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Ultra-high molecular weight polyethylene (UHMWPE) fibers were modified by chromic acid. The effects of surface modification were evaluated with Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electron microscope (SEM). The results showed that both the content of O-containing functional groups and surface roughness of modified fibers increased. The polar groups on the modified fiber surface decreased the contact angles with water and ethylene glycol, as evidenced by contact angle measurement. The tensile test results showed the strength and the elongation at break of UHMWPE fibers decreased but the modulus increased after chromic acid modification. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the present paper, new H 2 S gasochromic nanomaterial of mixed silver nickel ammonium phosphomolybdate synthesized by microwave assisted technique is reported. The microwave treatment was performed in the solid phase using urea and ammonium nitrate as the promoter and oxidizer agents. The designed process allows rapid synthesis of large amounts of this product in nanosized particulate morphology. Morphological and structural features of the prepared products were studied in detail. Chemical analyses indicated a stoichiometry of (NH 4 ) 0.5 Ni 0.75 AgPMo 12 O 40 ·4H 2 O revealing a Keggin-type framework with substitution of silver and nickel cations in its secondary structure. A home-made set-up was used to test gasochromic effect via monitoring light intensity variations passing through the samples based on their color change during exposure to different H 2 S gas concentrations. Response in coloration was obtained about 12% to 61.8% for concentrations from 8.5 to 100 mg L −1 . It is suggested that the presence of Ag and Ni ions (especially silver as counter cations) in the secondary structure of a Keggin ion plays an important role in the coloration effect of the substituted phosphomolybdate compared with the un-substituted one. In fact, color centers can be originated from the interaction of these cations of the phophomolybdate network with thiol functional group of H 2 S molecules. [ABSTRACT FROM AUTHOR]

Traditionally, a highly concentrated mixed solution of chromic acid and sulphuric acid has been used as an etchant for electroplating on ABS plastics. However, this etchant is hazardous and the subject of impending legislation. Therefore, the fine-bubbles low ozonated water treatment as an alternative to the chromic acid etching process has been investigated. Adhesion strengths of 0.9–1.0 kN m−1were obtained for treatment of 30 min. From the observation of surface morphology, dimples of several hundred nanometres were formed after surface modification. Cross-sectional observation of the interface suggested that formation of a thin nano-porous anchor layer on the ABS surface was responsible for plating adhesion. This method with low ozonated water treatment provides an environmentally friendly process for plating on ABS. [ABSTRACT FROM PUBLISHER]

A number of electromembrane processes used for the regeneration and purification of chromium plating electrolytes based on chromic acid and its recovery from the rinse water have been described, as well as the solution to the problem of stabilization of the chemical composition of the chromium plating electrolytes based on trivalent chromium salts using the electromembrane method. [ABSTRACT FROM AUTHOR]

Chromic acid anodizing has been used for almost a century to enhance corrosion protection of aerospace alloys. For some applications, hydrothermal sealing in hexavalent chromium-containing solution is required to enhance further the corrosion resistance but, due to environmental concerns, the use of hexavalent chromium must be discontinued. Good progress has been made to replace chromates during anodizing but comparatively less effort has focused on the sealing process. In this work, for the first time, electrochemical impedance spectroscopy (EIS) has been used to characterize in-situ the sealing processes occurring during hot water sealing, sodium chromate sealing and cerium sealing. The results suggest that the processes occurring during sodium chromate sealing are significantly different compared to hot water and cerium sealing. In particular, during chromate sealing, the porous skeleton is significantly attacked, suggesting that the anticorrosion performance is likely to arise from the residuals of chromate rather than from the improvement of the barrier properties. In contrast, during hot water sealing, little attack occurs on the porous skeleton, and the improved corrosion protection is due to the enhanced barrier effect. During cerium sealing, precipitation of cerium products occurs, providing an inhibitor reservoir, and little, if any, attack occurs on the pre-existing oxide. [ABSTRACT FROM AUTHOR]

