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.     

Isotope (18)O/(16)O Ratio Measurements of Water Vapor by use of Photoacoustic Spectroscopy

We applied a photoacoustic spectroscopy technique to isotope ratio measurements of (16)O and (18)O in water-vapor samples, using a pulsed tunable dye laser pumped by a Nd:YAG laser. The fourth overtone bands (4nu(OH)) of water molecules near 720 nm were investigated. We identified the absorption lines of H(2)(16)O and H(2)(18)O in the photoacoustic spectra that we measured by using an (18)O-enriched water sample and the HITRAN database. We measured the difference in the (18)O/(16)O isotope ratios for normal distilled water and Antarctic ice, using the photoacoustic method. The value obtained for the difference between the two samples is delta(18)O = -32 ? 16 per thousand, where the indicated deviation was a 1varsigma value among 240-s measurements, whereas the value measured with a conventional isotope mass spectrometer was delta(18)O = -28 ? 2 per thousand. This method is demonstrated to have the potential of a transportable system for in situ and quick measurements of the H(2)(18)O/H(2)(16)O ratio in the environment.     

Enrichment of H(2)(17)O from tap water, characterization of the enriched water, and properties of several (17)O-labeled compounds

A low-abundance form of water, H(2)(17)O, was enriched from 0.04% to ～90% by slow evaporation and fractional distillation of tap water. The density and refractive index for H(2)(17)O are reported. Gas chromatography-mass spectrometry (GC-MS) of (16)O- and (17)O-1-hexanols and their trimethyl silyl ethers and of (16)O- and (17)O-hexamethyl disiloxanes was used to determine the percentage of (17)O enrichment in the H(2)(17)O. Furthermore, the chemical shifts of labeled and nonlabeled water dissolved in CDCl(3) differed sufficiently that we could verify the enrichment of H(2)(17)O. (17)O hexanol was synthesized by the reaction of iodohexane with Na(17)OH. (17)O-Labeled trimethylsilanol and (17)O-labeled hexamethyldisiloxane were prepared by the reaction of H(2)(17)O with bis(trimethylsilyl)trifluoroacetamide (BSTFA). To generate standards for (17)O NMR, H(2)(17)O(2), and (17)O camphor were prepared. H(2)(17)O was electrolyzed to form (17)O-labeled hydrogen peroxide which was quantified using two colorimetric assays. (17)O-Labeled camphor was prepared by exchanging the ketone oxygen of camphor using H(2)(17)O. The (17)O-labeled compounds were characterized using (17)O, (1)H, and (13)C NMR and GC-MS. While we were characterizing the labeled camphor, we also detected an unexpected oxygen exchange reaction of primary alcohols, catalyzed by electrophilic ketones such as camphor. The reaction is a displacement of the alcohol OH group by water. This is an example of the usefulness of (17)O NMR in the study of a reaction mechanism that has not been noticed previously.     

Ametryn degradation in the ultraviolet (UV) irradiation/hydrogen peroxide (H2O2) treatment

Ultraviolet (UV) irradiation (253.7nm) in the presence of hydrogen peroxide (H(2)O(2)) was used to decompose aqueous ametryn. The concentrations of ametryn were measured with time under various experiment conditions. The investigated factors included H(2)O(2) dosages, initial pH, initial ametryn concentrations, and a variety of inorganic anions. Results showed that ametryn degradation in UV/H(2)O(2) process was a pseudo-first-order reaction. Removal rates of ametryn were greatly affected by H(2)O(2) dosage and initial concentrations of ametryn, but appeared to be slightly influenced by initial pH. Furthermore, we investigated the effects of four anions (SO(4)(2-), Cl(-), HCO(3)(-), and CO(3)(2-)) on ametryn degradation by UV/H(2)O(2). The impact of SO(4)(2-) seemed to be insignificant; however, Cl(-), HCO(3)(-), and CO(3)(2-) considerably slowed down the degradation rate because they could strongly scavenge hydroxyl radicals (OH) produced during the UV/H(2)O(2) process. Finally, a preliminary cost analysis revealed that UV/H(2)O(2) process was more cost-effective than the UV alone in removal of ametryn from water.     

