共查询到20条相似文献,搜索用时 15 毫秒
1.
Gholamreza Ebrahimzadeh Rajaei Hosein Aghaie Karim Zare Mehran Aghaie 《Research on Chemical Intermediates》2013,39(8):3579-3594
Fine powder of Typha latifolia L. root was used for adsorption of copper and zinc ions from buffered and nonbuffered aqueous solutions. The adsorption reached equilibrium in 60 min. During this time, more than 90 % of the adsorption process was completed. The effect of initial pH, initial concentration of metal ion, and contact time was investigated in a batch system at room temperature. The optimum adsorption performance was observed at pH 5.00 and 4.25 for nonbuffered solutions of Cu(II) and Zn(II), respectively, while for buffered solutions it occurred at pH 6.00. The total metal uptake decreased on application of ammonium acetate buffer, from 37.35 to 17.00 mg g?1 and 28.80 to 9.90 mg g?1 for Cu(II) and Zn(II) solutions, respectively, with 100 mg L?1 initial concentration. The pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models were used to describe the adsorption kinetics. The experimental data followed the pseudo-second-order kinetic model. The biosorption equilibrium was well described by Langmuir and Freundlich isotherm models. 相似文献
2.
Synthesis and Crystal Structure of K2(HSO4)(H2PO4), K4(HSO4)3(H2PO4), and Na(HSO4)(H3PO4) Mixed hydrogen sulfate phosphates K2(HSO4)(H2PO4), K4(HSO4)3(H2PO4) and Na(HSO4)(H3PO4) were synthesized and characterized by X‐ray single crystal analysis. In case of K2(HSO4)(H2PO4) neutron powder diffraction was used additionally. For this compound an unknown supercell was found. According to X‐ray crystal structure analysis, the compounds have the following crystal data: K2(HSO4)(H2PO4) (T = 298 K), monoclinic, space group P 21/c, a = 11.150(4) Å, b = 7.371(2) Å, c = 9.436(3) Å, β = 92.29(3)°, V = 774.9(4) Å3, Z = 4, R1 = 0.039; K4(HSO4)3(H2PO4) (T = 298 K), triclinic, space group P 1, a = 7.217(8) Å, b = 7.521(9) Å, c = 7.574(8) Å, α = 71.52(1)°, β = 88.28(1)°, γ = 86.20(1)°, V = 389.1(8)Å3, Z = 1, R1 = 0.031; Na(HSO4)(H3PO4) (T = 298 K), monoclinic, space group P 21, a = 5.449(1) Å, b = 6.832(1) Å, c = 8.718(2) Å, β = 95.88(3)°, V = 322.8(1) Å3, Z = 2, R1 = 0,032. The metal atoms are coordinated by 8 or 9 oxygen atoms. The structure of K2(HSO4)(H2PO4) is characterized by hydrogen bonded chains of mixed HnS/PO4– tetrahedra. In the structure of K4(HSO4)3(H2PO4), there are dimers of HnS/PO4– tetrahedra, which are further connected to chains. Additional HSO4– tetrahedra are linked to these chains. In the structure of Na(HSO4)(H3PO4) the HSO4– tetrahedra and H3PO4 molecules form layers by hydrogen bonds. 相似文献
3.
Rokni SeyedEhsan Haji Seyed Mohammad Shirazi Reza Miralinaghi Mahsasadat Moniri Elham 《Research on Chemical Intermediates》2020,46(4):2247-2274
Research on Chemical Intermediates - The removal efficiency of two anionic dyes, namely direct red 81 (DR 81) and reactive blue 19 (RB 19), from aqueous solution was investigated through batch... 相似文献
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S.S. Tahir 《The Journal of chemical thermodynamics》2003,35(12):2003-2009
The adsorption behavior of Ni(II) onto bentonite was studied as a function of temperature under optimized conditions of shaking time, amount of adsorbent, pH, and concentration of the adsorbate. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were calculated from the slope and intercept of the linear plot of lgKD against 1/T. Analysis of adsorption results obtained at T=(298, 303, 313, and 323) K showed that the adsorption pattern on bentonite followed the Langmuir, Freundlich, and D-R isotherms. A flame atomic absorption spectrophotometer was used for measuring the concentration of Ni(II). 相似文献
6.
《Journal of solid state chemistry》1987,71(2):444-450
A new family of Nasicon-like zirconium phosphates of formula M0.5Zr2(PO4)3 with M = Ca, Cu, Sr, Cd or Pb has been described. The physical properties of the copper compound have been investigated in detail in which Cu2+ induces a Jahn-Teller distortion below 520°C. Crystal field, electron paramagnetic resonance, and magnetic data are consistent with an elongated octahedral surrounding of the Cu2+ ions. 相似文献
7.
