Inductively Coupled Plasma Analysis Research Articles

Comparison of laser-induced breakdown spectroscopy (LIBS) and ICP analysis results for measuring Pb and Zn in soil

Context Laser-induced breakdown spectroscopy (LIBS) is a rapid, multielement analytical technique. It is particularly suitable for the qualitative and quantitative analyses of heavy metals in solid samples. Aims To validate the technique, the LIBS data were compared with the data obtained via conventional inductively coupled plasma (ICP) spectroscopy for the same soil samples. Methods In this study, standard and unknown soil samples from contaminated areas were prepared and fixed to an adhesive tape for LIBS analysis. The soils were also digested with acids for ICP analysis. The emission intensity of one selected line for each of the two analytes, i.e. lead (Pb) and zinc (Zn), was normalised to the background signal and plotted as a function of the concentration values previously determined via ICP analysis. Key results The data demonstrated good linearity for the calibration lines drawn, and the correlation between the ICP and LIBS data was confirmed by the satisfactory agreement between the corresponding values. Conclusions The concentration coefficient of determination (R2) between LIBS and ICP-aqua regia digestion analysis or ICP-total digestion analysis were >0.86 and >0.89 for Pb and Zn, respectively. The total analysis time for the LIBS method was 310 min, which was 54.40% shorter than that for the ICP method (680 min). Implications Consequently, LIBS can be used to measure Pb and Zn in soils without any chemical preparation.

A new Schiff‐base complex of palladium nanoparticles on modified boehmite with di(pyridin‐2‐yl)methanone as a robust, reusable, and selective nanocatalyst in the C‐C coupling reaction

Boehmite is one of the stable phases of alumina that is easily available, and it also has a variety of applications. Therefore in this work, for preparation of AlOOH, Sodium hydroxide (NaOH) solutions was added to aluminum nitrate nonahydrate (Al(NO3)3.9H2O) solution. Then, the surface of AlOOH was modified with (3‐aminopropyl)triethoxysilane (APTES), due to high condensation of hydroxyl groups on its surface. Then, di(pyridin‐2‐yl)methanone (di(PM)) was immobilized on the surface of modified AlOOH toward synthesis of immobilized Schiff‐base on AlOOH (di(PM)@AlOOH) as a heterogeneous Schiff‐base ligand. Finally, a palladium complex was immobilized on its surface (Pd‐di(PM)@AlOOH) as a reusable, practical, and novel nanocatalyst. Pd‐di(PM)@AlOOH was characterized by thermogravimetric analysis (TGA) analysis, Fourier‐transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), scanning electron microscope (SEM) imaging, energy‐dispersive X‐ray spectroscopy (EDS) analysis, wavelength‐dispersive X‐ray spectroscopy (WDX) analysis, and inductively coupled plasma (ICP) analysis. After the characterization of Pd‐di(PM)@AlOOH, its performance was used as a highly practical, stable, retrievable, and hybrid organic–inorganic catalyst in the C‐C coupling of the Suzuki reaction. The hot filtration study of Pd‐di(PM)@AlOOH revealed that it acts heterogeneously in the Suzuki reaction. We found that this catalyst can be recycled for five runs without palladium leaching, as studied by hot filtration test and ICP analysis.

Intimately mixed copper, cobalt, and iron fluorides resulting from the insertion of fluorine into a LDH template.

