Addition Of Organic Ligands Research Articles

Facile construction of hierarchically porous CPO-27-Ni by mixed ligand strategy towards enhanced adsorption desulfurization from fuels

High-efficiency removal of macromolecular aromatic sulfide from fuel via adsorption technology remains a challenge due to the limited mass-transfer efficiency in traditional microporous materials. Constructing hierarchically porous structure might be an alternative route to overcome the problem. Herein, we propose an approach to prepare rationally defective Nickel(II) 2,5-dihydroxyterephthalate (CPO-27-Ni) using benzoic acid (BA) and 2, 5-dihydroxyterephthalic acid (DHTA) as mixed ligands, aiming at reducing the diffusion resistance of molecules in adsorbents through introducing mesopores and thus enhancing the performance of aromatic sulfide removal. By adjusting the ratio of BA and DHTA (x), CPO-27-Ni (BA-C-x) with rational defects was successfully synthesized. Compared with the single-channel CPO-27-Ni, the penetrating sulfur capacity in the dynamic adsorption experiment was increased by 9.97 times for thiophene (TP), 7.25 times for benzothiophene (BT) and 2.81 times for dibenzothiophene (DBT). After the addition of organic ligand B, additional mesoporous pores were formed in the microporous CPO-27-Ni. The obtained hierarchical structure possessed better textural properties and ensured structural constancy, which improved the utilization rate of high active sites and mass transfer rate of adsorbent, leading to promoted desulfurization performance. The reported method of introducing mesopores into MOFs to construct hierarchically porous structures would provide a meaningful reference for facile preparation of high-efficiency desulfurization adsorbents.

The Removal of Pertechnetate from Aqueous Solution by Synthetic Hydroxyapatite: The Role of Reduction Reagents and Organic Ligands.

The use of knowledge from technetium radiochemistry (even from nuclear medicine applications) allows us to select an sorbent for 99mTc radionuclide sorption, which is hydroxyapatite. Using radioisotope indication, the 99mTcO₄- sorption process on synthetic hydroxyapatite was studied by the batch method in the presence of SnCl2 and FeSO4 reducing agents. The complexing organic ligands' effect on the 99mTcO₄- sorption under reducing conditions was investigated. In the presence of Sn2+ ions without the addition of organic ligand, the sorption percentage reached above 90% independently of the environment. In the presence of Fe2+ ions without the addition of organic ligand, the sorption of 99mTcO₄- was significantly lower and was at approximately 6%, depending on the concentration of Fe2+ ions in solution. The effect of complexing organic ligands on the 99mTcO₄- sorption on hydroxyapatite from the aqueous solution, acetate buffer and phosphate buffer decreases in the following order for Sn2+: oxalic acid > ethylenediaminetetraacetic acid > ascorbic acid. In the presence of Fe2+ ions without organic ligands, the sorption reached up to 15% depending on the composition of the solution. The addition of oxalic acid and ascorbic acid increased the sorption up to 80%. The ethylenediaminetetraacetic acid had no significant effect on the sorption of technetium on hydroxyapatite.

Photothermal catalysis without solvent for fixing CO2 to cyclic carbonate

Photocatalytic cycloaddition of CO2 with epoxides to produce cyclic carbonate is a hot research topic for achieving carbon neutrality. In this work, a catalyst (CoFe2O4@TPA) with bimetallic oxides doped with organic ligands was synthesized, which could efficiently fix CO2 to synthesize cyclic carbonate in solvent-free and atmospheric environment by photothermal catalysis. Various characterization results suggest that the catalyst exhibited efficient photocatalytic performance upon the addition of organic ligands (TPA). This pathway of using photocatalytic catalytic reactions under simple conditions provides a new idea for the synthesis of valuable compounds from fixed CO2.

