Electrochemical Reaction Process Enhanced By High Gravity Technology And Applied To The Treatment Of Phenol Wastewater

Because of processing condition of electrochemical method is mild and clean,it has been applied in wastewater treatment.But the problems are "bubble effect" and "mass transfer limited",that lead to increase of energy consumption and be limitated of widely application.High gravity technology using in the electrochemical reaction process can eliminate bubble effect and strengthen mass transfer.So a novel high gravity electrochemical reactor with multi-concentric cylindrical electrodes was developed and used in the treatment of phenol wastewater by electrochemical method in this paper in order to eliminate bubble effect and strengthen mass transfer,and then improve the processing efficiency and reduce the energy consumption.Related research was studied theoretically and experimentally.There was no related research report.The studies of this paper have important practical significance.Analyzed the photos of the bubbles gathering on the electrode surface,gathering on the reactor cover,scattering in the wastewater and the color changing of wastewater on both sides of the electrode,it showed that high gravity technology weakened the "bubble effect" because of accelerating the bubbles from the electrode surface and electrolyte and strengthened the mass transfer process.The reasons were analyzed from the formation and the trajectory of bubbles.Strring technology strengthened the mass transfer process limited because it could not eliminate "bubble effect" and accelerated the diffusion of ions to a certain extent.The paper studied the phenol wastewater treatment by electrolysis method in high gravity field.Research showed that the high gravity factor was the main influence factor.Under the appropriate operating conditions and on the same processing time,the phenol removal efficiency was high in the high gravity field,and reached up to about 46.2%,which was about 2.2 times the value achieved in the normal gravity field,and the wastewater counld be biochemical treated.It showed that high gravity technology counld shorten electrolysis time,improve the effect and biodegradability of treated wastewater.The chemical reaction kinetics study showed that the electrochemical degradation in both high gravity field and normal gravity field accorded with the apparent first-order kinetics law.The reaction rate constant obtained from electrochemical degradation in high gravity field was more than it obtained from electrochemical degradation in normal gravity field.The energy of activation obtained from electrochemical degradation in high gravity field is very small,which is less than it obtained from electrochemical degradation in normal gravity field.It indicated that high gravity technology used in electrochemical treatment of phenol wastewater counld accelerate the degradation rate and improve the degradation effect.Through the analysis of UV-VIS and HPLC of phenol wastewater,it educed the degradation process:phenol → hydroquinone and pyrocatechol → p-quinone → maleic acid → ethanediol → carbon dioxide and water.Cyclic voltammetry studies showed that the oxygen evolution and anode dissolution reaction counld lower the efficiency of wastewater treatment.High gravity technology can just improve it.In order to the further improve the efficiency,phenol wastewater treatment by Electro-Fenton method in high gravity field was studied.Research showed that the high gravity factor was one of the main influence factors.Under the appropriate operating conditions,the removal efficiency of phenol and COD were 92.2%and 80.4%of phenol waserwater treated by Electro-Fenton method in high gravity field,which were high respectively than 79.7%and 71.2%obtained in normal gravity field.Although wastewater treated by both of them counld be biochemical treated,the removal efficiency in high gravity field was higher than that in normal gravity field.Through the analysis of UV-VIS and HPLC of phenol wastewater,it inferred the degradation process:phenol →hydroquinone→ p-quinone → maleic acid → carbon dioxide and water.The process of phenol wastewater treatment by Electro-Fenton method in high and normal gravity field produced less intermediate and chieved high removal efficiency compared to that produced by electrolysis in high and normal gravity field.Especially EF-Feox method was the most efficient in phenol wastewater treatment.The economic analysis indicated that the cost of phenol wastewater treatment by EF-Feox method in high gravity field was lower than any other method under the condition of the same phenol removal efficiency.Low cost was due to short processing time,low energy consumption and less reagent.Therefore,appling high gravity technology to electrolysis and Eletro-Fenton reaction process can shorten the reaction time,improve the treatment effect,reduce the energy consumption and save the dosage of reagent.High gravity electrochemical method is a high efficency and save energy method of wastewater treatment.It will have broad application prospects.