Study On The Degradation Of Rhodamine B By Electrochemical Synergistic Bentonite@Fe₃O₄ Activated Persulfate

The high concentration of pollutants in dye wastewater,high chroma,complex components,and high toxicity will cause serious pollution to the water environment.In order to improve the dye wastewater treatment capacity and deeply degrade the pollutants in the dye wastewater,it was urgent to develop new dye wastewater treatment technologies.The refractory dye Rhodamine B（RhB）was taken by this article as the research object,and the electrochemical synergistic heterogeneous catalyst bentonite@Fe₃O₄ to co-activate persulfate（PS）was used for the advanced treatment of RhB.The high-efficiency catalytic performance of bentonite@Fe₃O₄ was mainly investigated,and the synergistic catalytic effect of electrochemical and heterogeneous catalyst bentonite@Fe₃O₄ was explored.The specific research content and corresponding results was as follows:（1）The experimental effect of the homogeneous degradation of RhB in the Fe²⁺/PS system was explored,and the optimal reaction conditions were obtained:the p H value was 3,the concentration of PS was 0.3g/L,and the concentration of Fe SO₄·7H₂O was 0.15g/L.After the Fe²⁺/PS system was reacted for 60 minutes under the optimal reaction conditions,the removal rate of RhB was 82.08%,but the removal rate of TOC was only 37.25%.The degree of mineralization of RhB dye wastewater was relatively low.（2）Heterogeneous catalyst bentonite@Fe₃O₄ was prepared and characterized by SEM,EDS,XRD,XPS and other characterization methods.The results showed that Fe₃O₄ nanoparticles were successfully loaded on bentonite,possessing a large specific surface area,abundant active sites,and avoiding the agglomeration of Fe₃O₄nanoparticles.（3）The single factor experiment of degrading RhB in bentonite@Fe₃O₄/PS system gave the best reaction conditions as follows:without adjusting the initial p H of the reaction solution,the dosage of bentonite@Fe₃O₄ was 1.5g/L,and the concentration of PS was 1g/L.Under the optimal reaction conditions,the bentonite@Fe₃O₄/PS system only had 3.33mg/L total iron ions dissolved,which accounted for 0.83%of the iron content in the added catalyst,indicating that the new catalyst had good stability.The effect of 5 regular inorganic salt anions on the degradation of RhB in bentonite@Fe₃O₄/PS system was explored.Among them,CO₃^2-and HCO₃^-had the strongest inhibitory effect on the degradation of RhB in the bentonite@Fe₃O₄/PS system,SO₄^2-had weak inhibitory effect,and NO₃^-and Cl^-had no inhibitory effect.（4）The main mechanism of the degradation of RhB in the bentonite@Fe₃O₄/PS system was explored.Free radical quenching experiments showed that SO₄^·-and·OH were the main active products of bentonite@Fe₃O₄/PS system.The reaction mechanism of bentonite@Fe₃O₄/PS system to degrade RhB was mainly as follows:adsorption of bentonite@Fe₃O₄,activation of PS by Fe（Ⅱ）and a small amount of Fe²⁺on the catalyst surface,self-decomposition of PS,and the reaction of SO₄^·-conversion to·OH.（5）The effect of electrochemical synergistic bentonite@Fe₃O₄/PS system on the degradation of RhB was explored.The electrochemical synergistic bentonite@Fe₃O₄/PS system had a RhB removal rate of 93.06%and a TOC removal rate of86.54%,compared to the bentonite@Fe₃O₄/PS system with 85.11%RhB removal rate and 77.67%TOC removal rate.The efficiency was significantly improved.