The structural properties of neutral (CrO 3 ) 3 cluster and its ability to oxidise nitric oxide have been studied by employing exchange correlation functionals defined within the formalism of DFT in conjunction with 6-311+G(d)/effective core potentials basis set. The terminal oxygen atom of the Cr 3 O 9 cluster oxidises NO to NO 2 and reduces to one of the local isomer of Cr 3 O 8 . The Cr 3 O 8 cluster oxidises the second NO molecule again through one of its terminal oxygen atom and forms Cr 3 O 7 cluster. While the addition of next NO molecule to Cr 3 O 7 cluster results in its oxidation to NO 2 , resulting the Cr 3 O 6 cluster does not react further with NO. The reaction route has been investigated through IRC calculations, change in bond lengths, MEP surfaces, frontier molecular orbital analysis and change in free energy. Considering the fact that Cr 3 O 8 and Cr 3 O 7 clusters formed in the oxidation process are local minima isomers, their global minimum geometries have also been optimized to investigate the reactivity of global isomers of Cr 3 O 8 and Cr 3 O 7 clusters with NO. [ABSTRACT FROM AUTHOR]

The aerospace industry progressively develops alternatives for chromic acid anodizing, because Cr(VI) is known to be toxic and carcinogenic. In this work, potentiodynamic anodizing of AA1050 and AA2024-T3 clad was performed in phosphoric-sulfuric acid (PSA) and sulfuric acid (SAA). All anodizing cycles startedwith a linear voltage sweep, followed by a constant voltage, or a dynamic voltage. Current density responses were recorded during each anodizing cycle and comprised different stages, which could be related to growth phases of the anodic oxide film. Interesting differences were found between cycles with an intermediate increase in anodizing voltage versus cycles with an intermediate decrease in voltage. Cycles including an increase in voltage resulted in higher anodic oxide formation efficiencies because of a temporary exceedance of the steady state current (recovery period) directly after the voltage step. Also, a sudden decrease in voltage led to distinct border between a fine and coarse region in the filmmorphology, while a sudden increase in voltage did not. For prolonged anodizing in PSA, coarsening of the upper film part was observed because of the high solubility of Al2O3 in phosphoric acid. Pore walls close to the outer surface did not only get thinner, but completely dissolved in the electrolyte. Consequently, anodic oxide formation efficiencies were higher for SAA than for PSA. [ABSTRACT FROM AUTHOR]

In the transition to environmentally friendly production, chromic acid anodizing is being replaced by sulfuric acid, phosphoric acid or phosphoric-sulfuric acid anodizing. While it is known that using these acids leads to the incorporation of anions into the oxide, little is known on how they affect the nature of the oxide and how this, in turn, affects the interactions across the oxide-primer interface. In the current work, we investigate these changes in the interactions, especially the acid-base bonding, across the interface as a function of the pretreatment. To exclude contribution of surface roughness, oxides with no surface features were prepared in the aforementioned anodizing solutions by stopping the oxide growth during the formation of the barrier layer. Treatments in alkaline solution and boiling water were also included. XPS and Fourier transform infrared were first used to probe the acid-base properties of the oxide before its interactions with 4-ethylphenol (4-EP), and 4-hydroxybenzyl alcohol (4-HbA) was measured. These two molecules represent functional groups of phenolic-based thermoset resins with different acidities. Results show that both the pretreatments and the choice of molecule play a role in the interactions across the interface. While 4-HbA showed no preference, thin films of 4-EP were not detected on oxides that were prepared in phosphoric acid. [ABSTRACT FROM AUTHOR]

