Coupled Plasma Atomic Emission Spectrometer Research Articles

Mineral content in fishes in the lower course of the itapecuru river in the state of Maranhão, Brazil

Concentrations of calcium, iron, potassium, magnesium, phosphorus, zinc, copper, selenium and nickel were determined in the muscle tissue of seven species of fish (Plagioscion squamosissimus, Geophagus surinamensis, Prochilodus lacustres, Curimata sp., Schizodon dissimilis, Ageneiosus ucayalensis and Hypostomus plecostomus) collected from the lower course of the Itapecuru River in the state of Maranhao, Brazil. The samples were digested in a nitricperchloric solution and analyzed using an inductively coupled plasma atomic emission spectrometer, with the construction of specific calibration curves for each element. The highest concentrations of constituent minerals were found for phosphorus, potassium, nickel and magnesium (399.83, 144.60, 90.20 and 29.49 mg 100 g−1, respectively) in G. surinamensi, P. lacustres and Curimata sp. The lowest concentrations were found for copper, zinc, iron and selenium (0.12, 0.51, 1.05 and 8.31 mg 100 g−1, respectively) in Curimata sp., S. dissimilis, A. ucayalensis and P. squamosissimus. The concentrations of all minerals can be considered low and are below the maximum limit established by Brazilian legislation for the human ingestion of fish meat. A comparison of the seven species of fish investigated revealed no statistically significant differences regarding the concentrations of minerals, suggesting that size and different dietary habits do not exert an influence on absorption. The low concentrations of metals, such as Fe, Cu, Zn and Ni, may be related to the environmental conditions of the mouth of the river, which receives ocean inputs that produce particular tide cycles with a strong dispersion capacity, thereby diminishing residence time in the water column and reducing the availability of these metals to species of fish.

Evaluation of the antidiabetic property of aqueous leaves extract of Zanthoxylum armatum DC. using in vivo and in vitro approaches

The present study was designed to evaluate the antidiabetic potential of the aqueous leaves extract of Zanthoxylum armatum DC. leaves using in vivo and in vitro approaches. For in vivo studies, blood glucose level was monitored at different intervals after administration of varying doses of the extract for its hypoglycemic (100–6000 mg/kg b.w.) and antihyperglycemic (250 mg/kg b.w.) effect in normoglycemic and diabetic mice. In vitro enzymatic inhibition activity was tested against α-amylase, α- and β-glucosidase and lipase. Additionally hydroxyl radical, hydrogen peroxide scavenging assay and phytochemical screening were also performed. Element analysis of the plant was studied by Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). The plant extract showed significant hypoglycemic and antihyperglycemic effect in normoglycemic and diabetic mice. The IC50 values of extract for α-amylase, β-glucosidase, lipase, hydroxyl radical scavenging activity, hydrogen peroxide scavenging activity were 7.40 mg/ml, 0.30 mg/ml, 8.35 mg/ml, 3.25 mg/ml, 9.62 mg/ml respectively and the percentage of inhibition for α-glucosidase was 79.82% at 0.8 mg/ml. In vitro studies were compared with their respective standards. Elemental analysis revealed the presence of essential elements such as Mg, V, Fe, Cr, Zn, Cu, Mo, Mn, K, Ca, P and Sr which are all known to play a role in regulating blood glucose. The results demonstrate that Z. armatum aqueous leaves extract possess antidiabetic property in both in vivo and in vitro condition.

Layer-by-layer fabrication of polydopamine functionalized carbon nanotubes-ceria-palladium nanohybrids for boosting ethanol electrooxidation

The polydopamine functionalized carbon nanotubes-ceria-palladium nanohybrids (Pd-CeO2−x/PDA-CNTs) is fabricated through layer-by-layer synthetic strategy, aiming to integrate the functions of support (PDA-CNTs), metal oxides (CeO2−x) and Pd nanoparticles (NPs). Various instrumental techniques including transmission electron microscopy (TEM), X-ray diffraction (XRD), inductive coupled plasma atomic emission spectrometer (ICP-AES) and X-ray photoelectron spectroscopy (XPS) not only confirm the formation of nanohybrids but also provide the morphology, structure and composition properties of the as-prepared catalysts. As an anode catalyst towards ethanol electrooxidation reaction (EOR) in direct ethanol fuel cells, the Pd-CeO2−x/PDA-CNTs reveals promoted electrocatalytic performance, accelerated kinetics and enhanced stability. Based on the control experiments and related reports, the synergistic action of PDA, CeO2−x and Pd NPs is the key factor for the superior electrochemical behavior of Pd-CeO2−x/PDA-CNTs, which originates from the integration of various components through layer-by-layer synthetic strategy.

