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Journal articles on the topic 'Oxalate ions'

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Published: 4 June 2021
Last updated: 2 February 2022

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1

Gavris, Georgeta, Oana Stanasel, Rodica Pode, Marcela Stoia, and Virgil Chitac. "Study upon the Recuperative Purging of Nickel and Cobalt Ions from Residual Solutions by Means of Chemical Precipitation." Revista de Chimie 59, no. 1 (February 9, 2008): 61–64. http://dx.doi.org/10.37358/rc.08.1.1708.

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The study introduces a cleaning method of waste waters with nickel and cobalt ions content, by the precipitation of these ions as oxalates. The aim of the study is to establish the optimum conditions for a high degree of a metal recovery like nickel oxalate or cobalt oxalate, due to the low value of their products of solubility. The parameters studied were: pH, excess of reactant reagents, concentration of ions and temperature. The crystalline form of the obtained products corresponds to: NiC2O4�2H2O and CoC2O4�2H2O and extraction degree of metals was around 99%.
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2

Hind, A. R., S. K. Bhargava, W. Van Bronswijk, S. C. Grocott, and S. L. Eyer. "On the Aqueous Vibrational Spectra of Alkali Metal Oxalates." Applied Spectroscopy 52, no. 5 (May 1998): 683–91. http://dx.doi.org/10.1366/0003702981944355.

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Fourier transform infrared attenuated total reflectance and Fourier transform Raman spectra of the series of aqueous alkali metal oxalates—lithium oxalate (Li2C2O4), sodium oxalate (Na2C2O4), potassium oxalate (K2C2O4), rubidium oxalate (Rb2C2O4), and cesium oxalate (Cs2C2O4)—are presented for the first time. Fourier transform Raman spectra of the solid oxalates are also presented for the first time. The solid and aqueous oxalate ions are assumed to possess D2 h and D2 d symmetry, respectively, and the assignment of fundamental vibrational modes is made accordingly. The effect of increasing alkali metal ion concentration on the aqueous spectra of these oxalates is also reported. Spectral changes are explained in terms of the ability of the respective alkali metal cations to interact with the oxalate anion in solution. It is proposed that these differences arise because the alkali metal cations associate with the aqueous oxalate anions to varying degrees, depending upon the nature of the cation. The extent of the binding is found to decrease down the alkali metal series (Li > Na > K > Rb > Cs). Similar results obtained for the tetramethylammonium cation [(CH3)4N+] suggest that it is a softer cation than cesium.
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3

Puzan, Anna N., Vyacheslav N. Baumer, and Pavel V. Mateychenko. "Novel modification of anhydrous transition metal oxalates from powder diffraction." Acta Crystallographica Section C Structural Chemistry 73, no. 11 (October 13, 2017): 911–16. http://dx.doi.org/10.1107/s2053229617012839.

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The known metal–C2O4 structures may be divided into two modifications, α and β. The α-modification has an order–disorder struxture, revealing one-dimensional disordering of the metal–oxalate chains, and the β-modification is ordered. The crystal structures of orthorhombic γ-MnC2O4 {poly[μ-oxalato-manganese(II)]; space group Pmna, a = 7.1333 (1), b = 5.8787 (1), c = 9.0186 (2) Å, V = 378.19 (1) Å3, Z = 4 and Dx = 2.511 Mg m−3} and γ-CdC2O4 {poly[μ-oxalato-cadmium(II)]; space group Pmna, a = 7.3218 (1), b = 6.0231 (1), c = 9.2546 (2) Å, V = 408.13 (1) Å3, Z = 4 and Dx = 3.262 Mg m−3} have been obtained from powder diffraction patterns. The structures are isostructural. Each metal atom in each structure is coordinated by seven O atoms which belong to five oxalate ions. The crystal packing, which contains noticeable cavities in the [101] and [001] directions, is not close packed and essentially differs from the known disordered α- and ordered β-modifications of transition metal oxalates. This modification seems to be metastable. It was found that a spontaneous γ→β phase transition takes place for γ-CdC2O4.
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4

Piro, O. E., G. A. Echeverría, and E. J. Baran. "Spontaneous enantiomorphism in poly-phased alkaline salts of tris(oxalato)ferrate(III): crystal structure of cubic NaRb5[Fe(C2O4)3]2." Acta Crystallographica Section E Crystallographic Communications 74, no. 7 (June 8, 2018): 905–9. http://dx.doi.org/10.1107/s2056989018008022.

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We show here that the phenomenon of spontaneous resolution of enantiomers occurs during the crystallization of the sodium and rubidium double salts of the transition metal complex tris(oxalato)ferrate(III), namely sodium pentarubidium bis[tris(oxalato)ferrate(III)], NaRb5[Fe(C2O4)3]2. One enantiomer of the salt crystallizes in the cubic space groupP4332 withZ= 4 and a Flack absolute structure parameterx= −0.01 (1) and its chiral counterpart in the space groupP4132 withx= −0.00 (1). All metal ions are at crystallographic special positions: the iron(III) ion is on a threefold axis, coordinated by three oxalate dianions in a propeller-like conformation. One of the two independent rubidium ions is on a twofold axis in an eightfold coordination with neighbouring oxalate oxygen atoms, and the other one on a threefold axis in a sixfold RbO6coordination. The sodium ion is at a site ofD3point group symmetry in a trigonal–antiprismatic NaO6coordination.
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5

Yusenko, Elena, Evgeniya Polyntseva, Anna Lyzhova, and Olga Kalyakina. "Determination of Oxalate and Some Inorganic Anions in Green and Black Tea." Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences 67, no. 4-5 (November 1, 2013): 429–32. http://dx.doi.org/10.2478/prolas-2013-0076.

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Abstract Oxalate concentration differs in various daily consumed food products. The role of oxalic acid in the human body is very significant, as its compounds are responsible for the stability of biological membranes. However, insoluble calcium and magnesium oxalates can be accumulated in the body in the form of kidney stones. Oxalate concentration has been measured by high performance liquid, gas after derivatization and ion chromatography (IC). The most effective method for the simultaneous determination of oxalate and inorganic anions is ion chromatography with conductometric detection. Here, we report the results of the measurement of oxalic acid in bleak and green tea samples. Separation was performed by IC on an anion-exchange column Shodex IC SI-90 with surface-layer sorbent and conductimetric detection. The main analytical features of the method were: limit of detection of oxalic acid 0.03 mg/l, linear range 0.1-20 mg/l, correlation 0.9998, relative standard deviation 1%. The method did not need specific sample treatment and was successfully applied to the analysis of black and green tea samples. Oxalic acid was determined in the ranges 16.7-84 mg/l for green tea and 63-116 mg/l for black tea. Green tea contained lower oxalate ions concentration than black tea. The IC method has a lower detection limit for oxalate ions than HPLS and GC, ten and two times less, respectively
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6

Hsu, Yu-Chao, Li-Cheng Pan, and Lie-Ding Shiau. "A Photomicroscopic Study on the Growth Rates of Calcium Oxalate Crystals in a New Synthetic Urine without Inhibitors and with Various Inhibitors." Crystals 11, no. 3 (February 25, 2021): 223. http://dx.doi.org/10.3390/cryst11030223.

