Preconcentration and determination of trace metal ions from aqueous samples by newly developed gallic acid modified Amberlite XAD-16 chelating resin

Gallic acid was immobilized on Amberlite XAD-16 by coupling it through -N=N group. The resulting chelating resin Amberlite XAD-16 gallic acid, characterized by thermogravimetric analysis (TGA), infrared (IR) spectra and BET analysis, was used to preconcentrate Cr(III), Mn(II),Fe(III),Co(II), Ni(II) and Cu(II)ions. The resin was employed for the preconcentration of the metal ions present in river water and industrial area aqueous samples. Several parameters like effect of pH, effect of time, effect of sample volume and flow rate of sample were investigated. The sorption capacities for the resin were 216 micromol g(-1), 180 micromol g(-1), 403 micromol g(-1), 281 micromol g(-1), 250 micromol g(-1) and 344 micromol g(-1) for Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) respectively. The preconcentration factors for Cr(III), Mn(II), Fe(III), Ni(II), Co(II) and Cu(II) were found out to be 300, 200, 400, 285.7, 300 and 400 respectively. The effect of various interfering ions was also studied. Results were validated by using standard addition method for river water sample.     

Extensive measurements of H216O line frequencies and strengths: 5750 to 7965 cm(-1)

High-resolution spectra of H(2)(16)O vapor covering the region from 5750 to 7965 cm(-1) were used to determine experimental values of line positions and strengths of over 3750 vibration-rotation transitions in the (110)-(000), (011)-(000), (040)-(000), (120)-(000), (021)-(000), (200)-(000), (101)-(000), (002)-(000), (031)-(010), (210)-(010) and (111)-(010) bands from which rotational energy levels in the (040), (120), (021), (200), (101) and (002) vibrational states were obtained. The line strengths and frequencies reported here are considered to be a marked improvement over the values listed in the 1986 edition of the HITRAN database, and a preliminarly listing from this work has been included in the 1993 HITRAN edition.     

Transition frequencies and strengths of H217O and H218O: 6600 to 7640 cm(-1)

High-resolution spectra of O(17)- and O(18)-enriched water-vapor samples have been recorded with a Fourier transform spectrometer covering the region between 6600 and 7640 cmcm(-1). Experimental values of line positions and strengths of 1807 absorptions in the (120)-(000), (021)-(000), (200)-(000), (101)-(000), (002)-(000), bands of the two isotopic species were derived from the spectra. The analysis included the determination of accurate rotational levels belonging to the (120), (021), (200), (101), and (002) vibrational states of H(2)(17)O and H(2)(18)O.     

Vacuum Carbosilicothermic Reduction of Zirconium,Hafnium, Vanadium,Niobium, Tantalum,and Chromium Oxides

Inorganic Materials - This paper reports on vacuum carbosilicothermic reduction of zirconium(IV), hafnium(IV), vanadium(V), niobium(V), tantalum(V), and chromium(III) oxides at a temperature of...     

Hiral Effects of Single Wall Carbon Nanotube Fluorination and Hydrogenation

Abstract

In the paper the results of calculations of the electronic and energy characteristics of atomic hydrogen and fluorine adsorption processes on an external surface of single wall hiral carbon nanotubes (n, m) are represented. Molecular cluster model within a framework of quantum chemical semi‐empirical schemes MNDO and PM3 has been used. Sorption properties of (4, 1), (4, 2), (4, 3), (5, 1), (5, 3), (5, 4), (6, 1), (6, 2), (6, 3), (6, 4), and (6, 5) tubes have been considered. Periodical behavior of the chemical bond and activation energies as nanotube diameter functions has been found. It appeared that (4, 2), (4, 3), (5, 1) nanotubes show more effective adsorption processes and (5, 3), (5, 4), (6, 2), (6, 3) tubes are not advantage for the chemisorptions.     

