Concentrated HNO3 Research Articles

Assessment of Some Heavy Metals and Physico-Chemical Parameters of Surface Water of Matara-Uku Wetlands

The study assessed the levels of Nitrogen, Phosphorous and some heavy metals in Matara-Uku wetland. Twenty water samples were collected from surface water of Matara-Uku using polyethene plastic container, the physicochemical parameters of the samples were measured and the samples were analyzed for Nitrogen, Phosphorous and heavy metals. Results from physicochemical analysis are obtained as; pH (7.6 – 8.0), total dissolve solid (70.82 - 84.26 mg/l), electric conductivity (105.0 – 163.0 μs/cm) and temperature (24.4 – 25.4ºC). All the results are in line with World Health Organization standard of 6.5 - 8.5, <600 mg/l, 400 μs/cm and ambient temperature respectively. The Nitrogen and phosphorous were analyzed using UV- Visible spectrophotometer. From the results, it was found that all the samples had Nitrogen level below the World Health Organization maximum contaminant level of 10 mg/L with a mean concentration range (0.2293 ± 0.0057) mg/L to (2.2455 ± 0.0216) mg/L. Phosphorus was also analyzed and the results indicated that all the sampling sites had phosphorus level above the WHO maximum contaminant level of 0.03 mg/L with a mean concentration range (3.8208 ± 0.4109) mg/L to (4.56 ± 0.1325) mg/L. The water samples were digested using concentrated HCl and HNO3, in which the digested samples were used for heavy metals analysis using Atomic Absorption Spectrophotometer (AAS). The mean concentrations of the heavy metals analyzed were between the ranges Pb (0.1272 ± 0.0445) mg/L to (0.2727 ± 0.1285) mg/L, Cd (0.0026 ± 0.0024) mg/L to (0.0053 ± 0.0054) mg/L and Ni (0.0705 ± 0.0235) mg/L to (0.1411 ± 0.0819) mg/L respectively. Concentrations of Cd and Ni are generally below the maximum permissible limit of 0.03 mg/L and 0.02 mg/L, whereas concentrations of Pb exceeded the maximum permissible limit of 0.01 mg/L for surface water. It was concluded that the surface water of Matara-Uku is polluted with respect to Pb, which is known to bio-accumulate and even undergo bio-magnification in organisms such as fishes and even plants with serious health implications to human being.

Surface oxidized/silanized graphite nanoplatelets for reinforcing an epoxy matrix

A simplistic and economical process was employed for the oxidation of graphite nanoplatelets (GNPs) using concentrated HNO3, followed by their surface modification by amine functionalization via silanization with 3-aminopropyltriethoxysilane (APTES). The impact of the oxidation time of the GNPs (varied from 12 h to 72 h) and their surface functionalization was studied with respect to the change in thermo-mechanical and mechanical properties of the GNPs/epoxy nanocomposites. The degree of oxidation and functionalization of the GNPs was characterized using field emission scanning electron microscope (FESEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and thermo-gravimetric analysis (TGA). The optimized oxidation time (60 h) and surface functionalization of the GNPs resulted in the significant improvement in the storage modulus (~176%), glass transition temperature (Tg) (~15 °C), tensile strength (~98.71%) and tensile modulus (~142.66%) of the GNPs/epoxy nanocomposites as compared the to neat epoxy (NE) system. Such tremendous enhancement in the material properties by a facile and economical approach can exhibit an inordinate potential to replace the costly multistep oxidation methods of fabrication of graphene/epoxy nanocomposites at industrial scale.

Pd(II) and Rh(III) Complexes with Isoquinoline Derivatives Induced Mitochondria-Mediated Apoptotic and Autophagic Cell Death in HepG2 Cells

Nonplatinum metal complexes of [Pd(L1)Cl2] (C1), [Rh(L1)Cl3(DMSO)] (C2), [Pd(L2)Cl2] (C3), and [Rh(L3)Cl3(DMSO)] (C4) with isoquinoline derivatives have been prepared and characterized. C1–C4 exhib...

