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1.
Tetraethylenepentamine-modified sugarcane bagasse (SCB) was prepared to improve its adsorption capacity and selectivity toward Cu2+. Adsorption performances of the modified sorbent for Cu2+ were studied in batch system. Separation of Cu2+ from Pb2+ by the modified sorbent fixed-bed column were studied under dynamic system with initial molar concentration ratio \(\left( {C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}} } \right)\) ranging from 1:1 to 1:100. The amount of Cu2+ and Pb2+ adsorbed on the saturated column was calculated by the elution curve. Batch experimental results showed that the adsorption capacity of the sorbent for Cu2+ increased from 0.12 to 0.21 mmol g?1 after modification. Dynamic adsorption results showed that the modified SCB had higher adsorption affinity toward Cu2+ than Pb2+. 0.07 mmol g?1 of adsorbed Pb2+ was pushed off by Cu2+ during the competitive adsorption process at \(C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}} = {\text{1:1}}.\) The breakthrough curves and adsorption kinetics of Cu2+ in the column could be fitted well by the Yoon–Nelson and modified Yoon–Nelson model, respectively. According to the elution curve, the amount of Cu2+ adsorbed on the fixed-bed column were 0.16, 0.16 and 0.15 mmol g?1, while that of Pb2+ were 0.0016, 0.0051 and 0.0094 mmol g?1 when \(C_{0}^{\text{Cu}} /C_{0}^{\text{Pb}}\) increased from 1:1 to 1:10 and 1:100. Cu2+ could be selectively adsorbed and separated from Pb2+ by using the modified sorbent fixed-bed column.  相似文献   

2.
The problem associated with multi-metals contaminated soils has generated increasingly more attention. Thus, it is necessary within the field to study the mutual influence of environmental factors on competitive adsorption. The majority of studies carried out to date have concentrated on the variation of adsorption capacity or the removal efficiency, with only a single factor changed (including pH, ionic strength, and metal concentration). However, the interaction effect among various environmental factors was ignored in these studies. The purpose of this study was mainly aimed toward the investigation of the interaction of two influential factors, as well as the influential degree of each factor (such as the initial pH, ionic strength, initial metal concentration, and the competitive metal concentration) on competitive adsorption using the response surface method. These results demonstrated that the influential degree of each factor studied on the competitive adsorption of Zn2+ and Cd2+ followed the trend of having the initial concentration of the target metal?>?initial pH?>?concentration of competitive metal?>?ionic strength. When the metal concentration was held constant, we found that the competitive adsorption of Zn2+ initially increased, followed by a decrease with increasing initial pH. However, this was found to change minimally with increasing ionic strength. When the initial pH or ionic strength was held constant, the competitive ability was observed to increase with increasing Zn2+ concentration. However, with increasing Zn2+ or Cd2+ concentrations, the variation degree of the competitive adsorption was found to become smaller. These results provide novel information toward a better understanding of the effect of multifactors on the competitive adsorption of Zn2+ and Cd2+.  相似文献   

3.
The objective of the present study is to evaluate the absorption efficacy of H. fusiformis biochar (HFB) for the removal of phenol and heavy metals from single and mixed solute systems of these species under different experimental conditions. The effects of contact time, pH change, initial phenol concentration, and heavy metal concentration on the adsorption capacity of HFB were investigated. The kinetics and equilibrium models of sorption of the components of the single and mixed solute systems on HFB were also studied. The experimental data were fitted to kinetic and equilibrium models. The batch experiments revealed that 360 min of contact time was sufficient to achieve equilibrium for the adsorption of both phenol and heavy metals. The adsorption of phenol and nickel by HFB followed the pseudo-second-order kinetic model, which was quite adequate for describing the adsorption mechanism. The equilibrium data for the adsorption of phenol and heavy metals fit well to the Langmuir model with regression coefficients of R 2 > 0.819. The maximum Langmuir adsorption capacities were 10.39, 12.13, 22.25, 2.24, 2.89, and 22.03 mg/g for phenol, Ni2+, Zn2+, Cu2+, Pb2+, and Cd2+, respectively. Moreover, HFB exhibited optimal sorption under slightly acidic conditions at pH 6. The HFB used in the present study exhibited higher adsorption capacity for the removal of phenol and heavy metals from aqueous solutions compared to documented sorbents. These results demonstrate that HFB is potentially useful for alleviating the harmful effects of phenol and heavy metal in wastewater treatment systems.  相似文献   

