Enrichment of nervonic acid in Acer truncatum Bunge oil by combination of two-stage molecular distillation,one-stage urea complexation and five-stage solvent crystallization

Nervonic acid is the world’s first and only potent substance that can repair damaged nerve fibers and promote nerve cell regeneration with high nutritional value.The wide variety of fatty acids in plant oils and fats with similar structures makes the large-scale separation and purification of high-purity nervonic acid very difficult.A new combined process of molecular distillation,urea inclusion and solvent crystallization was established to prepare high-purity nervonic acid with the mixed fatty acids obtained after saponification and acidification of Acer truncatum Bunge oil as raw materials.First,according to the difference in the mean free path of fatty acids,molecular distillation was used to separate and remove C16 saturated fatty acid of palmitic acid and four C18-C20 fatty acids of stearic,oleic,linoleic,and linolenic acids.The content of C16-C20 fatty acids decreased from 72.92% to 19.22% after two-stage molecular distillation processes,in which the contents of saturated fatty acid of palmitic acid decreased to about 0.5%.Then,according to the difference in carbon chain length and saturation of fatty acid,the contents of C22-C24 saturated fatty acids of tetracosanoic and docosanoic acids decreased to 0.21% and 0.07% by urea inclusion with urea/free fatty acid preparation by saponification(SPOMFs)ratio as 0.6.In addition,all saturated fatty acids were basically separated.Finally,according to the difference in the solubility of fatty acids in solvents,the C18-C20 unsaturated fatty acids of oleic,linoleic,and linolenic acids and C22 unsaturated fatty acid of erucic acid were removed by solvent crystallization.The content of C18-C20 unsaturated fatty acids decreased to less than 5% with pentanol as the solvent after the first stage solvent crystallization.The content of erucic acid decreased to 3.47% with anhydrous ethanol as the solvent after the second to fifth stage solvent crystallization.The combined process of molecular distillation,urea inclusion and low temperature crystallization innovatively adopted an efficient,simple and easy-toindustrial solvent crystallization method to separate erucic and nervonic acids,obtaining nervonic acid with purity of 96.53% and final yield of 47.99%.

Ultra-deep Removal of Metal Ions from Coal Tar by Complexation:Experimental Studies and Density Functional Theory Simulations

As one of the important aspects of upgrading coal tar,the ultra-deep removal of metal ions via the complexation method was investigated by screening four complexing agents and performing density functional theory(DFT)simulations.Analysis of the compositions and contents of the metallic compounds in the coal tar revealed that the main components were iron and calcium naphthenates.Direct filtration reduced the mechanical impurity content from 0.24%to 0.0752%,indicating that most of the large particles could be easily removed.Among the four complexing agents,namely,acetic acid,oxalic acid,citric acid,and ethylenediaminetetraacetic acid,oxalic acid exhibited the best demetallization performance.The DFT simulations suggested that the high performance of oxalic acid originated from its 1:1 coordination mode,rigid dicarboxyl structure,and greater binding energy.

Complexation with pre-formed“empty”V-type starch for encapsulation of aroma compounds

Aroma compounds are low-molecular-weight organic volatile molecules and are broadly utilized in the food industry.However,due to their high volatility and evaporative losses during processing and storage,the stabilization of these volatile ingredients using encapsulation is a commonly investigated practice.Complexation of aroma compounds using starch inclusion complex could be a potential approach due to the hydrophobicity of the left-handed single helical structure.In the present study,we used starch of three different V-type structures,namely V,V,and V,to encapsulate six different aroma compounds,including1-decanol(DN),cis-3-hexen-1-ol(HN),4-allylanisole(AN),γ-decalactone(DA),trans-cinnamaldehyde(CA),and citral(CT).The formed inclusion complexes samples were characterized using complementary techniques,including X-ray diffraction(XRD)and differential scanning calorimetry(DSC).The results showed that upon complexation with aroma compounds,all V-subtypes retained their original crystalline structures.However,different trends of crystallinity were observed for each type of the prepared inclusion complexes.Additionally,among three V-type starches,V-type starch formed inclusion complexes with aroma compounds most efficiently and promoted the formation of FormⅡcomplex.This study suggested that the structure of aroma compounds and the type of V starch could both affect the complexation properties.

Species distribution of polymeric aluminium ferrum——timed complexation colorimetric analysis method of Al-Fe-Ferron

The effects of the calorimetric buffer solutions were investigated while the two colorimetric reactions of AI-ferron complex and Fe-ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexatian colorimetric analysis method of Al-Fe-ferron in view of the total concentration of {AI + Fe} was then established to determine the species distribution of polymeric Al-Fe. The testing wavelength was recommended at 362 net and the testing pH value was 5. With a comparison of the ratios of n(Al)/n(Fe), the standard adsorption curves of the polymeric Al-Fe solutions were derived from the experimental results. Furthermore, the solutions' composition were carious in both the molar n(Al)/n(Fe) ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total ( Al + Fe which ranged from 10(-5) to 10(-4) mol/L..