Electrochemical activation and capacitance enhancement of expanded mesocarbon microbeads for high-voltage, symmetric supercapacitors

To increase the specific energy of supercapacitors (SCs), the expanded mesocarbon microbead (EMCMB) is electrochemically activated in 1 M tetraethylammonium tetrafluoroborate in propylene carbonate (TEABF4/PC) to construct a high-voltage but symmetric SC. The EMCMB is successfully made from MCMB through the oxidation in a solution containing concentrated H2SO4, HNO3 and KMnO4 followed by a thermo-expansion treatment at 800°C. This carbon with a specific surface area of only 93.2 m2 g−1 shows excellent capacitive performance after the electrochemical activation process in the highly positive or very negative potential regions in 1 M TEABF4/PC, especially when an aqueous-based binder, KOH-partially-neutralized polyurethane-polyacrylic acid (denoted as PUPAH6K4) was employed. These electrochemically activated EMCMB-PUPAH6K4 electrodes are able to be charged and discharged reversibly in a wide potential range between −2.6 V and 1.4 V (vs. Ag/AgNO3). Consequently, a 4V SC consisting of two identical EMCMB-coated electrodes, i.e., symmetric, with good capacitive performances in 1 M TEABF4/PC has been successfully demonstrated, showing the great application potential in the advanced high-voltage SCs.

On the stability of the passive Ti-6Al-4V film of friction stir welds with stainless steel: Effect of not native metal species

Mechanical and microstructural characteristics of Ti-6Al-4V/stainless steel (SS) dissimilar friction stir welds have been well described in the literature; however, little is known about the electrochemical properties of such welds in terms of the passive film stability of TiO2 grown in oxidizing media. To clarify this issue, potentiodynamic polarization, cyclic voltammetry, and electrochemical impedance measurements were carried out in the Ti-6Al-4V alloy to analyze the effects of Fe and Cr contamination from the underlying SS on the passive film stability of TiO2 in concentrated (6.0 and 11.5 mol L–1) HNO3 solutions. Lower transpassive potentials were observed for samples in the stirred zone (SZ) than those of the base metal (BM) due to Fe and Cr contamination. Anodic charges obtained during cyclic voltammetry using 6.0 mol L–1 HNO3 showed that the grown passive film was completely dissolved and regrown after consecutive scans, except for the BM sample. According to the results of X-ray photoelectron spectroscopy (XPS) analyses an Al depleted layer was obtained for the latter condition, which confirms the stability of TiO2 film. The increasing values of charge transfer resistance obtained through electrochemical impedance measurements at distinct potentials in the passive region also supported the stability of the TiO2 film grown in 6.0 mol L–1 HNO3 solution. The formation of a medium frequency inductive loop and low frequency constant phase element are related to the dissolution of the oxide film and adsorption of NO3 species into the formed passive film, respectively, as evidenced by XPS analyses.

Comparison of Wet Destruction, Dry Ashing, and Acid Homogenic Methods In Determining Na And K in Beef and Chicken Using Flame Photometer

This research was purposed to compare the yield of destruction method in determining sodium (Na) and potassium (K) content in beef and chicken by using flame photometer. The destruction methods used they are wet destruction, dry ashing, and acid homogenic method. In acid homogenic method two types of acid are used as solvents are HCl and HNO3 with concentration variation of 0.5 M; 1 M; and 1.5 M. While the wet destruction method uses a mixture of concentrated HNO3 and HClO4 (1: 2) and the dry ashing method uses only HNO3. The highest Na content obtained from the three methods after being analyzed by Analysis of Variance (ANOVA) and the Smallest Significant Difference (SSD) test was found in the dry ashing method that is 86.33 mg Na in beef, when compare with the literature is around 64 – 69 mg. While the highest K content was found in acid homogenic method using HCl solvent is 618.77 mg K in beef, when compare with the literature is around 334 – 355 mg.

Facile electrochemical synthesis of Ni(OH)2/MoSx catalyst on oxidized carbon fiber for efficient alkaline hydrogen evolution reaction

The efficient electrochemical hydrogen evolution reaction in alkaline media through the use of earth-abundant catalysts has received significant attention, as it is a crucial means for sustainable H2 production. Here, we present a facile synthesis approach for Ni(OH)2/MoSx (MoSx: amorphous molybdenum sulfide) catalyst on oxidized carbon fiber support. Carbon fibers are first oxidized by a hydrothermal treatment in a concentrated HNO3 solution, while Ni(OH)2 and MoSx films are consecutively deposited onto the substrate through simple electro-deposition methods from their plating solutions. Benefiting from the hydrophilicity of the oxidized carbon fiber, the abundant electrochemically reactive sites and the synergistic effect between Ni(OH)2 and MoSx, this hybrid catalyst shows a low HER onset potential of 80 mV at 1 mA/cm2, an overpotential of 180 mV at 10 mA/cm2 and a remarkable stability of at least 35 working hours at a H2-evolving current density of 10 mA/cm2 without any obvious overpotential changes.