4.
Novel bionanocomposites, S. cerevisiae–AgNPs, were synthesized by in situ formation of AgNPs on S. cerevisiae surface using fulvic acids as reductants under simulated sunlight. S. cerevisiae–AgNPs were characterized using UV–Vis spectroscopy, scanning electron microscope, transmission electron microscope and Fourier transform infrared spectroscopy. These analyses showed that AgNPs were distributed on the surface of S. cerevisiae. The application of S. cerevisiae–AgNPs in bacteria killing and heavy metal removal was studied. S. cerevisiae–AgNPs effectively inhibited the growth of E. coli with increasing concentrations of S. cerevisiae–AgNPs. E. coli was killed completely at high concentration S. cerevisiae–AgNPs (e.g., 100 or 200 µg mL?1). S. cerevisiae–AgNPs as excellent heavy metal absorbents also have been studied. Using Cd2+ as model heavy metal, batch experiments confirmed that the adsorption behavior fitted the Langmuir adsorption isotherms and the Cd2+ adsorption capacity of S. cerevisiae–AgNPs was 15.01 mg g?1. According to adsorption data, the kinetics of Cd2+ uptake by S. cerevisiae–AgNPs followed pseudo second-order kinetic model. Moreover, S. cerevisiae–AgNPs possessed ability of different heavy metals’ removal (e.g., Cr5+, As5+, Pb2+, Cu2+, Mn2+, Zn2+, Hg2+, Ni2+). The simulated contaminated water containing E. coli, Cd2+ and Pb2+ was treated using S. cerevisiae–AgNPs. The results indicated that the bionanocomposites can be used to develop antibacterial agents and bioremediation agents for water treatment.  相似文献   

5.
A novel complex continuous system of solid solutions involving vauquelinite Pb2Cu(CrO4)(PO4)(OH), bushmakinite Pb2Al(VO4)(PO4)(OH), ferribushmakinite Pb2Fe3+(VO4)(PO4)(OH), and a phase with the endmember formula Pb2Cu(VO4)(PO4)(H2O) or Pb2Cu(VO4)(РО3ОН)(ОН) is studied based on samples from the oxidation zone of the Berezovskoe, Trebiat, and Pervomaisko-Zverevsky deposits in the Urals, Russia. This is the first natural system in which chromate and vanadate anions show a wide range of substitutions and the most extensive solid solution system involving (CrO4)2– found in nature. The major couple substitution is Cr6+ + Cu2+ ? V5+ + M3+, where M = Fe, Al. The correlation coefficients calculated from 125 point analyses are: 0.96 between V and (Fe + Al), 0.96 between Cr and (Cu + Zn),–0.96 between V and (Cu + Zn),–0.97 between Cr and (Fe + Al), and–0.97 between (Fe + Al) and (Cu + Zn). The substitutions V5+ ? Cr6+ (correlation coefficient–0.98) and to a lesser extent P5+ ? As5+ (correlation coefficient–0.86) occur at two types of tetrahedral sites, whereas the metal–nonmetal/metalloid substitutions, i.e., V or Cr for P or As, are minor. The substitution Fe3+ ? Al3+ is also negligible in this solid solution system.  相似文献   

6.
Because of their physicochemical properties, biochars can be used as sorption materials for removal of toxic substances. The purpose of the present study was to determine whether biochar obtained from cones of larch (Larix decidua Mill. subsp. decidua) and spruce (Picea abies L. H. Karst) could be used as a sorbent for Cd2+, Pb2+ and Co2+ in aqueous solutions. So far, this feedstock had not been tested in this respect. The material was subjected to pyrolysis at 500 and 600 °C for the duration of 5, 10 and 15 min. The obtained pyrolysates were found to differ in terms of pH and the contents of the essential macroelements. The different values of these parameters were determined for varying temperature, duration of the pyrolysis process and type of feedstock. Sorption capacities of the biochars for removal of Cd2+, Pb2+ and Co2+ were examined using simulated contamination of aqueous solutions with salts of these metals. The findings showed the highest, nearly complete, removal for Pb2+ were maximum 99.7%, and almost three times lower value for Cd2+ and Co2+ (respectively, 35.7 and 24.8%). It was demonstrated that pyrolysis of conifer cones produced optimum sorption capacities when the process was conducted at a temperature of 500 °C for the duration of 5 min. It was shown that products of spruce cone pyrolysis were characterized by better sorption capacity in comparison with products of larch cone pyrolysis. The properties of conifer cone biochar create the possibility of using it as an adsorbent in water and wastewater treatment as well as in production of filters and activated carbon.  相似文献   

