| In this study, saccharomyces cerevisiae and saccharomyces cerevisiae that embedded by sodium alginate, gelatin and polyvinyl alcohol was used to study the mechanism of saccharomyces cerevisiae to adsorption Pb2+, Cu2+、Ni2+. Response surface method was used to study a variety of factors effect on the adsorption process, get the optimum adsorption conditions. At the same time, biosorption kinetics as well as equilibrium isotherm was studied, some modern analytical techniques such as scanning electron microscopy and fourier-transform infrared analysis spectroscopy was used to study the interaction between saccharomyces cerevisiae and heavy metal ions, so that can find out the adsorption mechanism between them. Apart from this, competitive adsorption of mixed heavy metal ions was preliminary studied.The results showed that the best conditions for saccharomyces cerevisiae adsorption heavy metal ions were:for Pb2+pH value was5.15, the concentration of cerevisiae was1.36g/L, the concentration of Pb2+was21.20mg/L, time wasl h, temperature was30℃, under this conditions the adsorption rate was67.46%; for Cu2+pH value was4.13, the concentration of cerevisiae was1.10g/L, the concentration of Cu2+was31.33mg/L, time wasl h, temperature was30℃, under this conditions the adsorption rate was47.20%; for Ni2+pH value was4.83, the concentration of cerevisiae was1.37g/L and the concentration of Ni2+was36.36mg/L, time wasl h, temperature was30℃, under this conditions the adsorption rate was40.27%The results of single factor experiment showed that the best conditions for saccharomyces cerevisiae adsorption mixed heavy metal ions were:pH value was3, the concentration of cerevisiae was2.0g/L, the concentration of ions was60mg/L, adsorption time was1h, optimized by response surface methodology the best conditions were:pH value was3.15, adsorbent amount was2.04g/L, concentration of heavy metal ions was62.78mg/L, and the adsorption rate was62.78%. The adsorption process obeys the pesudo second-order kinetic model, Langmuir and Freundlich model. The order of affinity between saccharomyces cerevisiae and heavy metal ions was Pb2+>Cu2+>Ni2+, the order of binding stability was Ni2+> Pb2+>Cu2+, the order of adsorption capacity was Pb2+>Cu2+>Ni2+. The results of SEM and FTIR showed that cell morphology of saccharomyces cerevisiae was changed, and in the cell wall the groups like hydroxyl, carboxyl were involved in the adsorption behievor.The best conditions for immobilized saccharomyces cerevisiae adsorption heavy metal ions were:for Pb2+pH value was6.10, concentration of immobilized saccharomyces cerevisiae was34.29g/L, concentration of Pb2+was22.20mg/L, time wasl h, temperature was30℃, under this conditions the adsorption rate was90.29%; for Cu2+pH value was4.10, concentration of immobilized saccharomyces cerevisiae was31.97g/L, the concentration of Cu2+was32.30mg/L, time was1h, temperature was30℃, under this conditions the adsorption rate was83.24%; for Ni2+pH value was3.97, the concentration of immobilized saccharomyces cerevisiae was33.78g/L, the concentration of Ni2+was31.39mg/L, time was1h, temperature was30℃, under this conditions the adsorption rate was41.43%; The results of single factor experiment showed that the best conditions for immobilized saccharomyces cerevisiae adsorption mixed heavy metal ions were:pH value was3, the concentration of immobilized saccharomyces cerevisiae was32g/L, the concentration of ions was60mg/L, adsorption time was4h, optimized by response surface methodology the best conditions were:pH value was3.24, adsorbent amount was32.48g/L, concentration of heavy metal ions was59.80mg/L, and the adsorption rate was68.50%. The adsorption process obeys the pesudo second-order kinetic model, Langmuir and Freundlich model. The order of affinity between immobilized saccharomyces cerevisiae and heavy metal ions was Pb2+>Cu2+>Ni2+, the order of binding stability was Ni2+> Pb2+>Cu2+, and the order of adsorption capacity was Pb2+>Cu2+>Ni2+. |
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