Including Inductively Coupled Plasma Research Articles

Efficient, selective and mild oxidation of sulfides and oxidative coupling of thiols catalyzed by Pd(II)-isatin Schiff base complex immobilized into three-dimensional mesoporous silica KIT-6

In this study, a palladium(II)-isatin Schiff base complex immobilized into three-dimensional (3D) mesoporous silica KIT-6 (Pd-isatin Schiff base@KIT-6) was synthesized and characterized by various techniques including inductively coupled plasma (ICP) and Fourier transform infrared (FT-IR) spectroscopies, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) technique and thermal gravimetric analysis (TGA). This new heterogeneous catalyst was successfully employed for the selective oxidation of sulfides to sulfoxides with tert-butyl hydroperoxide (tert-BuOOH) and oxidative coupling of thiols into corresponding disulfides using 30% H2O2 at room temperature. The products were obtained in good to excellent yields and no over-oxidation of sulfoxides and disulfides was observed. This catalytic system could also be applied for the chemo-selective oxidation of sulfides and thiols in the presence of other functional groups. The studied catalyst can be recovered easily by a simple filtration and reused five times in both oxidation reactions without a remarkable decrease in catalytic activity.

Synthesis of 5‐hydroxymethylfurfural from fructose and inulin catalyzed by magnetically‐recoverable Fe3O4@SiO2@TiO2–HPW nanoparticles

AbstractBACKGROUND5‐Hydroxymethylfurfural (HMF) is an important platform chemical that can be generated from biomass using catalysts and used for the production of biofuels and biobased polymers.RESULTSIn this study, a novel magnetically‐recoverable catalyst (Fe3O4@SiO2@TiO2−HPW) was synthesized for the first time by immobilizing H3PW12O40 (HPW) on the surfaces of SiO2 and TiO2‐coated Fe3O4 nanoparticles. A number of techniques, including inductively coupled plasma (ICP) spectroscopy, transmission electron microscopy (TEM), Fourier‐transform infrared (FTIR) spectroscopy and nitrogen (N2) adsorption–desorption analysis, were used to characterize the catalyst. Results showed that the catalyst had a porous structure and the Keggin structure of HPW on the surface of the catalyst was well‐preserved. The catalyst was then used for the syntheses of HMF from fructose and inulin using dimethyl sulfoxide (DMSO) as a solvent, and the influences of reaction temperature and reaction time were investigated. Results showed that HMF yields obtained from fructose and inulin reached 83% and 54%, respectively. After reaction, the catalyst could be easily separated from reaction mixture using an external magnet, and the catalytic activity of the catalyst was well‐preserved after more than five reuses.CONCLUSIONThis magnetically‐recoverable catalyst is efficient not only for the syntheses of HMF from fructose and inulin, but also potentially for the one‐step production of HMF from inulin‐containing biomass, and its magnetic property may overcome the difficulty of catalyst separation from the insoluble biomass residues. © 2019 Society of Chemical Industry

Sonochemical in situ immobilization of Pd nanoparticles on green tea extract coated Fe3O4 nanoparticles: An efficient and magnetically recyclable nanocatalyst for synthesis of biphenyl compounds under ultrasound irradiations

This work describes (i) an eco-friendly approach for in situ immobilization of Pd nanoparticles on the surface of Fe3O4 nanoparticles, with help of green tea extract and ultrasound irradiations, without using any toxic reducing agents and (ii) development of ultrasound assisted simple protocol for synthesis of biphenyl compounds. The structural, morphological and physicochemical characteristics of the catalyst were determined by different analytical methods including inductively coupled plasma (ICP) analysis, Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). Catalytic performance of Pd/Fe3O4 NPs as magnetic and heterogeneous catalyst was evaluated in synthesis of various biphenyl compounds throughout Suzuki coupling reactions by using the ultrasound-assisted method that was developed in this study. The Pd/Fe3O4 NPs demonstrated a noticeable catalytic activity by giving high product yields. Furthermore, the heterogeneous nanocatalyst was successfully recovered up to six times without significant activity loss. Additionally, with respect to conventional coupling reactions, the ultrasound-assisted synthesis reactions presented the advantages of green conditions, short reaction times, high yields and easier work-up.

Dry etching of copper thin films in high density plasma of CH3COOH/Ar

Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO2 masks was carried out using CH3COOH/Ar gas. The etch rate, etch selectivity to SiO2 mask, and the etch profiles of copper films were examined. The evolution study of the etch profile as a function of gas concentration and etch depth revealed the etch sequence and etch mechanism. In the optimized CH3COOH/Ar gas, the systematic approach on the etch characteristics of copper films was performed by changing the etch parameters including inductively coupled plasma (ICP) rf power, dc-bias voltage to substrate, and process pressure. As the ICP rf power and dc-bias voltage increased and the process pressure decreased, the etch rate increased and the etch profile improved. X-ray photoelectron spectroscopy was used to determine the etch mechanism in CH3COOH/Ar gas. Finally, the etching of copper films in the CH3COOH/Ar was achieved with good etch profile with a high degree of anisotropy.