7.
Biosorption is a promising technology for the removal of heavy metals from industrial wastes and effluents. In the present study, biosorption of Pb2+, Cu2+, Fe2+ and Zn2+ onto the dried biomass of Eucheuma denticulatum (Rhodophyte) was investigated as a function of solution pH, contact time, temperature and initial metal ion concentration. The experimental data were evaluated by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The sorption isotherm data followed Langmuir and Freundlich models, and the maximum Langmuir monolayer biosorption capacity was found as 81.97, 66.23, 51.02 and 43.48 mg g?1 for Pb2+, Cu2+, Fe2+ and Zn2+, respectively. The sorption kinetic data followed pseudo-second-order and intraparticle diffusion models. Thermodynamic study revealed feasible, spontaneous and endothermic nature of the sorption process. Fourier transform infrared analysis showed the presence of amine, aliphatic, carboxylate, carboxyl, sulfonate and ether groups in the cell wall matrix involved in metal biosorption process. A total of nine error functions were applied in order to evaluate the best-fitting models. We strongly suggest the analysis of error functions for evaluating the fitness of the isotherm and kinetic models. The present work shows that E. denticulatum can be a promising low-cost biosorbent for removal of the experimental heavy metals from aqueous solutions. Further study is warranted to evaluate its potential for the removal of heavy metals from the real environment.  相似文献   

8.
Zinclipscombite, a new mineral species, has been found together with apophyllite, quartz, barite, jarosite, plumbojarosite, turquoise, and calcite at the Silver Coin mine, Edna Mountains, Valmy, Humboldt County, Nevada, United States. The new mineral forms spheroidal, fibrous segregations; the thickness of the fibers, which extend along the c axis, reaches 20 μm, and the diameter of spherulites is up to 2.5 mm. The color is dark green to brown with a light green to beige streak and a vitreous luster. The mineral is translucent. The Mohs hardness is 5. Zinclipscombite is brittle; cleavage is not observed; fracture is uneven. The density is 3.65(4) g/cm3 measured by hydrostatic weighing and 3.727 g/cm3 calculated from X-ray powder data. The frequencies of absorption bands in the infrared spectrum of zinclipscombite are (cm?1; the frequencies of the strongest bands are underlined; sh, shoulder; w, weak band) 3535, 3330sh, 3260, 1625w, 1530w, 1068, 1047, 1022, 970sh, 768w, 684w, 609, 502, and 460. The Mössbauer spectrum of zinclipscombite contains only a doublet corresponding to Fe3+ with sixfold coordination and a quadrupole splitting of 0.562 mm/s; Fe2+ is absent. The mineral is optically uniaxial and positive, ω = 1.755(5), ? = 1.795(5). Zinclipscombite is pleochroic, from bright green to blue-green on X and light greenish brown on Z (X > Z). Chemical composition (electron microprobe, average of five point analyses, wt %): CaO 0.30, ZnO 15.90, Al2O3 4.77, Fe2O3 35.14, P2O5 33.86, As2O5 4.05, H2O (determined by the Penfield method) 4.94, total 98.96. The empirical formula calculated on the basis of (PO4,AsO4)2 is (Zn0.76Ca0.02)Σ0.78(Fe 1.72 3+ Al0.36)Σ2.08[(PO4)1.86(AsO4)0.14]Σ2.00(OH)1. 80 · 0.17H2O. The simplified formula is ZnFe 2 3+ (PO4)2(OH)2. Zinclipscombite is tetragonal, space group P43212 or P41212; a = 7.242(2) Å, c = 13.125(5) Å, V = 688.4(5) Å3, Z = 4. The strongest reflections in the X-ray powder diffraction pattern (d, (I, %) ((hkl)) are 4.79(80)(111), 3.32(100)(113), 3.21(60)(210), 2.602(45)(213), 2.299(40)(214), 2.049(40)(106), 1.663(45)(226), 1.605(50)(421, 108). Zinclipscombite is an analogue of lipscombite, Fe2+Fe 2 3+ (PO4)2(OH)2 (tetragonal), with Zn instead of Fe2+. The mineral is named for its chemical composition, the Zn-dominant analogue of lipscombite. The type material of zinclipscombite is deposited in the Mineralogical Collection of the Technische Universität Bergakademie Freiberg, Germany.  相似文献   

