Quantity Of Fe2 Research Articles

Anti-corrosion and flame-retardant properties of environmentally benign smart functionalized WS2/rGO in epoxy coatings for enhanced steel structural protection in natural seawater

The epoxy matrix (EP) was filled with the rGO-APOD/WS2 nanofiller that was generated through mixing the surface-modified WS2 with reduced graphene oxide (rGO) and 2-amino-5-(4-aminophenyl)− 1, 3-oxadiazole (APOD). The effectiveness of epoxy coating on mild steel as a barrier against various concentrations of rGO-APOD/WS2 in naturally occurring seawater was assessed using EIS, SECM, and salt spray tests. In order to achieve the best coating performance, it was found that the optimal weight ratio of rGO-APOD/WS2 in the EP matrix was 0.3. The limiting oxygen index (LOI) test showed that the rGO-APOD/WS2 considerably enhanced the flame retardancy properties of the epoxy coating. In comparison to pure epoxy coating, the EP-rGO/APOD-WS2 demonstrated better flame retardancy with considerable reductions in the values of PHRR and THR, i.e., 81% and 70%, respectively. It was discovered that the coating resistance of EP-rGO/APOD-WS2 was much higher (Rcoat: 9.89E10 kΩ.cm2) than that of pure matrix (1.49E5 kΩ.cm2) after being exposed to natural seawater for one hour. The EIS experiments showed that the EP-rGO/APOD-WS2 nanocomposite had increased coating resilience even after 200 h of submersion in seawater. Because the coated substrate is more resistant to anodic dissipation than the uncoated substrate, SECM investigations showed that the least quantity of Fe2+ ions discharged at the scratch of the EP-rGO/APOD-WS2 coating. WS2 was found in rusted parts, producing an excellent inert layer at the surface, according to FE-SEM/EDX investigation. The newly created EP-rGO/APOD-WS2 composite has higher barrier and hydrophobic characteristics, according to the results (WCA:162°). The epoxy matrix's mechanical properties were enhanced by the addition of rGO/APOD-WS2. It was discussed how graphene-based polymer nanocomposites might prevent corrosion. As a result, an industrial coating made of the EP-rGO/APOD-WS2 nanocomposite may be used.

Enriching Trace Level Adsorption Affinity of As3+ Ion Using Hydrothermally Synthesized Iron-Doped Hydroxyapatite Nanorods

Contamination of arsenic in the form of arsenite (As3+) and arsenate (As5+) in potable water causes serious illness in the human body even at a very low concentration (10 µg/L). As3+ is comparatively 60 times more toxic than As5+ species. This work is focused on the preparation of adsorbents for efficient removal of As3+ with higher adsorption affinity at trace level (≤ 50 µg/L). The iron-doped hydroxyapatite (Fe-HAp) synthesized by hydrothermal technique is employed as an efficient adsorbent. A significantly less quantity of Fe2+ ion (0.5 wt%) is incorporated in the tetrahedral and octahedral sites of the HAp lattice along the c-axis, which leads to a drastic reduction in particle size (400% in length and 225% in width) and enhances the specific surface area (105%), colloidal stability, and adsorption affinity. The maximum adsorption capacity of As3+ is 139 ± 2 µg/g and 183 ± 2 µg/g for HAp and Fe-HAp, respectively. The adsorption rate of Fe-HAp is very rapid, which is 538% higher than HAp. Also, the As3+ adsorption affinity or sensitivity (0.71 µg/L) significantly improved 83–99% when compared to the adsorbents reported in the previous literature. The adsorption capacity of As3+ ion was unaffected by other competing ions and obtained 97% recycling efficiency up to 7 cycles using Fe-HAp. The monolayer adsorption of As3+ is purely strong chemisorption as confirmed by the Langmuir and Dubinin–Radushkevich (DKR) isotherm. The structure and morphology of HAp and Fe-HAp remain unchanged after the adsorption of As3+ ions and also no secondary toxic products were observed. Hence, the above results reveal Fe-HAp as an efficient and low-cost adsorbent for the removal of highly toxic As3+ ions at the trace level.Graphic Abstract