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A photomicroscopic growth apparatus was used to study the growth rates of calcium oxalate crystals in a new synthetic urine without inhibitors and with various inhibitors, including magnesium ions, citrate ions, chondroitin sulfate ions, and phytate ions. The dependence of growth rates on supersaturation at different temperatures without inhibitors was investigated using a power law model in terms of the Arrhenius form. The effects of various inhibitors on the growth rates of calcium oxalate indicated that the inhibition of growth rates increases in the order magnesium ions < citrate ions < chondroitin sulfate ions < phytate ions. The polymorphic forms of calcium oxalate crystals without inhibitors and with various inhibitors were examined by scanning electron microscopy.
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7

El MostafaMtairag, Abdelaziz ELAmrani. "Inhibiting Effect of Moroccan Medicinal Plants on Crystallization of Oxalo-calcic Calculations in vitro." Universities' Journal of Phytochemistry and Ayurvedic Heights 1, no. 30 (June 26, 2021): 18–26. http://dx.doi.org/10.51129/ujpah-june2021-30-1(3).

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Abstract- The aim of this work is to study the inhibitory effect of some Moroccan medicinal plants: parsley, nettle, oregano and corn beard on the crystallization of oxalocalcium urinary stones under experimental conditions which simu l a t e t h e u ri n a r y e n v ir o nme n t (physiological concentrations in calcium and oxalate, temperature and pH). The experimental tests were followed by the turbidimetric method using UV-Visible Model SP8-400 spectrophotometry, the response of which restores the concentration of calcium oxalate. The results showed that the potassium and magnesium ions which constitute the main elements of these plants compete with the calcium ions in order to combine with the oxalate ions. All the competitive reactions reflecting the affinities of the different ions towards each other contribute to the observed overall inhibition of the crystallization of calcium oxalate. Keywords: Crystallization, Urinary Calculus, Calcium oxalate, Inhibition, Moroccan Medicinal Plants
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8

Li, Jia Ming, Shu Qing Xu, and Zhong Feng Shi. "Molecular and Crystal Structure Analysis of an Oxalate-Bridged Sodium 2D Polymer: [Na(μ1,1,2,3-Oxalato)(di-μ1,1-H2O)]N." Advanced Materials Research 399-401 (November 2011): 916–20. http://dx.doi.org/10.4028/www.scientific.net/amr.399-401.916.

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The title compound, [Na(μ1,1,2,3-oxalato)(di-μbelongs to triclinic, space group P-1 with a = 5.6982 (11), b = 6.5040 (12), c = 6.6647 (13) Å, α = 75.040 (2), β = 84.990 (3), γ = 70.072 (3), V = 224.34 (7) Å3, C2H3NaO5, Mr = 130.03, Z = 2, Dc = 1.925 g/cm3, μ = 0.270 mm–1and F(000) = 132. Each sodium ions is located on crystallographic inversion symmetry centre and surrounded by six oxygen donors from three oxalate ligands and two di-μ1,1-waters in a distorted octahedron geometry. Two planar 4-member cyclβes crystallographic inversion are found in alternate repeated Na2O2subunit, which is further extended to two dimensional supermolecular fragment via μ1,1,2,3-oxalato-bridged. The crystal structure is aggregated to a 3D network through O-H…O hydrogen bonding involving the water molecules and oxalate oxygen atoms.
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9

Liu, Chen, and Khalil A. Abboud. "Crystal structures of μ-oxalato-bis[azido(histamine)copper(II)] and μ-oxalato-bis[(dicyanamido)(histamine)copper(II)]." Acta Crystallographica Section E Crystallographic Communications 71, no. 11 (October 28, 2015): 1379–83. http://dx.doi.org/10.1107/s2056989015019908.

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The title compounds, μ-oxalato-κ4O1,O2:O1′,O2′-bis[[4-(2-aminoethyl)-1H-imidazole-κ2N3,N4](azido-κN1)copper(II)], [Cu2(C2O4)(N3)2(C5H9N3)2], (I), and μ-oxalato-κ4O1,O2:O1′,O2′-bis[[4-(2-aminoethyl)-1H-imidazole-κ2N3,N4](dicyanamido-κN1)copper(II)], [Cu2(C2O4)(C2N3)2(C5H9N3)2], (II), are two oxalate-bridged dinuclear copper complexes. Each CuIIion adopts a five-coordinate square-pyramidal coordination sphere where the basal N2O2plane is formed by two O atoms of the oxalate ligand and two N atoms of a bidentate chelating histamine molecule. The apical coordination site in compound (I) is occupied by a monodentate azide anion through one of its terminal N atoms. The apical coordination site in compound (II) is occupied by a monodentate dicyanamide anion through one of its terminal N atoms. The molecules in both structures are centrosymmetric. In the crystals of compounds (I) and (II), the dinuclear complexes are linked through N—H...Xand C—H...X(X= N, O) hydrogen bonds where the donors are provided by the histamine ligand and the acceptor atoms are provided by the azide, dicyanamide, and oxalate ligands. In compound (I), the coordinatively unsaturated copper ions interact with the histamine ligandviaa C—H...Cu interaction. The coordinatively unsaturated copper ions in compound (II) interactviaa weak N...Cu interaction with the dicyanamide ligand of a neighboring molecule. The side chain of the histamine ligand is disordered over three sets of sites in (II).
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10

Chandra, N. R., M. M. Prabu, J. Venkatraman, S. Suresh, and M. Vijayan. "X-ray Studies on Crystalline Complexes Involving Amino Acids and Peptides. XXXIII. Crystal Structures of L- and DL-Arginine Complexed with Oxalic Acid and a Comparative Study of Amino Acid–Oxalic Acid Complexes." Acta Crystallographica Section B Structural Science 54, no. 3 (June 1, 1998): 257–63. http://dx.doi.org/10.1107/s0108768197011543.