9.
Sized aggregates of glasses (47–84 wt% SiO2) were fused from igneous-derived cohesive fault rock and igneous rock, and step-heated from ~400 to >1,200 °C to obtain their 39Ar diffusion properties (average E=33,400 cal mol?1; D o=4.63×10?3 cm2 s?1). At T<~1,000 °C, glasses containing <~69 wt% SiO2 and abundant network-forming cations (Ca, Fe, Mg) reveal moderate to strong non-linear increases in D and E, reflecting structural modifications as the solid transitions to melt. Extrapolation of these Arrhenius properties down to typical geologic T-t conditions could result in a 1.5 log10 unit underestimation in the diffusion rate of Ar in similar materials. Numerical simulations based upon the diffusion results caution that some common geologic glasses will likely yield 40Ar/39Ar cooling ages rather than formation ages. However, if cooling rates are sufficiently high, ambient temperatures are sufficiently low (e.g., <65–175 °C), and coarse particles (e.g., radius (r) >~1 mm) are analyzed, glasses with compositions similar to ours may preserve their formation ages.  相似文献   

10.
The crystal structure of Pb6Bi2S9 is investigated at pressures between 0 and 5.6 GPa with X-ray diffraction on single-crystals. The pressure is applied using diamond anvil cells. Heyrovskyite (Bbmm, a = 13.719(4) Å, b = 31.393(9) Å, c = 4.1319(10) Å, Z = 4) is the stable phase of Pb6Bi2S9 at ambient conditions and is built from distorted moduli of PbS-archetype structure with a low stereochemical activity of the Pb2+ and Bi3+ lone electron pairs. Heyrovskyite is stable until at least 3.9 GPa and a first-order phase transition occurs between 3.9 and 4.8 GPa. A single-crystal is retained after the reversible phase transition despite an anisotropic contraction of the unit cell and a volume decrease of 4.2%. The crystal structure of the high pressure phase, β-Pb6Bi2S9, is solved in Pna2 1 (a = 25.302(7) Å, b = 30.819(9) Å, c = 4.0640(13) Å, Z = 8) from synchrotron data at 5.06 GPa. This structure consists of two types of moduli with SnS/TlI-archetype structure in which the Pb and Bi lone pairs are strongly expressed. The mechanism of the phase transition is described in detail and the results are compared to the closely related phase transition in Pb3Bi2S6 (lillianite).  相似文献   

11.
Vitis vinifera (grape) leaf litter, an abundant agricultural waste in South Africa was chemically modified with H3PO4 and carbonized for use as biosorbent. Characterization and the potential application of the adsorbent in simultaneous removal of 4-nitrophenol and 2-nitrophenol from aqueous solutions were investigated. The adsorbent was characterized using FTIR, SEM and EDX elemental microanalysis. The EDX and FTIR analysis revealed the presence of surface oxygen moieties capable of binding to adsorbate molecules while the SEM micrographs showed the development of pores and cavities in the adsorbent. Batch adsorption experiments were conducted at a varying contact time, adsorbent dosage, pH and initial adsorbate concentration to investigate optimal conditions. The maximum adsorption capacity of the adsorbent was 103.09 and 103.10 mg/g for 4-nitrophenol and 2-nitrophenol, respectively. The adsorption process was best fitted into Freundlich isotherm while the adsorption kinetics followed a pseudo-second-order model. Liquid film and intra-particle diffusion contributed to the adsorption process. Thermodynamic parameters of ΔG°, ΔH° and ΔS° were evaluated. The adsorption was exothermic, feasible and spontaneous. The results suggest a possible application of grape leaf litter as a precursor for activated carbon and for cheaper wastewater treatment technologies.  相似文献   

12.
Single crystals of B2O3 are needed for the precise determination of the refractive indices used to calculate the electronic polarizability α of 3-coordinated boron. The α(B) values in turn are used to predict mean refractive indices of borate minerals. Since the contribution of boron to the total polarizability of a mineral is very low, the synthetic compound B2O3 represents an ideal model system because of its high molar content of boron. Millimeter-sized crystals were synthesized at 1 GPa in a piston-cylinder apparatus. The samples were heated above the liquidus (800 °C), subsequently cooled at 15 °C/h to 500 °C and finally quenched. The refractive indices were determined by the immersion method using a microrefractometer spindle stage. The refractive indices n o = 1.653 (3) and n e = 1.632 (3) correspond to a total polarizability for B2O3 of α = 4.877 Å3. These values were used to determine the electronic polarizability of boron of α(B) = 0.16 Å3. Although the surface of the B2O3 crystals was coated with a hydrous film immediately after being exposed to air, its bulk crystallinity is retained for a period of at least 2 months.  相似文献   