Catalytic hydrolysis of HCN over Fe–Ti-O catalysts prepared by different calcination temperatures: Effect of Fe chemical valence and Ti phase

Abstract A series of Fe–Ti-Ox catalysts calcined at different temperatures (signed as Fe–Ti-x, and x symbolized the calcination temperature of 300, 400, 500, 600 and 700 °C, respectively) were prepared and studied for the catalytic hydrolysis of HCN in the presence of H2O. The results implied that Fe–Ti-4 (the calcination temperature was 400 °C) showed the best catalytic hydrolysis efficiency of HCN and the abundant productions (CO and NH3). With the calcination temperature increasing, the catalytic hydrolysis of HCN activity decreased dramatically, which was related to the reduction of specific surface areas and redox property, the formation of rutile TiO2 and decline in quantity of Fe2+ species. Besides, Fe–Ti-Ox catalysts with amorphous states of TiO2 could enhance catalytic hydrolysis of HCN, which depended on the effect of calcination temperature during the preparation process of Fe–Ti-Ox catalysts.

An activated carbon fiber-supported graphite carbon nitride for effective electro-Fenton process

Advanced oxidation processes based on the electro-Fenton process are alternative technologies for water and wastewater remediation. In the present work, an activated carbon fiber-supported graphite carbon nitride (g-C3N4/ACF) was prepared by a wet impregnation method, followed by calcination. The results from scanning electron microscopy and X-ray photoelectron spectroscopy demonstrated that the g-C3N4 was successfully supported on the surface of the ACF, leading to a slight decrease in the Brunauer-Emmett-Teller surface area. In the presence of externally added Fe2+ to the electrolyte, the g-C3N4/ACF used as a cathode exhibited a relatively higher activity in the electrochemical degradation of aqueous rhodamine B (RhB) compared to the ACF cathode. The effect of several experimental conditions, such as initial pH, current density, the quantity of Fe2+ added, and the loading amounts of g-C3N4, on the removal of total organic carbon was explored. In the range investigated, the mineralization of RhB had the most rapid progression, with an initial pH of 3.0, current density of 3.0 mA cm−2, initial Fe2+ concentration of 0.25 mM and g-C3N4 load of 0.03 g. The removal efficiency of total organic carbon was ∼91% after 240 min of electrolysis. In addition, the g-C3N4/ACF electrode was stable as evidenced by five successive cyclic tests. On the basis of quantitative measurements of iron (zero-valent iron, ferrous ion, and ferric ion) and qualitative determination of hydroxyl radicals, and with the help of electrochemical characterization in the form of linear sweep voltammetry, cyclic voltammetry and chronoamperometry, it could be concluded that the RhB mineralization proceeded via a surface process. The supported g-C3N4 facilitated the electro-generation and adsorption of H2O2, as well as the regeneration of ferrous ions from surface-adsorbed ferric ions.

Mössbauer Spectroscopic and Chromaticity Analysis on the Colourative Mechanism of Ancient Goryeo Celadon from GangJin and Buan

In ancient Goryeo celadon excavated from the kiln sites in the GangJin and Buan areas, the effect of the chemical composition and ionic state of Fe on the colour was evaluated by Mössbauer spectroscopy and chromaticity analysis. According to chromaticity analysis, the L* value (brightness) of the glaze was shown to be affected more by TiO2 and MnO than by Fe2O3, and the body was affected more by Fe2O3 than by TiO2. The a* value was found to be affected by Fe2O3 and TiO2 in the glaze, whereas there was hardly any change in the body according to the composition. As for the b* value, changes due to the composition were shown to be smaller than those for the L* and a* values. According to the Mössbauer spectroscopy results, as the quantities of TiO2 and Fe2O3 are increased, Fe2+/Fe3+ decreases; while the changes in Fe2+/Fe3+ with MnO and P2O5 are negligible. As the quantity of Fe2+/Fe3+ increases, the a* and b* values decrease, which results in the change of colour from red–yellow to blue–green. The characteristic green colour can be attributed to increased L* (brightness) and decreased a* and b* values (blue–green shift) due to the reduced Fe ion, which is mainly determined by the TiO2 and Fe2O3 contents.

