Study On Degradation Of Alizarin Red In Simulated Dye Wastewater By Strong Ionization Discharge

Dyes wastewater is characterized by deep color,relatively complex composition,high organic content and difficult biodegradability.It will cause irreparable damage to the aquatic ecological environment if it is discharged into the water body without meeting the standards.And also its toxicity,distortion and carcinogenesis will pose a great threat to human health.Alizarin red is one of the representative anthraquinone dyes,belonging to the dyes with complex molecular structure,refractory degradation and potential hazards.And it will undoubtedly cause serious pollution to the water environment if this kind dye enters the water body,so it is significant make a progress in the treatment of anthraquinone dye wastewater containing alizarin red.In this paper,Alizarin red was selected as the target pollutant,and its aqueous solution was degraded by strong ionization discharge water treatment technology.The relationship between ozone concentration,applied voltage and oxygen flow rate was discussed,and the effects of different factors on the degradation rate of alizarin red were studied.The optimum degradation conditions were obtained by orthogonal experiments,and the reaction process under various factors was analyzed.Chemical oxygen demand（COD）,total organic carbon（TOC）,ultraviolet-visible absorption spectroscopy（UV-Vis）,high performance liquid chromatography（HPLC）,liquidchromatography-massspectrometry（LC-MS）,gas chromatography-mass spectro-metry（GC-MS）and ion chromatography（IC）were applied to detect the intermediate products of alizarin red degradation to figure out the degradation mechanism and degradation path of Alizarin red.The main research results of this paper are as following:（1）The effects of applied voltage and oxygen flow rate on ozone concentration were studied respectively,and the ozone concentration in gas and in water were compared.The results show that with the increase of applied voltage,the ozone concentration in the gas increases continuously,and the ozone concentration both in the air and water increases first,then decreases with the increase of oxygen flow rate,reaching 35.9 mg/L and 13.4 mg/L when the oxygen flow rate is 5 L/min.（2）The effects of different factors on the degradation of alizarin red were studied.The order of influence of applied voltage,initial concentration of solution and initial pH of solution on the degradation efficiency of alizarin red was obtained by orthogonal experiment:initial pH of solution>initial concentration of solution>applied voltage.The best experimental conditions were obtained by combining（1）:the applied voltage was 3.0 kV,the initial concentration of the solution was 50 mg/L,the pH was 7.39,and the oxygen flow rate was 4L/min.（3）The kinetics of degradation of alizarin red by strong ionization discharge was analyzed.The experimental results showed that the reaction process of each factor accorded with the first-order kinetics equation,and the corresponding lowest R² values were 0.95682,0.9439,0.9391,0.90091 and 0.93686,respectively.The results showed that-ln（[A]₀/[A]）had a good linear relationship with time t.（4）Alizarin red dye wastewater was degraded by strong ionization discharge.The power consumption of treating 1 t of wastewater was 0.593 kW·h,and the cost was 0.297 yuan.Compared with other dye wastewater treatment methods,this method has the characteristics of low operation cost.（5）The degradation mechanism and possible pathway of alizarin red dye were studied by TOC,COD,UV-Vis,HPLC,LC-MS,GC-MS and IC.The intermediate products detected by analysis were o-hydroxybenzoic acid,phthalic anhydride,1,2-naphthalene dicarboxylic acid and 1,4,5,8-tetrahydroanthraquinone bisphenol,1,4-butenedioic acid,2-oxobutyric acid,1,4-butanediol or oxalic acid or 1,4-butanediol and oxalic acid,propionic acid or butanol or propionic acid and butanol.