The advancement of lithium-ion batteries (LIBs) with high performance is crucial across various sectors, notably in space exploration. This advancement hinges on the development of innovative cathode materials. Our research is dedicated to pioneering a new category of cathodes using fluorinated multimetallic materials, with a specific focus on diverging from the traditional Ni, Co, and Mn-based NMC chemistries by substituting nickel and manganese with copper and iron which are more sustainable elements. Our goal is also to enhance the robustness of cathodes upon cycling by substituting oxygen with fluorine as the metal-ligand. To achieve this, an intimate composite blend of CuF2 and FeF3, through the multi-metallic template fluorination (MMTF) methodology using a layered double hydroxide (LDH) as a precursor has been designed. Each of these components was carefully selected for its distinct attributes, including high redox potential, elevated energy density, substantial theoretical capacity, and improved cyclability. The composition denoted as (Cu1.5Co0.5)2+(Fe0.75Al0.25)3+ has been selected for fluorination because it maximizes Fe3+ and Cu2+ amount in the screened LDHs. Subsequently, this particular LDH was fluorinated through solid-gas fluorination at different temperatures (200, 350, and 500 °C) using gaseous molecular fluorine (F2). A comprehensive characterization of these materials using various techniques, including X-ray diffraction (XRD), 57Fe Mössbauer spectrometry, scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), and inductively coupled plasma analyses (ICP-AES) was conducted, and the evolution of LDH upon fluorination has revealed an intermediate porous texture particularly sensitive to hydration. Two original crystallographic phases are else obtained by fluorination: one formed by the hydration of the amorphous intermediate compound: Cu3Fe1.5Al0.5F12(H2O)12 an anti-perovskite structure and another stabilized through the combination of solid gas fluorination and LDH precursor yielding an original CoFeF5-type phase. Raman operando during cyclic voltammetry measurement applied on a sample fluorinated at 500 °C and used as a cathode in front of lithium metal was finally conducted to validate redox activity and mechanism.

The antibacterial activity of three zeolitic-imidazolate frameworks and zinc oxide nanoparticles derived from them.

Zinc has been widely studied for its antibacterial properties due to its low toxicity, availability, and low cost. This research focused on analysing the antibacterial effects of three types of MOFs (metal-organic frameworks) with zinc as the central metal: ZIF-4, ZIF-7, and ZIF-8. The study found that ZIF-8 had the strongest antibacterial effect, while ZIF-7 had the weakest among them. These findings were consistent with the results of the ICP (inductively coupled plasma) analysis, which measured the amount of zinc released. Additionally, the antibacterial effect of ZIF-8 was found to be higher than that of zinc oxide species obtained from calcination of the compounds. Among the zinc oxide samples, ZnO nanoparticles which derived from ZIF-4 showed the highest antibacterial activity.

The thermo-therapeutic applications of Chitosan- CTAB coated Nickel Ferrite (NiFe2O4) magnetic nanoparticles

In this study, we used a hydrothermal-assisted co-precipitation method to synthesize the nickel ferrite (FN), Chitosan coated nickel ferrite (FN-Ch) and cetyltrimethylammonium bromide coated nickel ferrite (FN-CT) nanoparticles with small sizes and good biocompatibility. These nanoparticles were then evaluated for their potential use in magnetic hyperthermia. The particles were characterized using a variety of techniques, including x-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), Inductively coupled plasma (ICP), magnetic characterization (VSM), zeta potential analysis, and in vivo studies (blood hemolysis and MTT test). The results of the x-ray diffraction analysis showed that the nanoparticles had a spinel phase of NiFe2O4. TEM analysis revealed that all three samples contained particles with nearly quadrilateral and hexagonal shapes. FT-IR spectroscopy confirmed the presence of Chitosan and CTAB coatings on the particle surface. Magnetic hysteresis curves showed that all of the synthesized samples exhibited superparamagnetic behavior at room temperature. The findings from the ICP analysis indicated that the FN-Ch and FN-CT nanoparticles contained iron and nickel, while no substantial quantities of other trace elements were identified in either of the samples. Blood hemolysis and MTT tests were used to assess the toxicity of the nanoparticles when in contact with red blood cells, fibroblast cells, and MCF7 cancer cells. Overall, our findings suggest that FN-Ch and FN-CT nanoparticles have potential for use in cancer diagnosis and treatment as part of a new nano-carrier system. Furthermore, combining hyperthermia with other treatment methods could enhance the effectiveness of cancer therapy.