13.
Yemeni natural zeolite was characterized by XRD, SEM, FTIR and XRF as well as its applicability as a sorbent material for Cd2+ ions in aqueous solutions. The zeolitic sample is clinoptilolite-K of heulandite group with intermediate Si/Al ratio. The removal% of Cd2+ by natural clinoptilolite was investigated as a function of contact time, zeolite dose, pH and initial concentration of Cd2+ ions. Kinetic experiments indicated that sorption of Cd2+ follows two steps: rapid ion exchange process on the outer surface is followed by slow adsorption process on the inner surface of clinoptilolite. The equilibrium was attained after 120 min, and the results were fitted well with pseudo-second order and Elovich kinetic models. The Cd2+ removal% is strongly dependent on pH value and increases with the increasing pH value. Equilibrium sorption isotherm of Cd2+ by clinoptilolite was described well using the Langmuir, Freundlich, and Temkin isotherms models. However, the data relatively well fitted with Freundlich model (R 2 = 0.97) rather than by the other models. Response surface methodology in conjunction with central composite rotatable statistical design was used to optimize the sorption process. The model F-value indicated the high significance of second-order polynomial model to represent the interaction between the operating parameters. From the Design Expert’s optimization function, the predicted optimum conditions for maximum removal% of Cd2+ (80.77%) are 116 min contact time, 0.27 gm dose, and pH 7 at an initial Cd2+ concentration of 25 mg/L.  相似文献   

14.
The local structures and the g factors g // and g ⊥ for the isoelectronic 3d9 ions Cu2+ and Ni+ in CdS are theoretically investigated from the perturbation formulas of these parameters for a 3d9 ion under trigonally distorted tetrahedral environments. In consideration of significant covalency of the [MS4] combinations (M = Cu and Ni), the ligand orbital and spin–orbit coupling contributions are taken into account using the cluster approach. Based on the studies, the substitutional impurity Cu2+ (or Ni+) on Cd2+ site is found to undergo a small inward displacement 0.026 Å (or a slight outward shift 0.017 Å) towards (or away from) the ligand triangle along C 3 axis. The theoretical g factors for both ions based on the above impurity displacements are in good agreement with the experimental data.  相似文献   

15.
Removal of dyes by low-cost adsorbents is an effective method in wastewater treatment. Iranian natural clays were determined to be effective adsorbents for removal of a basic dye (methylene blue) from aqueous solutions in batch processes. Characterizations of the clays were carried out by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis and field-emission scanning electron microscopy. Effects of the operational parameters such as adsorbent dosage, initial dye concentration, solution pH and temperature were investigated on the adsorption performance. Adsorption isotherms like Langmuir, Freundlich and Temkin were used to analyze the adsorption equilibrium data and Langmuir isotherm was the best fit. Adsorption kinetics was investigated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models and the results showed that the adsorption system conforms well to the pseudo-second-order model. The thermodynamic parameters of adsorption (ΔS°, ΔH° and ΔG°) were obtained and showed that the adsorption processes were exothermic.  相似文献   

16.
Acacia nilotica was used for the adsorption of Reactive Black 5 (RB5) dye from an aqueous solution. Both the raw and activated (with H3PO4) carbon forms of Acacia nilotica (RAN and ANAC, respectively) were used for comparison. Various parameters (including dye concentration, contact time, temperature, and pH) were optimized to obtain the maximum adsorption capacity. RAN and ANAC were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The maximum experimental adsorption capacities for RAN and ANAC were 34.79 and 41.01 mg g?1, respectively, which agreed with the maximum adsorption capacities predicted by the Langmuir, Freundlich, and Dubinin–Radushkevich equilibrium isotherm models. The adsorption data of ANAC showed a good fit to the isotherm models based on the coefficient of determination (R 2): Langmuir type II (R 2 = 0.99) > Freundlich (R 2 = 0.9853) > Dubinin–Radushkevich (R 2 = 0.9659). This result suggested monolayer adsorption of RB5 dye. The adsorption of RB5 dye followed pseudo-second-order kinetics. The RAN adsorbent reflected an exothermic reaction (enthalpy change, ΔH = ?0.006 kJ mol?1) and increased randomness (standard entropy change, ΔS = 0.038 kJ mol?1) at the solid–solution interface. In contrast, ANAC reflected both exothermic [?0.011 kJ mol?1 (303–313 K)] and endothermic [0.003 kJ mol?1 (313–323 K)] reactions. However, the ΔS value of ANAC was lower when the RB5 adsorption increased from 313 to 323 K. The negative values for the Gibbs free energy change at all temperatures indicated that the adsorption of RB5 dye onto RAN and ANAC was spontaneous in the forward direction.  相似文献   