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The DL- and L-arginine complexes of oxalic acid are made up of zwitterionic positively charged amino acid molecules and semi-oxalate ions. The dissimilar molecules aggregate into separate alternating layers in the former. The basic unit in the arginine layer is a centrosymmetric dimer, while the semi-oxalate ions form hydrogen-bonded strings in their layer. In the L-arginine complex each semi-oxalate ion is surrounded by arginine molecules and the complex can be described as an inclusion compound. The oxalic acid complexes of basic amino acids exhibit a variety of ionization states and stoichiometry. They illustrate the effect of aggregation and chirality on ionization state and stoichiometry, and that of molecular properties on aggregation. The semi-oxalate/oxalate ions tend to be planar, but large departures from planarity are possible. The amino acid aggregation in the different oxalic acid complexes do not resemble one another significantly, but the aggregation of a particular amino acid in its oxalic acid complex tends to have similarities with its aggregation in other structures. Also, semi-oxalate ions aggregate into similar strings in four of the six oxalic acid complexes. Thus, the intrinsic aggregation propensities of individual molecules tend to be retained in the complexes.
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11

Kanižaj, Lidija, Pavla Šenjug, Damir Pajić, Luka Pavić, Krešimir Molčanov, and Marijana Jurić. "Magnetic and Electrical Behaviors of the Homo- and Heterometallic 1D and 3D Coordination Polymers Based on the Partial Decomposition of the [Cr(C2O4)3]3− Building Block." Materials 13, no. 23 (November 25, 2020): 5341. http://dx.doi.org/10.3390/ma13235341.

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One-dimensional (1D) oxalate-bridged homometallic {[Mn(bpy)(C2O4)]·1.5H2O}n (1) (bpy = 2,2’-bipyridine) and heterodimetallic {[CrCu3(bpy)3(CH3OH)(H2O)(C2O4)4][Cu(bpy)Cr(C2O4)3]·CH2Cl2·CH3OH·H2O}n (2) coordination polymers, as well as the three-dimensional (3D) heterotrimetallic {[CaCr2Cu2(phen)4(C2O4)6]·4CH3CN·2H2O}n (3) (1,10-phenanthroline) network, have been synthesized by a building block approach using a layering technique, and characterized by single-crystal X-ray diffraction, infrared (IR) and impedance spectroscopies and magnetization measurements. During the crystallization process partial decomposition of the tris(oxalato)chromate(III) happened and 1D polymers 1 and 2 were formed. The antiferromagnetic interactions between the manganese(II) ions were mediated by oxalate ligands in the chain [Mn(bpy)(C2O4)]n of 1, with intra-chain super-exchange interaction ? = (−3.134 ± 0.004) K; magnetic interaction between neighbouring chains is negligible making this system closer than other known Mn-chains to the ideal 1D Heisenberg antiferromagnet. Compound 2 comprises a 1D coordination anion [Cu(bpy)Cr(C2O4)3]nn− (Cr2–Cu4) with alternating [Cr(C2O4)3]3− and [Cu(bpy)]2+ units mutually bridged through the oxalate group. Another chain (Cr1–Cu3) is similar, but involves a homodinuclear unit [Cu(bpy)(H2O)(µ-C2O4)Cu(bpy)(CH3OH)]2+ (Cu1–Cu2) coordinated as a pendant group to a terminal oxalate oxygen. Magnetic measurements showed that the Cu1−Cu2 cationic unit is a strongly coupled antiferromagnetic dimer, independent from the other magnetic ions within ferromagnetic chains Cr1–Cu3 and Cr2–Cu4. A 3D polymer {[CaCr2Cu2(phen)4(C2O4)6]·4CH3CN·2H2O}n (3) comprising three different metal centers (Ca2+, Cr3+ and Cu2+) oxalate-bridged, contains Ca2+ atoms as nodes connected with four Cr3+ atoms through oxalate ligands. The network thus formed can be reduced to an underlying graph of diamondoid (dia) or (66) topology. Magnetization of 3 shows the ferromagnetic oxalate-bridged dimers [CuIICrIII], whose mutual interaction could possibly originate through the spin polarization of Ca2+ orbitals. Compounds 1 and 3 exhibit lower electrical conductivity at room temperature (RT) in comparison to compound 2.
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12

Janusz, Władysław, and Ewa Skwarek. "Comparison of Oxalate, Citrate and Tartrate Ions Adsorption in the Hydroxyapatite/Aqueous Electrolyte Solution System." Colloids and Interfaces 4, no. 4 (October 15, 2020): 45. http://dx.doi.org/10.3390/colloids4040045.

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The kinetics of adsorption/desorption of oxalate, citrate and tartrate anions was investigated using hydroxyapatite from solutions at the initial concentrations of 0.000001 and 0.001 mol/dm3 anions. The adsorption process from a solution with a concentration of 0.001 mol/dm3 takes place in three stages and is well described by the multiexponential equation of adsorption kinetics. The process of tartrate and citrate ion desorption after increasing the pH to 10 is irreversible, while the oxalate ions undergo significant desorption with the increasing pH. The adsorption of oxalate ions decreases with the increasing pH. This effect is weaker in the adsorption of citrate and tartrate ions. Ion adsorption studies were supplemented with the measurements of zeta potential, FTIR and particle distribution of hydroxyapatite particles.
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13

Shimizu, K., H. Habazaki, P. Skeldon, G. E. Thompson, and G. C. Wood. "Migration of oxalate ions in anodic alumina." Electrochimica Acta 46, no. 28 (August 2001): 4379–82. http://dx.doi.org/10.1016/s0013-4686(01)00660-0.

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14

Rez, Peter, and Michail Reilly. "Low-voltage SEM of urinary stones." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 416–17. http://dx.doi.org/10.1017/s0424820100147910.

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Urinary stones are predominantly composed of calcium oxalate and calcium apatite while a minority of stones are formed from uric acid. The oxalate stones occur with greatest frequency, mainly in the form of the monohydrate (whellewite) with some dihydrate (wedellite) present. Despite many years of extensive research, the mechanisms for kidney stone nucleation and growth are still unknown. In particular the urine from recurrent stone formers, and the urine from those who do not form stones, does not show large differences in concentration of either calcium or oxalate ions. Recent work has emphasised the role of possible “inhibitors” or “promoters” in the growth of urinary stones though the quest for these substances remains elusive. Much effort has been devoted to the study of crystallization of calcium oxalates in an attempt to understand nucleation, aggregation and growth as a function of pH and the presence of possible promoters or inhibitors.Many analytical techniques have been applied to urinary stone analysis with X-ray diffraction, wet chemistry and infrared spectroscopy being the most successful for routine characterisation.
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15

Borges, Fernanda T., Yara M. Michelacci, Jair A. K. Aguiar, Maria A. Dalboni, Andrezza S. Garófalo, and Nestor Schor. "Characterization of glycosaminoglycans in tubular epithelial cells: Calcium oxalate and oxalate ions effects." Kidney International 68, no. 4 (October 2005): 1630–42. http://dx.doi.org/10.1111/j.1523-1755.2005.00577.x.