Preparation of GO/Cys-Cu(II) as a novel, effective and recoverable catalyst for the multi component synthesis of spirooxindoles under mild conditions

Modified graphene oxide (GO/CPTES/Cys-Cu(II)) was prepared as a reusable catalyst and characterized by various analytical and spectroscopic methods, including Fourier transform spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and inductively coupled plasma (ICP) techniques. Obtained results from demonstrated the existence of cystein/Cu(II) on the MWCNTs surfaces. EDX and ICP analysis shown about 11% Cu (II) and about 8.5% of N element in the catalyst structure. Also, other characterization data confirmed the successfully preparation of synthesized catalyst. The efficiency of this novel catalyst was evaluated through the green synthesis of two variety of spirooxindole derivatives in a One-pot multi component reaction in ethanol as a green solvent. The catalyst showed high efficiency in this process and all of spirooxindoles were obtained after short time (18 min) in high to excellent yields (89–95%). The structure of all obtained products was assigned with hydrogen and carbon nuclear magnetic resonance (1H and 13C NMR) and FTIR. Furthermore, the catalyst could be easily recovered and directly reused at least five times without a notable reduction in activity. The other advantages of the presented methodology are high yields of products without the formation of by-products, simple and clean process, mild reaction conditions and agreement with green chemistry protocols.

Fabrication and evaluation of PLA/MgAl2O4 scaffolds manufactured through 3D printing method

In this study, we synthesized magnesium aluminate spinel (MgAl2O4) with a particle size ranging from 35 to 70 nm using a facile combustion approach. Then, we used a 3D printing (FDM) machine to produce PLA/x wt% MgAl2O4 (x = 0, 2, 4, 6, and 8) scaffolds. To investigate the crystal structure, microstructure, biodegradability, and thermal characteristics of the produced materials, we employed X-ray diffraction analysis (XRD), field emission scanning electron microscope (FESEM), Inductively Coupled Plasma (ICP), Simultaneous Thermal Analysis (STA), and compressive strength analyses. The results showed that PLA/6 wt% MgAl2O4 scaffolds possess the highest amounts of compressive strength. We evaluated the bio-activation and biodegradability of scaffolds by immersing them in simulated body fluid (SBF) for four weeks. Interestingly, the highest strength was achieved in PLA/6 wt% MgAl2O4 scaffolds, while the improper dispersion of ceramic particles happened on the polymer substrate in cases where x>6. ICP analysis showed that the addition of spinel nanoparticles to PLA increased the biodegradability of the scaffolds. Our FESEM results supported this finding and also revealed that the dispersion of ceramic particles on the polymer substrate was not uniform in cases where x>6. Also, according to the results of STA, the presence of MgAl2O4 nanoparticles effectively reduces the rate of thermal decomposition from 95 to 85 percent.

Cadmium and Lead Concentration in Drinking Instant Coffee, Instant Coffee Drinks and Coffee Substitutes: Safety and Health Risk Assessment

The presence of heavy metals in food is a global problem. The paper aimed to examine the content of cadmium (Cd) and lead (Pb) in instant coffee and instant coffee substitutes. The safety of consumption of the beverages by adult Poles was estimated based on the following parameters: tolerable weekly intake (TWI) %, benchmark dose lower confidence limit (BMDL) %, chronic daily intake (CDI), target hazard quotient (THQ) and hazard index (HI), for three beverage consumption patterns—one, two or three servings a day. Forty-nine samples of coffee, instant coffee drinks and coffee substitutes were analysed. The content of cadmium and lead was determined by ICP (inductively coupled plasma) analysis. The maximum level of Cd in the analysed beverages was 3.2 µg, and that of Pb was 82.6 µg per 1 kg. The tolerable level of intake of Cd (TWI) and Pb (BMDL) with the analysed beverages did not exceed 2.5%. The value of CDI, THQ and HI was not higher than 1, which means that the risk of diseases related to chronic exposure to Cd and Pb consumed with coffee should be evaluated as very low. However, special note should be taken of Pb, as the level of this metal was higher than that of Cd, and for beverages with a higher weight per serving (e.g. Cappuccino), the intake of Pb can exceed consumer-safe levels if they are consumed on a regular basis. Therefore, it should be considered whether it is advisable for flavoured multi-ingredient instant coffee drinks to be consumed from time to time only, and natural coffee with optional milk and/or sugar be the choice of regular coffee drinkers.

Adsorption and photocatalytic properties of porphyrin loaded MIL-101 (Cr) in methylene blue degradation.