Equilibrium studies of the sorption of Cu(II) ions onto chitosan 总被引:2,自引:0,他引:2
Chitosan is a polymer that can be obtained from the shells of seafood such as prawns, crabs, and lobsters. Chitosan has free amino groups, which can attract metal ions, and has been used as an adsorbent for the removal of metal ions from effluents. In this research, the sorption of copper ions from solution onto chitosan at two pHs has been investigated. DSC, TGA, surface area, SEM, and NMR studies have been used to report the pure physical states of chitosan and the chitosan-copper complex. The experimental isotherm data were analyzed using the Langmuir, Freundlich, and Redlich-Peterson equations. Correlation coefficients were determined for each isotherm analysis. Error functions have been used to determine the alternative single component parameters by nonlinear regression due to the inherent bias in using the correlation coefficient resulting from linearization. The error function method provided the best parameters for the isotherm equations in this system and is demonstrated for error comparison purposes. 相似文献
8.
Andrew D. Bond Sren P. V. Foghmoes Terence E. Warner 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(3):i21-i23
The title compound, Cu0.5Mn2.5(PO4)2, is a copper–manganese phosphate solid solution with the graftonite‐type structure, viz. (Mn,Fe,Ca,Mg)3(PO4)2. The structure has three distinct metal cation sites, two of which are occupied by MnII and one of which accommodates CuII. Incorporation of CuII into the structure distorts the coordination geometry of the metal cation site from five‐coordinate square‐pyramidal towards four‐coordinate flattened tetrahedral, and serves to contract the structure principally along the c axis. 相似文献
9.
M. Chakrabarty A. Batabyal M. S. Morales-Ríos P. Joseph-Nathan 《Monatshefte für Chemie / Chemical Monthly》1995,126(6-7):789-794
Summary Unambiguous1H and13C NMR assignments for 4(3H)-quinazolinones1–6 and their corresponding 4-thiones7–12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones1,2,4, and5. Thionation of the nucleophilic amides1–6 has been found to cause a distinct change in the13C chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.
Kernresonanzspektroskopie von 4(3H)-Chinazolinonen und 4(3H)-Chinazolinthionen
Zusammenfassung Die1H- und13C-NMR-Spektren der 4(3H)-Chinazolinone1–6 und ihrer entsprechenden 4-Thione7–12 wurden zugeordnet. Dabei zeigte sich, daß eine frühere Zuordnung der beiden benzoiden Kohlenstoffe (C-5 und C-8) der Chinazolinone1,2,4 und5 falsch war. Ersatz des Sauerstoffs durch Schwefel in den nukleophilen Amiden1–6 führt insbesondere für C-4, aber auch für C-4a, C-5 und C-8a zu einer deutlichen Änderung der chemischen Verschiebung. Heteronukleare Kopplungskonstanten über eine und über mehrere Bindungen wurden bestimmt.相似文献
10.
The use of a natural palygorskite clay for the removal of Pb(II) from aqueous solutions for different contact times, pHs of suspension, and amounts and particle sizes of palygorskite clay were investigated. The variations of the pH value of Pb(II) solutions on natural palygorskite in the adsorption process were determined. Batch adsorption kinetic experiments revealed that the adsorption of Pb(II) onto palygorskite clay involved fast and slow processes. It was found that the adsorption mechanisms in the lead/palygorskite system follow pseudo-second-order kinetics with a significant contribution from film diffusion. SEM observations demonstrated that an important interaction at the lead-granule interface occurred during the adsorption process. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms and the Langmuir model represents the adsorption process better than the Freundlich model. The maximum adsorption capacity of Pb(II) onto natural palygorskite was 104.28 mg g(-1). 相似文献
11.
