Biosorption of uranyl ions from aqueous solution by Saccharomyces cerevisiae was studied in a batch system. The influence of contact time, initial pH, temperature and initial concentration was investigated.
The optimal conditions were found to be 3.5 h of contact time and pH = 4.5. Temperature had no significant effect on adsorption.
The uptake of uranyl ions was relatively fast and 85 % of the sorption was completed within 10 min. The experimental data
were well fitted with Langmuir isotherm model and pseudo-second order kinetic model. According to this kinetic model, the
sorption capacity and the rate constant were 0.455 mmol UO22+/g dry biomass and 1.89 g mmol−1 min−1, respectively. The Langmuir isotherm indicated high affinity and capacity of the adsorbent for uranyl biosorption with the
maximum loading of 0.477 mmol UO22+/g dry weight.
The present investigation entails the biosorption studies of radiotoxic Strontium (90Sr), from aqueous medium employing dry cow dung powder (DCP) as an indigenous, inexpensive and, eco-friendly material without
any pre or post treatments. The Batch experiments were conducted employing 90Sr(II) as a tracer and the effect of various process parameters such as optimum pH, temperature, amount of resin, time of
equilibration, agitation speed and concentration of metal ions have been studied. The kinetic studies were carried out employing
various models but the best fitting model was Lagergren pseudo-second order model with high correlation coefficient R2 value of 0.999 and cation exchange capacity of DCP was found to be 9.00 mg/g. The thermodynamic parameters for biosorption
were evaluated as ΔG° = −5.560 kJ/mol, ΔH° = −6.396 kJ/mol and ΔS° = 22.889 J/mol K, which indicated spontaneous and exothermic process with high affinity of Sr(II) for DCP.
Authors:H. Yang, N. Tan, F. WU, H. Liu, M. Sun, Z. She, and Y. Lin
The uranium(VI) accumulation was studied in detail by using the biomass of mangrove endophytic fungus Fusarium sp.#ZZF51 from the South China Sea. The uranium(VI) biosorption process onto the tested fungus powders was optimized at pH 4.0,
adsorption time 60 min, and uranium(VI) initial concentration 50 mg L−1 with 61.89% of removal efficiency. According to Fourier transform infrared spectra for the tested fungus before and after
loaded with uranium(VI), the results showed that both of hydroxyl and carboxyl groups acted as the important roles in the
adsorption process. In addition, the experimental data were analyzed by using parameter and kinetic models, and it was obtained
that the Langmuir isotherm model and the pseudo-second-order kinetic model provided better correlation with the experimental
data for adsorption of uranium(VI).
The uranium(VI) biosorption by grapefruit peel was studied from aqueous solutions. Batch experiments was conducted to evaluate
the effect of contact time, initial uranium(VI) concentration, initial pH, adsorbent dose, salt concentration and temperature.
The equilibrium process was well described by the Langmuir, Redlich–Peterson and Koble–Corrigan isotherm models, with maximum
sorption capacity of 140.79 mg g−1 at 298 K. The pseudo second order model and Elovish model adequately describe the kinetic data in comparison to the pseudo
first order model and the process involving rate-controlling step is much complex involving both boundary layer and intra-particle
diffusion processes. The effective diffusion parameter Di and Df values were estimated at different initial concentration and the average values were determined to be 1.167 × 10−7 and 4.078 × 10−8 cm2 s−1. Thermodynamic parameters showed that the biosorption of uranium(VI) onto grapefruit peel biomass was feasible, spontaneous
and endothermic under studied conditions. The physical and chemical properties of the adsorbent were determined by SEM, TG-DSC,
XRD and elemental analysis and the nature of biomass–uranium (VI) interactions was evaluated by FTIR analysis, which showed
the participation of COOH, OH and NH2 groups in the biosorption process. Adsorbents could be regenerated using 0.05 mol L−1 HCl solution at least three cycles, with up to 80% recovery. Thus, the biomass used in this work proved to be effective materials
for the treatment of uranium (VI) bearing aqueous solutions.