The kinetics of chromic acid oxidation of l -tryptophan in H 2 SO 4 medium at a constant ionic strength of 0.6 mol dm −3 and at 25 °C have been investigated spectrophotometrically. The reaction exhibits a 3:2 stoichiometry (tryptophan:chromic acid). The reaction shows a first order dependence on [chromic acid], a fractional-first order dependence on [tryptophan] and fractional-second order dependence on [acid]. Increasing ionic strength and dielectric constant had no significant effect on the oxidation rate. The final oxidation products of tryptophan were identified as the corresponding aldehyde (indole-3-acetaldehyde), ammonium ion and carbon dioxide. A spectral evidence for the formation of chromium(III) product was obtained. The experimental results suggest formation of an intermediate complex between the protonated tryptophan and chromic acid which decomposes in the rate-determining step to yield the products. The mechanism of such reaction has been proposed. The thermodynamic parameters with respect to the first step of the suggested mechanism were evaluated and discussed. [ABSTRACT FROM AUTHOR]

Aluminum has desirable characteristics of good thermal properties, good electrical characteristics, good optical properties, and the characteristic of being nonmagnetic and having a low atomic weight (26.98 g atoms), but because of its low melting point (660 °C) and ability as a reactive metal to alloy with most common metals in use, it has been ignored as a substrate material for use in processing thin films. The author developed a simple solution to this problem, by putting a permeation barrier of alumina (Al2O3) onto the surface of pure Al substrates by using a standard chemical oxidation process of the surface (i.e., anodization), before additional film deposition of reactive metals at temperatures up to 500 °C for 1-h, without the formation of alloys or intermetallic compounds to affect the good properties of Al substrates. The chromic acid anodization process used (MIL-A-8625) produced a film barrier of ~(500-1000) nm of alumina. The fact that refractory Al2O3 can inhibit the reaction of metals with Al at temperatures below 500 °C suggests that Al is a satisfactory substrate if properly oxidized prior to film deposition. To prove this concept, thin film samples of Cr, Mo, Er, Sc, Ti, and Zr were prepared on anodized Al substrates and studied by x-ray diffraction, Rutherford ion back scattering, and Auger/argon sputter surface profile analysis to determine any film substrate interactions. In addition, a major purpose of our study was to determine if ErD2 thin films could be produced on Al substrates with fully hydrided Er films. Thus, a thin film of ErD2 on an anodized Al substrate was prepared and studied, with and without the alumina permeation barrier. Films for study were prepared on 1.27 cm diameter Al substrates with ~500 nm of the metals studied after anodization. Substrates were weighed, cleaned, and vacuum fired at 500 °C prior to use. The Al substrates were deposited using standard electron beam cold crucible evaporation techniques, and after deposition the Er film was hydrided with D2 gas using a standard nonair exposure hydriding technique. All processing was conducted in an all metal ion pumped ultrahigh vacuum system. Results showed that e-beam deposition of films studied onto Al substrates could be successfully performed, if a permeation barrier of Al2O3 from 500 to 1000 nm was made prior to thin film deposition up to temperatures of 500 °C for 1-h. Hydrides also, could be produced with full gas/metal atomic ratios of ~2.0 as evidenced by the ErD2 films produced. Thus, the use of a simple permeation barrier of Al2O3 on Al substrates prior to additional metal film deposition was proven to be a successful method of producing both thin metal films and hydride films of various types for many applications. [ABSTRACT FROM AUTHOR]

Previous work has shown that a low level of sulphate impurity in chromic acid can significantly change the growth rate and the morphology of porous anodic films formed on aluminium at a constant voltage. The changes were associated with incorporation of sulphate into the films. The present study employs electron microscopy to reveal the growth of larger pores and cells at longer times of anodizing than previously used, leading to a duplex film morphology, with finer pores in the outer region. The change in pore size correlates with a reduction in the concentration of sulphate in the film. However, the behaviour of a tungsten tracer indicates that the sulphate does not alter the mechanism of pore generation significantly. From the results of sequential anodizing in sulphate-containing and sulphate-depleted electrolytes, it is suggested that incorporated sulphate ions lead to the generation of a space charge layer, which has an important role in determining the current density. [ABSTRACT FROM AUTHOR]