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16

Odabaşoğlu, Mustafa, and Orhan Büyükgüngör. "3,6-Dioxaoctane-1,8-diammonium oxalate." Acta Crystallographica Section E Structure Reports Online 62, no. 4 (March 22, 2006): o1524—o1525. http://dx.doi.org/10.1107/s1600536806009822.

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The title compound, C6H18N2O2 2+·C2O4 2−, crystallizes with one half-cation and one half-anion in the asymmetric unit. It contains cyclic N—H...O hydrogen-bonded rings involving 3,6-dioxaoctane-1,8-diammonium and oxalate ions, forming a three-dimensional network.
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17

Mishra, Indrajeet. "EPR and Optical Absorption Studies of Gd3+ Ions in Ammonium Oxalate Monohydrate Single Crystals." Journal of Advanced Research in Dynamical and Control Systems 12, SP7 (July 25, 2020): 482–90. http://dx.doi.org/10.5373/jardcs/v12sp7/20202131.

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18

Sharma, Ashwani K., and Tej P. Singh. "Structure of oxalate-substituted diferric mare lactoferrin at 2.7 Å resolution." Acta Crystallographica Section D Biological Crystallography 55, no. 11 (November 1, 1999): 1792–98. http://dx.doi.org/10.1107/s0907444999009439.

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Lactoferrin binds two Fe3+ and two CO^{2-}_{3} ions with high affinity. It can also bind other metal ions and anions. In order to determine the perturbations in the environments of the binding sites in the N and C lobes and elsewhere in the protein, the crystal structure of oxalate-substituted diferric mare lactoferrin has been determined at 2.7 Å resolution. The final model has a crystallographic R factor of 21.3% for all data in the resolution range 17.0–2.7 Å. The substitution of an oxalate anion does not perturb the overall structure of the protein, but produces several significant changes at the metal-binding and anion-binding sites. The binding of the oxalate anion is symmetrical in both the N and C lobes, unlike in diferric dioxalate human lactoferrin, where the oxalate anion binds the metal ion symmetrically in the C lobe and asymmetrically in the N lobe.
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19

McNeese, Timothy J., and Robert D. Pike. "Bis(tetraethylammonium) oxalate dihydrate." Acta Crystallographica Section E Structure Reports Online 68, no. 8 (July 7, 2012): o2382—o2383. http://dx.doi.org/10.1107/s160053681203022x.

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The title compound, 2C8H20N+·C2O42−·2H2O, synthesized by neutralizing H2C2O4·2H2O with (C2H5)4NOH in a 1:2 molar ratio, is a deliquescent solid. The oxalate ion is nonplanar, with a dihedral angle between carboxylate groups of 64.37 (2)°. O—H...O hydrogen bonds of moderate strength link the O atoms of the water molecules and the oxalate ions into rings parallel to thecaxis. The rings exhibit the graph-set motifR44(12). In addition, there are weak C—H...O interactions in the crystal structure.
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20

Gopal, Meera, and Sreesha Sasi. "Synthesis and Structural Characterization of Lanthanum(III) Complexes of 4-Nitrosoantipyrine." Asian Journal of Chemistry 33, no. 3 (2021): 617–21. http://dx.doi.org/10.14233/ajchem.2021.23047.

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A new series of La(III) complexes of the ligand with the general formula [La(L)2(a)3] and [La2(L)4(aa)3], (a = nitrate (1), thiocyanate (2), acetate (3) and propionate (4) ions, aa = sulphate (5), thiosulphate (6), oxalate (7) and malonate (8) ions with the ligand 4-nitrosoantipyrine (L) were synthesized and characterized using various physico-chemical studies. The primary ligand L acts as a bidentate ligand utilizing the carbonyl group and the nitroso group for bonding. The nitrate, thiocyanate, acetate and propionate ions are monovalent unidentate ligands, whereas sulphate, thiosulphate, oxalate and malonate ions are divalent bidentate ligands in the complexes 1-8. Based on spectral data and magnetic susceptibility measurements, geometry of the lanthanum(III) complexes were also proposed.
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21

Giscard, Doungmo, Théophile Kamgaing, Ranil Clément Tonleu Temgoua, Ervice Ymele, Francis Merlin Melataguia Tchieno, and Ignas Kenfack Tonlé. "Intercalation of oxalate ions in the interlayer space of a layered double hydroxide for nickel ions adsorption." International Journal of Basic and Applied Sciences 5, no. 2 (May 13, 2016): 144. http://dx.doi.org/10.14419/ijbas.v5i2.5672.

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In this study, sorption properties of a synthesized anionic clay were enhanced by the intercalation of oxalate ions in its interlayer space. The pristine and modified clay materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermal analysis. These techniques confirmed the presence of oxalate ions in the interlayer space of the clay. The intercalated clay was then used as a matrix for the sorption in batch mode of nickel ions in aqueous solution. The influence of a number of parameters such as contact time, pH, initial concentration of the analyte and adsorbent dosage were studied. The maximum adsorption of nickel was obtained at pH 6, that is, about 90% Ni2+ removal. The adsorbent/adsorbate equilibrium follows a pseudo-second order kinetics and best matches the Langmuir model. The modified clay was shown to be efficient matrix for the sorption of nickel ions.
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22

Satyabama, P., Susai Rajendran, and Tuan Anh Nguyen. "Corrosion inhibition of aluminum by oxalate self-assembling monolayer." Anti-Corrosion Methods and Materials 66, no. 6 (November 4, 2019): 768–73. http://dx.doi.org/10.1108/acmm-01-2019-2061.

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Purpose This paper aims to evaluate the inhibition efficiency (IE) of oxalate ions in controlling corrosion of aluminum at pH 10. Design/methodology/approach The IE has been determined by the classical weight loss method. The corrosion behavior of aluminum was investigated by using potentiodynamic polarization and electrochemical impedance measurements. Ultra violet (UV)-visible and Fluorescence spectra have been used to analyze the film formed on the aluminum surface after immersion. Findings The maximum IE was 88 per cent, which was offered by a mixture of 250 ppm oxalate ions and 50 ppm [Zn2+]. Potentiodynamic polarization data revealed that the protective film was formed on the metal surface. UV-visible and Fluorescence spectra indicated the presence of Al3+−oxalate complex in the protective film formed on aluminum substrate after immersion in [OX]/[Zn2+] solution. Originality/value The findings of this work shed more light on the corrosion inhibition of aluminum by oxalate self-assembling monolayers.
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23

Gupta, Asheesh Kumar, and Preeti Kothiyal. "In-vitro Antiurolithic activity of Kigelia africana fruit extracts." Indian Journal of Pharmaceutical and Biological Research 3, no. 01 (March 31, 2015): 77–81. http://dx.doi.org/10.30750/ijpbr.3.1.12.