Complexation separation for vanadium and chromium by dithiocarbamate and its application in treatment of chromium-vanadium-bearing slag

A novel method for the separation and reclamation of vanadium and chromium from acidic solution was proposed. The principle for the separation is based on selective complexation. In specific, V(V) can be complexated by dithiocarbamate to form VO(R1R2NCS2)3 precipitate, leaving Cr(Ⅲ) remained in the acidic solution. Then the reclamation of V and Cr from VO(R1R2NCS2)3 precipitate and Cr(Ⅲ)-bearing solution can be reached by decomplexation and neutralization, respectively. The kinetics of the complexation reaction was studied. In addition, the precipitation ratio of vanadium reached 97% and the loss of chromium was less than 4% after process optimization. The complexing agent could be regenerated with a high ratio of 99.5%. The method was successfully applied to treating chromium-vanadium-bearing slag produced in conventional vanadium production industry. Vanadium and chromium could be extracted from the slag in the form of calcium vanadate and Cr2O3 product with a purity of over 98%.

Enhancement of norfloxacin solubility via inclusion complexation with β-cyclodextrin and its derivative hydroxypropyl-β-cyclodextrin

The objectives of the study were to investigate the effects of β-cyclodextrin(βCD) and hydroxypropyl-β-cyclodextrin(HPβCD) on the solubility and dissolution rate of norfloxacin prepared using three different methods, at drug to cyclodextrin weight ratios of 1:1, 1:2, 1:4 and 1:8. All the methods increased the solubility and dissolution rate of norfloxacin via inclusion complexation with βCD and HPβCD. Norfloxacin was converted from crystalline to amorphous form through inclusion complexation. Solvent evaporation method was the most effective method in terms of norfloxacin solubilisation, while inclusion complex of HPβCD has higher solubility than βCD complex when prepared using the same procedure.

Adsorption，Oxidation and Complexation of Water－So－Inble Organic Snbstances in Soils

A greater part of water-solnble organic substances, accounting for 6070To of the total, could be adsorbedby soils, which included strongly and weekly reducing substances, positively and negatively charged substancesand substances containing amido. There existed a tendency of decrease in adsorption of the negativelycharged organic substances by the soil from South China to North China, with expression as Coulombianadsorption. A simultaneous reduction of iron and manganese appeared with clear voltammetric behavioursupon oxidation of water-soluble organic substances. Complexation of organic ligands with ferrons iron andmanganous manganese was proved by differential pulse voltammetric method, with disappearance of oxidationpeaks of ferrous iron and manganous manganese at 0.00 V and 0.35 V and occurrence of Fe`+-complex andMn￣2+ -complex at 0.75 V and 1.2 V respectively, whose peak potentials shifted backward.

Recent developments of surface complexation models applied to environmental aquatic chemistry

Based on numerous latest references, the current developments in surface complexation, surface precipitation and the corresponding models (SCMs and SPMs), were reviewed. The contents involved comparison on surface charge composition and layer-structure of solid-solution interface for the classical 1-pK and 2-pK models. In addition, the fundamental concept and relations of the new models, i. e., multi-site complexation (MUSIC) and charge- distribution (CD) MUSIC models were described as well. To avoid misuse or abuse, it must be emphasized that the applicability and limitation for each model should be considered carefully when selecting the concerned model(s). In addition, some new powerful techniques for surface characterization and analysis applied to model establishment and modification were also briefly introduced.

Removal of Co(Ⅱ) from aqueous solution by complexation-ultrafiltration and shear stability of PAA-Co complex

Removal of Co(Ⅱ) from aqueous solutions by complexation-ultrafiltration was investigated using polyacrylic acid sodium(PAAS) as complexing agent with the help of rotating disk membrane,and the shear ability of PAA-Co complex was studied. The effects of the mass ratio of PAAS to Co(Ⅱ)(P/M) and pH on the rejection of Co(Ⅱ) were studied,and the optimum conditions were P/M=8 and pH=7. The rejection of Co(Ⅱ) was over 97% when the rotating speed of the disk(n)was less than 710 r/min at the optimum P/M and pH. The distribution of the forms of cobalt on the membrane surface was established by the membrane partition model, and the critical shear rate,the smallest shear rate at which the PAA-Co complex begins to dissociate,was calculated to be1.4×10^4 s^-1,and the corresponding rotating speed was 710 r/min.The PAA-Co complex dissociated when the shear rate was greater than the critical one. The regeneration of PAAS and recovery of Co(Ⅱ) were achieved by shear-induced dissociation and ultrafiltration.