Removal of Cu(II), Zn(II) and Co(II) ions from aqueous solutions by adsorption onto natural bentonite 总被引:1,自引:0,他引:1
In this study, the removal of Cu(II), Zn(II) and Co(II) ions from aqueous solutions using the adsorption process onto natural
bentonite has been investigated as a function of initial metal concentration, pH and temperature. In order to find out the
effect of temperature on adsorption, the experiments were conducted at 20, 50, 75 and 90 °C. For all the metal cations studied,
the maximum adsorption was observed at 20 °C. The batch method has been employed using initial metal concentrations in solution
ranging from 15 to 70 mg L−1 at pH 3.0, 5.0, 7.0 and 9.0. A flame atomic absorption spectrometer was used for measuring the heavy metal concentrations
before and after adsorption. The percentage adsorption and distribution coefficients (K
d) were determined for the adsorption system as a function of adsorbate concentration. In the ion exchange evaluation part
of the study, it is determined that in every concentration range, adsorption ratios of bentonitic clay-heavy metal cations
match to Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich (DKR) adsorption isotherm data, adding to that every cation
exchange capacity of metals has been calculated. It is shown that the bentonite is sensitive to pH changes, so that the amounts
of heavy metal cations adsorbed increase as pH increase in adsorbent-adsorbate system. It is evident that the adsorption phenomena
depend on the surface charge density of adsorbent and hydrated ion diameter depending upon the solution pH. According to the
adsorption equilibrium studies, the selectivity order can be given as Zn2+>Cu2+>Co2+. These results show that bentonitic clay hold great potential to remove the relevant heavy metal cations from industrial
wastewater. Also, from the results of the thermodynamic analysis, standard free energy ΔG
0, standard enthalpy ΔH
0 and standard entropy ΔS
0 of the adsorption process were calculated. 相似文献
12.
Cu4O12 Groups Built of Square Planar CuO4 Polygones in the Barium Vanadyl Oxocuprate(II) Phosphate Ba(VO)Cu4(PO4)4 Single crystals of Ba(VO)Cu4(PO4)4 have been prepared by solid state reactions just below the melting points of the reaction mixtures of BaP2O6, Cu3(PO4)2, CuO, V2O5 and V2O3 in evacuated closed quartz glas tubes. The compound crystallizes with tetragonal symmetry, Space group D? P4212, a = 9.560(2), c = 7.160(2) Å, Z = 2. Special and new features of the crystal structure are to each other isolated Cu4O12 and (VO)(PO4)4 groups. The crystal chemistry of the Cu4O12 groups is discussed with respect to other compounds containing out of plane connected square planar MO4 polygones. 相似文献
13.
Jovica Stojanovi Tamara ?or?evi Ljiljana Karanovi 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(11):i91-i94
During an investigation of the insufficiently known system M1O–M2O–X2O5–H2O (M1 = Cd2+, Sr2+ and Ba2+; M2 = Cu2+, Ni2+, Co2+, Zn2+ and Mg2+; X = P5+, As5+ and V5+), single crystals of the novel compound dicadmium copper(II) bis[phosphate(V)], Cd2Cu(PO4)2, were obtained. This compound belongs to a small group of compounds adopting a Cu3(PO4)2‐type structure and having the general formula M12M2(XO4)2 (M1/M2 = Cd2+, Cu2+, Mg2+ and Zn2+; X = As5+, P5+ and V5+). The crystal structure is characterized by the interconnection of infinite [Cu(PO4)2]n chains and [Cd2O10]n double chains, both extending along the a axis. Exceptional characteristics of this structure are its novel chemical composition and the occurrence of double chains of CdO6 polyhedra that were not found in related structures. In contrast to the isomorphous compounds, where the M1 cations are coordinated by five O atoms, the Cd atom is coordinated by six. The dissimilarity in the geometry of M1 coordination between Cd2Cu(PO4)2 and the isomorphous compounds is mostly due to the larger ionic radius of the Cd cation in comparison with the Cu, Mg and Zn cations. Sharing a common edge, two CdO6 polyhedra form Cd2O10 dimers. Each such dimer is bonded to another dimer sharing common vertices, forming [Cd2O10]n double chains in the [100] direction. The Cu atoms, located on an inversion centre (site symmetry ), form isolated CuO4 squares interconnected by PO4 tetrahedra, forming [Cu(PO4)2]n chains similar to those found in related structures. Conversely, the [Cd2O10]n double chains, which were not found in related structures, are an exclusive feature of this structure. 相似文献
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《Journal of Saudi Chemical Society》2014,18(6):792-801
Release of heavy metals into water as a result of industrial activities may pose a serious threat to the environment. The objective of this study is to assess the uptake of Cu2+ from aqueous solutions onto multi-walled carbon nanotubes (MWCNT). The potential of the t-MWCNT to remove Cu2+ cations from aqueous solutions was investigated in batch reactor under different experimental conditions. The processing parameters such as initial concentration of Cu2+ ions, temperature, and adsorbent mass were also investigated. Copper uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) models. In addition, the adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 12.34 mg/g of Cu2+ cations on t-MWCNT. Various thermodynamic parameters, such as ΔG0, ΔH0 and ΔS0 were calculated. The thermodynamics of Cu2+ cations adsorption onto t-MWCNT system pointed at spontaneous and endothermic nature of the process. Using the second-order kinetic constants, the activation energy of adsorption (Ea) was determined as 27.187 kJ/mol according to the Arrhenius equation. 相似文献
17.
