Strong Sulfuric Acid Solutions Research Articles

Experimental study on the tensile load-carrying capacity of steel/GFRP bonding in moisture and acidic environments at high temperature

Steel plates are damaged in harsh environments, such as moisture and acidic environments, especially at high temperatures. Damaged areas in steel plates can be strengthened by bonding fiber reinforced polymer (FRP) composites. This paper investigates the effect of harsh environment on the load-carrying capacity of damaged steel specimens reinforced by the GFRP patch. The results of the patched samples immersed in accelerated harsh environments consisting of distilled water and strong sulfuric acid solution are compared to dry ones in the room and high-temperature conditions. The results show about 13% reduction in load-carrying capacity after 8 weeks of immersion in both harsh environments at room temperature. Moreover, the results of high-temperature tension test for patched samples immersed in high-temperature acidic solution show a significant reduction in displacement and load-carrying capacity even after 1 week. The failure mode investigation of dry specimens by numerical analyses shows good consistency with the experimental results.

황산용액에서 양이온계 추출제 및 TBP와의 혼합추출제에 의한 지르코늄(IV)과 하프늄(IV)의 용매추출

Abstract Separation of Zr(IV) and Hf(IV) from sulfuric acid solutions was investigated by extraction with several acidic extractantssuch as Versatic acid, LIX 63, and Cyanex 301. From strong sulfuric acid solutions, the separation of Zr(IV) and Hf(IV) by Ver-satic acid and LIX 63 was not possible, while selective extraction of Hf(IV) over Zr(IV) was obtained with Cyanex 301. How-ever, the extraction percentage of the two metals was much lower compared to that by D2EHPA. Mixing of TBP with Cyanex301 and D2EHPA led to negative effect on the extraction and separation of the two metal ions. The difference in the extractionreaction and separation selectivity between HCl, HNO 3 and H 2 SO 4 media with each extractant was discussed.Key words : Zirconium, Hafnium, Separation, Sulfuric acid, Acidic extractants · Received : January 18, 2016 · Revised : February 2, 2016 · Accepted : February 15, 2016Corresponding Author : Man Seung Lee (E-mail : mslee@mokpo.ac.kr)Department of Advanced Materials Science & Engineering, Mokpo National University, 1666 Yeongsan-ro, Cheonggye-myeon,Muan-gun, Chonnam, 58554, KoreaⓒThe Korean Institute of Resources Recycling. All rights reserved. This is an open-access article distributed under the termsof the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permitsunrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.

Selective Stripping of Zr (IV) over Hf (IV) in Loaded D2EHPA Extracted from Strong Sulfuric Acid Solutions

Selective Stripping of Zr (IV) over Hf (IV) in Loaded D2EHPA Extracted from Strong Sulfuric Acid Solutions

Development of a separation process for the selective extraction of hafnium(IV) over zirconium(IV) from sulfuric acid solutions by using D2EHPA

A new process for the separation of Zr(IV) and Hf(IV) from sulfuric acid solution by selective extraction and stripping was proposed. Firstly, Hf(IV) was preferentially extracted by di-2-ethylhexylphosphoric acid (D2EHPA) from moderate sulfuric acid solutions. From the loaded D2EHA, co-extracted Zr(IV) was selectively stripped by strong sulfuric acid solution with a separation factor of 10, leaving only Hf(IV) in the stripped D2EHPA. Hafnium(IV) was then completely stripped by oxalic acid solution and thus D2EHPA was regenerated. The McCabe–Thiele plots for the extraction and stripping isotherms were constructed and the results were verified by the simulated cross-current extraction and stripping experiments. Zirconium(IV) solutions of high purity were obtained in the extraction raffinate and sulfuric acid stripping solution, while Hf(IV) was present in the oxalic acid stripping solution.

Solvent extraction reaction of hafnium(IV) from strong sulfuric acid solutions with D2EHPA and PC 88A

ABSTRACTHafnium can be selectively extracted over zirconium from strong sulfuric acid solutions by D2EHPA or PC 88A. Solvent extraction experiments have been performed to identify the reaction of Hf from strong sulfuric acid solutions (1 to 7 M) by these two extractants. Hafnium extraction was gradually decreased and then increased again with the increase of sulfuric acid concentration. By applying a slope method, the extracted Hf species was proposed to be HfA4·(HA)2 by D2EHPA and Hf(HSO4)2A2·(HA)2 by PC 88A, respectively. This difference in the nature of the extracted species was verified by FT-IR spectra.

Ion-exchange recovery of nickel(II) and cobalt(II) from sulfuric acid solutions

Sorption recovery of nickel(II) and cobalt(II) in their joint presence in sulfuric acid solutions was studied on new samples of domestic ion exchangers of CYBBER brand. It was shown that the ion exchangers under study have a high sorption capacity for ions of both nonferrous metals, depending on the structure of a sorbent and on the acidity of a contacting solution. It was found that, after Co(II) and Ni(II) ions are extracted from weak or strong sulfuric acid solutions, they can be effectively eluted from the ion exchangers under study with a 2 M hydrochloric acid solution to an extent of 85–95% (nickel) and 87–95% (cobalt).