The present paper describes the kinetics of oxidation of p-chlorobenzaldehyde by chromic acid in aqueous and surfactant media in the presence of a promoter at 303 K. The rate constants were found to increase with introduction of hetero-aromatic nitrogen base promoters such as picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product p-chlorobenzoic acid has been characterized by NMR. The mechanism of both unpromoted and promoted reaction paths has been proposed. In presence of the anionic surfactant sodium dodecyl sulfate (SDS), cationic surfactant N-cetylpyridinium chloride (CPC) and non-ionic surfactant Triton X-100 (TX-100) the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation. Both SDS and TX-100 produce a normal micellar effect whereas CPC produces a reverse micellar effect in the presence of p-chlorobenzaldehyde. [ABSTRACT FROM AUTHOR]

The present paper describes the kinetics and mechanism for oxidation of D-arabinose by Cr(VI) in the presence of a micellar media. The anionic surfactant sodium dodecyl sulphate (SDS) and nonionic surfactant Triton-X-100 (TX-100) accelerate the process w h ile the cationic surfactant A/-cetylpyridinium chloride (CPC) retards the reaction. A suitable mechanism has been proposed. The reaction constants involved in different steps of the mechanism have been calculated. Formic acid and erythronic acid were reported as the products of oxidation of the sugar. [ABSTRACT FROM AUTHOR]

The formation of porous anodic alumina during potentiostatic anodizing of aluminium for times up to 900 s has been investigated using two grades of chromic oxide reagent. The anodic films were examined by ion beam analysis and scanning and transmission electron microscopies. Sulphate impurity in the chromic acid led to incorporation of sulphate into the anodic film, a lower current density, a smaller cell size and less feathering of the pore walls. In addition, the efficiency of film formation was increased. The sulphate concentration in the film was greatly enhanced relative to the electrolyte. [ABSTRACT FROM AUTHOR]

High temperature corrosion of austenitic TP347H steels with two grain sizes was studied at 600-750 °C in dry air. A relationship between oxidation rate and grain size was found. The surface oxides consisted of iron enriched (Fe,Cr)2O3 nodules and a (Cr,Mn)2O3 scale. Initial oxidation with both grain sizes followed cubic kinetics, a combination of fast oxide formation via oxide grain boundary diffusion at the beginning of oxidation and parabolic kinetics combined with oxygen dissolution to the steel through breakaway oxidation nodules. Above 650 °C, the breakaway oxidation became more severe in coarse grained steel and fine grained steel started to destroy the nodules. Better oxidation resistance was achieved with smaller grain size, especially at higher temperatures. Reducing the TP347H steel grain size lowers the critical chromium concentration needed for the formation and recovering of the protective oxide scale. [ABSTRACT FROM AUTHOR]

The steric and electronic requirements have been investigated for the synthesis of 2,3-dihydro-4(1 H)-quinolinones by the tandem Michael-SNAr reaction. Substrates bearing a single methyl group at the β-enone carbon gave excellent yields of the title compounds from both the E and Z isomers with X═H or NO2. Substrates with β,β-dimethyl substitution at the Michael terminus gave low yields of heterocyclic products in molecules having monoactivated SNAr aromatic acceptor rings (X═H) and very good yields for diactivated systems (X═NO2). For these hindered substrates, success in the final hinges on the ability of the aromatic acceptor to capture the pendant nitrogen nucleophile of the initial Michael adduct before this can revert to starting materials. [ABSTRACT FROM AUTHOR]