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Objectives: The plant Kigelia africana (Lam.) Benth. Family: Bignoniaceae is used in traditional medical practices of Africa and India to treat various diseases including renal disorders. The present study is designed to evaluate the effect of K. africana fruit extract (KAFE) for in-vitro anti-urolithic activity on generated calcium-oxalate crystals. Method: The aqueous and alcoholic (ethanolic) extracts of fruits were tested for anti-urolithiatic potential on generated calcium-oxalate crystals by homogenous precipitation method and simultaneously a supporting two step vice-versa reactions were assessed (New method). The activity was assessed by studying the crystal dissolution by microscopy and quantitative alimental ions analysis for calcium and oxalates. Result: They exhibited significant activity when compared to standard drug Cystone- a poly herbal formulation. The aqueous and alcoholic extracts significantly decreased (p 0.001) crystal size and increased calcium and oxalate concentration in reaction setup of all tested groups as compared to normal control. Simultaneously a supporting two step vice-versa reaction was assessed that have shown significant inhibition of crystal formation. Conclusion: All the interpretations of various result outcomes direct the use of this drug for urolithiasis prophylaxis and treatments.
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24

Artem'eva, M. Y., V. N. Serezhkin, and Y. N. Mikhailov. "Crystal chemical role of oxalate and malonate ions." Acta Crystallographica Section A Foundations of Crystallography 62, a1 (August 6, 2006): s272. http://dx.doi.org/10.1107/s0108767306094566.

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25

Zelenin, P. G., V. V. Milyutin, V. M. Bakhir, and D. V. Adamovich. "Electrochemical Oxidation of Oxalate Ions in Aqueous Solutions." Radiochemistry 63, no. 4 (August 2021): 439–45. http://dx.doi.org/10.1134/s1066362221040068.

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26

Kadir, Karim, Trifa Mohammad Ahmed, Dag Noreús, and Lars Eriksson. "Octaammonium diaquahexa-μ2-oxalato-dioxalatotetracopper(II) tetrahydrate." Acta Crystallographica Section E Structure Reports Online 62, no. 5 (April 29, 2006): m1139—m1141. http://dx.doi.org/10.1107/s1600536806014164.

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In the structure of the title compound, (NH4)8[Cu4(C2O4)8(H2O)2]·4H2O, isolated tetramers of [Cu(ox)2]2+ (ox is oxalate) are present. Each CuII ion coordinates to four O atoms in two oxalate ligands and to two more distant O atoms in a neighbouring oxalate ligand or a water molecule. An extensive hydrogen-bonding network connects the tetramers to two unique solvent water molecules and four ammonium ions.
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27

Umekawa, Tohru, Nasser Chegini, and Saeed R. Khan. "Oxalate ions and calcium oxalate crystals stimulate MCP-1 expression by renal epithelial cells." Kidney International 61, no. 1 (January 2002): 105–12. http://dx.doi.org/10.1046/j.1523-1755.2002.00106.x.

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28

Marino, Nadia, María Luisa Calatayud, Marta Orts-Arroyo, Alejandro Pascual-Álvarez, Nicolás Moliner, Miguel Julve, Francesc Lloret, Giovanni De Munno, Rafael Ruiz-García, and Isabel Castro. "Magnetic Switching in Vapochromic Oxalato-Bridged 2D Copper(II)-Pyrazole Compounds for Biogenic Amine Sensing." Magnetochemistry 7, no. 5 (May 12, 2021): 65. http://dx.doi.org/10.3390/magnetochemistry7050065.

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A new two-dimensional (2D) coordination polymer of the formula {Cu(ox)(4-Hmpz)·1/3H2O}n (1) (ox = oxalate and 4-Hmpz = 4-methyl-1H-pyrazole) has been prepared, and its structure has been determined by single-crystal X-ray diffraction. It consists of corrugated oxalato-bridged copper(II) neutral layers featuring two alternating bridging modes of the oxalate group within each layer, the symmetric bis-bidentate (μ-κ2O1,O2:κ2O2′,O1′) and the asymmetric bis(bidentate/monodentate) (μ4-κO1:κ2O1,O2:κO2′:κ2O2′,O1′) coordination modes. The three crystallographically independent six-coordinate copper(II) ions that occur in 1 have tetragonally elongated surroundings with three oxygen atoms from two oxalate ligands, a methylpyrazole-nitrogen defining the equatorial plane, and two other oxalate-oxygen atoms occupying the axial positions. The monodentate 4-Hmpz ligands alternatively extrude above and below each oxalate-bridged copper(II) layer, and the water molecules of crystallization are located between the layers. Compound 1 exhibits a fast and selective adsorption of methylamine vapors to afford the adsorbate of formula {Cu(ox)(4-Hmpz)·3MeNH2·1/3H2O}n (2), which is accompanied by a concomitant color change from cyan to deep blue. Compound 2 transforms into {Cu(ox)(4-Hmpz)·MeNH2·1/3H2O}n (3) under vacuum for three hours. The cryomagnetic study of 1–3 revealed a unique switching from strong (1) to weak (2 and 3) antiferromagnetic interactions. The external control of the optical and magnetic properties along this series of compounds might make them suitable candidates for switching optical and magnetic devices for chemical sensing.
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29

Shanthil, M., K. Sandeep, and P. K. Sajith. "Cooperative effects of Na+ and citrates on the dissolution of calcium oxalate crystals." Physical Chemistry Chemical Physics 22, no. 8 (2020): 4788–92. http://dx.doi.org/10.1039/c9cp06499k.

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30

Dziuk, Błażej, Bartosz Zarychta, and Krzysztof Ejsmont. "Allylammonium hydrogen oxalate hemihydrate." Acta Crystallographica Section E Structure Reports Online 70, no. 8 (July 5, 2014): o852. http://dx.doi.org/10.1107/s1600536814015190.