Effect of Tungsten Addition on Nickel-Based Catalyst for Combined Steam and CO2 Reforming of Methane.

In this study, we investigated the effect of tungsten addition on Ni-based catalyst in methane steam-CO₂ reforming. All the catalysts were prepared by the co-impregnation method with varied tungsten loading. The as-prepared catalysts were characterized by inductively coupled plasma atomic emission spectrometer, X-ray diffraction, temperature-programmed reduction and thermogravimetric analysis. The tungsten-loaded catalyst showed improved coke resistance and CO₂ reactivity by the conducting activity test under fixed conditions.

Electrochemical Extraction of Holmium and Thermodynamic Properties of Ho-Bi Alloys in LiCl-KCl Eutectic

The electrochemical reduction of Ho (III) on W electrode and liquid Bi film electrode was investigated in LiCl-KCl eutectic by various electrochemical techniques. The reduction reaction of Ho (III) was found to be diffusion-controlled process with three electrons exchanged, which was considered as quasi-reversible. The diffusion coefficient of Ho (III) was determined by cyclic voltammetry and chronopotentiometry. The results of cyclic voltammetry and square wave voltammetry obtained on Bi film electrode exhibited two new reduction peaks at less negative potential than that on W electrode due to the formation of different Ho-Bi intermetallic compounds. Furthermore, the thermodynamic properties on the formation of Ho-Bi intermetallic compounds were measured using open circuit chronopotentiometry in the temperature range from 773 K to 863 K. The electroextraction of holmium was performed on liquid Bi electrode by potentiostatic and galvanostatic electrolysis. The extractive products were characterized by scanning electron microscopy and energy dispersive spectrometry (SEM-EDS) and X-ray diffraction (XRD). It was showed that Ho-Bi alloys consisted of HoBi and Bi phases. The concentration of Ho (III) was monitored by square wave voltammetry and analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES). The calibration curve was obtained on linear relationship of peak currents and concentration of Ho (III). Meanwhile, the extraction efficiencies were calculated by ICP-AES and calibration curve, respectively, the highest extraction efficiency could reach 95.9% by potenostatic electrolysis at −1.6 V for 27 h.

Electrochemical behaviour of erbium(III) and its extraction on Cu electrode in LiCl-KCl melts

The electrochemical behaviour of Er(III) was studied on W and Cu electrodes in LiCl-KCl melts by a series of electrochemical techniques. The studies indicated that Er(III) ions were reduced to Er(0) in a one-step diffusion-controlled process exchanging three electrons. The diffusion coefficient of Er(III) was determined and the activation energy for diffusion of Er(III) ions was found to be 35.2 kJ mol−1. The equilibrium potential of the Er(III)/Er(0) redox couple was measured via open circuit chronopotentiometry in the temperature range of 773–923 K, with subsequent calculation of the apparent standard potential, EEr(III)/Er(0)∗0, and the apparent Gibbs free energy of formation for ErCl3, ΔGf∗0(ErCl3). The cyclic voltammogram and square wave voltammogram obtained on Cu electrode, compared with those on W electrode, showed several new pairs of reduction peaks observed at more positive potential, which means that the underpotential deposition of erbium occurs. The thermodynamic properties of the Cu-Er intermetallic compound, Cu5Er, were estimated by open circuit chronopotentiometry. Potentiostatic and galvanostatic electrolysis was performed on Cu electrode to extract erbium. The extraction products, consisting of CuEr, Cu2Er and Cu5Er, were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). Furthermore, the extraction efficiencies were evaluated during potentiostatic electrolysis at different electrolysis times using an inductive coupled plasma atomic emission spectrometer (ICP-AES), which showed that the highest extraction efficiency of Er(III) could reach about 98.92%.

