Green Synthesis And Application Of Yeast Cell-Supported Nano Zero-valent Iron

In this thesis,yeast cell supported zero-valent iron?nZVI/SC?was prepared by the in situ reduction of ferrite with tobacco leaf extraction,and the properties of the as-prepared nZVI/SC in the removal of Cr?VI?and degradation of 2,4,6-trichlorophenol?2,4,6-TCP?,were investigated also.The results are as follows:?1?The reactivity of nZVI/SC for Cr?VI?removal is affected by the preparation condition of nZVI/SC.These factors including the drying method of tobacco leaf,the extraction solvent,the extraction volume,the mass ratio of ferrite to yeast as well as the reaction time and temperature.The most effective nZVI/SC for Cr?VI?removal was synthesized by 3hours'reduction of 150 milligrams of ferrite with 3 gram of flue-cured extraction extracted by 50%ethanol under the ferrite to yeast cell mass ratio of 0.30:1.?2?The removal rate of Cr?VI?by nZVI/SC is affected by the reaction temperature,pH value,nZVI/SC dosage and initial concentration of Cr?VI?.The removal efficiency of Cr?VI?by nZVI/SC decreases with the increase of pH and the initial Cr?VI?concentration,but increases with the dosage of nZVI/SC,while the ionic strength have no significant effects on removal of Cr?VI?.The reaction follows the pseudo-first-order reaction kinetic model.In the range of pH 2⁸,the removal efficiency of Cr?VI?by nZVI/SC decreases with the increase of pH value;The k_obs of Cr?VI?removal dropping from 0.1536±0.0044 h^-1?0.0401±0.0029h^-1?0.0261±0.0027 h^-1 to 0.0190±0.0020 h^-1,with the initial Cr?VI?concentration increased from 25 mg·L^-1,50 mg·L^-1,75 mg·L^-1 to 100 mg·L^-1,and the corresponding R² were 0.9974,0.9992,0.9898 and 0.9931,respectively.?3?The reactivity of nZVI/SC in 2,4,6-TCP degradations affected by the drying method of tobacco leaf,the extraction volume,the reaction time and the mass ratio of ferrite to yeast,but not influenced by the extraction solvent and the reaction temperature.An effective nZVI/SC for 2,4,6-TCP degradation was synthesized by the reduction of 150 milligrams of ferrite with 3 gram of dried-tobacco extraction for 3 hours under the ferrite to yeast mass ratio of 0.30:1.?4?The degradation efficiency of 2,4,6-TCP by nZVI/SC decreases with the increase of pH and the initial concentration of 2,4,6-TCP,but increases with the dosage of nZVI/SC and reaction temperature,while the ionic strength has little effect on the degradation of 2,4,6-TCP,and the presence of phosphate ions in the solution inhibits the degradation of 2,4,6-TCP.71.85%of 4.00 mL of 0.10 mmol?L^-1 2,4,6-TCP was degraded within 24 h by 25.0mg of nZVI/SC at pH 6.0 under the condition of 30?.