On The Residual Hydrogen Perxide Removing In The Low Intensity Ultrasonic Irradiation

With the development of society and economy,the production scale of the modern industry is gradually expanding.During the production process,a large number of poisonous and harmful organic pollutants that are difficult to degrade will remain in the water.Traditional methods such as physical methods,chemical methods,biological methods,etc.are difficult to meet the technical and economic requirements of the purification process.Research on wastewater treatment technology has become a hot topic.With the deepening of research,Advanced Oxidation Technology?AOPs?came into being.Advanced oxidation technology is a new type of water treatment technology that degrades organic pollutants by substances that generate strong oxidizing properties at near ambient temperature and pressure.Hydrogen peroxide is an effective,economical source of·OH and is commonly used for AOPs and in situ chemical oxidation.However,current studies have found that the residual hydrogen peroxide has become a problem,not only hinders the subsequent microbial action of wastewater biological treatment,but also affects the COD and BOD measurement of treated water quality,resulting in measurement errors.Hydrogen peroxide acts as a reducing agent under strong acidic conditions and is oxidized by potassium dichromate,causing high COD values or the formation of dark blue dipotassium dichromate,obscuring the titration end point.The purpose of this study was to explore a method for removing hydrogen peroxide using an ultrasonic-assisted catalyst in order to achieve the objective of not affecting the subsequent COD determination but effectively decomposing hydrogen peroxide.Firstly,the effect of hydrogen peroxide on the determination of COD and the effect on organic matter in three kinds of water samples,the effect of ultrasonic on organic matter,and the effect of different water sample properties,ultrasonic power,and catalyst type on hydrogen peroxide removal were studied.The catalytic mechanism was preliminary discussed.The main results of this research are as follows.The contribution of hydrogen peroxide to the COD is in a linear relationship.The ratios of COD/H₂O₂ in different water samples are different due to different substances in different water samples.The ratios of deionized water,glucose simulated wastewater or secondary effluent of printing and dyeing are respectively different.0.2626,0.2099,0.4013 mg COD/mg H₂O₂;The low-intensity ultrasonic wave has a certain decomposition effect on the glucose simulated wastewater,but the ultrasonic wave has no decomposition effect on the secondary wastewater of the dyeing wastewater that is more difficult to be degraded by the organic matter;the ultrasonic wave is used for deionized water and glucose simulated wastewater in the water sample.The residual hydrogen peroxide in the secondary treatment of printing and dyeing wastewater has a certain decomposition effect,and the removal rate of 150W power in deionized water after 60 min is the highest,only 18.09%.Ultrasound alone acts to remove hydrogen peroxide while glucose is degraded,and secondary treatment of printing and dyeing wastewater is not affected.Ultrasonic irradiation had a certain effect on the removal of hydrogen peroxide,but,the effect of ultrasonic irradiation combined with scavenger sodium carbonate or sodium bicarbonate was more significant.The removal of hydrogen peroxide reached 97.3%after 80 min in the secondary treatment effluent of printing and dyeing wastewater added sodium bicarbonate as a hydroxyl radical scavenger.However,highly oxidized superoxide ions formed by N sodium bicarbonate and hydrogen peroxide to degrade organic matters in wastewater.Therefor,the actual COD values of the water samples were reduced.After 80 min irradiating with addition of sodium carbonate,the COD test values were compared with the calculative values by the ratio of COD value to the concentration of hydrogen peroxide to confirm the organic matters in the secondary treatment effluent of printing and dyeing wastewater samples were not degraded.The method of ultrasonic irradiation combined with sodium carbonate to remove the low concentration of hydrogen peroxide is feasible.