Synthesis of hollow ceria-zirconia solid solution particles by spray pyrolysis with organic ligands and its oxygen storage capacity

CeO2-based materials have been explored as oxidative catalysts owing to the reversible oxygen absorption and release behavior. The catalytic property is stabilized by addition of ZrO2 to form the solid solution. Hollow CeO2-ZrO2 solid solution particles were prepared by a spray pyrolysis method with organic additives, characterized by SEM, XRD and TEM, and evaluated for oxygen storage capacity (OSC). Spherical hollow particles with a size of about 500 nm formed, which were composed of about 10 nm nanoparticles. CeO2-rich particles had cubic crystal structure, while tetragonal phase was included in ZrO2-rich particles. The addition of organic ligands was effective to form uniform solid solution and increase specific surface area. The spray-pyrolysis temperature should be low to keep the specific surface area. At 50 mol% ZrO2, although the specific surface area was not so high as 20 m2/g, the maximum OSC of 650 μmol-O2/g was achieved. It was found that the OSC depends on ZrO2 content and the oxygen release rate increases with specific surface area.

Removal of Tannic Acid Stabilizes CuO Nanoparticles from Aqueous Media by PAFC: Effect of Process Conditions and Water Chemistry.

The increased utilization of CuO nanoparticles (CuO NPs) in various fields has raised concerns about their discharge into water containing a wide range of organic ligands. Moreover, the adsorption of these ligands can stabilize the CuO NPs in drinking water treatment plants. Thus, their removal from potable water is important to mitigate the risk to humans. The present study explored the efficacy of the coagulation–sedimentation (C/S) process for the removal of tannic acid (TA)-stabilized CuO NPs using polyaluminum ferric chloride (PAFC) as a coagulant. Moreover, the influence of process conditions (stirring speed) and water chemistry (i.e., pH and ionic strength (IS)) were also investigated to determine their impact on removal. The results showed that stirring speed in the reaction phase significantly affected the removal due to increased flocculation compared with stirring speed in the mixing phase. In addition, pH and IS affect the colloidal stability and removal efficiency of CuO NPs. A relatively better removal performance (<99%) of CuO NPs was found at lower coagulant dosage in the pH range 6–8. The addition of organic ligands reversed the surface charge potential and enhanced the colloidal stability of CuO NPs, resulting in the destabilization of TA-CuO NPs, thereby reducing the optimum PAFC dosage for removal. By contrast, the IS above the critical coagulation concentration decreased the removal efficiency due to inhibition of the ionic activity of PAFC hydrolysate in the aqueous environment. Fourier transform infrared findings of TA-CuO NPs composite flocs suggest that the primary removal mechanism might be mediated via the combined effect of neutralization, complexation as well as adsorption.

Novel d- and f-metal phthalocyaninates based on 4-(2,4,5-trichlorophenoxy)phthalonitrile. Synthesis, spectroscopic and fluorescent properties

The work reports synthesis and spectroscopic-luminescent properties of first obtained zinc, magnesium, erbium and gadolinium trichlorophenoxy-phthalocyanine complexes. The initial building unit being 4-(2,4,5-trichlorophenoxy)phthalonitrile is synthesized by nucleophilic substitution reaction. Zinc and magnesium complexes are obtained by template condensation of the phthalodinitrile and corresponding acetates. A demetallization of magnesium phthalocyaninate results in the formation of free tetra-4-(2,4,5-trichlorophenoxy)phthalocyanine ligand. Rare-earth element complexes are synthesized by two approaches: template condensation and metallization of free phthalocyanine ligand. The planar complex is found to be yielded higher in case of template fusion. Influence of lanthanide salts anion (acetate, chloride) on formation ability of sandwich-type complex is analyzed. A double-decker complex is testified to be formed only upon the template fusion of gadolinium acetate with 4-(2,4,5-trichlorophenoxy)phthalonitrile. The as-obtained compounds are studied in terms of spectral-luminescent characteristics. A bathochromic shift of absorption Q-band maximum is found to accompany d-to-f-metal transition. The zinc complex being associated in chloroform exhibits higher quantum yield of fluorescence than monomeric forms generated upon addition of organic ligand.