Release of TiO2 – (Nano) particles from construction and demolition landfills

A large fraction of engineered nanomaterials (ENM) will be deposited in landfills and it is assumed that ENM are securely locked in landfill sites and cannot leach into the environment (e.g. surface waters). However, experimental evidence supporting this assumption is lacking, as current production volumes of ENM are still too small and/or analytical techniques not sensitive enough to allow for the detection and quantification of ENM in landfill leachates. TiO2 particles are currently used in large quantities, for example in construction materials such as paints and renders as white pigments and their sizes extend into the nano-size range. We, therefore, selected TiO2 particles as a surrogate to assess the potential release of ENM from construction and demolition (C&D) landfill sites. We collected leachate samples from a landfill over one year and used complementary analytical techniques, including inductively coupled plasma (ICP) – optical emission spectroscopy (OES), automated scanning electron microscopy (auto SEM), transmission electron microscopy (TEM) and single particle ICP - mass spectrometry (spICPMS) to quantify TiO2 particles in landfill leachates. Total elemental Ti contents were mostly around a few tens of μgL−1 and were strongly correlated with total suspended solids. Based on the volumetric discharge of the landfill leachate water from the landfill, we estimate a total amount of ~0.5kg of TiO2 particles that are released annually from the landfill. Ti concentrations derived from ICP-OES measurements were in good agreement with quantifications based on TiO2 particles detected by auto SEM analyses. spICPMS measurements indicated a number concentration of Ti-containing particles in the order of 105mL−1 and TEM analyses dominantly revealed nanoscale TiO2 particles with a spherical shape typically observed for TiO2 particles used as white pigments. In addition, angular TiO2 particles with a well-defined crystal habitus were detected, suggesting that also natural TiO2 particles of comparable sizes are present in the landfill leachates.The results from this study indicate that (nanoscale) TiO2 particles are released from C&D landfill sites (~5g/year). Although the amount of TiO2 particles released from C&D landfill sites may still be rather low, these particles may serve as proxy for assessing the future release of ENM from C&D landfill sites, which may become relevant as an increasing use of ENM is predicted for construction materials in general.

Biosorption of tetracycline onto dried alligator weed root: effect of solution chemistry and role of metal (hydr)oxides

Dried powder of alligator weed root (AWR), a promising biosorbent, was employed to remove tetracycline (TC) from aqueous solution, using acid-pretreated AWR (HAWR) for comparison. The effects of ionic strength, pH, and environmentally coexisting substances on the adsorption of TC on AWR were also investigated. The results indicated a negligible impact of ionic strength but a significant effect of solution pH on the adsorption, with apparent inhibition observed in relatively acidic or alkaline pH regions. The impact of coexisting substances on TC adsorption depended on the species and concentration of interfering components. The mechanism of desorption was explored using NaCl/MgCl2 solution and cyclohexane–methanol mixture, revealing intense TC adsorption on the AWR surface. The biosorbent was characterized using various techniques, including inductively coupled plasma (ICP), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared (FTIR) spectroscopy, and zeta potential and N2 adsorption/desorption analyses. The results of the ICP, SEM–EDS, and FTIR analyses indicated that metals including Mn, Fe, and Al were enriched mainly over the AWR surface with metal (hydr)oxide (MHO) morphology. When the MHOs were denuded by HCl solution pretreatment, the resulting HAWR totally lost the adsorption capability. Based on the nature of AWR and TC as well as the adsorption/desorption performance, MHOs over the AWR surface were verified to play an essential role in driving adsorption via surface complexation. Furthermore, MHO-based complexation provides a reliable explanation for the TC adsorption/desorption performance. The obtained results will aid adsorption mechanism elucidation and potential applications of such low-cost biosorbent.

Design, fabrication and actuation of a MEMS-based image stabilizer for photographic cell phone applications

This work presents a MEMS-based image stabilizer applied for anti-shaking function in photographic cell phones. The proposed stabilizer is designed as a two-axis decoupling XY stage 1.4 × 1.4 × 0.1 mm3 in size, and adequately strong to suspend an image sensor for anti-shaking photographic function. This stabilizer is fabricated by complex fabrication processes, including inductively coupled plasma (ICP) processes and flip-chip bonding technique. Based on the special designs of a hollow handle layer and a corresponding wire-bonding assisted holder, electrical signals of the suspended image sensor can be successfully sent out with 32 signal springs without incurring damage during wire-bonding packaging. The longest calculated traveling distance of the stabilizer is 25 µm which is sufficient to resolve the anti-shaking problem in a three-megapixel image sensor. Accordingly, the applied voltage for the 25 µm moving distance is 38 V. Moreover, the resonant frequency of the actuating device with the image sensor is 1.123 kHz.