Facile synthesis of a boronate affinity sorbent from mesoporous nanomagnetic polyhedral oligomeric silsesquioxanes composite and its application for enrichment of catecholamines in human urine

A boronate-decorated nanomagnetic organic-inorganic hybrid material was facilely synthesized by utilizing the nanomagnetic polyhedral oligomeric silsesquioxanes (POSS) composite (Fe3O4@POSS) as the base platform. A simple copolymerization occurred between 3-acrylamidophenylboronic acid (AAPBA) and the residual end vinyl groups supplied by the substrate. Here the special emphasis was placed on the octavinyl POSS, which not only acted as the building blocks for a hybrid architecture but also facilitated the process of grafting boronate groups onto the surface of POSS based nanomagnetic composite (Fe3O4@POSS). The successful immobilization of affinity ligand-AAPBA on the Fe3O4@POSS was confirmed by Fourier transform infrared (FT-IR), elemental analysis, inductively coupled plasma atomic emission spectrometer (ICP-AES), field emission scanning electron microscope. A magnetic solid-phase extraction (MSPE) for cis-diols enrichment was developed using the as-prepared Fe3O4@POSS-AAPBA material as an affinity sorbent and three catecholamines (CAs), namely noradrenaline, epinephrine and isoprenaline, as model analytes. Under the optimal extraction conditions, sensitive and simultaneous analysis of three CAs from the urine sample was achieved by high-performance liquid chromatography with UV detection (HPLC-UV). The limits of detection (LOD, S/N = 3) and the limits of quantitation (LOQ, S/N = 10) for the target analytes were 0.81–1.32 ng mL−1 and 2.70–4.40 ng mL−1, respectively. Also good recoveries (85.5–101.7%) and repeatability (RSD≤10.1%) were obtained by this method. This work not only showed a facility for the utilization of Fe3O4@POSS as a substrate for constructing a boronate functionalized nanomagnetic sorbent, but also demonstrated the capability of the derived material for recognition of trace amount of cis-diols biomolecules presented in complicated biological matrices.

Assessment of radon concentration and heavy metal contamination in groundwater samples from some areas of Fazilka district, Punjab, India

Groundwater samples taken from 20 villages of Fazilka district, Punjab, India were analysed for radon concentration using RAD7, which is an electronic radon detector. Radon concentration varies from (1.4 ± 1.0) × 103 Bq/m3 to (4.9 ± 3.0) × 103 Bq/m3, which is much below the safe limits proposed by US Environmental Protection Agency (US EPA) and UN Scientific Committee on the Effects of Atomic Radiation. The mean annual effective dose calculated for these samples was also found to be within the limits provided by WHO and EU council. These samples were also analysed for concentration of certain heavy elements like As, Pb, Zn, Cu, Hg, Ni and Cd using inductively coupled plasma atomic emission spectrometer. Out of these, concentrations of As and Pb were found to exceed the permissible limits suggested by US EPA.

Removal process of nickel(II) by using dodecyl sulfate intercalated calcium aluminum layered double hydroxide

Calcium aluminum layered double hydroxides (LDH) modified with sodium dodecyl sulfate (SDS) (Ca/Al-DS LDH) was prepared to investigate the unique removal mechanism of metal cations by organic calcium-contained LDHs. The as-prepared sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma atomic emission spectrometer (ICP-AES) and elemental analysis (EA). Ni(II) was selected as the target metal cation and its removal kinetics could be well described by the pseudo-second-order kinetic model (R2=0.990). The maximum removal capacity of Ni(II) reached 2.45mol/g at the LDH dosage of 0.5gL−1. The XRD and element analysis results indicate that a new Ni/Al-DS LDH phase and CaCO3 were formed as well as a portion of Ca/Al-DS LDH remained in the final products after the removal process. Therefore, the removal of Ni(II) was contributed to the surface complexation, isomorphic substitution and sorption on the CaCO3. The pillared interlayer organic anions might help to keep the layered structure of LDH. This study revealed the multi-interaction mechanism of metal ions with Ca/Al LDH and proposed a novel strategy to generate organic intercalated LDHs by isomorphic substitution.