Stabilization of Plutonium(V) Within a Crown Ether Inclusion Complex

Crystalline coordination complexes of actinides, especially in atypical oxidation states, are not only fundamentally important for expanding the notably limited knowledge on the bonding nature of a...

Nanostructured NiMoS₂/Carbon Catalysts for Syngas Conversion to Higher Alcohols.

Syngas conversion to higher alcohols remains a very attractive alternative due to the abundance of syngas feedstock, such as renewable carbon and waste-carbon resources. Catalysts suitable for syngas conversion still show low selectivity to alcohols. In this article, we present nanostructured NiMoS₂ and CoMoS₂ catalysts supported on activated carbon pellets and design strategies to improve its selectivity towards higher alcohols. Activated carbon pellets were treated with concentrated HNO₃ to enlarge porous channels and enable better dispersion of NiMoS₂ and CoMoS₂. These treatment steps lead to a formation of nanostructured NiMoS₂ and CoMoS₂ catalysts and promoted higher selectivity to ethanol, propanol and butanol. BET surface area of 532 m² g-1 was obtained for NiMoS₂/Carbon catalysts from the nitrogen physisorption analysis. In catalytic tests, the highest CO conversion (39.1%) was achieved by the NiMoS₂/Carbon, whereas the CoMoS₂/Carbon showed the highest alcohol selectivity (74.4%). CoMoS₂ catalysts supported on activated carbon pellets proved to be highly active towards undesired by-product "filamentous carbon."

Determination of Cadmium (Cd) Metal Content in Milkfish at Port of Tanjung Mas

The location of milkfish ponds around the Port of Tanjung Mas is adjacent to an industrial area. This can increase the possibilities of milkfish being contaminated by heavy metals, for example Cadmium (Cd) metal. Therefore it is necessary to determine the levels of Cadmium metal in milkfish that are cultivated in ponds around the Port of Tanjung Mas. The aims of this study is to find out the levels of Cadmium metal in milkfish samples at the Port of Tanjung Mas whether or nor it exceeds the threshold. The method commonly used for metal analysis is the Atomic Absorption Spectrophotometry (AAS) method, because this method is simple, selective and sensitive for analyzing metal content in a sample of animal origin, such as milkfish. In the initial treatment, milkfish samples were separated between meat and bones. The milkfish was then dried by heating at 150oC for 1 hour and continuing with ashes up to 550oC. The ash-shaped sample was dissolved in concentrated HNO3 and diluted with aquabidest. The aqueous sample solution was analyzed using ASS at a wavelength of 228 nm to determine the metal content of Cd in the sample. The level of Cd metal in milkfish samples analyzed using ASS, showed that it was still in accordance with the quality standard, which was below the threshold set in SNI No. 7387: 2009. Samples of milkfish taken from several pond locations showed that the farther pond was from the industrial area, the less Cd metal pollution in milkfish in the pond area.

One-pot nitrodebromination and methyl bi-functionalization of 5-bromo 6-methylpyrimidines: a unique simultaneous transformation

A unique one-pot, simultaneous nitrodebromination and methyl bromonitration occurred upon treatment of 5-bromo-2,4-di-tert-amino-6-methylpyrimidine derivatives with a cold mixture of concentrated H2SO4–HNO3 in moderate yields. It is actually a facile and rapid transformation that has been reported neither on pyrimidines nor simultaneously on other organic compounds.

Application of an Augmentation Method to MCR-ALS Analysis for XAFS and Raman Data Matrices in the Structural Change of Isopolymolybdates.

We measured X-ray absorption fine structure (XAFS) and Raman spectra of isopolymolybdates(VI) in highly concentrated HNO3 solution (0.15 - 4.0 M), which change their geometries depending on the acid concentration, and performed the simultaneous resolution of the XAFS and Raman data using a multivariate curve resolution by alternating least-squares (MCR-ALS) analysis. In iterative ALS optimization, initial data matrices were prepared by two different methods. For low sensitivity of the XAFS spectra to the geometrical change of the isopolymolybdates, the MCR-ALS result of single XAFS data matrix shows a large dependence on the preparation method of the initial data matrices. This problem is improved by the simultaneous resolution of the XAFS and Raman data: the MCR-ALS result of an augmented matrix of these data has little dependence on the initial data matrices. This indicates that the augmentation method effectively improves the rotation ambiguities in the MCR-ALS analysis of the XAFS data.

