The use of starch‐modified magnetic Fe0 nanoparticles for naphthalene adsorption from water samples: Adsorption isotherm,kinetic and thermodynamic studies

This study was aimed at investigating the effectiveness of starch‐modified magnetic nanoparticles for the removal of naphthalene, which is a polycyclic aromatic hydrocarbon present in the majority of water sediments, from water resources. Magnetic Fe⁰ nanoparticles have recently been considered because of their high efficiency for contaminant removal. In the present study, Fe⁰ nanoparticles were synthesized using sulfate method and starch was used as a stabilizer. The size of the Fe⁰ nanoparticles was measured as approximately 45 nm using X‐ray diffraction and scanning electron microscopy analyses. The removal efficiency of naphthalene from water using the nanoparticles was evaluated based on various factors including the viscosity of naphthalene dissolved in water, and operation factors such as nanoparticle dosage, contact time, initial naphthalene concentration and pH in non‐continuous reactors were optimized. The results revealed that the starch‐modified nanoparticles have high efficiency for removal of dissolved naphthalene from aqueous solution. Under the optimum conditions, more than 99% of naphthalene at a pH of 5.0 with nanoparticle dosage of 0.05 g was removed from aqueous solution in 5 min. The equilibrium adsorption data were interpreted in terms of Langmuir, Freundlich and Temkin isotherm models and the goodness of fit was inspected using linear regression analysis. Our results indicated that the Langmuir model with maximum adsorption capacity was best fitted, suggesting monolayer adsorption. Moreover, it was found that the adsorption process followed the pseudo‐second‐order kinetic model. In addition, a thermodynamic study indicated that the adsorption process of naphthalene from aqueous solution by the starch‐modified nanoparticles was spontaneous and exothermic.     

Column preconcentration of titanium in aluminium and zinc alloys with oxalic acid-ascorbic acid and the ion-pair of sodium 1,2-dihydroxybenzene-3,5-disulphonic acid and tetradecyldimethylbenzylammonium chloride supported on naphthalene using spectrometry

A solid ion-pair compound produced from sodium 1,2-dihydroxybenzene-3,5-disulphonic acid (Tiron) and tetradecyldimethylbenzylammonium chloride(TDBA) supported on naphthalene in a simple glass-tipped funnel tube provides a simple adsorbent system for preconcentrating titanium from some alloys. Titanium reacts with Tiron to form a water-soluble coloured chelate anion which in turn forms a water-insoluble stable titanium/Tiron/TDBA complex with the ion-pair on the surface of naphthalene packed in a column. Titanium is quantitatively retained on the naphthalene in the presence of L-ascorbic acid and oxalic acid in the pH range 3.0-4.5 and at a flow-rate of 1 mil/min. The metal complex and naphthalene were dissolved from the column with 5 ml of dimethylformamide(DMF), and the absorbance of the solution was measured at 398 nm. A calibration graph was linear over the range 1-18 mug of titanium in 5 ml of the final DMF solution. The complex has a molar absorptivity of 1.39 x 10(4) l.mole(-1).cm(-1) and a sensitivity of 3.44 x 10(-3) mug/cm(2) for 0.001 absorbance. Eight replicate determinations for a sample containing 12 mug of titanium gave a mean absorbance of 0.697 with a relative standard deviation of 0.82%. The interference of various ions was studied and optimum conditions were developed for the determination of titanium in various aluminium and zinc alloys.     

Dissolution of polycyclic aromatic hydrocarbons from a non-aqueous phase liquid into a surfactant solution using a rotating disk apparatus

The mass transfer of two polycyclic aromatic hydrocarbons (PAHs), naphthalene and phenanthrene from a multicomponent non-aqueous phase liquid (NAPL) into a nonionic surfactant solution, Brij 35 was investigated using a rotating apparatus. Few experimental methods have been applied to the study of solubilization kinetics in organic liquids because in those systems, the interfacial area during mixing is more difficult to maintain and measure. This challenge was overcome by permeating the NAPL through a membrane. Mass transfer experiments were conducted in the absence and presence of surfactant, and the concentrations of naphthalene and phenanthrene in the bulk aqueous phase were determined in samples collected at different time intervals from the time of initial contact of the NAPL phase with the aqueous solution phase. Experiments in pure water demonstrated that the rotating apparatus behaves as in much the same way as the Levich's rotating disk. The mass transfer coefficients and the dissolution of PAHs into the surfactant solution were measured at different doses of Brij 35. As the surfactant concentration increased, the mass transfer coefficients for both PAHs from the NAPL decreased.     

