Construction Of Bio-fenton System And Study On Degradation Of Rhodamine B

With the increasing discharge of industrial wastewater,the treatment of high concentration refractory organic wastewater has become a recognized problem at home and abroad.Fenton oxidation technology is widely used in the treatment of various refractory organic wastewater due to its features of green economy and strong oxidation ability.In this paper,Fenton oxidation technology and enzymatic reaction are combined to form a bio-Fenton system.The optimal reaction conditions of Fenton reaction and enzymatic reaction are studied respectively,and then the hydrogen peroxide?H₂O₂?generated in situ by the enzymatic reaction is used.Add a certain concentration of Fe²⁺solution to build a bio-Fenton system to degrade the self-made simulated wastewater Rhodamine B.In the process of bio-Fenton degradation of organic matter,H₂O₂ is produced continuously,which reduces the transportation and storage risks of H₂O₂,thereby reducing the chance of accidents.The production of H₂O₂ through an enzymatic reaction is a sustainable method,with low power consumption and the ability to generate hydrogen peroxide in situ,and compared with the traditional Fenton,the bio-Fenton method can be applied in a larger pH range.At the same time,bio-Fenton system also faces challenges,such as whether the enzyme activity can maintain high stability under various reaction conditions in the degradation process.In this paper,through the study of the factors affecting Fenton oxidation technology and enzymatic reaction,the following conclusions are obtained:?1?In the chemical Fenton reaction,it was determined through single-factor experimental research that the degradation rate of 50 mg/L RhB solution after adding H₂O₂ and Fe²⁺increased rapidly,and the degradation rate tended to be stable after 10 minutes.As the concentration increases,the degradation rate gradually decreases;Fenton reaction is more sensitive to pH,and overacid or overbase will make the degradation effect worse.At pH=3,the degradation rate of 50 mg/L RhB and the removal rate of TOC is the best,the degradation rate can reach more than 90%,and the TOC removal rate can reach 21.8%.The concentration of H2O2 in the Fenton reaction is directly related to the generation of hydroxyl radicals??OH?.When the concentration of H2O2 is 5 mmol/L,the degradation effect reaches the best,the degradation rate reaches 90%and the TOC removal rate reaches 23.2%,continue to increase the concentration of H2O2,the degradation rate of RhB and TOC removal rate both decreased slightly,so the optimal H2O2 concentration for degrading 50 mg/L RhB is 5 mmol/L;[Fe²⁺]:[H₂O₂]=1:5,the degradation rate and mineralization effect of RhB are the best,the degradation rate can reach 94.75%,and the TOC removal rate reaches 30%.?2?During the enzymatic reaction,the output of H2O2 is greatly affected by the reaction time,substrate concentration,pH,and temperature.After the enzymatic reaction is carried out for 120 minutes,the H2O2 concentration in the system tends to be stable.Under the reaction time of 120 minutes,the optimal conditions for the enzymatic reaction of glucose solution to produce H2O2 at the pH of 6 and the temperature of 40°C.After 120 minutes of reaction,the concentration of hydrogen peroxide in the system can reach 0.6792 mmol/L;Based on the relationship between the enzymatic reaction rate and glucose concentration,the Michaelis constant of glucose oxidase was calculated to be 0.2660 by double reciprocal mapping.?3?Using the H2O2 produced by the enzymatic reaction,adding a certain concentration of Fe2+solution to build a bio-Fenton system:It was found that the degradation rate of RhB gradually decreased with the increase of the initial RhB concentration.When the RhB concentration was 5 mg/L,10 mg/L,20 mg/L,40 mg/L,the degradation rate decreased from87.03%to 57.76%;after increasing the glucose concentration,the degradation rate of RhB increased significantly.When the glucose solution reached 4 g/L,the degradation rate reached more than 99%after 60 minutes of reaction.First-order kinetics were fitted to the degradation data of the reaction within 0 to 90 minutes,and the degradation process was found to conform to pseudo-first-order kinetics.In the model,the rate constant K₁ is the largest when the glucose concentration is 4 g/L,which is 0.06091 min^-1,which is consistent with the degradation process.The rate constants corresponding to each glucose concentration?1 g/L,2 g/L,3 g/L,4 g/L,5g/L?are 0.0094 min^-1,0.0140 min^-1,0.0203 min^-1,0.0609 min^-1,0.0501 min^-1.The optimal pH for reaction degradation of RhB is 4,when the pH is 3 to 6,the degradation process is more in line with the pseudo-first-order kinetic model,and the corresponding rate constants K₁ are0.0623 min^-1,0.0643 min^-1,0.0410 min^-1,0.0327 min^-1;As the temperature rises,more hydrogen peroxide is produced due to the increased enzyme activity of glucose oxidase,and finally the degradation rate of RhB at 20 mg/L can reach more than 99%,but at the temperature of 45?,RhB The degradation rate is less than 90%.It should be noted that a high temperature for a period of time will cause the loss of enzyme activity.At the same time,the optimal temperature of the reaction can be considered as 40?.