effects of three different FQs antibiotics and common anions(Cl^—,NO₃^—,CO₃^2—and HPO₄^2—)on the catalytic performance of WS₂/Bn were further investigated.The catalyst still maintained a high catalytic activity after five consecutive cycles of degradation.·OH plays a major role in heterogeneous Fenton system of WS₂/Bn by free radical quenching experiments.·O₂^—and ¹O₂ are auxiliary components in the reaction process.In order to reduce the dosage of H₂O₂,visible light was introduced to construct WS₂/Bn photoassisted heterogeneous Fenton system.The light absorption performance of WS₂/Bn catalyst was verified by means of DRS and other characterization methods.The photocatalytic performance of WS₂/Bn catalyst was studied by LEV degradation experiment.In the single photocatalytic system,about 43.6%of LEV can be removed,and LEV can be effectively removed in a wide p H range.Under the photoassisted heterogeneous Fenton system,the optimal dosage of H₂O₂ can be reduced to 1/10 of that of the heterogeneous Fenton system,and 88.3%of LEV can be removed,which greatly saves the cost.The effects of three different FQs antibiotics and common anions(Cl^—,NO₃^—,CO₃^2—and HPO₄^2—)on the catalytic performance of the photoassisted heterogeneous Fenton system of WS₂/Bn were further investigated.The catalytic activity of WS₂/Bn catalyst remained high after five consecutive cycles of degradation.·OH plays a major role in the WS₂/Bn photoassisted heterogeneous Fenton system,and h⁺,·O₂^—and ¹O₂ are auxiliary components in the reaction process,according to free radical quenching experiments.With the introduction of visible light,electron hole pairs are generated on the surface of WS₂/Bn,which enhances the redox ability of WS₂/Bn catalyst.Finally,a dynamic reactor with photoassisted heterogeneous Fenton catalyst was established to degrade FQs wastewater.Catalytic tests were carried out on LEV in 20mg/L FQs wastewater by adding WS₂/Bn heterogeneous Fenton catalyst.After the dynamic reactor was stabilized,the removal rate of LEV was still up to 84%.