Dependence of the volume characteristics and viscosity of solutions of methanol-octane-naphthalene on composition at 25°C

The limiting solubility of naphthalene in a mixture of methanol-octane at 25°C is determined via isothermal saturation. The kinematic viscosity of a mixture of methanol-octane-naphthalene is measured at 25°C. Data on the density of triple mixtures of methanol-octane-naphthalene, used to calculate the partial and apparent molar volumes of naphthalene, are obtained with a high degree of accuracy. The obtained results are discussed in terms of the interactions that occur in solution.     

New thermally stable and organosoluble heterocyclic poly(naphthaleneimide)s

As majority of polyheteroarylenes based on bis(naphthalic anhydrides), are difficult to process due to their infusiblity and insolubility in common organic solvents and solubility only in strong acids, this study is concerned with the synthesis and properties of new, easily processable polyimides and copolyimides containing naphthalene and oxadiazole rings. These polymers have been synthesized and their properties have been compared with regard to the influence of oxadiazole and naphthalene units on their physical properties. The polyimides were prepared by polycondensation reaction in solution of the aromatic diamines containing preformed oxadiazole ring with two dianhydrides having naphthalene units, at high temperature. Also, copolyimides were prepared by using a mixture of each naphthalene‐containing dianhydride, with hexafluoroisopropylidene‐dianhydride in the polycondensation reaction with the same diamino‐oxadiazoles. Most of the resulting polyimides and copolyimides were soluble in polar amidic solvents and in less polar solvents, and their solutions gave flexible films when spread onto glass plates. The thermal stability and glass transition temperature of these polyimides and copolyimides were measured and compared. The quality and the roughness of the spin‐coated films of these polymers were investigated by atomic force microscopy. The photoluminescence properties of the polymers in solution were studied to determine the color of emission. The UV absorption was also studied to determine the Stokes shift, and hence the possible reabsorption effects. The properties of the present polyimides make them attractive for applications in advanced optoelectronics and other related fields. Copyright © 2009 John Wiley & Sons, Ltd.     

Tetradecyldimethylbenzylammonium thiocyanate adsorbent supported on naphthalene for the preconcentration and determination of cobalt in aluminium alloys and steels using atomic absorption spectrometry

A solid ion-pair material produced from tetradecyldimethylbenzylammonium chloride (TDBA) and ammonium thiocyanate on naphthalene provides a simple, rapid and selective technique of preconcentrating cobalt from up to 200 ml of aqueous solution. Cobalt reacts with sodium 1-nitroso-2-naphthol-3,6-disulphonate (nitroso-R salt) to form a brown, water-soluble chelate anion. The chelate anion forms a water-insoluble Co-nitroso-R salt-TDBA complex on naphthalene packed in a column and trace cobalt is quantitatively retained on the naphthalene in the pH range 2.7–11.0 at a flow-rate of 2 ml min^?1. The solid mass is stripped from the column with 5 ml of dimethylformamide (DMF) and cobalt is measured by atomic absorption spectrometry (AAS) at 241 nm. The calibration graph is linear over the concentration range 0.5–15μg Co in 5 ml of dimethylformamide solution. Seven replicate determinations of 9 μg of cobalt gave a mean absorbance of 0.095 with a relative standard deviation of 1.7%. The sensitivity for 1% absorption was 0.0834μg ml^?1 (0.240 μg ml^?1 for direct AAS on the aqueous solution). The proposed method was utilized for the determination of cobalt in standard aluminium alloys and steel samples.     

ENHANCEMENT OF ENERGY TRANSFER FROM THE TERMINAL CHROMOPHORE OF POLYETHER TO EUROPIUM CATION(Ⅲ)VIA COMPLEXATION

The fluorescence spectra of naphthalene end-labelled polyethylene glycol)(N-P_nN) in methanol solution in the presence of europium cation(Ⅲ) was investigated. Selective excitation of the naphthalene group of N-P_n-N re-sults in the emission of europium cation. suggesting that the polyether chain complexes with europium cation, thus efficient energy transfer from naphthalene chromophore to europium cation occurs. Photoirradiation of N-P-N in solution leads to intramolecular dimerization of the two terminal naphthalene groups to give a crown ether. The complexation of this photochemically synthesized crown ether and europium cation was also studied.     

主链含茜草双酯亚结构单元的聚磷酸酯的合成,降解及释药性能研究

通过茜草双酯与磷酰二氯的溶液缩聚合成了８种主链含茜草双酯亚结构单元的聚磷酸酯，并以元素分析、核磁共振氢谱和红外光谱确证了它们的结构。测定了它们的数均分子量。研究了其体外降解性能，并用高效液相色谱跟踪５－氟尿嘧啶从部分聚合物基质片中的释放行为。     

Carbon-13 NMR relaxation study of 1,8-bis(dimethylamino)naphthalene in isotropic solution

Carbon-13 nuclear spin relaxation in 1,8-bis(dimethylamino)naphthalene (DMAN) was investigated in a dimethylformamide- d 7 solution. In addition, the chemical shielding tensors were measured in the crystalline powder. Detailed analysis of (13)C longitudinal relaxation in this molecule yielded its rotational diffusion tensor. Comparison to the protonated form of DMAN, DMANH(+), leads to conclusions concerning interaction of the latter with its counterion.     

