| DBP is one of phthalic acid esters and a common environmental hormones organic pollutant. In this study, a strain was isolated from DBP contaminated soil. The strain was characterized as a strain of Burkholderia with higher DBP tolerance. The adsorption behavior and mechanism of DBP on the Burkholderia and Burkholderia-minerals (goethite, kaolinite and montmorillonite) were investigated. The adsorbent kinetic, adsorption isotherm model, desorption and other factors such as pH, different concentration of DMPP were also studied here. Surfactant groups of Burkholderia before and after adsorption were determined by FTIR. In the bacteria-mineral composites, the adsorption quantity (percentage), desorption quantity (percentage) and the influence of different proportion and different concentration of DMPP were discussed. The surface morphology of bacteria-mineral composites were observed by the SEM. Furthermore, the relative hydrophobicities of sorbents were measured to clarify the adsorption behavior and mechanism of the composite system.In this paper, the research conclusions were as follows:(1) The adsorption of DBP on Burkholderia was fit to Freundlich isothermal model (R2=0.94), and the equation was qe=2.16×Ce1/1.02.(2) The desorption experiment found that the adsorption of DBP on Burkholderia includes physical adsorption and chemical adsorption, and chemical adsorption was mainly.(3) The FTIR spectra revealed that the adsorption mechanism of DBP on bacteria was mainly C-H stretching vibration. At the same time, active groups on the bacterial surface and cell walls also played an important role in the adsorption behavior.(4) The most difference between adsorption values and predicted values appeared in the 1:1 Burkholderia-to-minerals ratio. It is indicated that 1:1 ratio resulted in the significant impacts on DBP adsorption by composites. Compared with predicted values, the measured values of bacteria-goethite and bacteria-montmorillonite composites were increased by 1.10 mg/g and 1.83 mg/g, respectively. However, that of bacteria-kaolinite composite was decreased by 1.16 mg/g.(5) The SEM analysis showed that the attachment between Burkholderia cells and goethite/montmorillonite were closely, but kaolinite were relatively loose.(6) The growth of bacteria was influenced by different concentrations of DMPP, the similarly to the adsorption of DBP on bacteria and complex system, and the adsorption of DBP was improved on bacteria-montmorillonite composite system by 2 mmol/L DMPP. |
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