Thermophilic adsorption of Pb2+ onto bacterium from deep-sea hydrothermal vent

Abstract

Hydrothermal vents bacteria naturally adapted to high temperature and high salinity environments may provide a new idea for the treatment of industrial wastewater with extreme conditions. In this study, a high-salinity and high-temperature resistance bacteria, Pseudomonas sp. 4–2 was isolated from a deep-sea hydrothermal vent, and proved having good adsorption efficiency for Pb2+ through batch experiments. The maximum adsorption capacity of Pb2+ was 226.24 mg/g at 55 ℃ for active cells, while it was 204.91 mg/g for inactivated cells at 35 ℃ (5% w/v NaCl, pH 6.0 and 0.2 g/L biosorbent dose). The adsorption was a spontaneous endothermic reaction that had the best fit with Langmuir isotherm model and the pseudo-second-order kinetic model. The biosorption process was studied by SEM-EDS, TEM, XRD, XPS, VTIS and 2D-COS analysis, showing that PbS and Pb(OH)2 precipitates were mainly species formed during the adsorption process, and the percentage of PbS was significantly higher than Pb(OH)2. For the molecular structure of the strain 4–2, the respond degree from large to small was lipids, polysaccharides and proteins, the response sequence was proteins, lipids and polysaccharides. The molecular structure of polysaccharides may be the main factor affecting the thermostability and adsorption efficiency at high temperatures. Diffusion, surface adsorption, micro-precipitation, complexation and intracellular accumulation (only active cells) were involved in the adsorption process. Pseudomonas sp. 4–2 may expand the bacterial resource library for microbial remediation and facilitate the development of novel treatment method for extreme industrial wastewater.