In this study for the very first time, zinc tetraphenylporphyrin (ZnTPP) was loaded into MIL-101 (Zn[TPP]@MIL-101) to perform an adsorptive and photocatalytic dye removal. The physicochemical attributes of the catalyst were thoroughly determined by the usage of XRD, FTIR, FESEM, BET, UV-vis, and inductively coupled plasma (ICP). The obtained XRD pattern exhibited the phase purity of MIL-101 and its structural stability. The solid-phase diameter of the catalyst was observed to be ~ 270.76 ± 119.95nm, while its gas adsorption data was indicative of a decrease in the specific surface area after the loading of ZnTPP. The ICP analysis displayed the amount of encapsulated Zn[TPP] (~ 17%) in MIL-101. The UV-vis confirmed the presence of Zn[TPP] in MIL-101 with the lack of any interferences or overlaps with the λmax of methylene blue (MB) with the support. The dye removal of MB was investigated under dark conditions (adsorption) and UV light (photodegradation). The observed adsorption under dark conditions using Zn[TPP]@MIL-101 (99.27% yield) demonstrated a superior dye removal in comparison to the cases of photodegradation of MB by MIL-101 and Zn[TPP]@MIL-101 or adsorption by MIL-101. In conformity to the gathered results, [ZnTPP] was able to increase the adsorption capacity at pH = 7 at room temperature.

Probing surface-adsorbate interactions through active particle dynamics

Adsorbate molecules present in a reaction mixture may bind to and block catalytic sites. Measurement of the surface coverage of these molecules via adsorption isotherms is critical for modeling and design of catalytic reactions on surfaces. However, it is challenging to measure isotherms in solution in a way that is directly relevant to catalytic activity under reaction conditions, particularly since adsorbates may bind with an enormous range of surface affinity parameters. Here we used the motion of self-propelled catalytic Janus particles, which employ the decomposition of hydrogen peroxide fuel as a propulsion mechanism, to determine the effective surface coverage of thioglycerol, furfural, and ethanol on a platinum surface as a function of concentration in aqueous solution by measuring the decrease in active motion due to the blocking of active sites. For strongly adsorbing thioglycerol, this effective coverage was compared and contrasted to the total adsorbed amount measured using inductively-coupled plasma analysis. Demonstrating the broad applicability of this approach, the surface affinity of the three adsorbates spanned more than four orders of magnitude. For each species, the adsorbate-mediated attenuation of active motion occurred over a wide concentration range and was well-described by a Langmuir isotherm. The strongly interacting thioglycerol had the highest affinity towards the surface (Ka = 15.5 ± 4.3 mM−1) and fully deactivated the active particle motion at surface saturation. Furfural had an intermediate affinity (Ka = 0.42 ± 0.07 mM−1) but did not fully block H2O2 access to the surface at apparent saturation, consistent with a maximum fractional surface coverage of θmax = 0.67. Ethanol exhibited even lower affinity (Ka = 0.0025 ± 2x10-4 mM−1) and its coverage saturated at only θmax = 0.38. Analysis of isotherms at elevated temperatures enabled direct extraction of the enthalpies of adsorption. The degree of surface coverage at adsorbate saturation appeared to correlate with the relative energies of adsorption for the different adsorbate species and was consistent with adsorbate saturation of one of multiple active site populations towards H2O2 decomposition. Moreover, computational investigations into solvent effects on furfural adsorption showed good quantitative agreement with the experimental results. This work leverages unique properties of active particles to explore fundamental catalysis questions and demonstrates a novel paradigm for significant and experimentally accessible multidisciplinary research.