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In the title hydrated molecular salt, C3H8N+·C2HO4−·0.5H2O, the water O atom lies on a crystallographic twofold axis. The C=C—C—N torsion angle in the cation is 2.8 (3)° and the dihedral angle between the CO2and CO2H planes in the anion is 1.0 (4)°. In the crystal, the hydrogen oxalate ions are linked by O—H...O hydrogen bonds, generating [010] chains. The allylammonium cations bond to the chains through N—H...O and N—H...(O,O) hydrogen bonds. The water molecule accepts two N—H...O hydrogen bonds and makes two O—H...O hydrogen bonds. Together, the hydrogen bonds generate (100) sheets.
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31

Connolly, Jon H., Walter C. Shortle, and Jody Jellison. "Translocation and incorporation of strontium carbonate derived strontium into calcium oxalate crystals by the wood decay fungus Resinicium bicolor." Canadian Journal of Botany 77, no. 1 (June 1, 1999): 179–87. http://dx.doi.org/10.1139/b99-018.

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The white-rot wood decay fungus Resinicium bicolor (Abertini & Schwein.: Fr.) Parmasto was studied for its ability to solubilize and translocate ions from the naturally occurring mineral strontianite. Resinicium bicolor colonized a soil mixture culture medium containing strontianite sand, solubilized strontium ions from this mineral phase, translocated the ions vertically, and reprecipitated the strontium into strontium-containing calcium oxalate crystals. Storage of the Sr in crystals was highest in mycelial cords and was dynamic in character. These results suggest that non-mycorrhizal saprotrophic fungi should be evaluated for their potential participation in forest nutrient cycling via biologically weathering parent material and translocating the mobilized mineral nutrients vertically within soils.Key words: fungi, strontium, calcium oxalate, translocation, soil, minerals nutrient cycling.
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32

Dinca, Alina S., Sergiu Shova, Adrian E. Ion, Catalin Maxim, Francesc Lloret, Miguel Julve, and Marius Andruh. "Ascorbic acid decomposition into oxalate ions: a simple synthetic route towards oxalato-bridged heterometallic 3d–4f clusters." Dalton Transactions 44, no. 16 (2015): 7148–51. http://dx.doi.org/10.1039/c5dt00778j.

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33

Rückriem, Kai, Sarah Grotheer, Henning Vieker, Paul Penner, André Beyer, Armin Gölzhäuser, and Petra Swiderek. "Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II) oxalate precursor layers." Beilstein Journal of Nanotechnology 7 (June 13, 2016): 852–61. http://dx.doi.org/10.3762/bjnano.7.77.

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Copper(II) oxalate grown on carboxy-terminated self-assembled monolayers (SAM) using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II) acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II) oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS). Helium ion microscopy (HIM) reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS) confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor.
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34

Kaseem, Mosab, Jeong Hyeon Kwon, and Young Gun Ko. "Modification of a porous oxide layer formed on an Al–Zn–Mg alloy via plasma electrolytic oxidation and post treatment using oxalate ions." RSC Advances 6, no. 108 (2016): 107109–13. http://dx.doi.org/10.1039/c6ra21696j.

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35

Rusakov, Aleksei, Maria Kuz’mina, and Olga Frank-Kamenetskaya. "Biofilm Medium Chemistry and Calcium Oxalate Morphogenesis." Molecules 26, no. 16 (August 19, 2021): 5030. http://dx.doi.org/10.3390/molecules26165030.

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The present study is focused on the effect of biofilm medium chemistry on oxalate crystallization and contributes to the study of the patterns of microbial biomineralization and the development of nature-like technologies, using the metabolism of microscopic fungi. Calcium oxalates (weddellite and whewellite in different ratios) were synthesized by chemical precipitation in a weakly acidic environment (pH = 4–6), as is typical for the stationary phase of micromycetes growth, with a ratio of Ca2+/C2O42− = 4.0–5.5, at room temperature. Additives, which are common for biofilms on the surface of stone in an urban environment (citric, malic, succinic and fumaric acids; and K+, Mg2+, Fe3+, Sr2+, SO42+, PO43+ and CO32+ ions), were added to the solutions. The resulting precipitates were studied via X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). It was revealed that organic acids, excreted by micromicetes, and some environmental ions, as well as their combinations, significantly affect the weddellite/whewellite ratio and the morphology of their phases (including the appearance of tetragonal prism faces of weddellite). The strongest unique effect leading to intensive crystallization of weddellite was only caused by the presence of citric acid additive in the medium. Minor changes in the composition of the additive components can lead to significant changes in the weddellite/whewellite ratio. The effect of the combination of additives on this ratio does not obey the law of additivity. The content of weddellite in the systems containing a representative set of both organic acids and environmental ions is ~20 wt%, which is in good agreement with natural systems.
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36

Hornkjøl, Sverre, B. Haugsdal, K. Grjotheim, Lev V. Vilkov, Hans V. Volden, Knut Maartmann-Moe, and Svante Wold. "Effects of Oxalate Ions on the Corrosion of Niobium." Acta Chemica Scandinavica 44 (1990): 404–5. http://dx.doi.org/10.3891/acta.chem.scand.44-0404.

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37

IWATA, Yoshihiro, Hisanori IMURA, and Nobuo SUZUKI. "Coprecipitation equilibrium of lanthanoid(III) ions with calcium oxalate." Analytical Sciences 6, no. 5 (1990): 753–56. http://dx.doi.org/10.2116/analsci.6.753.

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38

Jones, Franca, Mark I. Ogden, and Tomoko Radomirovic. "The impact of oxalate ions on barium sulfate crystallization." Journal of Crystal Growth 498 (September 2018): 148–53. http://dx.doi.org/10.1016/j.jcrysgro.2018.06.014.

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39

Cantrell, Kirk J., and Robert H. Byrne. "Rare earth element complexation by carbonate and oxalate ions." Geochimica et Cosmochimica Acta 51, no. 3 (March 1987): 597–605. http://dx.doi.org/10.1016/0016-7037(87)90072-x.

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40

Gelbrich, Thomas, Christoph Langes, Marijan Stefinovic, and Ulrich J. Griesser. "Naloxegol hydrogen oxalate displaying a hydrogen-bonded layer structure." Acta Crystallographica Section E Crystallographic Communications 74, no. 4 (March 9, 2018): 474–77. http://dx.doi.org/10.1107/s2056989018003675.