A Calixarene-Based Fluorogenic Reagent for Selective Mercury(II) Recognition

The first calixarene-based fluorogenic Hg(II)-selective extractant, 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(N-(5-dimethylaminonaphthalene-1-sulfonyl)carbamoylmethoxy)-26,28-dimethoxycalix[4]arene (2), is reported. In solvent extraction from aqueous acidic solutions (HNO(3)), 2 exhibits excellent selectivity for Hg(II) over a wide range of transition, alkali, and alkaline earth metal cations. Quenching of its fluorescence due to Hg(II) coordination is unaffected by the presence of 100-fold excesses of alkali metal cations, alkaline earth metal cations, Ag(I), Tl(I), Cd(II), Co(II), Cu(II), Ni(II), Pb(II), Pd(II), Zn(II), or Fe(III).     

Theoretical Migration Model for Micellar Capillary Electrophoresis and Its Application to the Separation of Anionic Metal Complexes of HEDTC and CDTA

A mathematical model relating the effective mobility of an analyte in micellar capillary electrophoresis (MCE) to the concentration of surfactant and organic modifier in the background electrolyte (BGE) was derived. Effective mobility is expressed in terms of the electrophoretic mobility of the analyte, the partition coefficient of the analyte into the micelle, and the influence of organic modifier on these two factors. The performance of the model was evaluated using Cd(II), Pb(II), Co(II), Ni(II), Bi(III), Cu(II), and Hg(II) complexes of bis(2-hydroxyethyl)dithiocarbamate, all of which carry a partial negative charge, and Cd(II), Pb(II), Co(II), Ni(II), Bi(III), Cu(II), Hg(II), Fe(III), Ag(I), Tl(I), and Mn(II) complexes of trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, all of which are anionic having charges in the range -1 to -3. These analytes were separated in borate BGEs containing 10-50 mM sodium dodecyl sulfate and 0-20% (v/v) methanol. Nonlinear regression was used to derive parameters for the model from experimental data and these parameters were used to predict effective mobilities of the analytes. Predicted values of effective mobilties agreed with experimental values to within 3.1%. Values of parameters from the model equation are used to explain changes in separation selectivity observed at different BGE compositions and the model equation is shown to be applicable to computer-assisted optimization of the BGE composition, in MCE using a limited number of experiments.     

Pesticide adsorption in relation to soil properties and soil type distribution in regional scale

Study was focused on the evaluation of pesticide adsorption in soils, as one of the parameters, which are necessary to know when assessing possible groundwater contamination caused by pesticides commonly used in agriculture. Batch sorption tests were performed for 11 selected pesticides and 13 representative soils. The Freundlich equations were used to describe adsorption isotherms. Multiple-linear regressions were used to predict the Freundlich adsorption coefficients from measured soil properties. Resulting functions and a soil map of the Czech Republic were used to generate maps of the coefficient distribution. The multiple linear regressions showed that the K(F) coefficient depended on: (a) combination of OM (organic matter content), pH(KCl) and CEC (cation exchange capacity), or OM, SCS (sorption complex saturation) and salinity (terbuthylazine), (b) combination of OM and pH(KCl), or OM, SCS and salinity (prometryne), (c) combination of OM and pH(KCl), or OM and ρ(z) (metribuzin), (d) combination of OM, CEC and clay content, or clay content, CEC and salinity (hexazinone), (e) combination of OM and pH(KCl), or OM and SCS (metolachlor), (f) OM or combination of OM and CaCO(3) (chlorotoluron), (g) OM (azoxystrobin), (h) combination of OM and pH(KCl) (trifluralin), (i) combination of OM and clay content (fipronil), (j) combination of OM and pH(KCl), or OM, pH(KCl) and CaCO(3) (thiacloprid), (k) combination of OM, pH(KCl) and CEC, or sand content, pH(KCl) and salinity (chlormequat chloride).     