PPy-assisted fabrication of Ag/TiO2 visible-light photocatalyst and its immobilization on PAN fiber

Sliver-coated titanium dioxide nanoparticles (Ag/TiO2 NPs) were successfully fabricated by calcination after removal of polypyrrole (PPy)-assisted template which was synthesized by chemical redox polymerization and deposited onto TiO2 NPs. The microstructure, composition and photocatalytic activity of Ag/TiO2 NPs were investigated by inductively coupled plasma atomic emission spectrometer (ICP-AES), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), X-ray powder diffraction analyses (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV–visible absorption spectroscopy and thermogravimetric analysis (TG). The results reveal that Ag/TiO2 NPs have a lower energy band (2.95eV) than core-shell PPy-Ag/TiO2 (3.06eV), which is responsible for high photocatalytic activity. Rhodamine B (RhB) and Methylene blue (MB) can be significantly degraded in the presence of Ag/TiO2 NPs under visible light irradiation. From an application point of view, as-prepared Ag/TiO2 NPs were immobilized on polyacrylonitrile (PAN) fiber by a co-dispersion solution dip-coating method. Ag/TiO2-coated PAN fibers have an excellent performance for both dye degradation and reusability, which shows great potential as an environment-friendly, easy handling and recyclable photocatalyst for dye effluent treatment.

Synthesis and kinetics investigation of meso-microporous Cu-SAPO-34 catalysts for the selective catalytic reduction of NO with ammonia

A series of meso-microporous Cu-SAPO-34 catalysts were successfully synthesized by a one-pot hydrothermal crystallization method, and these catalysts exhibited excellent NH3-SCR performance at low temperature. Their structure and physic chemical properties were characterized by means of X-ray diffraction patterns (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), N2 sorption-desorption, nuclear magnetic resonance (NMR), Inductively Coupled Plasma-Atomic Emission spectrometer (ICP-AES), X-ray absorption spectroscopy (XPS), Temperature-programmed desorption of ammonia (NH3-TPD), Ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS) and Temperature programmed reduction (TPR). The analysis results indicate that the high activities of Cu-SAPO-34 catalysts could be attributed to the enhancement of redox property, the formation of mesopores and the more acid sites. Furthermore, the kinetic results verify that the formation of mesopores remarkably reduces diffusion resistance and then improves the accessibility of reactants to catalytically active sites. The 1.0-Cu-SAPO-34 catalyst exhibited the high NO conversion (>90%) among the wide activity temperature window in the range of 150–425°C.

Electrochemical behavior of Th(IV) and its electrodeposition from ThF4-LiCl-KCl melt

The electrochemical behavior of Th(IV) ion on molybdenum (Mo) electrode was studied by cyclic voltammetry (CV) and square wave voltammetry (SWV) technologies at 773 K in ThF4-LiCl-KCl melt. The reduction of Th(IV) to metal Th at −1.67V (vs. Ag/AgCl) is a four-electron exchange process, which is quasi-reversible and diffusion-controlled. The diffusion coefficient (D) and activation energy of diffusion process for Th(IV) were determined to be 3.77×10−5cm2s−1 and 59.2kJmol−1. The pulse potential electrolysis of ThF4-LiCl-KCl melt revealed that 86.8% of Th(IV) can be separated from the melt based on the inductively coupled plasma atomic emission spectrometer (ICP-AES) results.

Surface modification of alpha-tricalcium phosphate with inositol phosphate for cement fabrication