Biotic ligand model explains the effects of competition but not complexation for Sm biouptake by Chlamydomonas reinhardtii

The applicability of the biotic ligand model (BLM) was tested with respect to the biouptake of the lanthanide Sm by the freshwater green alga, Chlamydomonas reinhardtii. In the absence of organic ligands, Sm uptake was well described by the Michaelis-Menten equation, consistent with the BLM assumption of single transporter, with the maximum influx rate (Jmax) of 1.5 × 10−14 mol cm−2 s−1 and a binding constant (KSm) of 107.0 M−1. The addition of organic ligands (i.e., malic acid, diglycolic acid and citric acid) decreased Sm influx rates, however, the decreases were much less than that predicted by the BLM, possibly due to the direct contribution of the Sm complexes. Competition effects of two major cations (Ca2+ and Mg2+) and three lanthanide cations (La3+, Ce3+ and Eu3+) were successfully modeled by the BLM, with binding constants corresponding to KCa = 104.0 M−1, KMg = 102.7 M−1, KLa = 106.8 M−1, KCe = 106.9 M−1 and KEu = 107.0 M−1. The binding constants and Jmax were very similar among the four investigated lanthanides and varied progressively with atomic number; therefore, the results obtained in the present study can probably be extrapolated to other rare earth metals.

Synthesis of kesterite nanopowders with bandgap tuning ligands

A rapid development of solar cells has been observed within recent years. Semiconducting materials based on Cu2ZnSnS4 with the kesterite structure offer a promise of low‐cost and environmentally friendly solar cells. The energy gap of Cu2ZnSnS4, which is about 1.5 eV, can be optimized with addition of organic ligands. We report a method of obtaining kesterite nanopowders with grain diameter of approximately 5 nm via solution synthesis using metal chlorides and sulfur in oleylamine at 230 °C. The ligand exchange for diphenylamine upshifted the value of the bandgap to 2.2 eV, which makes it a promising material for an upper layer in tandem photovoltaic devices.

Bottom-Up Synthesis of Titanate Nanosheets in Aqueous Sols and Their Morphology Change by the Addition of Organic Ligands and Dialysis

The size, shape, and stacking of titanate nanosheets synthesized by heating aqueous mixtures of titanium complexes and tetrabutylammonium hydroxide were dependent on the type and amount of organic ligands and the amount of tetrabutylammonium ion (TBA+). When titanium isopropoxide was used as the titanium source, most titanate crystals were smaller than 10 nm in lateral size. However, the use of titanium complexes provided a lateral size of about 100 nm. The titanate crystals were synthesized by the acid–base reaction of titanic acid and TBAOH. The decrease in titanic acid concentration by titanium complex formation led to larger titanate crystals by the inhibition of crystal nucleation. Moreover, the use of triethanolamine and lactic acid as an organic ligand provided round and hexagonal titanate crystals, respectively. However, when the concentration of organic ligands was decreased by the dialysis of the titanate sols, the form of titanate crystals was changed to a rhombic shape. Thus, the adsorption of...

Effect of Ligands on the Dispersion of Ni Nanoparticles in Ni/SBA-15 Hydrogenation Catalysts

ABSTRACTIn the present work, a comparison study of the Ni catalysts supported on SBA-15 silica support prepared with and without the addition of organic ligands (citric acid and ethylenediaminetetraacetic acid (EDTA) was undertaken. The aim of this study was to inquire on the effect of the addition of organic ligands on the characteristics of the supported NiO and Ni nanoparticles and on their activity and selectivity in hydrogenation (HYD) of aromatics. Catalysts with different metal loadings (5, 10 and 20 wt. % of Ni) were prepared, characterized by nitrogen physisorption, small-angle and powder XRD, TPR, UV-vis DRS, and HRTEM, and tested in HYD of naphthalene (NP). It was found that Ni(II)-Ligand complexes were formed in aqueous solutions of Ni(NO3)2 containing citric acid (CA) or EDTA. Catalysts prepared from impregnation solutions with and without ligands had different textural characteristics and dispersion of NiO particles after calcination at 500 °C for 4 h. As it was shown by XRD, DRS and TPR, dispersion of NiO particles significantly increased when EDTA was used, whereas it noticeably decreased after the addition of CA. Similar trends were observed in the dispersion of metallic Ni particles after reduction of the NiO/SBA-15 precursors (HRTEM). In line with the characterization results, catalytic activity tests revealed strong differences in the activity of the prepared Ni/SBA-15 catalysts in hydrogenation of naphthalene. Catalysts prepared with the addition of EDTA were more active than those prepared without ligands. On the contrary, the HYD activity of a series of the Ni catalysts prepared with citric acid was lower than of other corresponding samples. The reasons of such a different behavior of the catalysts prepared with two organic ligands used are discussed on the basis of the obtained characterization results.