Green Kenaf-Based Adsorbent for Adsorption of Pb (II) Ions in Water

Excessive toxic metals are commonly found in polluted water bodies. This study aimed to synthesise kenaf-based adsorbents for the adsorption of lead (II) ions. The physical and chemical characteristics of the kenaf (KNF) core and fibre were determined using field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). The further synthesised kenaf-chitosan-alginate (KNF-CHT-ALG) beads were characterised through FESEM and FTIR, while inductively coupled plasma (ICP) was employed to determine the percentage of adsorption. The FESEM analysis demonstrated that the KNF core had a rougher surface morphology than the KNF fibre. The TGA analysis confirmed that the KNF core was coarser and contained a higher residue of approximately 75.91%. The FTIR spectra established intense functional groups in the KNF core, such as hydroxyl and carboxyl, attracting more Pb (II) ions. The KNF core was then used to synthesise KNF-CHT-ALG beads. The beads confirmed the enhancement in surface morphology and the existence of numerous functional groups for Pb (II) ions to bind. The ICP analysis demonstrated 95% of Pb (II) ion adsorption. Additionally, batch adsorption experiments were conducted at pH 2–7 and the contact time was within 5–60 minutes. The kinetic study of the adsorption followed the pseudo-second order model with an R2 value of 0.9999. The KNF is a crop found in abundance in Malaysia, which could reduce the production cost of adsorbents. The significant outcomes would minimise the dependency on chemical adsorbents and accelerate the removal process of heavy metals in natural bodies of water.

Precise Construction of Stable Bimetallic Metal–Organic Frameworks with Single-Site Ti(IV) Incorporation in Nodes for Efficient Photocatalytic Oxygen Evolution

Precise Construction of Stable Bimetallic Metal–Organic Frameworks with Single-Site Ti(IV) Incorporation in Nodes for Efficient Photocatalytic Oxygen Evolution

Secondary Iron Mineral Detection via Hyperspectral Unmixing Analysis with Sentinel-2 Imagery

The exposition of minerals to oxygen as well as non-treated tailings in mining activities alter the balance of the ecosystem, specifically leading to the generation of acidic solutions in the presence of sulfidic minerals. Several secondary iron minerals are precipitated in these settings that can be detected via remote sensing applications. The purpose of this research is to investigate the capacity of hyperspectral analysis to determine the abundance of Acid Mine Drainage (AMD)-indicator secondary iron minerals in mine sites with the guidance of ground truth information. To this end, we focus on an abandoned coal mine site in Turkey to detect secondary iron minerals associated with AMD via multispectral Sentinel-2 imagery, in accordance with the laboratory analysis of field-collected samples through X-Ray Diffraction (XRD), Inductive Coupled Plasma (ICP), and ASD spectral analysis. In relation with the conducted laboratory XRD and ICP results, the proposed methodology first reveals the iron-induced absorption feature located between 700 and 900 nm on field-collected ASD spectra and reference USGS spectra through a baseline method, namely parabola fitting method. The subsequent remote sensing analysis then applies hyperspectral unmixing to Sentinel-2 imagery and identifies the spectral endmember indicating iron-absorption behavior by computing its spectral angle distance to reference spectra. The experiments reveal that while the iron absorption characteristics are not apparent in pixel spectra, the utilized unmixing methodology enables capturing of those features at sub-pixel level on the resulting endmembers. Second, the comparison between the calculated abundances with unmixing and iron levels obtained with ground based ICP analysis indicate coherent correlation values. Finally, among the utilized unmixing methods, the performance of SISAL is found better than MVSA with the resulting correlation values of 0.76 and 0.63, respectively, while also returning closer endmembers to the reference iron spectra. The performed research demonstrates the potential of hyperspectral applications on Sentinel-2 data to uncover the sub-pixel iron-induced spectral features in the visible region, proving compatible results between the spectral and laboratory analysis.

Effect of chemical aging on color stability and surface properties of stained all-ceramic restorations.

To study the effect of artificial aging on color stability, translucency, and surface roughness of stained all-ceramic restorations. Disc-shaped specimens were fabricated from six different all-ceramic materials: two glass ceramics (Vita Mark II and Empress CAD), two lithium disilicate based ceramics (e.max and Suprinity), and two zirconia-based materials (ZirCAD LT and ZirCAD MT Multi). The discs were stained using two universal stains; IPS Ivocolor stain or Vita Akzent stain. Color change (ΔE) and the translucency parameter (TP) were measured before and after artificial aging. The surface roughness (Ra) was evaluated using atomic force microscopy, while the surface microstructure was evaluated using scanning electron microscopy (SEM). Quantitative elemental analysis was performed using the energy dispersive X-ray (EDX). Leached ions were analyzed by inductively coupled plasma (ICP) (n=12, α=0.05). Artificial aging had significantly changed the color (ΔE) and decreased the translucency (TP) of all stained ceramics. The mean surface roughness (Ra) was significantly increased in all specimens, which was also confirmed in the SEM scans. EDX analysis revealed a decrease in the elemental composition of the stained surface as a result of ceramic degradation, except for Ca and Zn in IPS Ivocolor stain. Furthermore, the ICP analysis revealed that most compositional elements of stain and glaze were detected in the aging solution. Chemical aging had significantly affected the optical parameters and surface texture of stained monolithic ceramics. Stained ceramics are liable to color degradation. Each type of stain should be used with its corresponding type of ceramic. Stained all-ceramic restorations are liable to color change and surface degradation during function.