Integrated effects of selected ions on 2,4,6-trinitrotoluene-removal by O3/H2O2

Considering the components of 2,4,6-trinitrotoluene (TNT)-containing water, this paper aims to research the integrated effects of ions on TNT-removal by O(3)/H(2)O(2) through the selection of CO(3)(-), HCOO(-), Cu(2+) and Al(3+). In view of TNT-removal rate and its constant, we find that the test with HCO(3)(-) or HCOO(-) or Cu(2+) results in lower TNT-removal rate and its constant than control test. Therefore, it may conclude that HCO(3)(-) or HCOO(-) and Cu(2+) has a potential to inhibit the efficacy of O(3)/H(2)O(2), and that their inhibitions increase with an order from HCOO(-) to Cu(2+) and to HCO(3)(-). However, Al(3+) is an exception, because it has a potential to improve the efficacy. When the two selected ions coexist, HCO(3)(-) and HCOO(-) inhibit the efficacy. The inhibition is greater than that of either one alone, and also greater than their sum, and thus the integrated effect of HCO(3)(-) and HCOO(-) follows the synergistic effect. The inhibition of Cu(2+) and HCOO(-) coexistence also is greater than that either alone, but smaller than their sum, and thus their integrated effect follows the independent effect. The integrated effect of Al(3+) and HCOO(-) follows the addition effect.     

Crystal Structure of An(VI) Complexes with Succinate Anions, [PuO2(C4H4O4)(H2O)] and Cs2[(AnO2)2(C4H4O4)3]·H2O (An = U,Np, Pu)

Radiochemistry - Actinide(VI) complexes with succinate anions [PuO2(succ)(H2O)] and Cs2[(AnO2)2(succ)3]·H2O (An = U, Np, Pu), where succ = [C4H4O4]2 ?, were synthesized and studied by...     

Synthesis and Structure of Neptunium(V) Selenate Complexes M[(NpO2)(SeO4)(H2O)] (M = K,Rb, Cs)

Radiochemistry - New Np(V) selenate complexes with various outer-sphere cations, K[(NpO2)(SeO4)(H2O)] (1), Rb[(NpO2)(SeO4)(H2O)] (2), and Cs[(NpO2)(SeO4)(H2O)] (3), were synthesized and studied by...     

TiO_2-Fe_3O_4/MIL-101(Cr)磁性复合光催化材料的制备及其光催化性能

采用原位水热法合成了TiO_2-Fe_3O_4/MIL-101(Cr)磁性复合光催化材料,利用XRD、SEM、UV-Vis DRS、BET和磁学测量系统对复合光催化材料的结构和性能进行了表征,并以亚甲基蓝(MB)为模拟污染物,研究了该复合光催化材料的可见光催化活性,并考察了光催化材料的稳定性。结果表明:巯基官能化的Fe_3O_4和TiO_2与MIL-101(Cr)结合成功,复合后的TiO_2-Fe_3O_4/MIL-101(Cr)光催化材料的可见光响应范围得到明显拓宽;当TiO_2的添加量为400mg时所制得的磁性复合光催化材料具有相对较好的光催化降解效果,经过120min光照后,对MB的去除率高达80%;该磁性复合光催化材料具有良好的稳定性和磁分离性能。     

Generation of O2 from BaSO4 using a CO2-laser fluorination system for simultaneous analysis of delta18O and delta17O

With the observation of mass-independent isotopic anomalies in numerous atmospheric molecules, the ability to measure both delta17O and delta18O in a range of samples is needed. Sulfate oxygen isotopic studies conventionally report only delta18O values. Recent findings indicate that sulfate delta17O and delta18O values, particularly the delta17O value (= delta17O - (0.52)(delta18O)), can provide independent information on the origin, mixing, and transformation of sulfate in the atmospheric and surface environments, which is not resolvable by only delta18O measurements. Existing methods for analyzing sulfate delta17O and delta18O are extremely laborious and demand high-purity BrF5. Here we report a novel method of generating O2 directly from Barite (BaSO4) for simultaneous analysis of delta18O and delta17O by isotope ratio mass spectrometry (IRMS). The method utilizes a CO2-laser fluorination system that can also be used to quantitatively generate O2 from silicates and oxides. Partial but consistent oxygen yields from BaSO4 are obtained for samples >4 mg. Correction factors of +9.4% for delta18O and 4.89% for delta17O are obtained, and there is no deviation in the delta17O value due to the nonquantitative O2 generation. The system may process more than a dozen samples per working day, with analytical error of +/-0.05% and +/-0.8% for delta17O and delta18O, respectively. This new method is ideal for studies emphasizing an accurate sulfate delta17O value.     

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%.     

