Biosorption of Uranyl Ions from Aqueous Solution by Parachlorella sp. AA1.
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ABSTRACT:
SUBMITTER: Yoon JY
PROVIDER: S-EPMC8037780 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:In this study, strain BAPb.1 was isolated from lead mining area and used as an adsorbent to remove lead(II) ions from aqueous solution. The physicochemical characteristics, heavy metal resistance and antibiotic sensitivity of strain BAPb.1 were investigated. Biosorption capacity was evaluated by batch biosorption experiments, and isothermal characteristics were discussed. Atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectrometry (FTIR) were conducted to explore the mechanism for lead(II) adsorption. Based on morphological and physiological characteristics as well as the phylogenetic analysis of 16S rDNA sequences, strain BAPb.1 was identified as a member of the genus Alcaligenes. It exhibited high resistances to multiple heavy metals such as lead(II), copper(II), zinc(II), nickel(II) and chromium(VI), and to antibiotics such as kanamycin, ampicillin, streptomycin, chloramphenicol, and tetracycline. The optimum conditions for maximum biosorption rate of 85.2% and maximum capacity of 56.8 mg g-1 were found at pH of 5, adsorbent dosage of 1.5 g L-1 (dry weight), initial lead(II) concentration of 100 mg L-1, and contact time of 30 min at 30 °C. Biosorption isotherms were well fitted with Langmuir isotherm model. Mechanism analysis reveals that the lead(II) ions may exchange with sodium and potassium ions, and the hydroxyl, carbonyl and phosphate groups on the cell surface can chelate the lead(II) ions, therefore, surface adsorption play significant role in the biosorption process.
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Project description:Uranium is one of the most common radioactive contaminants in the environment. As a major nuclear material in production, environmental samples (like soil and groundwater) can provide signatures on uranium production activity inside the facility. Thus, developing a new and portable analytical technology for uranium in aqueous media is significant not only for environmental monitoring, but also for nonproliferation. In this work, a label-free method for the detection of uranyl (UO22+) ions is developed by monitoring the translocation of a peptide probe in a nanopore. Based on the difference in the number of peptide events in the absence and presence of uranyl ions, nanomolar concentration of UO22+ ions could be detected in minutes. The method is highly selective; micromolar concentrations of Cd2+, Cu2+, Zn2+, Ni2+, Pb2+, Hg2+, Th4+, Mg2+, and Ca2+ would not interfere with the detection of UO22+ ions. In addition, simulated water samples were successfully analyzed.
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Project description:The strength of hydrogen bonding to and structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared (DDIR) spectroscopy and large-angle X-ray scattering (LAXS), respectively. Anions are hydrated by accepting hydrogen bonds from the hydrating water molecules. The oxygen atom of the permanganate and perrhenate ions form weaker and longer hydrogen bonds to water than the hydrogen bonds in bulk water (i.e., they act as structure breakers), while the oxygen atoms of the chromate, dichromate, molybdate, tungstate, and hydrogenvanadate ions form hydrogen bonds stronger than those in bulk water (i.e., they act as structure makers). The oxometallate ions form one hydration shell distinguishable from bulk water as determined by DDIR spectroscopy and LAXS. The hydration of oxoanions results in X-O bond distances ca. 0.02 Å longer than those in unsolvated ions in the solid state not involved in strong bonding to counterions. The oxygens of oxoanions with a central atom from the second and third series in the periodic table and the hydrogenvanadate ion hydrogen bind three hydrating water molecules, while oxygens of oxoanions with a heavier central atom only form hydrogen bonds to two water molecules.
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Project description:The adsorption performance and mechanism of extracellular polymeric substances (EPS) extracted from Klebsiella sp. J1 for soluble Pb (II) were investigated. The maximum biosorption capacity of EPS for Pb (II) was found to be 99.5 mg g(-1) at pH 6.0 and EPS concentration of 0.2 g/L. The data for adsorption process satisfactorily fitted to both Langmuir isotherm and pseudo-second order kinetic model. The mean free energy E and activation energy Ea were determined at 8.22- 8.98 kJ mol(-1) and 42.46 kJ mol(-1), respectively. The liquid-film diffusion step might be the rate-limiting step. The thermodynamic parameters (ΔG(o), ΔH(o) and ΔS(o)) revealed that the adsorption process was spontaneous and exothermic under natural conditions. The interactions between EPS system and Pb (II) ions were investigated by qualitative analysis methods (i.e Zeta potential, FT-IR and EDAX). Based on the strong experimental evidence from the mass balance of the related elements participating in the sorption process, an ion exchange process was identified quantitatively as the major mechanism responsible for Pb (II) adsorption by EPS. Molar equivalents of both K(+) and Mg(2+) could be exchanged with Pb(2+) molar equivalents in the process and the contribution rate of ion exchange to adsorption accounted for 85.72% (Δmequiv = -0.000541).