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In the salt (5α,6α)-6-[(2,5,8,11,14,17,20-heptaoxadocosan-22-yl)oxy]-3,14-dihydroxy-17-(prop-2-en-1-yl)-4,5-epoxymorphinan-17-ium hydrogen oxalate, C34H54NO11 +·C2HO4 − the polyether unit of the naloxegol cation adopts the shape of a squashed open letter `O'. In the crystal, the hydrogen oxalate anions are linked into a chain by O—H...O hydrogen bonds. Each naloxegol unit is hydrogen bonded to three hydrogen oxalate ions via two O—H...O and one N—H...O interactions. The resulting hydrogen-bonded two-dimensional layer structure is 3,5-connected and has the 3,5 L50 topology.
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41

Jennings, M. L., and M. F. Adame. "Characterization of oxalate transport by the human erythrocyte band 3 protein." Journal of General Physiology 107, no. 1 (January 1, 1996): 145–59. http://dx.doi.org/10.1085/jgp.107.1.145.

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This paper describes characteristics of the transport of oxalate across the human erythrocyte membrane. Treatment of cells with low concentrations of H2DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonate) inhibits Cl(-)-Cl- and oxalate-oxalate exchange to the same extent, suggesting that band 3 is the major transport pathway for oxalate. The kinetics of oxalate and Cl- self-exchange fluxes indicate that the two ions compete for a common transport site; the apparent Cl- affinity is two to three times higher than that of oxalate. The net exchange of oxalate for Cl-, in either direction, is accompanied by a flux of H+ with oxalate, as is also true of net Cl(-)-SO4(2-) exchange. The transport of oxalate, however, is much faster than that of SO4(2-) or other divalent anions. Oxalate influx into Cl(-)-containing cells has an extracellular pH optimum of approximately 5.5 at 0 degrees C. At extracellular pH below 5.5 (neutral intracellular pH), net Cl(-)-oxalate exchange is nearly as fast as Cl(-)-Cl- exchange. The rapid Cl(-)-oxalate exchange at acid extracellular pH is not likely to be a consequence of Cl- exchange for monovalent oxalate (HOOC-COO-; pKa = 4.2) because monocarboxylates of similar structure exchange for Cl- much more slowly than does oxalate. The activation energy of Cl(-)-oxalate exchange is about 35 kCal/mol at temperatures between 0 and 15 degrees C; the rapid oxalate influx is therefore not a consequence of a low activation energy. The protein phosphatase inhibitor okadaic acid has no detectable effect on oxalate self-exchange, in contrast to a recent finding in another laboratory (Baggio, B., L. Bordin, G. Clari, G. Gambaro, and V. Moret. 1993. Biochim. Biophys. Acta. 1148:157-160.); our data provide no evidence for physiological regulation of anion exchange in red cells.
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42

Cailleau, G., O. Braissant, and E. P. Verrecchia. "Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem." Biogeosciences Discussions 8, no. 1 (February 7, 2011): 1077–108. http://dx.doi.org/10.5194/bgd-8-1077-2011.

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Abstract. An African oxalogenic tree, the iroko tree (Milicia excelsa), has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the theoretical acidic conditions of these soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. Regarding the carbonate flux, another direct consequence of wood feeding is a concomitant flux of carbonate formed in wood tissues, which is not consumed by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter. Therefore, an oxalate pool is formed on the forest ground. Then, wood rotting gents (mainly termites, fungi, and bacteria) release significant amounts of oxalate crystals from decaying plant tissues. In addition some of these gents are themselves producers of oxalate (fungi). Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate pathway. The solution is pumped through the roots, leading to carbonate precipitation. The main pools of carbon are clearly identified as the organic matter (the tree and its organic products), the oxalate crystals, and the various carbonate features. A functional model based on field observations and diagenetic investigations with δ13C signatures of the various compartments involved in the local carbon cycle is proposed. It suggests that the iroko ecosystem can act as a long-term carbon sink, as long as the calcium source is related to non-carbonate rocks. Consequently, this carbon sink, driven by the oxalate carbonate pathway around an iroko tree, constitutes a true carbon trapping ecosystem as define by the ecological theory.
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43

Cailleau, G., O. Braissant, and E. P. Verrecchia. "Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem." Biogeosciences 8, no. 7 (July 5, 2011): 1755–67. http://dx.doi.org/10.5194/bg-8-1755-2011.

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Abstract. An African oxalogenic tree, the iroko tree (Milicia excelsa), has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the acidic conditions in these types of soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. In addition, a concomitant flux of carbonate formed in wood tissues contributes to the carbonate flux and is identified as a direct consequence of wood feeding by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter, and an oxalate pool is formed on the forest ground. Then, wood rotting agents (mainly termites, saprophytic fungi, and bacteria) release significant amounts of oxalate crystals from decaying plant tissues. In addition, some of these agents are themselves producers of oxalate (e.g. fungi). Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can then start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate pathway. The solution is pumped through the roots, leading to carbonate precipitation. The main pools of carbon are clearly identified as the organic matter (the tree and its organic products), the oxalate crystals, and the various carbonate features. A functional model based on field observations and diagenetic investigations with δ13C signatures of the various compartments involved in the local carbon cycle is proposed. It suggests that the iroko ecosystem can act as a long-term carbon sink, as long as the calcium source is related to non-carbonate rocks. Consequently, this carbon sink, driven by the oxalate carbonate pathway around an iroko tree, constitutes a true carbon trapping ecosystem as defined by ecological theory.
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44

Holland, Jason P., and Neil Vasdev. "Charting the mechanism and reactivity of zirconium oxalate with hydroxamate ligands using density functional theory: implications in new chelate design." Dalton Trans. 43, no. 26 (2014): 9872–84. http://dx.doi.org/10.1039/c4dt00733f.

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45

Ma, Wang Jing, Xin Min Yang, Zhi Li, Yao Shi, and Yuan Qing Li. "Cooperative Sensitization on Silver Bromoiodide (AgBr/I) GrainsEmulsion by Oxalate and Sulfur-Plus-Gold." Applied Mechanics and Materials 110-116 (October 2011): 1387–91. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.1387.

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After sulfur-plus-gold sensitization on silver bromoiodide (AgBr/I) microcrystal emulsions prepared by the emulsifying process in the double-jet apparatus controlled by a microcomputer, a certain amount of oxalate salt (1×10-1、1×10-2、1×10-3and 1×10-4mol/molAg) was respectively added at a specific time and pAg to a reactor to prepare a series of tabular silver bromoiodide (AgBr/I) microcrystal at whose surface oxalate ions and Ag2S or AuAgS were doped. The sensitometric results from these crystal emulsions showed: 1) that the sensitivities of oxalate-doped AgBr/I emulsion, relative to that of the undoped emulsion as the controlled one, were remarkably increased; 2) that a cooperative sensitization by oxalate dopant, sulfur-plus-gold was observed without any significant increase in fog level when 10-3—10-4 mol/molAg oxalate was doped；3） that sensitivity gain (SG) was maximal, when 10-3mol/molAg oxalate (in 10-1—10-4 mol/molAg ) was doped at the surface of AgBr/I grains.
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46

Lawal, J. A., E. O. Odebunmi, and F. A. Adekola. "Adsorption of Fe , Pb , Zn and Cr ions from aqueous solutions using natural, ammonium oxalate and sodium hydroxide modified Kaolinite clay." Ife Journal of Science 22, no. 3 (January 25, 2021): 1–23. http://dx.doi.org/10.4314/ijs.v22i3.1.