Kinetics of decolorization of an azo dye in UV alone and UV/H(2)O(2) processes

The decolorization of C.I. Acid Red 27 (AR27), a monoazo anionic dye, was studied in the ultraviolet radiation (UV) alone and UV plus hydrogen peroxide (UV/H(2)O(2)) processes. The experimental results indicated that the kinetics of both oxidation processes fit well by pseudo-first order kinetics. The reaction rate was sensitive to the operational parameters and increased with increasing H(2)O(2) concentration and light intensity. The reaction orders of H(2)O(2) concentration and light intensity in both processes were obtained with linear regression method. A regression model was developed for pseudo-first order rate constant (k(ap,UV/H(2)O(2))) as a function of the Cconcentration and UV light intensity. (k(ap,UV/H(2)O(2)))=(2 x 10(-4)I(0.75)(0) + k(3)I(1.38)(0)[H(2)O(2)](n)(0))phi(AR27). As a result of two opposing effects of H(2)O(2) concentration at low and high concentrations, n has a value of 0.49 and -0.39 and k(3) has a value of 3 x 10(-4) and 0.1 for the regions of 0 mg l(-1) < [H(2)O(2)](0) < 650 mg l(-1) and 650 mg l(-1) < [H(2)O(2)](0) < 1500 mg l(-1)1, respectively. PhiAR27 is the initial dye concentration correlation index for developing of model for different initial concentrations of AR27. This rate expression can be used for predicting k(ap,UV/H(2)O(2) at different conditions in UV alone and UV/H2O2 processes. The results show that UV alone cannot be an efficient method for decolorization of AR27 in comparison with UV/H(2)O(2) process, therefore the first term of the model can be neglected.     

H(2)O(2)-generating peroxidase electrodes as reagentless cyanide sensors

Inexpensive, reagentless, and simple (single-electrode) cyanide biosensors are developed using a pyrolytic graphite (PG) electrode on which horseradish peroxidase (HRP) is adsorbed. The electrode is poised at -300 mV vs Ag/AgCl for 40 s to reduce dissolved O(2) to H(2)O(2) at the PG surface. The generated H(2)O(2) accumulates in the diffusion layer. The potential is then stepped to 0 mV, at which the accumulated H(2)O(2) is reduced, though the O(2) reduction does not proceed. Since the H(2)O(2) reduction is catalyzed by HRP, the transient cathodic current is inhibited by cyanide. Therefore, the transient current is a function of the cyanide concentration. A HRP/PG electrode with saturated HRP coverage is reliable, and it can determine 10(-)(5)-10(-)(3) M cyanide. On the other hand, the electrode with lower HRP coverage is less reliable, though it is so sensitive as to detect 2 × 10(-)(7) M cyanide because the system is under kinetic control.     

Calcium Phosphate Phase Identification Using XPS and Time-of-Flight Cluster SIMS

Reproducible time-of-flight cluster static secondary ion mass spectra (ToF-SSIMS) were obtained for various standard calcium phosphate (CP) powders, which allowed for phase identification. X-ray diffraction was not able to detect signals from microscopic amounts of CP (～15 mmol m(-)(2)). The phases studied were α-tricalcium phosphate [α-Ca(3)(PO(4))(2)], β-tricalcium phosphate [β-Ca(3)(PO(4))(2)], amorphous calcium phosphate [Ca(3)(PO(4))(2)·xH(2)O], octacalcium phosphate [Ca(8)H(2)(PO(4))(6)·H(2)O], brushite (CaHPO(4)·2H(2)O), and hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)]. The SIMS spectra were obtained via bombardment with (CsI)Cs(+) projectiles. X-ray photoelectron spectroscopy (XPS) core levels of the P 2p, Ca 2p, and O 1s orbitals and the relative O 1s loss intensity were examined. The PO(3)(-)/PO(2)(-) ratios from ToF-SSIMS spectra in conjunction with XPS of the CP powders showed much promise in differentiating between these phases at microscopic CP coverages on the metal oxide surface.     

溶胶-凝胶法制备Ba_(3.99)Sm_(9.34)Ti_(18)O_(54)微波介质陶瓷粉体

用柠檬酸(C6H8O7)为络合剂,以硝酸钐(Sm(NO3)3)、钛酸四丁酯(C16H36O4Ti)、硝酸钡(Ba(NO3)2)为原料,采用溶胶-凝胶法制备单相Ba3.99Sm9.34Ti18O54微波介质陶瓷粉体。采用差热分析、X射线衍射表征Ba3.99Sm9.34Ti18O54前驱体的热行为和晶型转化过程,用场发射扫描电镜对粉体的形貌进行表征。结果表明:在1000℃下保温3h可以获得纯Ba3.99Sm9.34Ti18O54陶瓷粉体,形状为不规则片状,平均粒径为100~200nm。     

Raman and infrared spectroscopic investigations on aqueous alkali metal phosphate solutions and density functional theory calculations of phosphate-water clusters