Determination of the optimum conditions in the removal of Bomaplex Red CR-L dye from the textile wastewater using O3, H2O2, HCO3- and PAC

Bomaplex Red CR-L textile dye was used in the experimental studies. Taguchi method was applied to determine optimum conditions in the removal of dye from synthetic textile wastewater. After the parameters were determined to remove Bomaplex Red CR-L dye from synthetic textile wastewater, the experimental studies were realized. The chosen experimental parameters and their ranges: HCO3- (mM), 0-39; temperature (degrees C), 18-70; ozone-air flow rate (l min-1), 5-15; the dye concentration (ppm), 200-600; particulate activated carbon (PAC) (g), 0-1.5; H2O2 (mM), 0-0056; pH, 3-12; and treatment time (min), 10-30, respectively. An orthogonal array L18 (2(1)x3(7)) for experimental plan and the smaller the better performance statistics formula were selected to define optimum conditions. The optimum conditions were found to be as follows: HCO3- (mM), 0; temperature (degrees C), 70; ozone-air flow rate (l min-1), 10; the dye concentration (ppm), 200; particulate activated carbon (PAC) (g), 1; H2O2 (mM), 0.056; pH, 12; and time (min), 20. Under these optimum conditions, it was determined that the Bomaplex Red CR-L removal efficiency from textile wastewater was 99%.     

Refractive -index changes of thin films of photo-reactive α-, β-, and γ-cyclodextrin derivatives upon photo-irradiation

We have synthesized cyclodextrin (CD) derivatives with pendant norbornadiene (CD-NBD), with pendant azobenzene (CD-AZ), with pendant cinnamate (CD-CI), with pendant chalcone (CD-CH), and with pendant anthracene (CD-AT). In thin films of these CD derivatives under UV irradiation, photochemical isomerization of CD-NBD and CD-AZ, and photochemical dimerization of CD-CI, CD-CH, and CD-AT proceeded smoothly. The photochemical reactions were accompanied with large refractive index changes (Δn_D's) of 0.023-0.030 (CD-NBD), 0.015-0.023 (CD-AZ), 0.041-0.048 (CD-CI), 0.057-0.071 (CD-CH), and 0.062-0.083 (CD-AT), as determined by ellipsometry.     

Fluorescence quantum yields of a series of red and near-infrared dyes emitting at 600-1000 nm

The determination of the fluorescence quantum yields (QY, Φ(f)) of a series of fluorescent dyes that span the absorption/excitation and emission ranges of 520-900 and 600-1000 nm is reported. The dyes encompass commercially available rhodamine 101 (Rh-101, Φ(f) = 0.913), cresyl violet (0.578), oxazine 170 (0.579), oxazine 1 (0.141), cryptocyanine (0.012), HITCI (0.283), IR-125 (0.132), IR-140 (0.167), and four noncommercial cyanine dyes with specific spectroscopic features, all of them in dilute ethanol solution. The QYs have been measured relative to the National Institute of Standards and Technology's standard reference material (SRM) 936a (quinine sulfate, QS) on a traceably characterized fluorometer, employing a chain of transfer standard dyes that include coumarin 102 (Φ(f) = 0.764), coumarin 153 (0.544), and DCM (0.435) as links between QS and Rh-101. The QY of Rh-101 has also been verified in direct measurements against QS using two approaches that rely only on instrument correction. In addition, the effects of temperature and the presence of oxygen on the fluorescence quantum yield of Rh-101 have been assessed.     

Feasibility of laser-induced breakdown spectroscopy (LIBS) for classification of sea salts

We have investigated the feasibility of laser-induced breakdown spectroscopy (LIBS) as a fast, reliable classification tool for sea salts. For 11 kinds of sea salts, potassium (K), magnesium (Mg), calcium (Ca), and aluminum (Al), concentrations were measured by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and the LIBS spectra were recorded in the narrow wavelength region between 760 and 800 nm where K (I), Mg (I), Ca (II), Al (I), and cyanide (CN) band emissions are observed. The ICP-AES measurements revealed that the K, Mg, Ca, and Al concentrations varied significantly with the provenance of each salt. The relative intensities of the K (I), Mg (I), Ca (II), and Al (I) peaks observed in the LIBS spectra are consistent with the results using ICP-AES. The principal component analysis of the LIBS spectra provided the score plot with quite a high degree of clustering. This indicates that classification of sea salts by chemometric analysis of LIBS spectra is very promising. Classification models were developed by partial least squares discriminant analysis (PLS-DA) and evaluated. In addition, the Al (I) peaks enabled us to discriminate between different production methods of the salts.     