Self-Assembled Film of Tb^(3+) and Poly(3- Thiophene Acetic Acid) via Layer-by-Layer Complexation Technique and Its Photoluminescence

The layer by layer complexation technique of polymer and metal ion was successfully utilized to fabricate the ultrathin multilayer film of poly(3 thiophene acetic acid (PTAA) and Tb 3+ ion by dipping the substrates alternatively in polymer and Tb 3+ ion aqueous solutions. UV-vis measurement revealed that the absorbance has linearity with the bilayer number from layer to layer and the X ray photoelectron spectrum (XPS) confirmed the existence of Tb 3+ ion. The pH of both the polymer and TbCl 3 solutions influence the thickness dramatically while the concentration of the solutions is not so sensitive. The luminescent spectrum of the complex film shows the characteristic emission of Tb 3+ ion as well as the ligand indicating the formation of the complex.

Effects of Anions and Cations on π-Complexation Between Olefin and Metal Halide

An ab initio molecular orbital study was performed to determine the effects of anions and cations on the π-complexation of C_2H_4 on MX(M=Ag, Cu; X=F, Cl). The calculated results show the following order of adsorption strength: F ->Cl - for anions; Cu +>Ag + for cations. The results can be explained by the detailed analysis of atomic charge, orbital energy and orbital population by using the natural bond orbital(NBO) theory: (1) anions with stronger electronegativity can attract more electrons from the s orbital of M, while at the same time it does not obviously weaken the d orbital occupation of M, thus the nearly vacant s orbital and the sufficiently filled d orbitals of M help with forming σ-donation and d-π * backdonation with the π orbital and the π * orbital of olefin, respectively; (2) a smaller energy gap of symmetry-adapted orbitals between olefin and a cation can favor the electron transfer, that is why Cu + forms stronger adsorption with olefin than Ag + does.

Determination of complexation capacity of trace metal-organic in natural water

The complexation capacity for heavy metals (Cu, Cd, Pb) were determined by anodic stripping voltammetry in South China Sea, Hulun Lake and Wuliang Suhai. The conditional stability constants and complexation capacity index were calculated. The data showed that the complexation capacity of the Hulun Lake was greater than that of seawater and Wuliang Suhai. The sequence of complexation capacity is C (CuL)> C (CdL)> C (PbL), the values are in concord with results of analysis on dissolved organic carbon. The conditional stability constants were in an opposite sequence: K (CuL)< K (CdL)< K (PbL). When log K are similar, the greater the complexation capacity, the greater the complexation capacity index.

Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal

Thermodynamic parameters of complexation of naphto- 15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted. Complex of naphtha-15-crown-5 with calcium ion is very stable due to the synergism of static electric interaction and size selectivity between the host and the guest.

Recovery of Tungsten (Ⅵ) from Aqueous Solutions by Complexation-ultrafiltration Process with the Help of Polyquaternium

Polyquaternium-6 (PQ6) as the water-soluble polymer was used for complexing the anion forms of tungsten (Ⅵ) before ultrafiltration. Tungsten (Ⅵ)-PQ6 complex was retained by polysulfone hollow fiber ultrafiltration membrane in the complexation-ultrafiltration process. Effects of various operating parameters such as polymer metal ratio(PMR), pH and chloride ion concentration on permeate flux (J) and tungsten rejection coefficient (R) were investigated. The integration of four experiments including concentration, decomplexation, diafiltration and reuse of regenerated polymer was carried out. In the process of concentration, J declines slowly and R is about 1 at PMR of 3 and pH of 7. Tungsten concentration in the retentate increases linearly with volume concentration factor. Tungsten is concentrated efficiently with the membrane. The concentrated retentate was used further for the decomplexation. It takes about 6 min to reach the decomplexation equilibrium at chloride ion concentration of 50 mg·L-1 . The decomplexation percentage of tungsten (Ⅵ)-PQ6 complex reaches 56.1%. In the diafiltration process, tungsten (Ⅵ) can be extracted effectively by using 50 mg·L-1 chloride ion solution, and the purification of the regenerated PQ6 is acceptably satisfactory. The regenerated PQ6 was used to bind tungsten (Ⅵ) at various pH values. The binding capacity of the regenerated PQ6 is close to that of fresh PQ6, and the recovery percentage of binding capacity is higher than 90%.

Synthesis of a Novel Aromatic Diamino-bridged Bis(β-cyclodextrin) and its Inclusion Complexation with Dyes Molecules

A novel brideed bis（β-cvclodextrin）, 4, 4＇-diaminodiphenyl ether-bfiged-bis （6-aimino-6-deoxv-β-cyclodextrin） 3, has been synthesized and its inclusion complexation behavior with three linear＇guest dyes （AR, NR and MB ） has been investigated by. means of fluorescence spectrometry. The-result obtained demonstrated that the novel bridged bis（β-cyclodextnn） showed much higher affinities towards guest dyes than native β-cyclodextrin.

