Effects Of Fe And Mn On Single Benzene Ring Nonsteroidal Anti-inflammatory Drugs Degradation By Pseudomonas Putida

Residues acetaminophen?APAP?and salicylic acid?SA?in the environment are difficult to be degraded,which polluted environment and are poisonous to aquatic plants and animals.Pseudomonas putida widely exists in natural water bodies.In this paper,the possibility of biodegradation of APAP and SA by biogenic iron and manganese oxides?BioFeMnOx?produced by Pseudomonas putida was investigated.The degradation of 10-500 mg/L APAP was studied.10 mg/L APAP could be degraded completely.The removal rate gradually decreased to zero as APAP concentration increasing.The degradation kinetics of 10 mg/L APAP were studied in the subsequent research.The degradation conditions of APAP were investigated,the results showed that APAP could not be degraded without Fe and Mn,while its degradation efficiency was poorer with Fe only.The degradation efficiency was best when Fe and Mn coexisted,and Mn were necessary to the degradation of APAP.The change of Mn²⁺ druing APAP degradation process was investigated,the results showed that the degradation rate of APAP had a strong positive correlation with the oxidation rate of Mn²⁺.APAP could be degraded completely when Mn²⁺ was 8.13 mg/L,more than this could inhibit the APAP biodegradation,which indicated that excessive Mn²⁺ was poison to the bacteria.The influencing factors of APAP degradation were also discussed.It was found that the degradation rate of APAP was reduced to 30% when the activity of bacteria was inhibited by NaN3.The inhibition group contained 9.3 mg/L Mn²⁺,while the uninhibition group contained 0.5 mg/L Mn²⁺,indicating that Mn²⁺ oxidation could be affected by bacterial activity thus affecting APAP degradation.The degradation efficiency of APAP by biogenic manganese oxides?Bio MnOx?which produced by different concentration of Mn²⁺ was studied.The results showed that the degradation rate of APAP was enhanced with the increase of the amount of BioMnOx.The results of desorption experiments showed that there was no adsorption of APAP on BioFeMnOx,indicating that APAP was enventually degraded by BioFe MnOx.The TOC removal rate of APAP was 48.05% by determining the total organic carbon content in the degradation process.Above studies confirmed that the degradation of APAP occurred mainly in the process of soluble iron and manganese ions oxidization the insoluble BioMnOx caused by Pseudomonas putida.The degradation of 0.5-10 mg/L SA was studied.The removal rate decreased with the increase of SA concentration.0.5 and 1 mg/L SA could be completely degraded,while 5 and 10 mg/L SA removal rate were 74.87% and 61.98%,respectively.Subsequent research selected 1 mg/L SA as the study object.The SA degradation conditions were investigated and it was found that SA could not be degraded without Fe and Mn,while removal rate was less than 8% with Fe only,indicating that the effect of Fe on degradation of SA was very poor.The change of soluble iron and manganese ions druing SA degradation process was investigated.The results showed that the oxidation rate of Fe²⁺ at 1,5,10 mg/L for SA were 98.15%,96.75% and 23.33%,respectively,and the oxidation rates of Mn²⁺ were 99.59%,98.82%,44.48%,respectively.Indicating that the high concentration of SA could inhibit the oxidation rate of Fe²⁺ and Mn²⁺.The influencing factors of SA degradation were also discussed.The results showed that degradation efficiency of SA was affected by the activity of bacteria and the amount of Bio MnOx.The larger amount of Bio MnOx,the higher removal rate of SA.The results of desorption experiments showed that there was no adsorption of SA on BioFeMnOx,indicating that SA was degraded by Bio FeMnOx.The differences between APAP and SA in degradation were compared.It was found that APAP was more easily degraded by BioFe MnOx than SA,the removal rate was higher,the degradation time was shorter,and the concentration limit of degradation was higher.Compared with APAP,the oxidation of soluble iron and manganese ions by Pseudomonas putida was slower when SA existed in the medium.biogenic iron oxides?Bio FeOx?could degraded a certain amount of APAP,while the degradation of SA was very poor.The degradation of APAP required small amount of BioFe MnOx,while the degradation of SA required a large amount of BioFeMnOx,especially the large amount of Bio MnO_x.