Dissolution of basalts and peridotite in seawater, in the presence of ligands, and CO 2: Implications for mineral sequestration of carbon dioxide

Steady-state silica release rates ( r Si) from basaltic glass and crystalline basalt of similar chemical composition as well as dunitic peridotite have been determined in far-from-equilibrium dissolution experiments at 25 °C and pH 3.6 in (a) artificial seawater solutions under 4 bar pCO 2, (b) varying ionic strength solutions, including acidified natural seawater, (c) acidified natural seawater of varying fluoride concentrations, and (d) acidified natural seawater of varying dissolved organic carbon concentrations. Glassy and crystalline basalts exhibit similar r Si in solutions of varying ionic strength and cation concentrations. Rates of all solids are found to increase by 0.3–0.5 log units in the presence of a pCO 2 of 4 bar compared to CO 2 pressure of the atmosphere. At atmospheric CO 2 pressure, basaltic glass dissolution rates were most increased by the addition of fluoride to solution whereas crystalline basalt rates were most enhanced by the addition of organic ligands. In contrast, peridotite does not display any significant ligand-promoting effect, either in the presence of fluoride or organic acids. Most significantly, Si release rates from the basalts are found to be not more than 0.6 log units slower than corresponding rates of the peridotite at all conditions considered in this study. This difference becomes negligible in seawater suggesting that for the purposes of in-situ mineral sequestration, CO 2-charged seawater injected into basalt might be nearly as efficient as injection into peridotite.

The Soft Material Obtained from an Europium (III)-Containing Ionic Liquid

The addition of organic ligand (<TEX>${\beta}$</TEX>-diketone or heterocyclic compound) to the europium (III)-containing ionic liquid resulted in bright luminescent soft materials with the molar ratio of europium/ionic liquid (IL)/ligand being 1:3:1 that exhibit bright red light under UV lamp. The luminescent properties such as emission features and lifetime of <TEX>$^5D_0$</TEX> <TEX>$Eu^{3+}$</TEX> excited level are dependent on the organic ligands. The materials were characterized by FT-IR and luminescence spectroscopy. The data shows that at least parts of the ILs (carboxylic acid) are replaced with <TEX>${\beta}$</TEX>-diketone ligand rather than the formation of europium complex with the molar ratio of <TEX>$Eu^{3+}$</TEX>:IL: ligand being 1:3:1, while no ILs could be replaced by the heterocyclic ligand such as Bpy and Phen.

Molybdenum Peroxo Nanohybrid Compounds in Different Structures and Catalytic Properties

The new nanohybrid of molybdenum peroxo compounds based on pyridine dicarboxylate ligands were synthesized by employing one-pot procedure in aqueous media and characterized by infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermal analysis (TGA/DTA). The prepared compounds were used as catalysts for the epoxidation of cyclohexene and cyclooctene in a mild condition. Results showed that these molybdenum peroxo compounds have significant potentials as oxidants in oxygen atom transfer reactions. These reagents oxidized olefins to epoxides in presence of hydrogen peroxide with high conversions and selectivity. Comparison of the relative reactivity of those compounds shows that the electronic nature of ligands influences the rate and activity of oxygen transfer reaction. It is also found that the addition of organic ligands not only prevented the formation of diols in epoxidation of alkenes, but also increased the reaction rate.

Re-evaluating the effects of organic ligands on copper toxicity to barley root elongation in culture solution

In the presence of weak ligands, both free ion activity and organic complexes of Cu should b considered when predicting Cu toxicity in aquatic and soil-plant systems. However, there is littl information about the quantitative contribution of Cu that is organically complexed to Cu toxicity. In thi study, a bioassay using barley root elongation in culture solution was used to investigate the effects o organic ligands with different conditional stability constants on Cu toxicity and the quantitativ contribution of the organically complexed Cu to the Cu toxicity. The results indicated that a significan decrease (p<0.05) in Cu toxicity, assessed by barley root elongation, was observed in response to th addition of organic ligands. The decrease differed, to some extent, with different organic ligands o disodium ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), oxalate and malate at low and constant free Cu2+ activity. Addition of EDTA or NTA resulted in strong reduction of Cu toxicity while modest reduction of Cu toxicity was observed for the addition of malate as the relatively wea ligand. Furthermore, the results of the present study revealed that the CuNTA− and CuEDTA2− complexes were not toxic, while the Cu–malate complexes were mildly toxic to barley root elongation More importantly, it was found that the toxicity of Cu–malate complexes were nearly 0.5-fold less than that of free Cu2+ ions.