Phosphate (PO(4)(3-)) solutions in water and heavy water have been studied by Raman and infrared spectroscopy over a broad concentration range (0.0091-5.280 mol/L) including a hydrate melt at 23 degrees C. In the low wavenumber range, spectra in R-format have been constructed and the R normalization procedure has been briefly discussed. The vibrational modes of the tetrahedral PO(4)(3-)(aq) (T(d) symmetry) have been assigned and compared to the calculated values derived from the density functional theory (DFT) method for the unhydrated PO(4)(3-)(T(d)) and phosphate-water clusters: PO(4)(3-).H(2)O (C(2v)), PO(4)(3-).2H(2)O (D(2d)), PO(4)(3-).4H(2)O (D(2d)), PO(4)(3-).6H(2)O (T(d)), and PO(4)(3-).12H(2)O (T), a cluster with a complete first hydration sphere of water molecules. A cluster with a second hydration sphere of 12 water molecules and 6 in the first sphere, PO(4)(3-).18H(2)O (T), has also been calculated. Agreement between measured and calculated vibrational modes is best in the case of the PO(4)(3-).12H(2)O cluster and the PO(4)(3-).18H(2)O cluster but far less so in the case of the unhydrated PO(4)(3-) or phosphate-water cluster with a lower number of water molecules than 12. The asymmetric, broad band shape of v(1)(a(1)) PO(4)(3-) in aqueous solutions has been measured as a function of concentration and the asymmetric and broad band shape was explained. However, the same mode in heavy water has only half the full width at half-height compared to the mode in normal water. The PO(4)(3-) is strongly hydrated in aqueous solutions. This has been verified by Raman spectroscopy comparing v(2)(H(2)O), the deformation mode of water, and the stretching modes, the v(1)OH and v(3)OH of water, in K(3)PO(4) solutions as a function of concentration and comparison with the same modes in pure water. A mode at approximately 240 cm(-1) (isotropic R spectrum) has been detected and assigned to the restricted translational mode of the strong hydrogen bonds formed between phosphate and water, P-O...HOH. In very concentrated K(3)PO(4) solutions (C(0) > or = 3.70 mol/L) and in the hydrate melt, formation of contact ion pairs (CIPs) could be detected. The phosphate in the CIPs shows a symmetry lowering of the T(d) symmetry to C(3v). In the less concentrated solutions, PO(4)(3-)(aq) solvent separated ion pairs and doubly solvent separated ion pairs exist, while in very dilute solutions fully hydrated ions are present (C(0) < or = 0.005 mol/L). Quantitative Raman measurements have been carried out to follow the hydrolysis of PO(4)(3-)(aq) over a very broad concentration range. From the hydrolysis data, the pK(3) value for H(3)PO(4) has been determined to be 12.45 at 23 degrees C.     

Photodegradation of direct yellow-12 using UV/H2O2/Fe2+

A detailed investigation of photodegradation of direct yellow-12 (DY12) using UV/H(2)O(2)/Fe(2+) has been carried out in a photochemical reactor. Experiments studied degradation as a function of concentration, decolorization and reduction in chemical oxygen demand (COD). The effect of operating parameters, such as UV, pH, amount of Fenton's reagent (H(2)O(2) and FeSO(4)), and amount of DY12 dye has also been determined. It has been observed that simultaneous utilization of UV irradiation with Fenton's reagent increases the degradation rate of DY12 dye. The dye quickly losses its color and there is an appreciable decrease in COD value, indicating that the dissolved organic have been oxidized. The kinetics of degradation of the dye in dilute aqueous solutions follows pseudo-first order kinetics. Final products detected at the end of the reaction include NO(3)(-), NO(2)(-), N(2)O, NO(2), SO(2), CO(2) and CO. Results indicate that dye degradation is dependent upon pH, UV-intensity, concentration of Fenton's reagent and dye. Acidic pH has been found to be more suitable in comparison to neutral and alkaline. The optimum concentration of Fenton's reagent (H(2)O(2)/Fe(2+)) was found as 1500/500 mg l(-1) for 50 mg l(-1) DY12 dye in water at pH 4. The results indicate that the treatment of DY12 dye wastewater with UV/Fe(2+)/H(2)O(2) system is efficient.     