Pt-TiO2 Nanocomposite PEFC Electrocatalysts for High Potential Cycle Durability

Introduction Pt/C is widely used as the electrocatalysts for polymer electrolyte fuel cells (PEFCs). However, Pt/C has a difficulty in durability due to the thermochemical instability of carbon support and the weak binding energy between Pt and carbon support, which cause the detachment and aggregation of Pt nanocatalysts. In our group, we have developed electrocatalysts using oxides such as (SnO2) as catalyst supports, realizing high potential cycle durability[1-3].The use of oxide support suppresses the detachment and aggregation of Pt nanocatalysts due to the strong bonding between Pt and such oxides [4]. With increasing the contact area between Pt and oxides, such interaction could be further pronounced. Here, we prepare “nanocomposite electrocatalysts” maximizing the contact area between Pt and oxides. TiO2 is used as a model oxide. The purpose of this study is to develop a highly durable electrocatalysts and to establish a new nanocomposite concept for PEFCs by optimizing the ratio of Pt to TiO2 and the heat-treatment conditions. E xperimental Pt and TiO2 were co-loaded on the graphitized carbon black (GCB200 from Cabot) by the acetylacetonate (acac) method[5]. In this acac method, a one-step preparation procedure was applied where precursors of Pt and TiO2 (Pt(acac)2 and Ti(acac)2OiPr2, both from Sigma Aldrich) could be simultaneously dissolved in acetone. The volume ratio of Pt to TiO2 was set to be 1:1, 1:2, and 1:4. The loading of the Pt-TiO2 nanocomposite was set to be 20wt.%. In the heat-treatment for the Pt and TiO2 co-loading, an additional heat-treatment was made in a humidified N2 at a higher temperature for promoting the crystallization of TiO2, just after the typical heat-treatment at 210°C for 3 h and then 240°C for 3 h in the Pt-acac method. Pt loading and the ratio of Pt to TiO2 were quantitatively evaluated by inductively-coupled plasma (ICP) spectroscopy and thermogravimetry (TG) analysis. The degree of crystallization and the microstructure of nanocomposite electrocatalysts were evaluated by XRD and STEM, respectively. Half-cell and MEA tests were conducted to evaluate the electrochemical activity and durability of these electrocatalysts prepared. Results and Discussion From the results of the ICP and TG analysis, the loading and the ratio of Pt to TiO2 were derived. After the XRD measurements shown in Figure 1, it was confirmed that there was no change in Pt peak width and thus Pt particle size, even though the preparation conditions were varied. We also confirmed that the crystallization of TiO2 was promoted by the heat-treatment at higher temperature up to e.g. 500°C. STEM micrograph and EDS map in high-resolution STEM, shown in Figure 2, reveal that Pt nanocatalysts of about 1 to 2 nm in diameter were supported with high dispersion, and TiO2 was distributed between Pt nanocatalysts, indicating a successful preparation of Pt-TiO2 nanocomposite electrocatalysts. To mention a few, the electrochemical results of load potential cycle tests between 0.6 and 1.0 VRHE confirmed that sufficient crystallization of TiO2 actually improves the potential cycle durability of these nanocomposite electrocatalysts. R eferences A. Masao, S. Noda, F. Takasaki, K. Ito, and K. Sasaki,Electrochem . Solid-State Lett., 12 (9), B119-B122 (2009). F. Takasaki, S.Matsuie, Y. Takabatake, Z. Noda, A. Hayashi, Y. Shiratori, K. Ito, and K. Sasaki, J. Electrochem . Soc., 158 (10), B1270-B1275 (2011). D.Horiguchi, T. Tsukatsune, Z. Noda, A. Hayashi, and K. Sasaki, ECS Trans., 64 (3), 215-220 (2014). T. Daio, A.Staykov, L. Guo, J. Liu, M. Tanaka, S. M. Lyth, and K. Sasaki, Sci. Rep., 5, 13126 (2015). A. Hayashi, H.Notsu, K. Kimijima, J. Miyamoto, and I. Yagi, Electrochim . Acta, 53, 6117 (2008). Figure 1

