The adsorption thermodynamics and kinetics of uranium adsorption by Bacillus subtilis

desorption of U(Ⅵ) in saturated ethylene diamine tetraacetic acid (EDTA)

and phosphorus release into water were studied by static adsorption and desorption experiments. The mechanisms of action were discussed using data from scanning electron microscopy (SEM)

energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) measurements. Optimized uranium removal occurred at pH 5 of 50 mg·L-1 uranium solution and uranium removal efficiency and adsorption quantity reached 85.34% and 308.31 mg·g-1(dry weight)after 2 h

respectively. As the duration from 2 h increased to 48 h

desorption rate of uranium reduced from 52.13% to 36.25%

and concentration of P released from Bacillus subtilis increased from 0.12 mg·L-1 to 0.40 mg·L-1. Langmuir isotherm and pseudo-second equations could describe well the uranium adsorption behavior by Bacillus subtilis. The process was exothermic and spontaneous. SEM and EDS showed that the cell of Bacillus subtilis was sub-internal fracture

and uranium deposited on the surface and surrounding of Bacillus subtilis without obvious U-P crystal products. FTIR revealed that the surface of Bacillus subtilis possessed many active groups

such as hydroxyl

amide

and phosphate groups

and the amide and phosphate groups were involved in adsorption of U(Ⅵ) by Bacillus subtilis. FTIR spectra showed the characteristic absorption peak of UO22+.