Comparative Study of Cu(II) Adsorption by As-prepared and Oxidized Multi-walled N-Doped Carbon Nanotubes

The laws and mechanisms of adsorption of Cu(II) ions by well characterized and oxidized N‑doped multi-walled carbon nanotubes (N-CNTs) are discussed. The samples were synthesized by catalytic chemical vapour deposition method using n-butylamine as a carbon source and their surface was functionalized by oxidation with mixture of concentrated H2SO4 and HNO3. The morphology, chemistry and charge of surface groups were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and micro-electrophoresis methods. It has been shown that: adsorption of Cu(II) reached equilibrium value within 60 min; the degree of extraction of these ions from the solution increased with its dilution; adsorption resulted in a moderate decrease in the suspension pH for as-prepared N-CNTs (1.5 pH unit) and its considerable lowering for the oxidized sample (up to 2.5 pH unit); the adsorption isotherms can be described by the Langmuir model and the plateau amounts of adsorption (28–35 mg/g) were almost the same for both as-prepared and oxidized samples; at pH 6.5 and higher a sharp increase in adsorption was observed which was attributed to hydroxides precipitation. The spectroscopic, adsorption, electrophoretic and pH measurements data showed that below pH of hydroxide precipitation, the major mechanism of adsorption by as-prepared N-CNTs is the donor-acceptor interaction between the free electron pair of N atoms incorporated into nanotubes lattice and vacant d orbital of the adsorbing Cu(II) ions. For the oxidized N-CNTs ion-exchange processes with a release of H+ ions play also a role.

The Use of Silica Extracted from Kaolin as Catalyst Support for Esterification of 4-Hydroxybenzoic Acid with Sucrose

SiO2 was extracted from kaolin using concentrated HCl and HNO3 mixture and used as solid support for both Bronsted (HClO4 and H2SO4) and Lewis Acid (AlCl3 and ZnCl2). Before extraction, kaolin was calcined at 800°C for eight hours to form metastable kaolin. After the extraction procedure, silica was recovered in 51.6% yield. Silica and the resulting solid acids were then characterized using XRD, XRF, and FTIR. XRD pattern shows that silica synthesized from kaolin is in the mixture of amorphous and α-quartz silica. Immobilization of acids alters its structure becomes more crystalline. XRF analysis shows that the loading of AlCl3 and ZnCl2 was 9.5 and 24.8%, respectively. The acid catalysts were then used in the esterification reaction of 4-hydroxybenzoic acid with sucrose. The reactions were conducted in dimethyl sulfoxide (DMSO) solvent by varying reaction time and reaction temperature. The highest conversion of starting materials and selectivity towards ester was obtained over the AlCl3/SiO2 catalyst. DPPH radical scavenging test shows that the ester exhibits good antioxidant activity.

Effect of inoculation on the content of biogenic elements in the white lupine and grass pea

The aim of this work was to determine the influence of the inoculant on the content of biogenic elements in tenoreign varieties of white lupine (Lupinus albus) and threearieties of grass pea (Lathyrus sativus L.) of Slovak origin. Rizobine was used as the inoculum before sowing. Dried and homogenised seed samples were mineralised using concentrated HNO3 using the MARS X - Press 5 instrument. Analytical determination of macro- and microelements in all samples was performed using ARIAN DUO 240FS/240Z atomic absorption spectrometer. The determined values of biogenic elements content were expressed as mg.kg-1 of dry matter. The average content of Cu was lower for both crops in variant A compared to variant B. The addition of the inoculant increased the content of Cu in both crops in lupine by 3.7% and grass pea by 10.94%. The Zn content of variant A in lupine was 19.14% higher than that of the grass pea. Grass pea seeds contained 97.76% less Mn than white lupine seeds in both variants. The Cr content of white lupine was 67.74% higher in variant A than in grass pea. The inoculant also increased the content of Cr in lupine by 25.0%. Lupine contained 30.02% less Fe in variant A and 41.27% less Fe in variant B than the grass pea. The results we have obtained show that Ca, K, and P are the predominant elements in the seeds of grass pea in both variants. By comparing selected types of legumes we found that the grass pea features a higher content of Cu, Fe, K, and P. The analysed seeds of white lupine had a higher content of Zn, Mn, Cr, Ni, Co, Na, Ca, and Mg. In conclusion, inoculation does not significantly affect the content of biogenic elements of selected legume species.