Metal Sulfide Synthesis by Self-Propagating Combustion of Sulfur-Containing Complexes

Coordination compounds of thiourea with cadmium(II), zinc(II), bismuth(III), and indium(III) nitrates were synthesized. The self-sustained combustion of these complexes, as well as that of thiosemicarbazide coordination compounds of nickel(II), cobalt(II), iron(II), copper(II), lead(II), and zinc(II) nitrates, was studied in an inert atmosphere. All these compounds burn to yield metal sulfides. The particle size and morphology of the product depend on the pressure at which the process is carried out. For cadmium(II) and zinc(II) sulfides, which are capable of subliming at the combustion temperatures of their precursors, these parameters can be varied in wide ranges.     

菠萝香气成分的GC/MS分析

采用固相微萃取(SPME)方法提取成熟菠萝的芳香物质,经气相色谱-质谱联机(GC/MS)分析,结合计算机检索技术对分离化合物进行鉴定,应用色谱峰面积归一法测定各成分的相对含量。检测结果表明:共鉴定出29种芳香物质成分,约占总峰面积的91.53%,其中分离出烃类(8种,27.6%)、酯类(8种,27.6%)、酮类(3种,10.3%)、醇类(3种,10.3%)、醛类(2种,6.8%),还有酚、呋喃、酸、杂环、胺类各一种各占3.4%。为进一步评价菠萝品质和利用芳香物质提供基础数据。     

Research on Multidimensional Connotations of Megaproject Construction Organization Citizenship Behavior

Based on a literature review and the context characteristics of construction megaprojects (CMPs), a multidimensional connotation model of CMP citizenship behavior was proposed, including definitions, actors, and dimensions. Organizational citizenship behavior includes Cooperation Behavior (CoB), Collaboration Behavior (ClB), Innovation Behavior (IB), Voice Behavior (VB),Conscientiousness & Dedication Behavior (CDB), Benefit Defense Behavior (BDB) and Guanxi (Relations) Maintenance Behavior (GMB). Actors were divided into three levels that were project managers (individual), participant agents (group) and project organization (network).     

Mass spectrometric identification of water-soluble gold nanocluster fractions from sequential size-selective precipitation

This paper presents a simple and convenient methodology to separate and characterize water-soluble gold nanocluster stabilized with penicillamine ligands (AuNC-SR) in aqueous medium by sequential size-selective precipitation (SSSP) and mass spectrometry (MS). The highly polydisperse crude AuNC-SR product with an average core diameter of 2.1 nm was initially synthesized by a one-phase solution method. AuNCs were then precipitated and separated successively from larger to smaller ones by progressively increasing the concentration of acetone in the aqueous AuNCs solution. The SSSP fractions were analyzed by UV-vis spectroscopy, matrix-assisted laser desorption/ionization time-of-flight-MS, and thermogravimetric analysis (TGA). The MS and TGA data confirmed that the fractions precipitated from 36, 54, 72, and 90% v/v acetone (F(36%), F(54%), F(72%), and F(90%)) comprised families of close core size AuNCs with average molecular formulas of Au(38)(SR)(18), Au(28)(SR)(15), Au(18)(SR)(12), and Au(11)(SR)(8), respectively. In addition, F(36%), F(54%), F(72%), and F(90%) contained also the typical magic-sized gold nanoparticles of Au(38), Au(25), Au(18), and Au(11), respectively, together with some other AuNCs. This study shed light on the potential use of SSSP for simple and large-scale preliminary separation of polydisperse water-soluble AuNCs into different fractions with a relatively narrower size distribution.     