Authors:Ali Keshtkar, Fatemeh Kafshgari, and Mohammad Mousavian
Simultaneous biosorption of uranium(VI) and nickel(II) ions onto Ca-pretreated Cystoseira indica biomass was studied and compared with single uranium or nickel biosorption in a fixed-bed column. Results of single biosorption
showed the breakthrough and exhaustion time increase with the increase of the flow rate and inlet metal concentration for
both metal ions. Also, it was observed that there was an optimum flow rate of 1.4 mL min−1 (surface loading of 0.792 cm min−1) for both metal ions in the column. Results from both single and binary systems showed the adsorption capacity of C. indica for both metal ions increases with the increasing inlet concentration of each component and C. indica had a stronger affinity for uranium than nickel ions. The binary system results showed that the presence of the second component
affected the adsorption of the first one by C. indica so the antagonistic action was observed. Also, the inhibitory effect of uranium ions on the nickel adsorption was greater
than nickel ions on the uranium adsorption. The uranium and nickel breakthrough curves under different conditions were described
by the Thomas, Yoon-Nelson and Yan models. Among these models, the Yan model appeared to describe the experimental results
Authors:Qin Li, Yunhai Liu, Xiaohong Cao, Cui Pang, Youqun Wang, Zhibin Zhang, Yating Liu, and Ming Hua
The biomass pummelo peel was chosen as a biosorbent for removal of uranium(VI) from aqueous solution. The feasibility of adsorption
of U(VI) by Pummelo peel was studied with batch adsorption experiments. The effects of contact time, biosorbent dosage and
pH on adsorption capacity were investigated in detail. The pummelo peel exhibited the highest U(VI) sorption capacity 270.71 mg/g
at an initial pH of 5.5, concentration of 50 μg/mL, temperature 303 K and contacting time 7 h. The adsorption process of U(VI)
was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it followed both
the Langmuir adsorption isotherm and the Freundlich adsorption isotherm. The thermodynamic parameters values calculated clearly
indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that the
pummelo peel has potential application in the removal of the uranium(VI) from the radioactive waste water.
Authors:A. Hamzah, W. Arifin, K. Khoo, L. Lee, and S. Sarmani
Certain bacterial strains can be employed in the removal of heavy metals from the environment. The aim of this study was to
screen potential bacteria that were tolerant towards Cu and Cd and instrumental neutron activation analysis (INAA) was used
to determine the concentrations of heavy metals in the sludge samples. The sludge samples from oil refinery plant in Malaysia
contained Cr, Cs, Cu, Eu, Fe, Hg, Mn, Sb, Sc, Th, U and Zn. Seven bacterial isolates were identified to be tolerant to 100 mg/kg
of copper and cadmium.
Authors:Yating Liu, Yunhai Liu, Xiaohong Cao, Rong Hua, Youqun Wang, Cui Pang, Ming Hua, and Xiaoyan Li
The cross-linked chitosan (CS) gels synthesized by using glutaraldehyde (GLA), epichlorohydrin (EC), and ethylene glycol diglycidyl
ether (EGDE) as cross-linkers respectively were used to investigate the adsorption of U(VI) ions in an aqueous solution. The
pure chitosan (PCS) and the cross-linked chitosan gels were characterized by FTIR and SEM analysis. The kinetic, thermodynamic
adsorption and adsorption isotherms of U(VI) ions onto unmodified and modified cross-linked chitosan were studied in a batch
adsorption experiments. The effect of pH, contact time and temperature on the adsorption capacity were also carried out. At
the optimum pH, the maximum adsorbed amount of PCS, GLACS, ECCS and EGDECS were 483.05, 147.05, 344.83 and 67.56 mg/g, respectively.
The uranium (VI) adsorption process of PCS and ECCS followed better with pseudo-second-order kinetic model, while GLACS and
EGDECS followed pseudo-first-order kinetic model well. The results obtained from the equilibrium isotherms adsorption studied
of U(VI) ions were analyzed in two adsorption models, namely, Langmuir and Freundlich isothms models, the results showed that
the Langmuir isotherm had better conformity to the equilibrium data. The thermodynamic parameters such as enthalpy (ΔHº), entropy (ΔSº), and Gibbs free energy (ΔGº) showed that the adsorption process was both spontaneous and endothermic.
The effects of selenium on uranium biosorption were examined using 67 microorganisms (17 bacteria, 19 actinomycetes, 18 fungi, and 13 yeasts). The growth suppression by selenium in the medium was observed in most of the microorganisms tested. The amounts of selenium taken up in microbial cells differ with different species and groups of microorganisms. The marked enhancement of uranium adsorbing ability by Se-loading was only found in yeasts, such as Candida utilis. The amounts of uranium adsorbed by the cells were increased with increasing selenium in the cells. Thus, it is assumed that the selenium in the cells will play an important role in uranium binding.
The biosorption of radionuclide 241Am from solution by Saccharomyces cerevisiae (S. cerevisiae), and the effects of experimental conditions on the adsorption were investigated. The preliminary results showed thatS. cerevisiae is a very efficient biosorbent. An average of more than 99% of the total 241Am could be removed by S. cerevisiae of 2.1 g/l (dry weight) from 241Am solutions of 17.54–4386.0 mg/l (2.22 MBq/l–555 MBq/l) with adsorption capacities of 7.45–1880.0 mg/g biomass (dry weight) (0.94 MBq/g–237.9 MBq/g). The adsorption equilibrium was achieved within 1 hour and the optimum pH ranged 1–3. No significant differences on 241Am adsorption were observed at 10–45 °C, or in solutions containing Au3+ or Ag+, even 2000 times above 241Am concentration. The relationship between concentrations and adsorption capacities of 241Am indicated the biosorption process should be described by the Freundlich adsorption isotherm.