Event Abstract Back to Event Surface modification of alpha-tricalcium phosphate with inositol phosphate for cement fabrication Toshiisa Konishi1*, Michiyo Honda2, Tomohiko Yoshioka1, Satoshi Hayakawa1 and Mamoru Aizawa3 1 Okayama University, Graduate School of Natural Science and Technology, Japan 2 Meiji University, Organization for the Strategic Coordination of Research and Intellectual Property, Japan 3 Meiji University, Department of Applied Chemistry, School of Science and Technology, Japan Introduction: Calcium phosphate bioceramics have been used for bone grafting due to their biocompatibility and osteoconductivity. Among them, calcium phosphate cement has an advantage in that the users can form desired shapes during surgical operation and has therefore received much attention. We have previously developed novel α-tricalcium phosphate (α-TCP) cement with biodegradability and osteoconductivity, set by chelating capability of inositol phosphate (IP6)[1]. The cement powder was prepared by surface modification in IP6 solution[1]. However, the adsorption behavior of IP6 on the α-TCP powder is not studied in detail. In the present study, the adsorption behavior of IP6 on the α-TCP powder was circumstantially examined to optimize the IP6 concentration for surface modification of α-TCP powder. Materials and Methods: The starting α-TCP powder was ground for 120 min using zirconia balls (10 mm in diameter). The obtained α-TCP slurry was filtrated and freeze-dried for 24 h. The as-prepared α-TCP powder was surface-modified in IP6 solution (0, 500, 1000, 3000 ppm, pH7.3) up to 24 h. The slurry was centrifuged to collect supernatant solution and deposition. Amount of IP6 adsorbed on α-TCP powder was measured with an inductively coupled plasma atomic emission spectrometer (ICP-AES). Raman spectrometer was used to clarify IP6 adsorption on α-TCP powder. The release of Ca2+ and PO43- ions from the IP6 surface modified α-TCP powders was examined in acetic acid-sodium acetate (Ac-AcNa, pH 5.5) and 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES, pH 7.0) buffers. The change of crystal phase before and after the elusion test was examined using X-ray diffractometer (XRD). Results and Discussion: Amount of IP6 adsorbed on α-TCP powder increased with IP6 concentration and reached a plateau within 12 h. The XRD patterns of IP6-α-TCP powders after adsorption test (500-, 1000- and 3000-IP6-α-TCP) showed α-TCP single phase. The result indicates that the IP6 adsorption inhibited the phase transition of α-TCP to HAp. Raman spectroscopic study showed that the peaks corresponding to IP6 molecule were detected only in 3000-IP6-α-TCP spectra because of low IP6 concentration for surface modification of α-TCP in 500- and 1000-IP6-α-TCP powders. The release of Ca2+ and PO43- ions from the IP6 surface modified powders in Ac-AcNa and HEPES was constant value till 7 days. The crystal phase of 500-, 1000- and 3000-IP6-α-TCP powders after release test was α-TCP single phase; however, the 0-IP6-α-TCP powder was converted to HAp single phase. These results show that the IP6-α-TCP powders were more stable in Ac-AcNa and HEPES buffers than 0-IP6-α-TCP powder without IP6 surface modification. Conclusion: It was found that the IP6 could adsorb on the α-TCP powder in 500, 1000, and 3000 ppm IP6 solution and amount of IP6 adsorbed on α-TCP powder reached a plateau within 12 h. The prepared 500-, 1000- and 3000-IP6-α-TCP powders were stable in Ac-AcNa and HEPES buffers. Thus, surface modification of α-TCP powder in 500, 1000, and 3000 ppm IP6 solution would be suitable for preparation of stable cement powder.

氮化碳负载铂催化剂的制备、表征及对肉桂醛加氢的催化性能

通过尿素的高温聚合制备了片层状氮化碳g-C3N4，采用乙二醇还原法载铂得到Pt/g-C3N4催化剂。以X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、比表面与孔隙度分析和电感耦合等离子体原子发射光谱(ICP-AES)等对所制备催化剂进行了表征，并在肉桂醛加氢反应中考察了其催化性能。结果表明，载体g-C3N4含有大量的含N基团，能有效稳定金属纳米粒子；Pt纳米粒子均匀分散在g-C3N4表面，且Pt粒径在2~3 nm之间；载体煅烧温度对催化剂的择性加氢性能有明显影响，550℃煅烧后的g-C3N4，所负载Pt在较温和的条件下表现出较明显的活性，肉桂醛转化率为30%，肉桂醇选择性为66%左右。重复使用3次，催化剂活性基本不变，具有良好的稳定性。 Layered carbon nitride g-C3N4 was prepared through high temperature polymerization of urea, and highly dispersive Pt nanoparticles were loaded onto g-C3N4 by ethylene glycol reduction to fabricate Pt/g-C3N4 catalyst. The catalyst was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, surface area/porosity analysis and inductively coupled plasma atomic emission spectrometer (ICP-AES), and tested in the hydrogenation of cinnamelaldehyde. The results indicated that the support contains a large amount of N-containing groups which help to stabilize metal nanoparticles effectively; Pt nanoparticles uniformly dispersed in the surface of the g-C3N4 and its size is between 2 - 3 nm; the calcination temperature in g-C3N4 preparation had a significant effect on the performance of the catalyst for selective hydrogenation. Pt supported on g-C3N4 being calcinated at 550˚C exhibited an appreciable activity, 30% conversion of cinnamic aldehyde and 66% selectivity for cinnamic alcohol under relatively mild condition. No obvious deterioration of the activity is observed after three times of usage, implying a good stability of the catalyst.