Multi-wavelength fluorescence-quenching model for determination of Cu2+ conditional stability constants and ligand concentrations of fulvic acid

In this work, a multi-wavelength model (MWM) is developed. It uses fluorescence bands in the fulvic acid (FA) spectrum that quench upon binding of inorganic Cu2+ to FA. Quenching data at pH values of 5, 6, and 7 are placed in sets, containing fluorescence measures at select wavelengths versus added copper (CM). Intensity data of wavelength set 1 are obtained from 25 nm constant offset synchronous fluorescence spectra (SyF), in which are observed distinct peaks (lambda(ex) = 415 nm, lambda(em) = 440 nm; and lambda(ex) = 471 nm, lambda(em) = 496 nm). Wavelength set 2 intensity data are obtained from the FA fluorescence excitation and emission maxima (lambda(ex) = 335 nm, lambda(em) = 450 nm; and X(ex) = 471 nm, lambda(em) = 496 nm). Application of MWM shows that the multi-wavelength data sets characterize ligands of different binding strength (log K(x)) and concentration (C(Lx)). Corresponding to pH values of 5, 6, and 7, mean and standard deviation values for wavelength set 1 are log K(415/440) = 4.66 (0.12), 5.03 (0.12), and 5.05 (0.08), log K(471/496) = 4.93 (0.06), 5.27 (0.11), and 5.39 (0.09), C(415/440) = 3.1 (1.5), 10.9 (4.5), and 7.9 (3.9) microM, C(471/496) = 14.3 (3.0), 1.7 (0.6), and 1.4 (0.5) microM. And for wavelength set 2, log K(335/450) = 4.50 (0.03), 4.96 (0.27), and 5.22 (0.08), log K(471/496) = 5.02 (0.04), 5.42 (0.32), and 5.71 (0.09), C(335/450) = 8.8 (0.5), 21.9 (7.9), and 18.7 (0.3) microM, C(471/496) = 21.0 (2.5), 7.17 (1.2), and 7.09 (0.3) micrpM. The ability of the 415/440 nm SyF transect to characterize the main excitation and emission maximum of FA at 335/440 nm is evaluated. Relatively low concentration values returned by the model for this transect (415/440 nm) suggest that it is not entirely illustrative of the maximum. The model predictive capability is verified at pH 6 with two fluorescing Cu2+ chelating organic compounds, L-tyrosine and salicylic acid. This test confirms that the model is capable of providing good estimates of equilibrium binding parameters from multi-wavelength measurements of a mixed ligand system.     

The prediction of the dissolution rate constant by mixing rules: the study of acetaminophen batches

The purpose of this article is to promote two simple and scalable methods to accelerate the formulation development of formulated granules using acetaminophen as a model system. In method I, formulated granules made from the batch of small particle-sized acetaminophen (1) by ball milling the batch of large particle-sized acetaminophen (2), and the mixture of the two batches at equal weights (mix) gave the dissolution rate constants (k) of k(1) = 0.43 +/- 0.15 minutes(-1), k(2) = 0.18 +/- 0.01 minutes(-1), and k(mix) = 0.30 +/- 0.03 minutes(-1) for 75 wt percent formulation; k(1) = 0.75 +/- 0.01 minutes(-1), k(2) = 0.18 +/- 0.01 minutes(-1), and k(mix) = 0.34 +/- 0.03 minutes(-1) for 62 wt percent formulation; and k(1) = 0.28 +/- 0.01 minutes(-1), k(2) = 0.16 +/- 0.01 minutes(-1), and k(mix) = 0.22 +/- 0.02 minutes(-1) for 30 wt percent formulation. In method II, the mixture of the formulated granules produced by mixing the formulated granules from the two batches at equal weights gave dissolution rate constants of k(mix) = 0.30 +/- 0.03 minutes(-1), 0.30 +/- 0.02 minutes(-1), and 0.22 +/- 0.01 minutes(-1) for 75 wt percent, 62 wt percent, and 30 wt percent formulations, respectively. After fitting the three data points of k(1), k(2), and k(mix) to the 10 mixing rules in materials science--series mixing rule, Hashin and Shtrikman upper bound, logarithmic mixing, Looyenga mixing rule, effective media approximation (EMA), three-point lower bound, Torquato approximation, three-point upper bound, Maxwell mixing rule, and parallel mixing rule--we found that the selection of the best suited mixing rules based on k(1), k(2), and k(mix) was solely dependent on the formulations under a given operating condition and regardless of whether the system was a powder mixture or a granular mixture. The values of k(1), k(2), and k(mix) in both the 75 wt percent and 30 wt percent formulations were enveloped by the parallel mixing rule and Maxwell mixing rule, whereas the values of k(1), k(2), and k(mix) for the 62 wt percent formulation were encompassed by the logarithmic mixing rule, Hashin and Shtrikman upper bound, and the series mixing rule. Apparently, the best suited mixing rules could be used to predict the right proportions of either the powder mixture (Method I) or the granular mixture (Method II) for obtaining any other desired dissolution rate constant, k(mix), whose value fell in between the values of k(1) and k(2).     