Composition and transformation of 1.4 nm minerals in cutan and matrix of alfisols in central China

Hydroxy interlayered vermiculite (HIV) and vermiculite are commonly referred to as 1.4 nm minerals. In the subtropical soils of central China, the concentration of vermiculites decreased while that of HIVs increased gradually from north to south as the intensity of soil formation or eluviation increases in the same direction. The cutans in these soils closely interact with air, roots, microbes, water and dissolved ions in soils. Cutans may therefore be expected to exert an important influence on the formation of 1.4 nm minerals relative to the matrix soils. However, little is known about the transformation of 1.4 nm minerals in Alfisols in central China. Here, we investigate the compositional differences of 1.4 nm minerals in cutans and matrix soils, and the probable transformation of vermiculite to HIV or vice versa when sodium citrate and sodium acetate are added to matrix Alfisols. Cutans and matrix soils were separated from three soils in the northern subtropical zone in China. The samples were analyzed for Fe, Mn, exchangeable cations, organic matter(O.M.), pH, and clay minerals. To 10 mL of matrix soil, suspensions containing about 250 mg (oven-dry weight) of clay was added with 5 mL of 0.4 mol/dm3 or 2 mol/dm3 of sodium citrate or sodium acetate solution and 5 mL of 0.2 mol/dm3 mixed solutions of CaCl2, Mg(NO3)2 and KCl. After its pH was adjusted to 6.0, the mixture was ‘incubated’ for 120 or 210 days (more than one season or half a year) during which period it was shaken for 1 hour every day. The clay mineral composition of the samples was determined after incubation. Both vermiculites and HIVs were present in matrix soils, but only vermiculties were detected in cutans. The addition of organic ligands (citrate and acetate) promoted the transformation of HIV to vermiculite. This transformation was obvious for the matrix soils that had been incubated with 0.5 mol/dm3 sodium citrate for 210 days while sodium acetate was less effective in this regard. The promoting effect of organic ligands is dependent on type and concentration as well as incubation time. This would suggest the reverse transformation occurred in the formation of cutans compared with a vermiculite-to-HIV transformation in the subtropical soils of central China from north to south. The position and environment of cutans in the B horizon together with the pH, organic matter and exchangeable base status in cutans seem conducive to the co-existence of vermiculite and HIV in the soils, but only vermiculite is found in cutans. The transformation of HIV to vermiculite in incubation experiments could be divided into two steps: 1) Cheluviation of organic matter to the interlayer hydroxy-aluminums from HIVs. 2) Rebasification of hydrated cations into the interlayers of vermiculites. The clay minerals in cutans can interact with organic ligands and nutrient elements excreted by roots. Under conditions of frequent wetting and drying and high pH, and when the concentrations of exchangeable bases, iron-manganese oxides, clays, and organic matter are high, the exchangeable cations can be incorporated into the interlayers of HIV, thereby promoting the partial transformation of HIV to vermiculite in rhizosphere soils. Cutan is at the interface of material and energy exchange involved in physical, chemical and biochemical reactions in the rhizosphere. These factors strongly affect the compositions of cutans. HIVs in (upper or adjacent) matrix soils may transform to vermiculites during cutan formation in these special soil environments.

Role of Phenolics and Organic Acids in Phosphorus Mobilization in Calcareous and Acidic Soils