多层自组装硫脲和纳米金电流型萘免疫传感器的研究

建立了基于硫脲和纳米金层层自组装技术的无标记、高灵敏电流型免疫传感器,用于萘的检测。利用循环伏安法研究了修饰电极表面的电化学特性以及测试溶液的pH值、孵育时间和温度对免疫传感器性能的影响。实验表明,此免疫传感器在含不同浓度萘抗原的PBS溶液(pH7.4)中37℃下孵育30 min后,在pH7.4的测试底液中测定,响应电流与萘浓度在0.5～100μg/L范围内有良好的线性关系,r=0.9986,检出限为0.08μg/L。此传感器制备简单,灵敏度高,稳定性好,可以重复使用。应用于实际水样中萘的测定,回收率为94.3%～107.0%。     

Analysis of metals by solid-liquid separation after liquid-liquid extraction spectrophotometric determination of palladium(II) by extraction of palladium dimethylglyoximate with melted naphthalene

A method of liquid-liquid extraction of palladium di-methylglyoximate with molten naphthalene followed by solid-liquid separation is successfully applied to palladium. The complex between palladium and dimethylglyoxime is easily extracted into molten naphthalene. After extraction, the very fine solidified naphthalene crystals are dissolved in chloroform, and the absorbance of the resultant solution is measured at 370 nm against a reagent blank. Beer's law is obeyed for 30-370 mug of palladium in 10 ml of chloroform, and the molar absorptivity is calculated to be 1.72 x 10(4) l.mole.(-1)mm(-1). Various alkali metal salts and metal ions do not interfere. The interference of nickel(II) is overcome by the extraction at pH 2, and that of iron(III) by masking with EDTA or by reduction to iron(II). The method is rapid and accurate.     

Spectrophotometric determination of iron(III) dimethyldithiocarbamate (ferbam)

A spectrophotometric method was developed for the determination of ferbam (iron(III) dimethyldithiocarbamate) by converting it into an iron-phenanthroline complex, which was then absorbed on microcystalline naphthalene in the presence of tetraphenylborate, and the absorbance was measured at 515 nm against a reagent blank. The molar absorptivity of the complex was 1.2 x 10(4)l mol(-1)cm(-1). Ten replicate analyses of a sample solution containing 150 mug of ferbam gave a relative standard deviation of 0.84%. Beer's law was obeyed over the concentration range 22.4-372.9 mug of ferbam. The effects of various factors such as reagent concentration and naphthalene, shaking time and diverse ions were studied in detail. The method is sensitive and selective and can be applied to the direct determination of ferbam in commercial samples and in mixtures containing various other dithiocarbamates (e.g. ziram, zineb and maneb) in foodstuffs.     

2,5-环己二烯酮类的固相光化学(Ⅱ)

本文报道了2,4,6-三叔丁基-4-甲氧基-2,5-环己二烯酮的固相光化学反应,所得三种产物的比率随温度而变化,而液相光化学反应与温度无关。用带有NaNO₂滤色液的光照射该化合物,几乎得到100％的列米酮。在列米酮中加入少量萘的固相光化学反应所得产物的比率随萘量而变化。     

The volume characteristics of solution of naphthalene in heptane-ethanol mixtures at 298.15 K

The solubility of naphthalene was studied by the isothermal saturation method, and the density of naphthalene-heptane-ethanol solutions at 298.15 K was measured using an oscillating tube densimeter. The results were used to calculate the volume characteristics of naphthalene in the systems specified. The solubility of naphthalene in heptane was substantially higher than in ethanol. The composition dependences of apparent partial molar volumes contained extrema. The reason for such nonlinear dependences can be a sharp change in the contribution to the entropy of mixing related to the packing of molecules of different diameters (naphthalene and heptane). Another possible mechanism of these anomalies can be related to the stabilization of the structure of alkanols in the solvation sheath of alkanes noticed earlier.     