The micellar catalyzed 2,2′-bipyridine (bipy)-promoted oxidation of glycerol to glyceraldehyde by chromic acid is investigated under the criteria [glycerol] ≫ [Cr(VI)] at 30 °C. The critical micellar concentrations values of the three representative surfactants, N-cetylpyridinium chloride (CPC), sodium dodecyl sulphate (SDS), and TX-100, are determined by conductometric and spectrophotometric methods. The oxidized product glyceraldehyde is identified by 2,4-DNP test and FTIR spectral measurement. The pseudo-first-order rate constants ( k, s) are calculated from the slope of plots of ln( A) versus time ( t) which are linear. From these plots, the kinetic parameter k values are calculated and the k value of SDS-catalyzed bipy-promoted reaction path was found to be highest among all the combinations. In the bipy-promoted oxidation path, Cr(VI)-bipy complex is the main active oxidant which undergoes attack by the substrate to form the product. The active oxidant Cr(VI)-bipy complex reacts with glycerol to form a ternary complex which undergoes redox decomposition in a rate-limiting step. Here, the anionic surfactant SDS and the neutral surfactant TX-100 both catalyze the reaction in the presence of bipy, whereas the cationic surfactant CPC and neutral surfactant TX-100 inhibit the reaction in the absence of bipy. SDS is found to be the most suitable micellar catalyst for the bipy-promoted chromic acid oxidation of glycerol. [ABSTRACT FROM AUTHOR]

• SAA anodising was compared with CAA for practical aerospace use on 7050 alloy. • No significant difference in HCF between SAA and CAA on 7050 aluminium. • SAA is a practical alternative for aerospace use, but thickness should not exceed 13 µm. • SAA anodising should only be used where adhesive bonding is not required. • Stripping and reapplication of CAA did not further reduce fatigue performance. The aim of the present study was to investigate the effect two commonly used anodising processes, i.e. Chromic acid anodising (CAA) and Sulphuric acid anodising (SAA) had on the fatigue life of 7050-T7451 (AMS4050). The fatigue results show that regardless of the anodising process employed, reductions in fatigue were observed when compared to the as machined condition. However, based on topographical, residual stress and surface roughness observations combined with the metallographic features observed from micro-sections taken through the anodised layers it would appear that mechanism by which fatigue was influenced was different between the two anodising processes. For example with regard to CAA the reduction in fatigue was due to a combination of grain boundary attack and dissolution of the non metallic precipitates from pickling and the CAA process in which fatigue cracks initiated in the substrate. Whereas, in the case of SAA the reduction in HCF was primarily considered to be due to the presence of surface cracking which initiated from pits caused by the dissolution of the non metallic precipitates during the anodising process. Differences in loss of fatigue and failure mode were also observed between the two anodising processes as a result of stress concentration in which fatigue loss was greater and the number of multi-failure sites higher when the SAA samples were notched, inferring the Kt factor was exerting a greater influence on SAA by effectively lowering its strain to fracture. [ABSTRACT FROM AUTHOR]

Hydroxypropylation is a significant industrial process for diverse applications of polysaccharides. In the present study hydroxypropylation of Cassia gum derived from ruderal Cassia tora species was investigated using Taguchi's L'16 orthogonal array design of experiments. The optimized reaction conditions comprised: reaction temperature 50 °C, time 240 min, sodium hydroxide (0.015 mol), propylene oxide (0.0755 mol) and 60% aq. propane-2-ol. The maximum hydroxypropyl content, 8.43 and 7.71% were achieved using chromic acid titration and 1H NMR spectroscopic analysis respectively in the optimized product. The chemical shift values of substituted hydroxypropyl groups for methyl, methine and methylene protons at 0.98, 3.87 & 3.41 ppm along with respective carbons at δ 18.23, 69.41 & 79.13, and other assignments, 1H and 13C signals, were confirmed by COSY and HSQC correlation spectral analysis. The substituted hydroxypropyl groups, C 6 of the β-D-1, 4-linked-Manp unit, were established at 66.18 ppm. [Display omitted] • Taguchi L'16 array design was used to prepare hydroxypropyl derivative of Cassia tora gum • Chromic acid titration method is an appropriate method to determine the hydroxypropyl content • Derivative and substituted hydroxypropyl group at C-6 of the β-D-1, 4-linked-Manp unit were studied by NMR techniques [ABSTRACT FROM AUTHOR]