Low-temperature synthesis of Mn(3)O(4) nanoparticles loaded on multi-walled carbon nanotubes and their application in electrochemical capacitors

A low-temperature, efficient and one-step deposition method, in which Mn(CH(3)COO)(2)·4H(2)O serves as precursor and O(2) as oxidant, was employed to deposit Mn(3)O(4) nanoparticles on multi-walled carbon nanotubes (MWCNTs) in ethanol solution at 150 and 200?°C. The resulting Mn(3)O(4)/MWCNT composites were characterized by means of different techniques including x-ray diffraction, x-ray photoelectron spectroscopy and transmission electron microscopy. It was indicated that the Mn(3)O(4) nanoparticles were attached uniformly on MWCNTs with sizes less than 10?nm, and the loading amount of Mn(3)O(4) could be tuned by changing the initial weight ratio of Mn(CH(3)COO)(2)·4H(2)O/MWCNT. The electrochemical behavior of the Mn(3)O(4)/MWCNT composites was examined by cyclic voltammetry, and the result indicated the specific capacitance of the composite electrode was 330?F?g(-1), nearly 18 times higher than that of the pure MWCNT electrode. The good performance of the as-prepared composites as electrode material may be attributed to the synergistic effects of the Mn(3)O(4) nanoparticles and the MWCNTs.     

Decolorization of methylene blue in layered manganese oxide suspension with H2O2

Layered birnessite-type manganese oxides (Na-OL-1) were prepared via a redox reaction involving MnO(4)(-) and Mn(2+) under markedly alkaline conditions. According to the XRD analysis, the resulting material exhibited a well-crystallized octahedral layer (OL) structure with several different phases, including β-MnOOH, α-MnOOH and γ-Mn(3)O(4). The catalyst was highly effective for the decolorization and degradation of methylene blue (MB) in the presence of H(2)O(2) at neutral pH. The tested MB was completely decolorized in Na-OL-1 suspension by the fraction dosing of H(2)O(2) (556.5mM at the beginning and then 183.8mM at 40 min). Based on the studies of electron spin resonance and the effect of radical scavengers, the (1)O(2) and O(2)(-) were the main reactive oxygen species (ROS) in the reaction. It was found that both oxygen and ROS were generated from the decomposition of H(2)O(2) in Na-OL-1 suspension, wherein the decomposition pathways were proposed. The generation of H(2)O(2) in Na-OL-1 suspension at air atmosphere indicated that the existence of multivalent manganese oxides greatly enhanced the interfacial electron transfer, leading to the high activity of Na-OL-1.     

Spectroscopic investigation in the mid- and far-infrared regions of phosphorus fertilizers derived from thermochemically treated sewage sludge ash

Inorganic phosphorus and nitrogen-phosphorus-potassium (NPK) fertilizers based on phosphates from thermochemically treated sewage sludge ash were analyzed using mid-infrared (mid-IR) and far-infrared (FIR) spectroscopy. The different compounds present in the fertilizers were qualitatively determined with the help of recorded reference spectra of pure substances. Differentiation between various phosphates and other compounds such as sulfates, nitrates, and oxides was possible using combined interpretation of the mid-IR and FIR spectra. The results are in agreement with previous X-ray diffraction (XRD) measurements of the same samples. The main phosphate phases detected were NH(4)H(2)PO(4), MgHPO(4)·3H(2)O, Mg(3)(PO(4))(2), Ca(5)(PO(4))(5)Cl, CaHPO(4)·2H(2)O, Ca(H(2-)PO(4))(2)·H(2)O, and AlPO(4). Furthermore, K(2)SO(4), NH(4)NO(3), Fe(2)O(3), and SiO(2) were identified in the IR spectra. However, ammonium and sulfate compounds were only identified in the mid-IR region but were not detectable in the FIR region.     

Prussian-blue-modified iron oxide magnetic nanoparticles as effective peroxidase-like catalysts to degrade methylene blue with H2O2

Prussian-blue (PB)-modified γ-Fe(2)O(3) magnetic nanoparticles (PBMNPs) were successfully synthesized based on electric interactions between negatively charged [Fe(CN)(6)](4-) and positively charged γ-Fe(2)O(3) nanoparticles. The in situ PB coating was generated by the coordinating reaction between the adsorbed [Fe(CN)(6)](4-) and the ferric ions on the surface of γ-Fe(2)O(3) NPs. The as-prepared PBMNPs were characterized by FT-IR, XRD, TEM, and used to remove organic pollutants from aqueous solution, namely, using methylene blue (MB) as model compound. The experimental results showed that the target compound could be removed efficiently from solution over a wide pH range from 3 to 10 in the presence of PBMNPs as peroxidase-like catalyst and H(2)O(2) as oxidant. Under optimal conditions, MB could be removed completely after 120 min of reaction at 298 K; the chemical oxygen demand (COD) removal efficiency and the total organic carbon (TOC) abatement efficiency were 53.6% and 35%, respectively. Furthermore, the PBMNPs catalysts showed high magnetization, temperature tolerance, long-term storage and operational stability, and they could be readily separated from solution by applying an external magnetic field. Finally, a possible reaction mechanism for MB degradation was also discussed.