M. Beaurain R. Astier A. van der Lee P. Armand 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):i5-i8
The structures of tripotassium digallium tris(phosphate), K3Ga2(PO4)3, and trisodium gallium bis(phosphate), Na3Ga(PO4)2, have different irregular one‐dimensional alkali ion‐containing channels along the a axis of the orthorhombic and triclinic unit cells, respectively. The anionic subsystems consist of vortex‐linked PO4 tetrahedra and GaO4 tetrahedra or GaO5 trigonal bipyramids in the first and second structure, respectively. 相似文献
18.
Algarra AG Fernández-Trujillo MJ Hernández-Molina R Basallote MG 《Dalton transactions (Cambridge, England : 2003)》2011,40(34):8589-8597
The kinetics of reaction between the [Mo(3)M'S(4)(H(2)O)(10)](4+) clusters (M' = Pd, Ni) and H(3)PO(3) has been studied in 4.0 M Hpts/Lipts (pts(-) = p-toluenesulfonate). For both complexes there is an initial kinetic step with small absorbance changes that corresponds to substitution of the water coordinated to Pd by a molecule of tetrahedral H(3)PO(3). For the Pd complex, tautomerization of H(3)PO(3) occurs in a slower kinetic step with much larger absorbance changes; it leads to formation of [Mo(3)Pd(pyr-H(3)PO(3))S(4)(H(2)O)(9)](4+) in which H(3)PO(3) adopts a pyramidal structure, but the process is not as favored as for H(3)PO(2). The kinetics of this second step is independent of the concentration of H(3)PO(3) but dependent on the concentration of Hpts on the supporting electrolyte. For the Ni complex, the second step is severely hindered and its kinetics could not be studied. DFT calculations indicate that tautomerization of H(3)PO(3) is expected to be less favoured than that of H(3)PO(2), both processes being less favored at the Ni cluster than at its Pd analogue. With regard to the tautomerization mechanism, the calculations indicate that the mechanism previously proposed for H(3)PO(2) can be the same for H(3)PO(3), although the initial H-shift can also occur through a protonation-deprotonation sequence with participation of external protons instead of a second molecule of the phosphorus acid. TD-DFT studies have been also carried out to understand the similarity between the spectra of the starting complex and the reaction intermediate formed in the first kinetic step as well as the large spectral changes associated to the tautomerization process. Although it contains contributions from several transitions, the intense band observed for clusters containing coordinated pyr-H(3)PO(3) involves essentially ligand-to-metal charge-transfer (LMCT) transitions. 相似文献
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《The Journal of chemical thermodynamics》2007,39(3):488-492
The Freundlich and Langmuir isotherms were used to describe the biosorption of Cu(II), Pb(II), and Zn(II) onto the saltbush leaves biomass at 297 K and pH 5.0. The correlation coefficients (R2) obtained from the Freundlich model were 0.9798, 0.9575, and 0.9963 for Cu, Pb, and Zn, respectively, while for the Langmuir model the R2 values for the same metals were 0.0001, 0.1380, and 0.0088, respectively. This suggests that saltbush leaves biomass sorbed the three metals following the Freundlich model (R2 > 0.9575). The KF values obtained from the Freundlich model (175.5 · 10−2, 10.5 · 10−2, and 6.32 · 10−2 mol · g−1 for Pb, Zn, and Cu, respectively), suggest that the metal binding affinity was in the order Pb > Zn > Cu. The experimental values of the maximal adsorption capacities of saltbush leaves biomass were 0.13 · 10−2, 0.05 · 10−2, and 0.107 · 10−2 mol · g−1 for Pb, Zn, and Cu, respectively. The negative ΔG∘ values for Pb and the positive values for Cu and Zn indicate that the Pb biosorption by saltbush biomass was a spontaneous process. 相似文献
20.
《The Journal of chemical thermodynamics》2007,39(6):862-865
A synthetic graft copolymer of cross-linked starch/acrylonitrile was used as an adsorbent for the removal of Cu(II) ions from an aqueous solution of copper nitrate hexahydrate Cu(NO3)2 · 6H2O at different temperatures and fixed pH. The amount adsorbed increased with increasing concentration of Cu(II) ions and decreasing temperature. The length of time taken to reach equilibrium of the adsorption of Cu(II) ions was the same at all temperatures tested. Kinetics studies showed that the adsorption process obeyed first-order reversible kinetics and the adsorption isotherms followed the Freundlich model. Furthermore, the thermodynamic parameters, i.e. standard free energy (ΔG∘), standard enthalpy (ΔH∘), and standard entropy (ΔS∘), of the adsorption process were calculated and the results are discussed in detail. 相似文献