Fenton-UV照射法对超高浓度聚乙烯醇有机废液的降解效能

Degradation Efficiency of Ultra-High-Concentration Polyvinyl Alcohol Organic Waste Liquid by Fenton-UV Irradiation

采用Fenton-紫外照射(Fenton-UV)联用工艺对核电厂超高浓度聚乙烯醇(PVA)有机废液进行处理,研究了PVA转化率、平均分子量、溶液黏度等随时间的变化规律。结果表明:对于50 g/L的PVA溶液,H_(2)O_(2)投加质量浓度为15 g/L,FeSO_(4)·7H_(2)O投加质量浓度为0.050 g/L,初始pH值为3,经过2 h Fenton反应和2 h UV照射(3 mW/cm^(2))之后,PVA转化率达到100%,溶液平均分子量从60000~80000 Da降低到1000 Da以下,黏度降低到1.1 mPa·s,但总有机碳和化学需氧量(COD)变化不大。Fenton-UV法可作为预处理方法,前期Fenton阶段提高PVA的溶解度,增加反应溶液中的PVA含量,并进行初步降解和氧化;后期UV法进一步降解溶液中的PVA,有效降低其分子量和黏度,为后续处理提供有利条件,最终形成经济可行的超高浓度PVA有机废液处理工艺。

Fenton-ultraviolet irradiation(Fenton-UV)combined process was used to treat ultra-high-concentration polyvinyl alcohol(PVA)organic waste liquid of nuclear power plants,and the changes of PVA conversion rate,average molecular weight,solution viscosity,etc.over time were studied.The results show:for 50 g/L PVA solution,the concentration of H_(2)O_(2)is 15 g/L,the concentration of FeSO_(4)·7H_(2)O is 0.050 g/L,the initial pH is 3,after 2 h Fenton reaction followed by 2 h UV irradiation(3 mW/cm^(2)),the removal efficiency of PVA reaches 100%,and the average molecular weight in solution decreases from 60000~80000 Da to<1000 Da.The viscosity decreases to 1.1 mPa·s,while only slight variations are observed for total organic carbon and COD.Fenton-UV method can be used as a pre-treatment.In the former Fenton stage,the solubility increases,and the concentration of PVA in solution can reach a very high level.A preliminary degradation and oxidation are also conducted in this stage.During the later UV stage,PVA can be further degraded,and the molecular weight and viscosity are significantly decreased.Fenton-UV treatment will be benefit to the further treatment,and it can be a cost-effective treatment method for ultra-high concentration PVA solution.