Phenolic acids (caffeic, CAF; protocatechuic, PCA; p-coumaric, COU; and vanillic, VAN), catechol (CAT), poly-galacturonic acid (PGA), and citric acid (CIT) were compared for their effectiveness in phosphorus (P) mobilization in three soils differing in chemical properties. The addition of organic ligands at 100 μmol g− 1 soil increased the concentrations of resin P (Pr), water-extractable P (Pw), and bicarbonate-extractable inorganic P (Pbi), thus improving the phosphorus availability. The magnitude of P mobilization in the calcareous soil can be expressed in the following order: CAF > CAT > PCA = CIT > VAN > COU > PGA, which was consistent with the number of phenolic hydroxyl groups they contained and the position of carboxyl on the benzoic ring. In the two acid soils tested, the order of P mobilization was CIT > CAT > PCA > CAF after 24 h incubation, and CIT > PCA > CAF > CAT after a 14 d incubation. The mobilized P originated partly from the organic P fractions, which could be extracted by 0.5 M NaHCO3. In addition, Pr decreased and Pw increased during incubation. The exceptions were that the CAF treatment increased Pr and the CIT treatment did not affect Pw. Calcium extraction from the soils after a 1 d or 14 d incubation could not fully account for the P mobilization. The results suggest that the inorganic P dissolution by the organic ligands was not the only mechanism of P mobilization in the calcareous soil, while in acid soils the chelation of metal cations by organic ligands is likely an important factor in P mobilization.

Giant platinum clusters with organic ligands: preparation and catalysis

Giant platinum clusters were prepared by a new method, i.e. by combination of the preparation of naked platinum clusters by photoirradiation of a hexachloroplatinic(IV) acid solution and the stabilization of the naked clusters by addition of organic ligands. Platinum clusters stabilized by 1,10-phenanthroline are more active as catalyst for both visible light-induced hydrogen generation from water and hydrogenation of olefins than those stabilized by triphenylphosphine. The difference of activity is discussed by the term of coordination probability.

Kinetic Study of Citrate Effects on Orthophosphate Solubility in an Acidic, Montmorillonitic Soil

AbstractPrevious studies by the authors on the effects of pH, organic acids, ionic strength, and Ca on residual orthophosphate solubility in an acidic montmorillonitic soil (Typic Chromoxererts) were extended to include the variation of reaction time. The objective of the experiments was to determine the time dependence of the reactions and to elucidate further the mechanism of orthophosphate solubility in a montmorillonitic soil separate containing exchangeable Al and added citric acid, and suspended in 20 mol NaCl m−3. In the absence of added organic acids, soluble orthophosphate and Al3+ activities were found to be consistent with the presence of an amorphous hydroxy‐Al‐phosphate solid at elapsed t ≥ 24 h. Initial citrate concentrations of 10, 100, and 400 mmol m−3 resulted in citrate sorption by the soil separate and an increase in soluble orthophosphate and Al for t ≤ 1 h. Citrate sorption continued throughout the time course of the experiments. For 1 &lt; t &lt; 8 h, orthophosphate solubility was not affected by the initial citrate concentration. For 8 &lt; t &lt; 27 h, orthophosphate solubility decreased to constant levels. Soluble Al decreased for 1 &lt; t &lt; 30 h and then remained constant in the 10 and 100 mmol citrate m−3 treatments. The samples reacted with 400 mmol citrate m−3 exhibited a steady increase in soluble Al for the same time period. The time‐dependent changes in aqueous orthophosphate and Al were consistent with a previously proposed reaction describing organic ligand‐induced formation of an insoluble hydroxy‐Al‐phosphate. The time trends in the solution concentrations of Ca and Si were not affected by the addition of organic ligands nor were they related to the changes in soluble Al or orthophosphate.

Scanning electron microscopy and infrared spectroscopy of iron sediments formed byThiobacillus ferrooxidans

Abstract Sediments from FeSO4 · 7H2O solutions oxidized by resting cell suspensions of Thiobacillus ferrooxidans in the absence of additional monovalent cations consisted of amorphous hydrated Fe(III) sulfate possessing reticular or filamentous microstructure. In the presence of additional sulfate supplied as Li2SO4, MgSO4, (CH3NH3)2SO4, or (CH3NH3)HSO4 at pH 2.4, hydronium jarosite crystallized in the form of pseudocubic rhombohedra. Other cations produced ammonio‐ and natrojarosites as pyramidal and bipyramidal rhombohedra or potassium and rubidium jarosites in rounded and botryoidal forms. Addition of Na2SeO4 yielded the selenium analog of amorphous hydrated Fe(III) sulfate, but in the presence of NH4 + or Rb+, selenojarosites formed instead. Addition of organic ligands, together with (NH4)2SO4, produced ammoniojarosite in the form of irregular granules and rounded and spheroidal crystals. Despite delayed precipitation, the infrared spectra of sediments were usually the same in the presence or absence ...