Studies On The Mechanism And Application Of Wast Saccharomyces Cerevisiae Adsorption Pb²⁺ From Sewage

There are a lot of urban sewage containing low concentrations of heavy metals (<100μg/mL) directlydischarged without treatment. Heavy metals would cause serious harm to human health and theenvironment by water migration，soil accumulation，food chain and amplification effect. In this paper，wast saccharomyces cerevisiae was used as an adsorbent material.Effects of coexisting ions on biosorptionkinetics and equilibrium of Pb2+by wast saccharomyces cerevisiae in waste water was studied for themechanism. To improve the adsorption capacity，wast saccharomyces cerevisiae was modified andcharacterized.Then modified wast saccharomyces cerevisiae was made into immobilized cells and itadsorption characteristics of Pb2+were studied.The immobilized cells were made into biological adsorptioncolumn and the dynamic adsorption was studies. The main findings are as follows:(1) The existence of Ni2+extended the Pb2+adsorption，slowed the rate of Pb2+adsorption，but it hadalmost no effect on Pb2+adsorption capacity. The existence of Cu2+reduced Pb2+adsorption capacitymarkedly.The adsorption belongs to selective adsorption.Competitive adsorption processes were fitted withpseudo-second order kinetics and Langmuir adsorption equation which showing that adsorption rate ofPb2+is under the control of chemisorption and the adsorption of Pb2+belongs to monolayer.(2) The optimal parameters of modification technology were: the treatment temperature is43℃，theliquid-solid ratio is41mL/g， the treatment time is270min and the modifier concentration is0.33mol/L.Under these conditions，the adsorption rates of Pb2+is89.96%. The picture of FTIR showed alot of functional groups such as﹣OH，N﹣H，C﹣H，C=O，﹣COO，C﹣O﹣C and HPO2-4.﹣OH and﹣COO were involved in the reaction.(3) The adsorption of Pb2+by the immobilized cells reached equilibrium at the60min， adsorptioncapacity increased with the initial concentration of Pb2+， the optimum adsorption temperature was30℃，the optimum pH is4～7， the optimum concentration of immobilized cells was22g/L. The existence ofCu2+and Ni2+reduced Pb2+adsorption capacity. Competitive adsorption processes were fitted withpseudo-second order kinetics and Langmuir adsorption equation.The dynamic adsorption curve of Pb2+bybiological adsorption column was "S" shape， saturation adsorption time was108h.