Adsorption Characteristics of Lead (Pb2+) and Cadmium (Cd2+) by an Isolated Bacterium from Soil Samples Obtained from a Tungsten Mine
2015
Ming Chen | Qingyun Cai | Jinxia Nie | Qinghua Zeng
unknown. Eight bacterial strains were isolated from lead-cadmium contaminated soil samples obtained from a Tungsten mine. Pb2+ and Cd2+ adsorption abilities of the isolated strains were screened. One isolate, referred to as Strains S, was selected for further study because of its relatively high adsorption ability. Five factors affecting adsorption of Pb2+ and Cd2+ were studied, namely, the initial concentration of Pb2+ or Cd2+, temperature, pH, biomass of Strains S, and adsorption time. Results indicated that Strains S best adsorbed Pb2+ when the initial concentration of Pb2+ was 100 mg/L, temperature was 35°C, pH was 6.5, dosage was 0.1 g, and adsorption time was 20 min. In contrast, Strain S best adsorbed Cd2+ at an initial Cd2+ concentration of 100 mg/L, temperature of 40°C, pH 6.5, dosage of 0.1 g, and adsorption time of 20 min. The experimental data were fitted to the Langmuir and Freundlich adsorption isotherm models, and the results indicated that the Langmuir model better fitted the experimental data. The results of infrared spectroscopy revealed that the functional groups involved in adsorption of Cd2+ and Pb2+ were -OH, -NH2, -S=O and -P=O. Using 16S rDNA sequencing and phenotypic properties test, Strains S was identified as Enterobacter sp.
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