Hydrogen generation from alkaline NaBH4 solution using Co–Ni–Mo–P/γ-Al2O3 catalysts

Co–Ni–Mo–P catalysts were synthesized on the γ-Al2O3 by electroless deposition. The as-prepared Co–Ni–Mo–P/γ-Al2O3 catalysts were characterized by inductively coupled plasma atomic emission spectrometer (ICP-AES), field emission scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption isotherm. The hydrogen generation activity of Co–Ni–Mo–P/γ-Al2O3 catalysts was tested through hydrolysis of sodium borohydride alkaline solution. The concentrations of Na2MoO4, NaOH and NaBH4, electroless deposition time as well as solution temperature were found to have considerable influences on the hydrogen generation rate of hydrolysis of alkaline NaBH4 solution. The results show that the obtained Co–Ni–Mo–P/γ-Al2O3 catalysts exhibit excellent catalytic activity. The hydrogen generation rate increases apparently from 10.125 L min−1 g catalyst−1 to 13.842 L min−1 g catalyst−1 with the concentration of Na2MoO4 increasing from 0.5 g L−1 to 0.8 g L−1 at 45 °C. The catalysts also exhibit favorable cycling performance and lower activation energy (52.43 kJ mol−1) in comparison with that of other reported catalysts.

Optimization of magnetosome production by Acidithiobacillus ferrooxidans using desirability function approach

Present study aimed to resolve the conflict between cell growth and magnetosome formation of Acidithiobacillus ferrooxidans (A. ferrooxidans) in batch experiments by applying response surface methodology (RSM) integrated a desirability function approach. The effects of several operating parameters on cell growth (OD600) and magnetosome production (Cmag) were evaluated. The maximum overall desirability (D) of 0.923 was achieved at iron concentration of 125.07mM, shake speed of 122.37rpm and nitrogen concentration of 2.40g/L. Correspondingly, the OD600 and Cmag were 0.522 and 1.196, respectively. The confirmation experiment confirmed that the optimum OD600 and Cmag obtained were in good agreement with the predicted values. The inductively coupled plasma atomic emission spectrometer (ICP-AES) and transmission electron microscopy (TEM) analyses revealed that the production of magnetosomes could be improved via optimization. X-ray diffraction (XRD) showed the magnetosomes are magnetite. Results indicated that RSM with a desirability function was a useful technique to get the maximum OD600 and Cmag simultaneously.

EX SITU DEGRADATION OF SILICONE RUBBERS WITH DIFFERENT HARDNESS IN A CATHODE OUTLET SOLUTION OF PEMFC

ABSTRACT Polymer electrolyte membrane fuel cells (PEMFCs) require gaskets and seals in each cell to keep the reactant gas and liquid within their respective regions. The durability of sealing materials is crucial to the operating life as well as the electrochemical performance of fuel cell stacks. In this study, the aging process of silicone rubbers, often used as gasket materials for fuel cells, with hardnesses of 30, 40, and 50 (Shore A) in a solution collected from the cathode of PEMFC is investigated. Fourier transform infrared spectroscopy and an inductively coupled plasma atomic emission spectrometer are used to study the chemical composition of the samples before and after exposure to the test environment over time. It is suggested that the degradation of silicone rubbers is attributed to the chemical decomposition of silicon-based backbone and the leaching of fillers. Although the silicone rubber with higher hardness loses more weight due to its larger amount of fillers, it seems more stable and durable in mechanical properties and surface morphology.