Ultrasensitive and Multi-Functional Rapid Screening Plasmonic Ag-Based SERS Substrate

Motivation The complex interpretation of the cause for some diseases and the lack of specificity in clinical manifestations lead to the difficulty in making early diagnosis and treatment. So far, several analytical methods, including radiation immunoassay (RIA), fluorescence immunoassay (FIA)[1] and enzyme-linked immunoassay (ELISA) [2], have been widely applied in the field of biomedical research. However, the above-mentioned techniques still suffer some disadvantages. For example, these immunoassay take at least 4~6 hours to complete the incubation and detection process. Also, attenuation of the fluorescence signal-to-noise ratio is low which may cause inaccurate detection easily. [3]As a consequence, it is necessary to develop a new and effective method to obtain the ‘3S’ goal, which are the sensitive, specific and speedy detection of biomarkers. Introduction With the mentioned motivations in mind, a plasmonic Ag-based SERS substrate is proposed to implement the ultrasensitive detection of biomarkers while cardiac troponin I (cTnI), which is the most reliable biomarker for cardiovascular disease (CVD), is chosen as the analyte in this work. The proposed substrate is mainly composed of silicon nanowires array decorated with silver nanoparticles. By exploiting this substrate, the appropriate length and interspace of silicon nanowires may offer a high surface-to-volume ratio for wider area of detection. On the other hand, the silver nanoparticles can contribute localized surface plasmon resonance (LSPR) for SERS enhancement as well. The superiority of this substrate includes (1) facile fabrication, (2) low detection limit, (3) wide linear range of concentration (4) time-saving and (5) label-free detection. Apart from this, the cost of this SERS substrate is very low while it can achieve multiple and repeated measurements by one sampling, hence shows great potential for practical application in clinical diagnosis. Experimental Procedures To begin with, the silicon nanowires scaffold was fabricated by metal-assisted chemical etching (MaCE) procedure. As shown in Fig. 1, after the first absorption of silver nanoparticles on a cleaned silicon substrate, it was then being immersed into a HF/H2O2 solution for etching. Next, the residual silver nanoparticles were removed by concentrated HNO3 solution and then immersed the prepared substrate into a KOH/IPA solution to enlarge the interspace between silicon nanowires. Finally, silver nanoparticles were deposited on the silicon nanowires by electroless metal deposition (EMD). After applying 5 mL of different concentrations of cTnI on each fabricated substrate by using pipette, a Confocal Micro-Raman Spectroscopy equipped with 633nm laser source and 17 mW of power was utilized to excite the SERS substrates, while the spectra were collected in the continuous mode with the integration time of 10 s. Results and Conclusions The morphology of silver nanoparticles deposited on silicon nanowires with different KOH etching time were characterized by scanning electron microscopy (SEM). As shown in Fig. 2, silicon nanowires are free-standing on the substrate with silver nanoparticles distribute uniformly on the tips, while the interspaces of the silicon nanowires are significantly enlarged after the KOH etching. To startup, a preliminary Raman measurement of 1.616 ppb cTnI was obtained and consistent to the referred Raman spectrum as shown in Fig. 3 [4]. By eliminating the overlapped signals from silicon on 520 cm-1 and 900 cm-1, the more significant characteristic peaks of cTnI which located at around 1300 cm-1 and 1600 cm-1 are mainly considered for further analysis. Also, taking into account the discrepancy in the state of focus and power for each measurement, every Raman spectrum was normalized by the intensity of the silicon peak at 520.6 cm-1. Fig. 4 shows the Raman results of substrates with different KOH etching time for three different concentrations of cTnI, while all of the results show that the one with 1 min KOH etching gives the most enhancement. Furthermore, Fig. 5 shows both the Raman spectra of blank substrate that without applying any analyte and that of cTnI with different concentrations from 0.012 ppb to 1.616 ppb. Herein, a clean background signal was successfully obtained for the blank substrate, demonstrating that the proposed substrate might be applicable for not only cTnI but also other chemical molecules such as food additives and drug. Importantly, the plot for the concentration-dependent SERS intensity of the peaks at 1300 cm-1 and 1600 cm-1 (Fig. 6) show that, both of them obey a good linear relationship, with R2=0.93368 and R2=0.91904 respectively. These experiment results demonstrate that the proposed strategy displays high detection sensitivity for cTnI up to 0.012 ppb in a wide and linear detection range from 0.012 ppb to 1.616 ppb, which exhibits the potential to perform quantitative analysis. Meanwhile, the specificity of the analyte is also verified by the unique Raman fingerprint of cTnI, which presents the superior ability to neglect the complex incubation process needed in many immunoassay methods.