Studies on the adsorption behavior of trace amounts of 90Sr 2+, 140La 3+, 60Co 2+, Ni 2+and Zr 4+ cations on synthesized inorganic ion exchangers

Three inorganic ion exchangers namely potassium zinc hexacyanoferrate(II) (PZF), magnesium oxide–polyacrylonitrile composite (MgO–PAN) and ammonium molybdophosphate (AMP) were synthesized. The physicochemical properties of these ion exchangers were determined using different techniques including inductively coupled plasma (ICP), CHNSO elemental analysis, infrared spectroscopy (IR), X-ray diffraction (XRD), thermogravimetric (TGA) and pH – titration curve analysis. The solubility of the synthesized ion exchangers in different acidic and alkaline media, their thermal stability and the effect of gamma irradiation were investigated. It was observed that the exchange capacity of the ion exchangers depend upon the pH value of the solution used. Furthermore, the adsorption of 90Sr 2+, 140La 3+, 60Co 2+ and the distribution coefficient of these ion exchangers for Ni 2+and Zr 4+ were studied. The effect of parameters such as pH and contact time on the adsorption was also investigated and the optimum conditions for separation of these ions were determined.

Small helicon plasma source for electric propulsion

An investigation was conducted for a very small helicon plasma source of a 2.5 cm i.d. glass tube. Since the operational features of electric propulsion are determined by its plasma density and degree of ionization, the helicon plasma including inductively coupled plasma (ICP) has a niche requirement as high as 10 13 cm − 3 density at the optimized condition of both RF frequency and applied magnetic field. In this paper, by using Ar, the RF frequency was scanned from 27.12 up to 67.80 MHz and the applied magnetic field was moderately varied from 0 to about 0.01 T. The maximum input power was 250 W at this time and 8 × 10 12 cm − 3 was achieved.

Deterministic Boltzmann solver for electron kinetics in plasma reactors for microelectronics applications

A kinetic module has been developed in the commercial software package CFD-ACE+ and applied to simulations of plasma reactors for microelectronics applications. The kinetic module solves the Boltzmann transport equation (BTE) using two-term spherical harmonics expansion (SHE) of the probability distribution function (PDF). This method reduces the 6D BTE to a Fokker Planck equation in a four-dimensional space (three spatial coordinates+energy) offering a very good compromise between physical accuracy and numerical efficiency. This paper describes the design of the kinetic module and its current status and applications to electron kinetics in gas discharges. The kinetic module is coupled to other modules in CFD-ACE+ for self-consistent kinetic simulations of plasmas. The Fokker–Planck equation is solved for the electron energy probability function (EEPF) providing macroscopic characteristics (electron density, fluxes, rates of electron induced chemical reactions, etc.). Using these quantities, the transport of ions and neutrals in plasmas is simulated using a continuum model. The electromagnetic fields are calculated by solving Maxwell equations in the potential formulation (scalar electric and vector magnetic potentials). Several examples of hybrid kinetic simulations of plasma reactors are described including inductively coupled plasma (ICP), and classical DC glow discharges in electropositive and electronegative gases. The developed Boltzmann solver expands the applicability of computational plasma models to low gas pressures and enhances accuracy and fidelity of plasma simulations.

Chemical Fingerprinting of Stratigraphic Surfaces to Refine Reservoir Architecture and Differentiate Fluid Flow Regimes: ABSTRACT

The variable development of depositional cycles within hydrocarbon reservoirs, especially reservoirs contained within platform carbonates, can have a profound influence on fluid flow. These cycles can be recognized in core and logs and should form the basis of subsurface geologic models. When placed into a sequence stratigraphic framework, cycle variability can be predicted. We herein investigate the use of chemostratigraphy to refine a reservoir-scale stratigraphic framework and demonstrate the influence of this framework on fluid flow. Using cores and outcrops of the Permian San Andres Formation in the Guadalupe Mountains of southeastern New Mexico, permeability distribution and waterflood response was modeled for a small-scale carbonate sequence (105 no thick) containing variably developed depositional cycles that formed in a carbonate ramp setting. Cross-sectional fractal permeability fields, used in simulated waterfloods, demonstrate sensitivities of oil recovery and overall injection rare to the stratigraphic framework. Major, minor and trace element variation measured on 44 interval composites from core, using a combination of techniques including inductively coupled plasma (ICP) and mass spectrometry, characterize and fingerprint important stratigraphic surfaces (sequence boundaries, cycle boundaries, and flooding surfaces). Less distinct cycles below this surface we characterized by compartmentalized flow and poor vertical sweep efficiency, whereas well-developed cyclesmore » above are characterized in our analog by a potential for early water breakthrough and relatively high vertical sweep efficiencies.« less