Migration of 17 Photoinitiators from Printing Inks and Cardboard into Packaged Food – Results of a Belgian Market Survey

Photoinitiators are widely used to cure ink on packaging materials used in food applications such as carton boards and can contaminate the food by migrating into the food. In this contribution, a fast and reliable confirmation method for the determination of photoinitiators in dry foodstuffs is described: benzophenone (BP), 4,4′‐bis(diethylamino)benzophenone (DEAB), 2‐chloro‐9H‐thioxanthen‐9‐one (CTX), 1‐chloro‐4‐ropoxy‐9H‐thioxanthen‐9‐one (CPTX), 2,2‐dimethoxy‐ 2‐phenyl acetophenone (DMPA), 4‐(dimethylamino)benzophenone (DMBP), 2‐ethylanthraquinone (EA), 2‐ethylhexyl‐4‐dimethylaminobenzoate (EDB), ethyl‐4‐dimethylaminobenzoate (EDMAB), 4‐hydroxybenzophenone (4‐HBP), 1‐hydroxycyclohexyl phenyl ketone (HCPK), 2‐hydroxy‐4‐methoxybenzophenone (HMBP), 2‐hydroxy‐4′‐(2‐hydroxyethoxy)‐2‐methylpropiophenone (HMMP), 2‐isopropyl‐9H‐thioxanthen‐9‐one (ITX), 4‐methylbenzophenone (MBP), 4,4′‐bis(dimethylamino)benzophenone (MK) and 4‐phenylbenzophenone (PBZ). Dry foodstuffs were extracted using acetonitrile, followed by the addition of inorganic salts to precipitate fatty residues. After filtration, the extract was analysed using ultra‐performance liquid chromatography in combination with tandem mass spectrometry (UPLC‐MS/MS). Quantification was carried out using benzophenone‐d₁₀ (BP‐d₁₀) as internal standard. The presented method was successfully validated in‐house. Afterwards, the procedure was applied in a marketing study, investigating 97 dry foodstuffs purchased on the Belgian market. In 89% of the samples, at least one photoinitiator was detected. The photoinitiators BP, EDMA and DMPA were most frequently found, while some photoinitiators (CPTX, DEAB, DMBP, HCPK, HMBP and MK) were never detected. Copyright © 2016 John Wiley & Sons, Ltd.     

磷化铟纳米材料制备方法的最新研究进展

详细介绍了InP纳米材料各种制备方法的特点和原理,主要包括金属有机化学气相沉积(MOCVD)、分子束外延(MBE)、化学束外延(CBE)、化学气相沉积(CVD)、热蒸发法、脉冲激光沉积(PLD)、溶剂热法、溶液-液相-固相法(SLS)、胶体化学法等,并通过比较各种制备方法的优缺点以及分析所得产物的特征概述了InP纳米材料制备技术的最新研究进展。