Effects of the Electrode Arrangements on Reductive Dechlorination of Trichloroethylene in an Electro-Enhanced Iron Wall

This study examined the factors that influence the reductive dechlorination of trichloroethylene (TCE) when direct current is externally supplied to a laboratory scale iron wall. Experimental results indicated that an anode electrode was placed in contact with the iron filling near the inlet of the column, and then a cathode was located on the top of the column. Excellent TCE degradation efficiency was displayed. The surface of the iron particles was acid-washed by H+, owing to water oxidation around the anode, and large quantities of Fe2+ were produced as a reductant which enhanced the TCE degradation, due to iron corrosion caused by the supply of external electrons. The cathode should be placed in sand fill atop the iron filling in order to avoid the formation of iron (hydr) oxide precipitates on the surface of the iron particles when the pH increases as a result of the release of OH- around the cathode. Due to more H+ being released, which benefited the acid-washing of the iron filling, the TCE removal efficiency increased from 32% to 100% when the electric potential increased to 60V. However, black precipitates of iron (hydr) oxide were observed coated on the iron surface, causing the blocking of pores in the iron wall with the increase in the electric potential application. The efficiency of TCE degradation was almost equal regardless of groundwater velocity when direct current was applied to the iron wall. Based on observations of TCE degradation during long-term operations, the TCE removal efficiency in the effluent reached 100% after seven days of operation and maintained this high level after 25 days of operation. Thus, iron wall by electroremediation displayed excellent potential for development in long-term operations.

Ｍｇ‐Ｚｎ系フェライトの色と磁性に関して

The effect of synthetic condition on the colour and magnetization of MG-Zn ferrite powders has been investigated.The colour of the ferrite (S-1), which was prepared by heating for 3 hrs at 1200°C in air, cooling slowly to room temperature and re-heating for 6 hrs at 800°C, shows reddish, while the colour of the ferrite (S-2), which was prepared by quenching from 1200°C after firing, is dark brown.The value of maganetization for S-2 was larger than that for the other heat treatment. It has been also confirmed that the quantity of Fe2+ ion is closely correlated to the colour and magnetization of the Mg-Zn ferrite.

Faraday Rotation of Co-Ferrite Thin Films Prepared by Single Source Evaporation

Fe-Co alloy film was oxidized to produce a transparent cobalt ferrite film. The amount of Faraday rotation was measured as a function of the quantity of Fe2+, which was increased and decreased by reduction and oxidation. In the film reduced to increase the amount of Fe2+, the Faraday rotation curve becomes positive. The absorption coefficient increases with increase in Fe2+. When the film is oxidized at 600°C, the Faraday rotation curve becomes negative again and the absorption coefficient decreases.

The kinetics of crystal growth in an aluminosilicate glass containing small amounts of transition-metal ions

SummaryQuantitative data are presented for the kinetics of crystal growth in an aluminosilicate glass to which a few wt % of a transition-metal oxide had been added. The composition of the base glass was CaO 3o, MgO 2, Al2O3 15, SiO2 53 wt %, to which the oxides of iron, vanadium, chromium, or zinc were added. Glasses were prepared with a range of high to low valency ratios in cases where the transition metal oxide could exist in two or more oxidation states.Small quantities of Fe2+, Fe3+, Zn2+, V3+, V4+, and V5+ were all found to increase the kinetics of crystal growth from the glass phase. The magnitude of the effect is compared with additions of Mg2+ to the glass. Cr2+, Cr3+, and Cr6+ were found to decrease the rates of crystal growth. Values for the apparent activation energy for crystal growth ranged from ∼50 kcal/mole to ∼150 kcal/mole. The high values were found to be of the same order of magnitude as that for the activation energy for viscous flow in the glass at the crystallization temperature.The results are interpreted in terms of the structure of the glasses and current theories on the rate of crystallization of glasses.