Study On MoS₂/Bernalite Heterogeneous Fenton-like Catalyst For Degradation Of Printing And Dyeing Wastewater

In recent years,printing and dyeing wastewater has been considered to be one of the most polluted industrial wastewater,the dye in the wastewater even if the concentration is very low,but also may be toxic,carcinogenic,mutagenesis or teratogenic,therefore,the treatment of printing and dyeing wastewater is of great significance.The heterogeneous Fenton system has attracted more and more attention in the treatment of printing and dyeing wastewater,but the Fe(?)/Fe(?)REDOX cycle in the heterogeneous Fenton reaction is still slow,and the use of metal sulfide as a co-catalyst can greatly accelerate the Fe(?)/Fe(?)REDOX cycle and promote the production of ·OH.The utilization rate of H2O2 was significantly improved.In this paper,the iron-based Bernalite(Bn)and MoS2 were synthesized by precipitation method and hydrothermal method respectively.Then,a MoS2/Bn heterogeneous Fenton catalyst for decolorization of printing and dyeing wastewater was successfully synthesized by blending the two materials together.On this basis,in order to reduce the dosage of H2O2,the photocatalytic synergistic MoS2/Bn heterogeneous Fenton catalysis system was constructed by introducing visible lightFirstly,MoS2/Bn heterogeneous Fenton catalyst was synthesized.The structure and morphology of MoS2/Bn were studied by XRD,XPS,SEM and other characterization methods.The lamellar MoS2 and block BN were successfully combined together with surface elements of Fe,Mo,S,O,etc.The decolorization performance of simulated printing and dyeing wastewater by MoS2/Bn-4 heterogeneous Fenton catalyst was studied.At room temperature,MoS2/Bn-4 heterogeneous Fenton catalyst system can remove more than 97%of the dye in simulated printing and dyeing wastewater within 30 min,and can effectively decolorize simulated printing and dyeing wastewater in the pH range of 3-10.The catalytic activity was still high after five successive cycles of degradation.The optimum conditions of decolorization were as follows:concentration of H2O2 is 100mmol/L,dosage of catalyst is lg/L,pH value is 6.0.The influence of the presence of anions on the decolorization rate was investigated.It was found that Cl-and NO3-had little effect on the decolorization rate,while CO32-and PO43-had certain inhibitory effect on the decolorization rate.In addition,the free radical quenching experiments confirmed that ·OH plays a major role in heterogeneous Fenton catalysis system,while superoxide radical(·O2-)and singlet oxygen(1O2)play a secondary roleIn order to reduce the amount of H2O2,the photocatalytic synergistic MoS2/Bn-4 heterogeneous Fenton catalytic system was constructed,and the photocatalytic technology and heterogeneous Fenton process were combined to decolorize the printing and dyeing wastewater.Its light absorption characteristics were studied by means of DRS and other characterization methods.MoS2/Bn-4 showed strong light absorption in the visible region.Through the study of decolorization of simulated printing and dyeing wastewater,a single photocatalytic system can remove about 50%of the dye in the simulated printing and dyeing wastewater within 30 minutes,and it can effectively decolorize the simulated printing and dyeing wastewater in the pH range of 3-10,and it can maintain a high catalytic activity after continuous 5 cycles of degradation.Compared with the MoS2/Bn-4 heterogeneous Fenton catalytic system,when the photocatalytic synergistic MoS2/Bn-4 heterogeneous Fenton catalytic system is constructed,the dosage of H2O2 can be reduced to 1/10 of the original,and more than 98%of the dyes in the simulated printing and dyeing wastewater can be removed within 30 min,which saves the cost of H2O2.At the same time,CO32-and PO43-inhibited decolorization.The reaction mechanism of photocatalysis synergistic MoS2/Bn heterogeneous Fenton catalysis system is proposed.The introduction of visible light not only accelerates the cycle between Fe(?)and Fe(?)again,but also produces more holes(h+)to degrade the dye.In the process of photocatalytic degradation of simulated printing and dyeing wastewater by MoS2/Bn inhomogeneous Fenton,the effects of active radicals are ·OH>h+>1O2>·O2-.A dynamic reactor for decolorization of printing and dyeing wastewater was established.The removal rate of dyes from simulated printing and dyeing wastewater reached 97%after 170 minutes of dynamic cycling under photocatalysis coupled with heterogeneous Fenton system.