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In this paper, Fe2+ , Pb2+ , Zn2+ and Cr6+ ions removal from contaminated water with natural Nigerian kaolinite clay (AK-clay), and that removed with kaolinite clay modified with either ammonium oxalate (AK-AO) or sodium hydroxide (AK-S) were presented. The clay was characterized using X-Ray Diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Brunanuer-EmmettTeller (BET) method. The parameters investigated include pH, adsorbent particle size, shaking speed, metal ion concentration and temperature. The optimum conditions were applied to the modified samples. Design-expert software was used to design the experimental conditions using Response Surface Methodology (RSM). The mineralogical characterization showed the purified 63 µm fraction of the clay as kaolin. Analysis of Variance shows the adsorption of the metal ions was statistically significant with p-valves > 0.0001 at 95 % confidence limit. Pseudo second-order kinetic model was found to fit the adsorption data for all the metal ions. The adsorption of Fe2+ , Pb2+ and Cr6+ ions was best described by the Langmuir isotherm model, while Freundlich isotherm model best fitted the adsorption data for Zn2+ ion. Thermodynamic analysis of adsorption data shows the metal ions adsorption was spontaneous, endothermic and accompanied by positive entropy change. Compared to unmodified natural clay, AK-S clay increased adsorption capacity for Fe2+ , Pb2+ , Zn 2+ and Cr 6+ ions from 14.1 to 18.425 mg/g, 18.4 to 19.8 mg/g, 16.875 to 19.9 mg/g and 7.65 to 8.15 mg/g respectively. The AK2+ AO2+ clay increased the uptake of Fe ion from 14.1 to 17.35 mg/g with a slight increase for Zn ion (16.875 to 16.95 mg/g). The adsorption capacity of AK-clay for all the metal ions was enhanced by NaOH modification 2+ while the ammonium oxalate modification significantly enhanced the adsorption capacity only for Fe ion. The results show that NaOH and ammonium oxalate modified kaolinite clay are effective for remediation of heavy metal-laden wastewater. Keywords: Kaolinite, metal ions, adsorption, kinetics, adsorption isotherm
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47

Chitra, R., and R. R. Choudhury. "Investigation of hydrogen-bond network in bis(glycinium) oxalate using single-crystal neutron diffraction and spectroscopic studies." Acta Crystallographica Section B Structural Science 63, no. 3 (May 16, 2007): 497–504. http://dx.doi.org/10.1107/s0108768107016965.

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Single-crystal neutron diffraction investigation of bis(glycinium) oxalate was undertaken in order to study its hydrogen-bonding network, particularly the very short hydrogen bond between the glycinum and oxalate ions, indicated by the X-ray diffraction study. The non-existence of any phase transition in these crystals was attributed to the fact that the short hydrogen bond in bis(glycinium) oxalate is asymmetric in nature, with no hydrogen disorder. The potential energy landscape for the above-mentioned H atom was found to have a single minimum closer to the glycinium ion. IR and Raman investigations of the title complex supported the above result.
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48

Androš Dubraja, L., M. Jurić, J. Popović, D. Pajić, Y. Krupskaya, V. Kataev, B. Bűchner, and D. Žilić. "Magneto-structural correlations in oxalate-bridged Sr(ii)Cr(iii) coordination polymers: structure, magnetization, X-band, and high-field ESR studies." Dalton Transactions 47, no. 11 (2018): 3992–4000. http://dx.doi.org/10.1039/c7dt04655c.

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Magneto-structural correlations in 1D oxalate-bridged Sr(ii)Cr(iii) coordination polymers with two crystallographically and magnetically non-equivalent Cr(iii) ions are studied by HF-ESR spectroscopy.
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49

Wrzeszcz, Grzegorz, Andrzej Wojtczak, and Magdalena Zawadzka. "Unusual potassium-oxalate coordination in the two-dimensional trimetallic [CoCl(NH3)5][KCr(C2O4)3]·0.5H2O complex." Open Chemistry 12, no. 6 (June 1, 2014): 652–58. http://dx.doi.org/10.2478/s11532-014-0517-3.

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AbstractA new heterometallic compound, [CoCl(NH3)5][KCr(C2O4)3]·0.5H2O (1), has been synthesized and characterized by elemental analysis, IR and electronic spectra, thermal analysis, variable temperature magnetic susceptibility measurements, and single crystal X-ray diffraction. Compound 1 consists of two-dimensional [{KCr(C2O4)3}n]2n− layers, [CoCl(NH3)5]2+ ions and water molecules. Within the 2-D layer, three different types of oxalate coordination modes are present. Each K cation is coordinated by eight oxygen atoms from oxalate groups and also weakly interacts with the ninth oxygen atom. The extensive network of hydrogen bond is formed between the [KCr(C2O4)3]2− layer and the [CoCl(NH3)5]2+ ions. These interactions involve all hydrogen atoms of ammonia ligads and water molecule.
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50

Li, Zhi-Feng, Yi-Chao Zhang, Xiao-Qin Hu, and Chun-Xiang Wang. "Crystal structure of poly[μ6-adipato-diaquadi-μ2-oxalato-didysprosium(III)]." Acta Crystallographica Section E Structure Reports Online 70, no. 12 (November 15, 2014): m399—m400. http://dx.doi.org/10.1107/s1600536814024544.

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Abstract:
In the title coordination polymer, [Dy2(C6H8O4)(C2O4)2(H2O)2]n, the asymmetric unit consists of one Dy3+cation, one half of an adipate anion, two halves of oxalate anions and one coordinating water molecule. The adipate and oxalate ions are located on centres of inversion. The Dy3+cation has a distorted tricapped trigonal–prismatic geometry and is coordinated by nine O atoms, four belonging to three adipate anions, four to two oxalate anions and one from an aqua ligand. The cations are bridged by adipate ligands, generating a two-dimensional network parallel to (010). This network is further extended into three dimensions by coordination of the rigid oxalate ligands and is further consolidated by O—H...O hydrogen bonds. A part of the adipate anion is disordered over two positions in a 0.75:0.25 ratio.
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