This paper concerns with the adsorption of bisphenol-A (BPA) by modified zeolites which were prepared using an orthogonal experimental design. The preparation process was optimized by the defined conditions, i.e., that 10% of cetyltrimethyl ammonium bromide was used as the optimal modifier and processing time and temperature were 36 h and 25 o C, respectively. The adsorption equilibrium of BPA onto the modified zeolite fits the Freundlich isotherm with a high correlation coefficient 0.996 and was defined by a second-order rate constant (K v) of 1.07 g (mg h)-1. Furthermore, the effects of solution chemical properties on the adsorption of BPA by modified zeolites were examined. The result reveals that the best adsorption temperature was 25 o C, and the optimal pH ranged from 5.0 to 10.0. In addition, the adsorption capacity of BPA increased with concentrations of HCO 3 and decreased with increasing in concentrations of NO 3-, OH-, and Al 3+ in the test solution.
The film doping with CdSe/ZnS quantum dots has been fabricated and the emission cross sections of CdSe/ZnS quantum dots have been obtained by applying the McCumber theory. With the calculated emission cross sections depending on wavelengths the emission lifetime of 1.12 ns is obtained. By comparison of the calculated lifetime and previously reported ones, we find excellent agreement between the measured and calculated ones. It has been found that the McCumber theory can still be used to calculate the emission cross sections of quantum dots with discrete energy level structure.
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