Cu(Ⅱ),Ni(Ⅱ)Complexation with Acid Alizarine Blue B in the Presence of Cetyltrimethylammonium Bromide

The coordination reactions of Cu（Ⅱ） and Ni（Ⅱ） with acid alizarine blue B （AABB） in the presence of cetyltrimethylammonium bromide （CTAB） micelle were investigated using the microsurface adsorptionspectral correction technique （MSASC）. The aggregation of AABB on CTAB followed the Langmuir isothermal adsorption law. The enrichment of AABB on CTAB sensitized the complexation between Cu（Ⅱ） or Ni（Ⅱ）and AABB. The binding ratio of AABB to CTAB was 1：2.5, and monomeric aggregate, AABB2CTAB5, was formed with an adsorption constant of 5.95×10^5 at 20 ℃ or 2.48×10^5 at 40 ℃. In the ternary complexation, the ratio of AABB：Cu and AABB：Ni were 1：1 and 1：2.5, respectively. Two types of aggregates, Cu2.AABB2·CTAB80 and Ni5.AABB2.CTAB80, were formed.

Concentration of linoleic acid from cottonseed oil by starch complexation

The extraction of linoleic acid from fatty acids(FA) of the cottonseed oil using starch–FA complexes was developed for the first time. We showed that starch can form inclusion complexes of different strengths with FA and that the different strengths stem from the differences in chain length, degree of unsaturation, and position of double bonds of FA. The optimal separation conditions were determined as follows: The inclusion temperature is 69 °C, the inclusion time is 30 min, the starch/FA mass ratio is 10:1, and the ratio of the volume of methanol–water solution and the mass of FA is 18:1. Compared to urea inclusion complexation, starch complexation has milder reaction temperature and shorter reaction time. Under these conditions, linoleic acid can be concentrated from 38.9% to 70.04% by one-off extraction. Moreover, the experimental results demonstrate the almost perfect reusability of starch. These results show that starch complexation is a promising method that can be used to obtain highly concentrated linoleic acid from cottonseed oil.

Synthesis and Spectroscopic Characterizations on the Complexation of Three Different Metal Ions Ba(Ⅱ),Ni(Ⅱ),and Ce(Ⅲ)with Atenolol Drug Chelate

Three types of metal ions barium(Ⅱ),nickel(Ⅱ)and cerium(Ⅲ)complexity of ATN drug have been prepared and characterized using molar conductance method,FT-IR,electronic,and 1H-NMR analysis measurements.The chemical and physical results for all atenolol complexes are agreement with the speculated structures.For the divalent(Ba&Ni)and trivalent(Ce)metal atenolol a molar ratio 1∶2 was established.Qualitative chemical analysis showed that for the divalent metal complexes,the chloride ions are not involved in the complexes,suggesting that all of these complexes,[Ba(ATN)2]·2 H2O and[Ni(ATN)2(H2O)2]·4 H2O are neutral.However,for the cerium(Ⅲ)complex,[Ce(ATN)2(NO3)]·3 H2O,the nitrate group is existed inside the coordination sphere.ATN make astable metal complexity with barium(Ⅱ),nickel(Ⅱ)and cerium(Ⅲ)ions.Electronic absorption analysis of Atenolol give two fundamental peaks at 225 nm and 274 nm refers to variation in transition electrons of ligand,UV spectral analysis of the three complexity obtained give asymmetric broad band in the range 200~400 nm,the reults are convenient with the suggestion of metal-nitrogen and metal-oxygen bonds.The infrared analysis data proved that ATN act as bidentate ligand through the N atom of the-NH group and O atom of the deprotonated alcoholic OH group.Nickel(Ⅱ)and cerium(Ⅲ)complexity make six-coordinate geometry,whereas the barium(Ⅱ)complex exhibit four-coordinate geometry.Ni(Ⅱ)-ATN complex has an effective magnetic moment equal 3.12 B.M,that is assigned to octahedral structure.The 1H-NMR spectral results of Ba(Ⅱ)-ATN complexity give strong signal at^4.00 ppm due to protons of-CH2 that influenced by low degree due to complexity.These results confirm the position of chelation through the N atom of the-NH group and O atom of the deprotonated alcoholic OH group.

~1H AND ^（13）C NMR STUDY OF INCLUSION COMPLEXATION OF DSS WITH β－CYCLODEXTRIN

The inclusion complexation of sodium 2,2-dimethylsilapentane-5-sulphonate(DSS) with β-cyclodextrin has been studied by means of NMR spectroscopy. The association constant (Kn) and thus the free energy change (-△G0) were determined to be 89. 5 L/mol and 11. 4 kJ/mol, respectively.