Research On GAC Enhanced O₃/PMS Treatment Of Rhodamine B Dye Wastewater

With the vigorous development of industry,pollution will follow,and the pollution of dye wastewater is one of the content that is very worthy of attention.Due to the application of new technologies and new processes in the production and use of dyes,dye wastewater has become more and more difficult to treat,and it is difficult for traditional treatment techniques to achieve good results.In this context,advanced oxidation technology based on persulfate has become an emerging research hotspot,and has gradually been applied to the field of dye wastewater.The current mainstream activation methods mainly have the following shortcomings:1.Low energy utilization and high energy consumption when activated by introducing external energy;2.High cost and difficult recovery of metal ions when using transition metal ions for activation,which will cause secondary pollution.In addition,SO4-·although it has strong oxidizing ability,it has a certain selectivity,and the treatment effect of some dyes is not ideal.This article aims to explore a new feasible scheme for the treatment of dye wastewater,and conduct preliminary verification of its practical application.In the experiment,the degradation rate of RhB and COD in the wastewater were used as observation indicators.Through single factor experiments,the effects of each reaction condition on the degradation of RhB dye wastewater in the O3/PMS system and the GAC enhanced O3/PMS system were investigated.The response surface method was used to react The optimization of the conditions and the kinetic analysis and mechanism analysis of the reaction provide a theoretical basis for GAC to strengthen the application of the O3/PMS system.The main results of the experiment are as follows:By comparing with O3 alone and PMS system alone,it is proved that the O3/PMS system has effective synergy.Single factor experiments show that the increase of O3 ventilation,PMS concentration,initial pH value and temperature of the solution can all enhance the effect of the O3/PMS system in treating RhB simulated dye wastewater.When the O3 ventilation is 7.5mg/min,the PMS concentration it is 4.8 mM,the initial pH of the solution is 10,and the temperature is 30℃ for 180 min.The degradation rate of RhB in the wastewater is 100%,and the mineralization rate is 66%.The kinetic analysis of the treatment of RhB dye wastewater by the O3/PMS system found that the reaction conforms to the quasi-first order kinetics,combined with the reaction rate and other parameters and the pHenomenon observed in the experiment,it is found that the initial pH value has a particularly prominent impact on the degradation effect of the system it is speculated that the generation efficiency of free radicals in the system is more sensitive to pH changes than other conditions.The identification of free radicals in the O3/PMS system found that the main active substances in the reaction are SO4-· and·OH.When the reaction time is 30 minutes,the contribution of the two free radicals to the degradation rate of RhB reaches 91.7%.and the contribution of the two free radicals is roughly 3:2,SO4-·the contribution is slightly larger.The investigation of common anions and organics in water found that CO32-、Cl-、HA will all have a negative impact on the treatment of RhB dye wastewater by the O3/PMS system.By comparing the GAC enhanced O3/PMS system with separate GAC and O3/PMS systems,it is found that the decolorization rate of RhB dye wastewater in the enhanced system is significantly faster,and the COD degradation rate is significantly increased.The synergy factor value calculated by the formula is greater than 1,which it shows that GAC can effectively strengthen the O3/PMS system.In the repeated use test of GAC,the mineralization rate of wastewater only dropped by 7.94%after 6 times of repeated use,which proved that GAC has good stability.In the single factor experiment,the relationship between O3 aeration rate,PMS concentration,GAC dosage,initial pH value and temperature of the solution and the treatment effect of RhB dye wastewater was investigated,and the optimal reaction conditions were roughly determined,and the reaction conditions were determined by response surface method.After optimization,the optimal reaction conditions are:O3 aeration rate of 6.15mg/min,PMS concentration of 3.72mM,GAC dosage of 8.2g/L,initial pH of the solution 10.20,and the mineralization rate of wastewater under these conditions 84.5%.The preliminary mechanism analysis of the reaction process shows that the active sites on the GAC surface can activate O3 and PMS to generate SO4-·and·OH active free radicals,and can accumulate the substances involved in the reaction in the surroundings,thereby speeding up during the degradation process of RhB molecule,the conjugated structure in RhB molecule disintegrates,the ethyl group at the nitrogen position is separated,and the benzene ring also opens.Through the observation and analysis of changes in chromaticity,COD,BOD5/COD and pH value during the treatment of actual dye wastewater by the GAC enhanced O3/PMS system,it is proved that this system can not only decolorize the dye wastewater quickly,but also efficiently degrade the water.The refractory organic matter can significantly improve the biodegradability of wastewater,which preliminarily verifies the good application prospect of the GAC-enhanced O3/PMS system in the field of dye wastewater treatment.