Novel Approach for Sandstone Acidizing Using in Situ-Generated Hydrofluoric Acid with the Aid of Thermochemicals.

In this study, an in situ-generated hydrofluoric acid (HF) was used for sandstone acidizing, where an acid precursor (ammonium fluoride NH4F) reacted with a suitable oxidizer (sodium bromates NaBrO3) in an exothermic reaction. First, the new chemical mixture was prepared to react with pure quartz samples and the reaction effluent was analyzed to identify the presence of Si+ ions using the inductively coupled plasma (ICP) technique. Core flooding experiments were performed using Gray Berea sandstone cores (6 in. length and 1.5 in. diameter). A preflush stage of 5 PV of 7 wt % HCl was injected to remove any calcite content in the core. The main chemicals were then flushed for 3 successive cycles of 1 PV each. To assure core integrity, scratch tests and NMR scans were run on the core sample before and after the treatment. The new chemical mixture could dissolve the quartz sample and reduce its weight by 80 mg. The concentration of the dissolved Si+ ions was more than 90 ppm. This proves the capability of the chemical mixture to generate HF. The initial core permeability was measured at a stabilized flow rate of 2 cm3/min to be 33 mD. After the acid preflush stage, the core permeability reduced to 31 mD. Core permeability increased immediately after the first treatment cycle and reached 41 mD. At the end, the core flooding results showed a permeability improvement for Gray Berea sandstone cores by almost 40%. The ICP analysis of the effluent showed a total amount of chelated Si+ ions of about 10.5 mg. In addition to the high temperature generated in the near-wellbore area, the pressure increased because of the produced nitrogen gas from the exothermic reaction and reached about 600 psi. The scratch test showed an increase in the sample uniaxial compressive strength from 7432 to 9235 psi. The dynamic Poisson’s ratio and the dynamic Young’s modulus increased as well from 0.17 to 0.19 and from 2159 to 3585 ksi, respectively. The enhancement in the mechanical properties of the core can be attributed to the presence of the potassium element in Berea cores and its solidification reaction with the HF generated. The NMR measurements of the core sample before and after the acidizing process show an increase in the core porosity; however, the core preserved its original pore system. Upon application of this new stimulation technology, the true production potential of sandstone reservoirs can be achieved, well tubular corrosion will be minimized, and handling hazardous chemicals such as HF will be avoided. Most importantly, controlling the reaction rate, by controlling the amount of exothermic chemicals, can ensure deep acid penetration as well.

Influence of the electrolyte composition on the electrochemical dissolution behavior of forged Inconel 718

The forged Inconel 718 anodic dissolution at fixed applied current density was investigated in different nitrate sodium based electrolytes, namely in NaNO3 8 wt% and 20 wt%, in NaNO3 15 wt% + NaClO3 20 wt%, and in NaNO3 20 wt% + sulfosalicylic acid 2 wt%. The analysis of the different anodic products on the surface sample, by X-Ray diffraction, Scanning Electron Microscopy, and Energy Dispersive X-ray spectroscopy, revealed a presence of oxides mainly constituted of Nb and Ti oxides and a smaller amount of γ″ phase precipitate than in raw material. Inductively coupled plasma (ICP) analysis has shown that the main elements of the matrix (Fe, Cr, Ni) are soluble in all tested electrolytes while Nb content is below the detection threshold in pure NaNO3 electrolyte and in 15 wt% NaNO3 + 20 wt% NaClO3. However, in presence of sulfosalicylic acid, acting as chelating agent, the amount of anodic products on the surface sample has considerably reduced comparatively to other tested electrolytes and Nb was detected by ICP analysis as additional element in the electrolyte. Therefore, this work shows that the Inconel 718 super alloy can be homogenously anodized by the use of an adapted chelating electrolyte, opening up possibilities for efficient electrochemical machining processes.