Column Preconcentration of Palladium Using Phenanthrenequinonedioxime Supported on Naphthalene by Atomic Absorption Spectroscopy

Abstract

A solid chelating compound, phenanthrenequinonedioxime(PQDO) supported on naphthalene provides a rapid and economical means of preconcentration of palladium from the aqueous samples. Palladium forms a complex with PQDO supported on naphthalene in the column at pH 1.2～2.7. The metal complex and naphthalene are dissolved out from the column with 5 ml of dimethylformamide-nitric acid (100+4) and the absorbance is measured atomic absorption spectrometer at 244.7 nm. A calibration curve is linear over the concentration range 1～24 μg of palladium in 5 ml of the final solution. The sensitivity for 1% absorption is 0.126 μg/ml (0.153 μg/ml for the direct AAS method from the aqueous medium). The method has been used for the determination of palladium in various synthetic samples and can be safely applied to the environmental samples too.     

Reactions of metal ions with dithizone in molten naphthalene

A comparative study has been made of the reactions of metal ions with dithizone in the two media, chloroform and molten naphthalene. The absorption spectra of several metal dithizonates, prepared in molten naphthalene, were recorded and were found to be the same as those of the dithizonates obtained by extraction of metal ions from aqueous solution with chloroform dithizone.     

Column chromatographic preconcentration of palladium with dimethyl glyoxime and acenaphthenequinone dioxime on naphthalene

A solid material consisting of dimethyl glyoxime (DMG), acenaphthenequinone dioxime (ANDO) or DMG-ANDO on naphthalene provides a very convenient, rapid and economical method for the preconcentration of palladium in synthetic samples. Pd-DMG, Pd-ANDO and Pd-DMG-ANDO are quantitatively retained on naphthalene in the column in the pH ranges 2.2–4.4, 1.8–5.6 and 1.7–6.8, respectively. The solid mixture consisting of the metal complex together with naphthalene is stripped from the column with 5 ml of dimethylformamide (DMF)-n-butylamine and the absorbance is measured at 247.6 nm with an atomic absorption spectrometer. Calibration graphs are linear over the palladium concentration range 5–25 μg per 5 ml of the final solution for all the three complexes. Ten replicate determinations of a sample solution containing 10 μg of palladium gave mean absorbances of 0.180, 0.225 and 0.230 with relative standard deviations of 1.8, 1.7 and 1.6% using the reagents DMg, ANDO and DMG-ANDO, respectively. The sensitivity of the method is better than the direct atomic absorption spectrometric determination of palladium. It is highest in case of the mixed ligands, i.e., DMG-ANDO (0.038 μg ml^?1 for 1% absorption). The method can be applied to the trace determination of palladium in complex materials.     

含萘环骨架液晶化合物的合成

含萘环骨架液晶化合物的合成;液晶;萘环;合成;熔点;清亮点;液晶相区间     

Polanyi-based models for the adsorption of naphthalene from aqueous solutions onto nonpolar polymeric adsorbents

In this research, naphthalene was adopted as the representative model compound of PAHs, and static adsorption of naphthalene from aqueous solution onto three commercial polymeric adsorbents with different pore structure was investigated. Nonlinear isotherms models, i.e., Freundlich, Langmuir, and Polanyi-Dubinin-Manes (PDM) models were tested to fit experimental data, and the experimental data were found to fit well by the PDM model. Through both isotherm modeling and constructing "characteristic curve," Polanyi theory was useful to describe the adsorption process of naphthalene by polymeric adsorbents, providing evidence that a micropore filling phenomenon was involved during the adsorption process. In addition, a good linear correlation was obtained between the naphthalene adsorption capacities and the micropore volume of adsorbents (Vmicro), whereas no linear relationship was found between the naphthalene adsorption capacities and the specific surface area of adsorbents. Based on the PDM model, the micropore volumes of adsorbents was introduced to normalize the equilibrium adsorbed volume (qv), plots of qv/V(micro) vs adsorption potential density for naphthalene on three different polymeric adsorbents were collapsed to a single correlation curve, which would be of great benefit to predict the adsorption capacity of adsorbent for the purpose of adsorption engineering design.     

Trace Analysis of Nickel by Extraction-Atomic Absorption Spectrophotometry Determination of its Acenaphthenequinone Dioxime Complex in Molten Naphthalene

A procedure is described for the trace analysis of nickel using the liquid-liquid extraction of nickel acenaphthenequinone dioxime complex with molten naphthalene followed by solid-liquid separation. Nickel complex cannot be extracted into any non-aqueous organic solvents, but can be quantitatively extracted into molten naphthalene. It is very stable at high temperature and is dissolved in the mixed solvent (HNO₃-DMF). The absorbance of the solution was measured at 231.5 nm against a reagent blank. Beer's law is followed in the concentration range of 5–100 μg of nickel in 10 ml of the final solution. The sensitivity for 1% absorption is 0.155 μg/ml nickel. The relative standard deviation is 1.0% for ten replicate determinations of 60 μg of nickel. The interference of various ions has been studied and the method has been applied to the determination of nickel in aluminium alloys.