17.
The crystal structure of a new compound, (H3O)[(UO2)(SeO4)(SeO2OH)] (monoclinic, P21/n, a = 8.6682(19), b = 10.6545(16), c = 9.846(2) Å, β = 97.881(17)°, V = 900.7(3) Å3), was solved by direct methods and refined to R 1 = 0.050. The structure contains two symmetrically different Se atoms. The Se1 site is coordinated by three O atoms as is characteristic of Se4+ cations. The Se2 site is coordinated by four O atoms and forms selenate anion SeO 4 2? . The structure is based on selenite-selenate sheets [(UO2)(SeO4)(SeO2OH)]? linked by the interlayer H3O? ions. The sheets are parallel to (101). The structure is compared to that of schmiederite, Pb2Cu2(SeO3)(SeO4)(OH)4.  相似文献   

18.
Heavy metal ions (Pb2+, Cd2+, Ni2+, and Zn2+) were biosorbed by brown seaweed (Hizikia fusiformis), which was collected from Jeju Island of South Korea. The metal adsorption capacity of H. fusiformis improved significantly by washing with water or by base or acid treatments. The maximum sorption by NaOH-pretreated biomass was observed near a slightly acidic pH (pH 4?6) for Pb2+, Cd2+, Ni2+, and Zn2+. This result suggests that the treatment of H. fusiformis biomass with NaOH helped increase the functional forms of carboxylate ester units. Kinetic data showed that the biosorption occurred rapidly during the first 60 min, and most of the heavy metals were bound to the seaweed within 180 min. The maximum metal adsorption capacities assumed by a Langmuir model were on the order of Pb2+ > Cd2+ > Ni2+ > Zn2+. Equilibrium adsorption data for the heavy metal ions could fit well in the Langmuir model with regression coefficients R 2 > 0.97.  相似文献   

19.
The crystal structure of a new compound Zn(SeO4)(H2O)2 (orthorhombic, Pbca, a = 9.0411(13), b = 10.246(2), c = 10.3318(15) Å, V = 957.1(3) Å3) has been solved by direct methods and refined to R 1 = 0.033 on the basis of 1076 observed reflections with |F hkl | ≥ 4σ|F hkl |. The structure contains one independent Zn2+ cation coordinated by two water molecules and four oxygen atoms of selenate group. The only independent (SeO4)2? tetrahedral oxoanion is tetradentate, sharing its corners with four adjacent [Zn2+O2(H2O4)]2+ octahedrons. The structure can be described as consisting of heteropolyhedral sheets parallel to the (001) plane and linked together into a three-dimensional network. The compound belongs to the variscite structure type and is the first structurally characterized selenate of this group.  相似文献   

20.
This paper investigates the potential of alginate-immobilised Chlorella sorokiniana for removing Cu2+, Ni2+ and Cd2+ ions from drinking water solutions. The effects of initial metal concentrations, contact times and temperatures on the biosorptions and removal efficiencies of the tested metals were investigated at initial pH values of 5, and pH effects were studied within the range of 3–7. When studying the effects of initial metal concentrations, the highest experimental removal yields achieved for Cu2+, Ni2+ and Cd2+ ions were 97.10, 50.94 and 64.61 %, respectively. The maximum biosorption capacities obtained by the Langmuir isotherm model for the biosorptions of Cu2+, Ni2+ and Cd2+ ions by alginate-immobilised C. sorokiniana were found to be 179.90, 86.49 and 164.50 mg/g biosorbent, respectively. The experimental data followed pseudo-second-order kinetics. At an initial metal concentration of 25 mg/L, immobilised algae could be used in at least 5 successive biosorption–desorption cycles. SEM and EDS analyses revealed that the metals bonded to the biosorbent. Bi- and multi-metal systems of Cu2+, Ni2+ and Cd2+ were investigated at initial metal concentrations of 30, 50 and 100 mg/L. The removal of Cd2+ as well as Ni2+ in such systems was negatively affected by the presence of Cu2+. The removal efficiency for Cu2+ in multi-metal systems decreased by 5–7 %, whilst in the cases of Cd2+ and Ni2+ the efficiencies decreased by up to 30 %. Nevertheless, the results obtained show that alginate-immobilised C. sorokiniana can efficiently remove the metals tested from polluted drinking water sources.  相似文献   

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