• Low-toxicity surface treatments have been performed on substrates for electroless plating. • 3D printed resins have been Silver electroless plated. • Ag coatings are well adherent and highly electrically conductive. • H 2 SO 4 surface treatment results in the highest coating adhesion. Electroless plating is a simple method to manufacture conductive coatings on electrically insulating substrates such as polymers. In this paper silver electroless plating has been performed on 3D printed polymeric samples manufactured by stereolithographic process. Three different surface treatments using acetone, ethanol and sulfuric acid solution, have been performed avoiding the use of highly toxic chemicals (i.e. chromic acid) typically applied in this process. All the surface treatments modify the surface wettability, even if sulfuric acid solution was the best performing one. The resulting silver coatings are compact and homogenous with an average thickness of 200 nm, they show high chemical purity and high electrical conductivity. The adhesion of the coating has been measured by scratch test and the results confirmed that all the three surface treatments produced well adherent coatings, although the treatment via sulphuric acid solution produced the coating with best adhesion. [ABSTRACT FROM AUTHOR]

This work addresses the fabrication and characterization of MCM-41-ceramic composite membrane on a porous circular shaped support by hydrothermal synthesis method. A facile uni-axial compaction method was employed for the preparation of ceramic support and sintered at 950 °C. The properties of MCM-41-ceramic composite membrane and MCM-41 powder were characterized by X-ray diffraction (XRD), porosity, thermogravimetric analysis (TGA), nitrogen adsorption–desorption isotherm (BET), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and zeta potential measurement. The average pore size of support and MCM-41-ceramic composite membrane are estimated to be 1.0 and 0.173 µm, respectively. The porosity of the ceramic support decreases from 47% to 23% by repeated cycle of coating (three times) with MCM-41 on the support. The obtained MCM-41 powder possesses high surface area (1305 m 2 /g) and pore volume (0.7472 cm 3 /g). Solvent permeation studies through the MCM-41-ceramic composite membrane reveals that non polar solvents are more permeable in comparison with polar solvents and the chemical nature of liquids are the main controlling factor for the transport of solvents. Further, the fabricated MCM-41-ceramic composite membrane was subjected to investigate the potential for the separation of Cr (VI) from aqueous solution. The influence of various parameters such as applied pressure, feed concentration and pH of the solution on the rejection of Cr (VI) was examined. The rejection and the flux behavior of Cr (VI) are found to be mainly dependent on the electrostatic interaction with charged molecules and the MCM-41-ceramic composite membrane. The permeate flux increases with an increase of applied pressure and follows Darcy׳s law. The highest rejection of 80% is observed at acidic pH (pH=2) for the feed concentration of 1000 ppm with an applied pressure of 207 kPa. [ABSTRACT FROM AUTHOR]

The chromic acid oxidation of formaldehyde in micellar solution of sodium dodecyl sulphate (SDS)/TX-100 at room temperature has been investigated under pseudo first-order condition. Heterocyclic bases such as picolinic acid (PA), 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) have been employed which acts as a promoter. The rate of this oxidation reaction increased 50 times by combination of bipy and SDS micelle compared to rate in pure aqueous media. Here, we can avoid hazardous organic solvents, high pressure and temperature which are required for conventional preparation of formic acid. The catalytic effect of SDS/TX-100 micelle has been explained. [ABSTRACT FROM AUTHOR]

Using converter dust as salt packing, adding MgO and Cr2O3, a high anticorrosion solid coating material was produced. The influences of adding MgO and Cr2O3 (ranging 10%~20%) on the performance of high anticorrosion solid coating were studied. The results show that when the amount of MgO(10%~20%) in converter dust increases, feeding MgO and Cr2O3 is beneficial to the decrease of coating solid component, but feeding only Cr2O3(10%~20%) has little effect. Thus, it is advisable to add MgO and Cr2O3 to improve the resistance of the coating to salt water and acid. The coating of 120h acid corrosion was almost no corrosion phenomenon. [ABSTRACT FROM AUTHOR]

