Study Of The Adsorption Of Copper And Lead Ions In The Aqueous Solutions By Beer Yeast And Chaff

The so-called biosorption is a combinative function of biology materials to removal the pollutant including heavy metals ion.In this paper we selected the scrap beer yeast and agricultural outgrowth of chaff as the biology adsorbent, and selected copper and lead as the heavy metals to be adsorbed. The biosorption of beer yeast and chaff to Cu2+ and Pb2+ in single metal system was studied in the different conditions, such as pH value, the initial concentration of metals ion, the dose of adsorbent, the adsorbing time, the adsorbing temperature. Two kinds of metals ion competitive adsorption were also studied by two kinds of biosorbent t when Cu2+ and Pb2+ are co-existence in the aquatic system.The results of experiment suggested that the beer yeast and chaff both have the adsorb ability to the heavy metals ion of Cu2+ and Pb2+ well. The velocity of two kinds of adsorbents adsorbs to the metals ion both quick, in ten minutes, the reaction of removal have nearly reached equilibrium. The beer yeast and chaff have no selectivity to adsorb Cu2+ and Pb2+, and can simultaneously removal metals from solution, furthermore, the ability of adsorbent did not change. In the normal temperature 20 ℃ , the pH value of the aqueous solution was 5.0 or so, the initial concentration of Cu2+ and Pb2+ was 20 mg·L-1 and 80 mg·L-1 respectively, the maxium equilibrium adsorptive quantity of beer yeast were 1.48 mg·g-1 and 4.41 mg·g-1, and the equilibrium adsorptive quantity of chaff were 1.78 mg·g-1 and 7.04 mg·g-1. The adsorbed ability of chaff to the heavy metals ion excelled that of beer yeast. It is benefit to the adsorption of copper when the temperarure increased, and the result is opposite to the adsorption of lead. In the acid term, high of the value pH is benefit to the adsorb reaction. The equilibrium adsorb model of beer yeast and chaff to Cu2+ and Pb2+ all match well to Langmuir model and Freunlich model. Furthermore the adsorption dynamics model of chaff was studied. The results expressed that the reaction of adsorption on chaff to Cu2+ and Pb2+ both match to the pseudo-second class reaction kinetics model. Chaff adsorbs copper and lead ions from solution in fixed-bed column, and the effect of several important parameters, including the pH value, current velocity and the initial metals ion concentration of inflow and the coexistences metals ion etc, was discussed. The Thomas model was applied to adsorption by chaff column at different flow rate and different initial concentration to predict the breakthrough curves and to determine the characteristic parameters of the column and the maximum adsorption quantity. The experimental results expressed that when pH value of the solution is below 7, the high pH value, the high initial concentration metals ion, low current velocity, were benefited to enhance the adsorption efficiency of chaff and the adsorption quantity of equilibrium. The Thomas model was found suitable for describing the dynamic behavior of the biosorption process of Cu2+ and Pb2+on the chaff column. The result of adsorption/desorption recycles experiments suggest that the adsorption ability of chaff decrease little and can be used repeatedly.Through the analysis of the experiment data and combined with the FT-IR, it was conclude that the beer yeast and the chaff have similar adsorption mechanism to heavy metals ion, furthermore the ion exchange and complexation play a great role during the process of biosorption.