Application Of Iron Nanoparticles Supported By Modified Yeast On The Removal Of Chromium,Lead And Cadimum Contaminant

Cr(Ⅵ),Pb(Ⅱ)and Cd(Ⅱ)are three common heavy metal pollutants.It is of great significance to develop green,environmental-friendly and inexpensive method for the removal of this three heavy metal pollutants.In this dissertation,the recent advances of nano-zero valent iron particles(n ZVI)and the removal of heavy mental pollutants are reviewed.The removal of Cr(Ⅵ),Pb(Ⅱ)and Cd(Ⅱ)are conducted based on the green synthesis of n ZVI and its removal technologies of heavy mental pollutants.The main contents are as follows.1.The modified yeast supported nano-zero valent iron particles(TB-Fe/SCM NPs)was synthesized by the in situ reduction of ferrous by waste tobacco leaf extract with modified S.cerevisiae as stabilizer and dispersing agent.The SEM results indicate that the iron nanoparticles loaded on the yeast is spherical with a particle size of(34.3 ± 17.9)nm,while XPS analyses demonstrate the presence of zero valent iron on TB-Fe/SCM NPs.2.The removal of aqueous hexavalent chromium by TB-Fe/SCM NPs was studied.The removal of Cr(VI)by TB-Fe/SCM NPs is mainly reduction,accompanied by the adsorption process,which conforms to the pseudo-second-order kinetic model and Freundlich adsorption model.The removal of hexavalent chromium is affected by the solution p H and the initial concentration of Cr(VI),while temperature infuences the Cr(VI)removal slightly.The removal amount of 100 mg·L-1 Cr(Ⅵ)is(32.16 ± 0.02)mg·g-1 under the condition of p H 5and 1.4 g·L-1 TB-Fe/SCM NPs,of which 6.16% is adsorbed and 93.84% is reduced.The coexistence of 2,4,6-TCP can promote the Cr(Ⅵ)removal,while no obvious effect of Cr(Ⅵ)removal was observed with the coexisting Cd(Ⅱ).3.The removal of aqueous Pb(Ⅱ)and Cd(Ⅱ)by TB-Fe/SCM NPs was incestigated.The removal of Pb(Ⅱ)and Cd(Ⅱ)is affected by the solution p H,temperature and the initial concentration of Pb(Ⅱ)/Cd(Ⅱ).Pb(Ⅱ)removal by TB-Fe/SCM NPs is a combined action of immobilization and adsorption,while Cd(Ⅱ)removal is mainly adsorption,accompanied by the immobilization process.The removal of Pb(Ⅱ)and Cd(Ⅱ)fitted well to the pseudo-secondorder kinetics model,and Pb(Ⅱ)removal conforms to the Freundlich adsorption model,while the removal of Cd(Ⅱ)conforms to the Langmuir adsorption model.The removal amount of200 mg·L-1 Pb(Ⅱ)is(38.59 ± 0.04)mg·g-1 under the condition of p H 5 and 3.0 g·L-1 TBFe/SCM NPs,of which 43.56% is adsorption and 54.29% is immobilization.The removal amount of 20 mg·L-1 Cd(Ⅱ)is(0.43 ± 0.00)mg·g-1 under the condition of p H 5 and 6.0 g·L-1TB-Fe/SCM NPs,of which 93.02% is adsorption and 6.97% is immobilization.The coexistence of 2,4,6-TCP can promote the Pb(Ⅱ)and Cd(Ⅱ)removal,while the coexistence of Cd(Ⅱ)and Pb(Ⅱ)does not affect their removal,but the coexistence of Cr(Ⅵ)can promote the Cd(Ⅱ)removal.