Electrochemiluminescence revealing that HNO3-oxidized single-walled carbon nanotubes are essentially tubular graphene quantum dot-nanoassemblies

Graphene quantum dots (GQDs) as recently emerging 0-D graphitic nanomaterials, have attracted much attention due to their unique optical, electrical and catalytic properties. However, some properties of GQDs, such as very small size, low density, and excellent water-solubility, make it difficult to be separated and immobilized. This may limit the recycle and purification of GQDs, and thus their applications in catalysis and sensing. In this work, we prepared tubular GQD-nanoassemblies (t-GQD-NAs) by etching single-walled carbon nanotubes (SWCNTs) with concentrated HNO3. The synthesized t-GQD-NAs were characterized by TEM, SEM, XPS, Raman spectroscopy and electrochemiluminescence (ECL) in details. t-GQD-NAs were much shorter and slimmer in morphology, bore more oxygen-containing groups, and had a higher surface defect density compared with SWCNTs. t-GQD-NAs not only maintained good UV absorption property of SWCNTs but also showed strong infrared ECL emission and broad ECL spectrum, verifying that t-GQD-NAs were assembled from GQDs of various sizes and some graphene nanoribbons. This is for the first time that 0-D GQDs were reported to be assembled into 1-D tubular carbon structures. The t-GQD-NAs with abundant surface states and good ECL activity could be easily separated, purified, and immobilized, suggesting their promising applications in ECL sensing and catalysis.

Synergetic electrochemical HNO3 reduction on the activated-CFP supported nano-Pt electrodes

The electrochemical activated-CFP supported nano-Pt electrode was designed for degrading concentrated HNO3. The influence of pre-thermal treatment of the activated-CFP on the electrodeposition of Pt was investigated, indicating that the decrease in surface oxygen content is beneficial to the electrodeposition of Pt nanoparticles. The nano-Pt/activated-CFP was directly used as a highly reactive electrode for electroreduction of HNO3, showing a high current density for the formation of ammonia ions. This study will provide a possibility for the electrochemical treatment of concentrated HNO3 with the formation of low- and non-toxic byproducts.

Carbon‐Microcuboid‐Supported Phosphorus‐Coordinated Single Atomic Copper with Ultrahigh Content and Its Abnormal Modification to Na Storage Behaviors

AbstractCarbon‐supported single atomic metals (SAMs) have aroused great interest in energy conversion and storage fields. However, metal content has to date, been far below expectation. Additionally, theoretical calculations show that SAMs are superb anchoring sites for alkali metal‐ion storage, but the experimental research remains untouched. Herein, a metal–organophosphine framework derived strategy is proposed to prepare carbon microcuboids‐supported single atomic Cu with a high content of 26.3 wt%. Atomic Cu is stabilized mainly by P moieties, exhibiting robust stability even in concentrated HCl and HNO3. Interestingly, experimental investigations and first‐principle calculations indicate that Cu atoms can alter the Na storage behavior and enable Na to maintain an ionic state at a fully discharging state for sodium‐ion batteries, which may be a new pathway to mitigate safety concerns of dendrite formation. The Cu atoms also enhance electron transfer and diffusion kinetics. As a result, the carbon cuboids can deliver a high capacity of 107.7 mAh g−1 at 5 A g−1 and show a long life of 1000 cycles for Na storage. This strategy offers a new possibility for fabricating high‐content P‐coordinated atomic metals for energy conversion and storage.

Evaluation of Zn- and Fe- rich organic coatings for corrosion protection and condensation performance on waste heat recovery surfaces

Abstract The corrosion protection performance of commercial organic coatings over Stainless Steel (304 L) was investigated in highly acidic media. Three coatings were applied by air spraying and subsequently evaluated for their performance against chemical corrosion by concentrated H2SO4, HNO3, and HCl in terms of % mass loss. Open current potential (OCP) and potentiodynamic polarization (PD) measurements were performed. The water condensation properties of the coatings were monitored for their evaluation as potential protective coatings in condensing economizer applications. ZN691 coating exhibited better protection than ANORZINC and TROPIS versus time in contact with 40% of H2SO4, HNO3 and 37% HCl. Electrochemical results confirmed the superior performance of ZN691 over ANORZINC and TROPIS with corrosion rates at 0.017, 0.098 and 0.097 mpy respectively. Condensation experiments for ZN691 showed a water collection rate of 1.487 ml m−2 h−1 at 40 °C and 100% RH. According to the results, the Zn rich epoxy-based coatings are promising for corrosion protection of condensing economizer elements.