The distribution of iodine and effects of phosphatization on it in the ferromanganese crusts from the Mid-Pacific Ocean

In the present paper, iodine (I), iron (Fe), manganese (Mn), cobalt (Co), phosphorus (P) and calcium (Ca) contents in three ferromanganese crusts from the Pacific Ocean are measured by spectrophotometric method and inductively coupled plasma atomic emission spectrometers (ICP-AES) to investigate the contents and distribution of iodine in ferromanganese crusts. The results show that iodine contents in three crusts vary between 27.1 and 836 mg/kg, with an average of 172 mg/kg, and the profile of iodine in the three crusts all exhibits a two-stage distribution zone: a young non-phosphatized zone and an old phosphatized zone that is rich in I, P and Ca. The iodine content ratios of old to young zone in MP5D44, CXD62–1 and CXD08–1 are 2.3, 3.4 and 13.7, respectively. The boundary depths of two-stage zone in MP5D44, CXD62–1 and CXD08–1 locate at 4.0 cm, 2.5 cm and 3.75 cm, respectively, and the time of iodine mutation in three crusts ranges from 17–37 Ma derived from 129I dating and Co empirical formula, which is consistent with the times of Cenozoic phosphatization events. The present study shows that the intensity of phosphatization is the main responsible for the distribution pattern of iodine in the crusts on the basis of the correlation analysis. Consequently, iodine is a sensitive indicator for phosphatization.

Electrochemical extraction and separation of praseodymium and erbium on reactive magnesium electrode in molten salts

The electrochemical behaviors of Pr(III) and Er(III) in LiCl-KCl melts were studied on inert tungsten and reactive magnesium electrodes by cyclic voltammetry, square wave voltammetry, and open-circuit chronopotentiometry at 823 K. On a W electrode, the reduction of Pr(III) and Er(III) were found to be through a one-step process: Pr(III) + 3 e− → Pr, Er(III) + 3e − → Er. On a Mg electrode, the reduction potentials of Pr(III)/Pr and Er(III)/Er were observed at more positive potential values than those on W electrode, due to the formation of Mg-Pr and Mg-Er intermetallic compounds when Pr(III) and Er(III) ions were reduced to Pr and Er metal and then react with the Mg substrate, respectively. The extraction of Pr(III) and Er(III) in LiCl-KCl melts were performed by galvanostatic electrolysis on Mg electrode, respectively. The Mg3Pr and Mg24Er5 intermetallic compounds were obtained, which characterized by X-ray diffraction (XRD) and scanning electron microscopy equipped with energy-dispersive spectrometry (SEM-EDS). In order to separate the Pr(III) and Er(III), potentiostatic electrolysis was performed at −1.9 V in LiCl-KCl-PrCl3-ErCl3 melts on a Mg electrode, only one Mg-Pr intermetallic compound, Mg12Pr, was found in the deposit. The separation efficiency was evaluated via inductively coupled plasma atomic emission spectrometer (ICP-AES) analysis at different electrolysis time during potentiostatic electrolysis at −1.9 V. The separation efficiency of Pr(III) was about 95.3 % from the mixture of PrCl3-ErCl3 in LiCl-KCl melts.

Preparation and characterization of mechanical properties of foam glass for artificial floating island carrier

Base compositions of the foam glasses in this study include commercial silica, alumina, boric acid, sodium carbonate, potassium carbonate, carbon powder, and disodium hydrogen phosphate. The foam glasses with partial Na2O replaced by Li2O were prepared and investigated as a possible artificial floating island carrier of water purifying unit. The effects of Li2O dosage on the density, mechanical strengths, and microstructures were studied. Foam glass with 15 mol% Na2O replaced by Li2O displayed a good compressive strength, 3.582 MPa, while the bulk density was relatively low, about 0.398 g/cm3. The chemical stability of samples was evaluated with inductively coupled plasma atomic emission spectrometer, which showed low ion dissolution content in different pH dissolutions. The experimental results showed that the foam glass sample with 15 mol% Na2O replaced by Li2O exhibited excellent comprehensive properties, and the reason may contribute to the mixed alkali effect that proper amount of Li+ could impede the migration of large-radius ions like Na+ and K+ and thus could improve the glass network structure.