Abstract
Batch experiments were conducted to investigate the capacity and mechanisms for adsorbing Cd2+ from aqueous solutions by the composite material. The composite material was manufactured with Plesiomonas shigelloides strain H5 and modified polyacrylonitrile-based carbon fiber. Experimental results showed that the surface areas of modified polyacrylonitrile-based carbon fiber increased by 58.54% and pore width increased by 40.19% compared with unmodified polyacrylonitrile-based carbon fiber. Boehm’s titration results show the surface acid sites of composite material were increased by 712% compared with unmodified polyacrylonitrile-based carbon fiber. The field emission scanning electron microscope results show P. shigelloides H5 can be grown on the surface of modified polyacrylonitrile-based carbon fiber closely. The equilibrium removal rate and sorption quantity of composite material were 71.56% and 7.126 mg g−1, respectively. With the pH value of aqueous solution increased, the removal rate of Cd2+ ions was also increased, but the change of temperature and ionic strength had no significant effect on the removal rate. Furthermore, the results showed the whole sorption process was a good fit to Lagergren pseudo-second-order model and Freundlich isotherms model. Therefore, the results infer that there was a heterogeneous distribution of active sites, and then the sorption process was chemical adsorption and multilayer adsorption. In a word, microbial composite carbon fiber material can adsorb Cd2+ ions from aqueous solution effectively, which might be helpful in wastewater treatment in the future.
Highlights
The development of human life and industrial activities, many heavy metals ions are discharged into the tributary rivers
field emission scanning electron microscope (FE-SEM) results reveal the surface of the modified polyacrylonitrile-based carbon fiber (PAN-CF) has been oxidized obvious and presented delamination (Figure 1(a) and (b))
The bacteria could be immobilized on the surface of modified carbon fibers, even after deionized water washing (Figure 1(c))
Summary
The development of human life and industrial activities, many heavy metals ions are discharged into the tributary rivers. The surface of polyacrylonitrile-based carbon fiber (PAN-CF) contains numerous micropores, –OH, –COOH, –C1⁄4O and other functional groups, which can adsorb small molecule’s pollutants like organic contaminant and ions in the environment effectively (Lu, 2005). In the wastewater treatment process, the biological carrier was used to be active sludge immobilization carrier, which can degrade organic contaminant. When the wastewater contains a large amount of heavy metals ions, it will have a negative effect on the activate sludge microorganisms. The practical significance of this study is that the composite materials can adsorb heavy metals ions in wastewater effectively and reduce the influence of heavy metals ions in the whole treatment process. The aim of this study was to manufacture a composite material (PAN-CF and P. shigelloides H5) and testify the effectiveness of this combination of biosorbents. The biosorption process was systematically studied using a combination of kinetics and isothermal modeling
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