The Synergistic Effect Of Cathode And Anode-generated Persulfate On 4-Bromophenol Degradation

In recent years,advanced oxidation technology based on the sulphate radicals has been widely researched.Sulphate radical can be generated by persulfate activation.This thesis aimed to explore the feasibility and the influence factorsof persulfate and the target pollutant degradation with generated persulfate in an electrochemical system.This thesis studied the processes of persulfate generation in electrochemical system.The results show that the divided system could take advantage of anode to generate persulfate.On the other hand,the effect of persulfate generation withammonium sulfate as electrolyte is better than that of sodium sulfate as electrolyte.In the experiment,put the sample as stewing which avoids light and aerating for 20min for eliminating the possibility of ozone generation.It is almost no persulfate generation in direct electrolysis of ammonium sulfate,and persulfate productivity and current efficiency increase in adding additives such as ammonium thiocyanate to improve the overpotential of oxygen generating.In the range of 0.1⁰.3g/L of ammonium thiocyanate,the production of persulfate and the current efficiency increase with the concentration of ammonium thiocyanate,while they increase little above this range.The productivity of persulfate increases with the current density in the range of study,while the variation of current efficiency is not the same as the persulfate productivity.The current efficiency of persulfate generation increases with current density in the range of 0.1A/cm² to 0.4A/cm²,while it is keeps constant above 0.4A/cm².Both the persulfate production and the current efficiency increase with the concentration of ammonium sulfate.The reason why to chose the range of ammonium sulfate concentration which belows 1M is the restriction of solubility.Aims to explore the feasibility and the influence factorsof degradating4-Bromophenol（4-BP）with generated persulfate,this thesis introduced Fe³⁺to the system of generating persulfate.It is feasible to degradate 4-BP with generated persulfate.Fe³⁺could be translated to Fe²⁺by cathode.Persulfate could be active by Fe²⁺to from SO₄^·-,which improving removal efficiency of 4-BP and TOC.The removal of 4-BP and TOC and the degradation rate are increased by current density and the concentration of Fe³⁺.With the increasing of current density it leads to adverse events such as hydrogen evolution reaction which wastes energy.The generated Fe²⁺could react with SO₄^·-when the concentration of Fe³⁺is too high.The initial concentration of 4-BP also has effect on its degradation.4-BP could be completely removed when the initial concentration of 4-BP is below 0.5mM.The rate of 4-BP degradation is decreased by the initial concentration of4-BP,while the persulfate decomposition and the TOC removal are not affected.