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Project description:Understanding the factors that govern aqueous solubility of uranyl minerals is important for predicting uranium mobility in groundwater and for designing effective remediation strategies. The uranyl-containing minerals metaschoepite [UO3∙(2H2O)] and uranophane [Ca(UO2)2(SiO3OH)2·5H2O] were synthesized and evaluated in batch solubility experiments conducted in the presence of common groundwater ions: calcium, bicarbonate/carbonate, and dissolved silica. Solid-phase characterization revealed the expected structural and thermogravimetric properties of metaschoepite and uranophane. Metaschoepite solubility in carbonate-free water followed a u-shaped pH dependency with minimum solubility near pH 8.5; uranium concentrations at pH ≳ 8.5 were approximately equivalent to the reference value for safe drinking water established by the EPA (30 μg/L). With increasing bicarbonate/carbonate concentration (1 mM - 50 mM) the solubility of metaschoepite increased, presumably due to the formation of uranyl-carbonate complexes. However, the experimental concentrations of uranium were lower than concentrations predicted from accepted complexation constants. For uranophane, equilibrium uranium concentrations were < 75 μg/L at typical groundwater concentrations of calcium and dissolved silica (pH > 7). The diversity of uranyl minerals that possibly form in the presence of common groundwater species: Ca-Mg-Na-K-Si-bicarbonate/carbonate-sulfate-chloride, has not been fully explored with respect to understanding potential mineral transformations and impacts on uranium solubility and mobility.
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Project description:The mining industry generates huge amounts of wastewater, containing toxic heavy metals. Treatment to remove heavy metals is necessary and recent work has been focused on finding more environmentally friendly materials for removing heavy metals from wastewater. Biosorption can be an effective process for heavy metal removal from aqueous solutions. Our objectives were to investigate the removal of copper (II) from aqueous solutions using dead cells of Mesorhizobium amorphae CCNWGS0123 under differing levels of pH, agitation speed, temperature, initial copper concentration, biosorbent dose and contact time using flame atomic absorption spectroscopy for metal estimation. The maximum copper removal rate was achieved at pH 5.0, agitation speed 150×g, temperature 28°C and initial Cu (II) concentration of 100 mg L(-1). Maximum biosorption capacity was at 0.5 g L?¹ and equilibrium was attained within 30 min. Langmuir and Freundlich isotherms showed correlation coefficients of 0.958 and 0.934, respectively. Fourier transform-infrared spectroscopy (FT-IR) analysis indicated that many functional groups, such as O-H, N-H, C-H, C=O, -NH, -CN, C-N, C-O, amide -I, -II, -III and unsaturated alkenes, alkyls and aromatic groups on the cell surface were involved in the interaction between CCNWGS0123 and Cu. Scanning electron microscope and energy dispersive X-ray scanning results showed deformation, aggregation, and cell-surface damage due to the precipitation of copper on the cell surface. Dead cells of CCNWGS0123 showed potential as an efficient biosorbent for the removal of Cu²? from aqueous solutions.
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Project description:The present work investigated the ability of algal biomass Chlorella vulgaris to remove mercury from aqueous solutions. The mercury biosorption process was studied through batch experiments 35 °C temperature with regard to the influence of contact time, initial mercury concentration, pH and desorption. The maximum adsorption capacity was registered at pH 6. The adsorption conduct of Hg(II) was defined by pseudo second order well rather pseudo first order as the experimental data (qe) come to an agreement with the calculated value. The kinetics of adsorption was fast and a high capacity of adsorption occurred within only 90 min. The adsorption data were signified by many models but Langmuir (qmax = 42. mg g-1) & Freundlich fitted well having regression coefficients near to unity. The thermodynamic parameters were also suited well as negative value of free energy cope up to spontaneity, positive value of the randomness described by ΔS attributed to affinity of Hg+2 towards algal bioadsorbant and high positive value of heat of enthalpy designates that the adsorption process is expected due to robust interactions between the Hg(II) ions and various functional groups on surface of algal bioadsorbant. Field emission scanning electron microscopy integrated with energy dispersive X-ray spectroscopy analysis before and after adsorption of Hg(II) reveals the adsorption of metallic ions over the surface. FTIR study supported the existence of various functional groups (carboxylix, amines, hydroxyls, amides etc.) helped in adsorption. Continuous adsorption desorption experiments proved that algal cells was excellent biosorbents with potential for further development.