Using converter dust as salt packing, adding MgO and Cr2O3, a high anticorrosion solid coating material was produced. The influences of adding MgO and Cr2O3 (ranging 10%~20%) on the performance of high anticorrosion solid coating were studied. The results show that when the amount of MgO(10%~20%) in converter dust increases, feeding MgO and Cr2O3 is beneficial to the decrease of coating solid component, but feeding only Cr2O3(10%~20%) has little effect. Thus, it is advisable to add MgO and Cr2O3 to improve the resistance of the coating to salt water and acid. The coating of 120h acid corrosion was almost no corrosion phenomenon. [ABSTRACT FROM AUTHOR]

A systematic study on the growth of Cr2O3 in three-dimensional cubic ordered mesoporous silica (KIT-6) and its replication through nanocasting is reported. By changing the loading time and amount of precursor, the size and shape of the obtained replica could be controlled to some extent. More interestingly, in contrast to previously published studies, when KIT-6 with an aging temperature of 100 °C, which has a high degree of interconnectivity, was used as a hard template, a cubic ordered mesoporous Cr2O3 replica with an open uncoupled subframework structure and reduced symmetry was obtained. Formation of a replica with different symmetry and uncoupled subframework structure is not only related to the degree of interconnectivity of the parent, but also strongly depends on the type of metal oxide and its growth mechanism in the silica template. Nanocasting of Cr2O3 with a low loading results in a replica with monomodal pore size distribution that has same symmetry as the hard template, whereas increasing the loading amount alters the symmetry of the replica and yields a replica with bimodal distribution. [ABSTRACT FROM AUTHOR]

The passive properties of chromium nitride (CrN) film deposited on AISI 304 stainless steel (UNS S30400) by magnetron sputtering were investigated using a series of electrochemical techniques. The results showed that the passive film followed the 3D grain growth. The nucleation type was instantaneous while it deviated to progressive gradually with the increase of sodium chloride (NaCl) content. The thickness of the passive film was 1.1 nm to 2.4 nm with the compositions mainly of Cr, CrN, chromic oxide (Cr2O3), chromic hydroxide (Cr[OH]3), and chromium trioxide (CrO3). With the increase of film formation potential, the vacancy density decreased exponentially. The obtained diffusion coefficient of defects was 5.493x10-17 cm²/s. Chromium cation in the CrN cation site also participated in the growth of passive film. Anions (Cl-) could adsorb on the passive surface in the free corrosion potential condition. [ABSTRACT FROM AUTHOR]

Highlights: [•] The importance of this study is that the oxidation has been carried out in aqueous micellar media. [•] Chemist’s increasing interest to carry out the organic transformation preferably in aqueous media. [•] Oxidation of 1-butanol totally converts the toxic hexavalent chromium into the non-toxic trivalent chromium. [•] PA, bipy and phen used as promoters to accelerate the reaction rate in presence and absence of SDS, CPC and TX-100. [•] Combination of SDS and bipy is the most efficient one for the oxidation of 1-butanol to 1-butanal. [ABSTRACT FROM AUTHOR]

Aldehydes produced from carbohydrates by oxidation or acid hydrolysis may be visualized by application of aqueous thiosemicarbazide followed by Schmorl's ferricyanide reduction. The thiosemicarbazide reacts with the aldehydes by its hydrazine group, while its thiocarbamyl group remains active. The thiocarbamyl moiety is a strong reducing group that converts ferricyanide to ferrocyanide in Schmorl's reaction. The ferrocyanide is trapped immediately by the ferric salt, which deposits Prussian blue at the site of the aldehydes thereby demonstrating the location of the original substance. [ABSTRACT FROM AUTHOR]