Generation of a Porous Scaffold with a Starting Composition in the CaO–SiO2–MgO–P2O5 System in a Simulated Physiological Environment

Magnesium-based ceramics are involved in orthopedic applications such as bone scaffolds or implant coatings. They provide structural support to cells for bone ingrowth, but highly porous matrices cannot resist severe mechanical stress during implantation. In this study, the laser floating zone (LFZ) technique is used to prepare a dense crystalline material with composition in the CaO–SiO2–MgO–P2O5 system. This material, under physiological conditions, is able to generate a porous scaffold controlled by the dissolution of the MgO phase, meeting the mechanical advantages of a dense material and the biological features of a porous scaffold. FESEM (Field emission scanning electron microscopy), XRD (X-ray Diffraction), EDS (Energy Dispersive X-rays spectroscopy), and ICP ((Inductively Coupled Plasma) analysis were carried out in order to characterize the samples before and after immersion in simulated body fluid (SBF).

Ion Exchange of One-Pot Synthesized Cu-SAPO-44 with NH4NO3 to Promote Cu Dispersion and Activity for Selective Catalytic Reduction of NOx with NH3

Cu-containing CHA type (Cu-CHA) zeolites have been widely investigated owing to their excellent low-temperature activity and high hydrothermal stability in selective catalytic reduction of NOx with NH3 (NH3-SCR). Herein, a series of Cu-SAPO-44 zeolites were prepared by one-pot method with dual-amine templates and the subsequent ion exchange (IE) with NH4NO3. The effect of NH4NO3 treatment on Cu species was investigated by X-ray powder diffraction (XRD), N2 adsorption-desorption isotherm, inductively coupled plasma (ICP); field-emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HRTEM), X-ray absorption fine structure (XAFS), and H2-temperature-programmed reduction (H2-TPR). The results indicated that—besides the main SAPO-44 structure—the CuO phase was detected by XRD in original samples. After IE with NH4NO3, the Cu contents decreased greatly from ICP analysis. The removal of CuO agglomerations and the presence of highly dispersed CuO nanoparticles (~2.36 nm) were confirmed by SEM, TEM and H2-TPR. Furthermore, a significant increase in the proportion of isolated Cu2+ was derived from XAFS. As a result, the activity at higher temperature (≥350 °C) was improved a lot.

Advances in Tropical Soil Characterization via Portable X-Ray Fluorescence Spectrometry

Portable X-ray fluorescence (pXRF) spectrometers can be used to determine the elemental composition easily, rapidly, and without using chemical reagents, which is very important for tropical regions due to the lack of detailed soil characterization data. Moreover, pXRF data can be used to predict the results of more expensive, time-consuming, and conventional laboratory analyses. This study sought to determine the elemental composition of various soil profiles using pXRF. Two operational modes (Trace Mode and General Mode) and two scanning time (30 and 60 s) were assessed to determine their effects on the correlation of pXRF dataset with respect to conventional inductively coupled plasma (ICP)-optical emission spectrometry analysis. This relationship has been reported in previous studies, however, few studies were performed on tropical soils, which are unique. Furthermore, such relationships establish the viability of developing prediction models directly from pXRF data. Linear regression was applied to develop calibration models for the prediction of ICP analysis results and exchangeable and available elemental contents based on pXRF data. High coefficients of determination (R2) were obtained for Ca (0.87), Cu (0.90), Fe (0.95), Mn (0.85), Cr (0.95), V (0.72), and Ni (0.90), with adequate validation. Statistically significant results were not found for Al, K, Zn, Ti, and Zr. The models predicting the exchangeable Ca based on the total Ca from pXRF reached an R2 of up to 0.85. Operational modes influenced the pXRF results. Our results illustrate that pXRF holds great promise for tropical soil characterization and the development of prediction models, justifying the need for larger-scale studies in tropical countries worldwide.