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Project description:In recent years, biosorption is being considered as an environmental friendly technology for the recovery of rare earth metals (REE). This study investigates the optimal conditions for the biosorption of neodymium (Nd) from an aqueous solution derived from hard drive disk magnets using green microalgae (Chlorella vulgaris). The parameters considered include solution pH, temperature and biosorbent dosage. Best-fit equilibrium as well as kinetic biosorption models were also developed. At the optimal pH of 5, the maximum experimental Nd uptakes at 21, 35 and 50°C and an initial Nd concentration of 250 mg/L were 126.13, 157.40 and 77.10 mg/g, respectively. Analysis of the optimal equilibrium sorption data showed that the data fitted well (R2 = 0.98) to the Langmuir isotherm model, with maximum monolayer coverage capacity (qmax) of 188.68 mg/g, and Langmuir isotherm constant (KL) of 0.029 L/mg. The corresponding separation factor (RL) is 0.12 indicating that the equilibrium sorption was favorable. The sorption kinetics of Nd ion follows well a pseudo-second order model (R2>0.99), even at low initial concentrations. These results show that Chlorella vulgaris has greater biosorption affinity for Nd than activated carbon and other algae types such as: A. Gracilis, Sargassum sp. and A. Densus.
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Project description:The present study investigated the biosorption capacity of live and dead cells of a novel Bacillus strain for chromium. The optimum biosorption condition was evaluated in various analytical parameters, including initial concentration of chromium, pH, and contact time. The Langmuir isotherm model showed an enhanced fit to the equilibrium data. Live and dead biomasses followed the monolayer biosorption of the active surface sites. The maximum biosorption capacity was 20.35 mg/g at 25 °C, with pH 3 and contact time of 50 min. Strain 139SI was an excellent host to the hexavalent chromium. The biosorption kinetics of chromium in the dead and live cells of Bacillus salmalaya (B. salmalaya) 139SI followed the pseudo second-order mechanism. Scanning electron microscopy and fourier transform infrared indicated significant influence of the dead cells on the biosorption of chromium based on cell morphological changes. Approximately 92% and 70% desorption efficiencies were achieved using dead and live cells, respectively. These findings demonstrated the high sorption capacity of dead biomasses of B. salmalaya 139SI in the biosorption process. Thermodynamic evaluation (ΔG⁰, ΔH⁰, and ΔS⁰) indicated that the mechanism of Cr(VI) adsorption is endothermic; that is, chemisorption. Results indicated that chromium accumulation occurred in the cell wall of B. salmalaya 139SI rather than intracellular accumulation.
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Project description:Many efforts have focused on the adsorption of metals from contaminated water by microbes. Synechococcus PCC7002, a major marine cyanobacteria, is widely applied to remove metals from the ocean's photic zone. However, its ability to adsorb cesium (Cs) nuclides has received little attention. In this study, the biosorption behavior of Cs(I) from ultrapure distilled water by living Synechococcus PCC7002 was investigated based on kinetic and isotherm studies, and the biosorption mechanism was characterized by Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, and three-dimensional excitation emission matrix fluorescence spectroscopy. Synechococcus PCC7002 showed extremely high tolerance to Cs ions and its minimal inhibitory concentration was 8.6 g/L. Extracellular polymeric substances (EPS) in Synechococcus PCC7002 played a vital role in this tolerance. The biosorption of Cs by Synechococcus PCC7002 conformed to a Freundlich-type isotherm model and pseudo-second-order kinetics. The binding of Cs(I) was primarily attributed to the extracellular proteins in EPS, with the amino, hydroxyl, and phosphate groups on the cell walls contributing to Cs adsorption. The biosorption of Cs involved two mechanisms: Passive adsorption on the cell surface at low Cs concentrations and active intracellular adsorption at high Cs concentrations. The results demonstrate that the behavior and mechanism of Cs adsorption by Synechococcus PCC7002 differ based on the Cs ions concentration.
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