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Heavy Metal Tolerance And Adsorption Properties Of Endophytic Fungi From Dysphania Ambrosioides

Posted on:2021-10-07Degree:MasterType:Thesis
Country:ChinaCandidate:Z Q ZhuFull Text:PDF
GTID:2480306095994089Subject:Cell biology
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Heavy metal(HM)pollution is a world wild environmental problem.Due to the stability,high solubility and migration activity of HM in aqueous media,the release of untreated or under-treated metal-contaminated wastewater into the environment can cause serious harm to human health.Therefore,the treatment of HM polluted wastewater has attracted much attention.Among all treatment methods,biological adsorption of HM shows good application prospect because of its in-situ,high efficiency and low cost.In our previous study,the endophytic fungus FT2G24(S.terrestris)and FZT214(E.nigrum)isolated from hypperaccumulator D.ambrosioides,which was collected from Zhehai Town,Huize County,Yunnan Province,showed a certain HM tolerance.Therefore,the tolerance and adsorption capacity of FZT214 to lead,zinc,and cadmium were further studied in the present study,and the results are showed as follows:1.The strain FT2G24 had good tolerance to zinc and cadmium(Medial lethal concentration was 5985.77 mg/L and 1573.45 mg/L),and the tolerance to zinc was better than that of cadmium.FZT214 had good tolerance to lead,zinc and cadmium(Medial lethal concentration was 689.32 mg/L,401.08 mg/L and 525.79 mg/L,respectively).Totally,the tolerance to zinc and cadmium of FT2G24 is better than that of FZT214.However,its adsorption capacity to zinc and cadmium is worse than that of FZT214.Therefore,FZT214 was chosen to further study.2.The adsorption capacity to lead of FZT214 was affected by factors such as the amount of adsorbent added,initial lead concentration,p H,and adsorption time,details are as follows: the adsorption rate of the strain rise with the increase of adsorbent added.When the dosage was 5.0 g/L,the adsorption rate reaches the maximum(98.8 %).As the initial concentration of lead continues to increased,the adsorption rate showed an inverted U pattern that increases first and then decreases.The adsorption rate reached the maximum(99.29 %)when the initial concentration of lead was 200 mg/L.As the initial p H of the solution increased,the adsorption rate of its strains continued to increase.When the p H was between 1.2 to 2.2,the strain adsorption rate was below 15 %,and the p H was between 3.2-5.2,the strain adsorption rate was more than 99 %.With the prolongation of adsorption time,the adsorption rate of strains continued to increase.The adsorption speed was faster at the beginning,and the adsorption rate reached 91.37 % in 1 hour.After 6 hours,the increase in adsorption rate slowed down,and after 12 hours,the adsorption reached equilibrium.3.The best adsorption conditions of the FZT214 strain for lead were: biomass5.0 g/L,lead ion concentration 200 mg/L,p H 3.2.The adsorption time is 12 h.4.Adsorption isotherms and adsorption kinetics studies show that among various isotherms and kinetic models,Langmuir model and quasi-second-order kinetic model are more in line with the adsorption process of strain FZT214 for lead.In summary,the strain FZT214 has good tolerance and adsorption capacity for lead,the medial lethal concentration is 689.32 mg/L,the optimal adsorption conditions are 5.0 g/L biomass,200 mg/L lead concentration,p H 3.2 and 12 h adsorption time,respectively.The isolate has potential application in lead-contaminated wastewater remediation.
Keywords/Search Tags:heavy metal pollution, endophytic fungi, heavy metal tolerance, biosorption, adsorption rate
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