전해도금에 의한 Ni-W 합금의 내식성 및 표면 전도도 특성 연구

A Ni-W thin-film was synthesized by electrodeposition, and its corrosion resistance and electrical surface conductivity were investigated. Amount of tungsten in the Ni-W thin-film increased linearly with current density during the electrodeposition, and crack-free and low-crystalline Ni-21 at.%W coating layer was obtained. Corrosion resistances of the Ni-W thin-films were examined with an anodic polarization method and a storage test in a strong sulfuric acid solution. As a result, the Ni-21 at.%W thin-film exhibited the greatest corrosion resistance, and maintained the electrical surface conductivity even after the severe corrosion test, which could be applicable as a surface treatment for advanced metallic bipolar plates in fuel cell or redox flow battery systems.

Kinetics of the dissolution of ilmenite in sulfuric acid solutions under reducing conditions

The kinetics of the dissolution of titanium and iron from an ilmenite sample has been studied in moderately strong sulfuric acid solutions in the absence and presence of reducing agents such as titanium(III) ions and sulfur dioxide. The effects of particle size, temperature, solid/liquid ratio, sulfuric acid concentration and titanium(III) concentration on the kinetics of dissolution have been investigated. The results have shown that both particle size and acid concentration have relatively minor effects on the rate of dissolution of titanium while temperature has a significant effect under the studied conditions.

Study on Ethanol Fermentation Using D-Glucose Rich Fractions Obtained from Lignocelluloses by a Two-step Extraction with Sulfuric Acid and Issatchenkia orientalis MF 121

Cellulosic oligosaccharides (720-920 mg) were prepared by a two-step extraction using 43.5% sulfuric acid and then 55% sulfuric acid from lignocelluloses (2 g each) of Japanese oak and eucalyptus as hardwood, Japanese cedar and cypress as softwood, and sugar cane bagasse and rice straw as annual plant residues. After the complete saccharification of the oligosaccharide and treatment with the appropriate amount of activated carbon, D-glucose with a comparatively high purity was prepared. As the D-glucose was in a strong sulfuric acid solution, the sugar solution was applied on a column packed with an ion exchanging resin (Diaion DSR01) in order to remove almost all of the acid. The fractions eluting the sugar were collected and concentrated with a rotary evaporator. Although the concentrated sugar solution showed an acidity of pH 2-3, acid tolerant Issatchenkia orientalis MF 121 could ferment ethanol successfully in YPD medium using the sugar as the sole source of carbon.

Surface Concentrations and Compound Formation in Aqueous Sulfuric Acid

The concentration of free water molecules at the surface of a strong sulfuric acid solution is found to be very low, mainly as a consequence of the formation of acid hydrates. Values of equilibrium constants and enthalpy changes for successive hydration reactions of H2SO4 have been calculated from the variation of water vapour pressure with acid strength and temperature. The results support the conclusion of Fried et al. that the rate of reaction of a molecule such as N2O5 with a sulfuric acid aerosol is controlled by the rate at which the molecule can penetrate into the bulk of the liquid.

Further improvements in the 2,4-xylenol spectrophotometric method for nitrate

Improvements are described for the 2,4-xylenol spectrophotometric method for nitrate that reduce the elapsed and working time. Diluted (22 + 3) sulfuric acid is added quickly to the sample solution while the flask is immersed in tap water. 2,4-xylenol solution is added, the 6-nitro-2,4-xylenol formed is steam-distilled into a composite ammonia—isopropanol reagent, and the absorbance of the ammonium salt of 6-nitro-2,4-xylenol is measured. Further possible interferences are described. Br 2, I 2, ClO -, CIO 3 -, BrO 3 -, and I0 4 -, cause low results by deactivating or destroying the 2,4-xylenol. Azide, hydrazine, and elemental carbon cause low results by reducing the nitrate in the strong sulfuric acid solution. Se + causes low results because 2,4-xylenol is consumed in reducing Se 4+ to the element. Pt 4+ and Os 8+ cause high results. Interferences from Br 2, I 2, ClO -, ClO 3 - lO 3 -, and I0 4 - can be eliminated by reduction to the halide with sulfurous acid and precipitation with silver sulfate. Sulfurous acid reduction also eliminates interferences from V 5+. Mn 7+, Cr 6+, S 2O 8 2-, and H 20 2. Interferences from N 3 -, Br 2, I 2, and S 20 8 2- are eliminated merely by boiling a 0.5% sulfuric acid solution for 30 min (and precipitating any residual halide with silver sulfate).

Inorganic interferences in the 2,4-xylenol spectro-photometric method for nitrate and their elimination

A study of inorganic interferences with the 2,4-xylenol spectrophotometric method for nitrate and their elimination is reported. Fifty-three substances do not interfere with the original method. Nitrite interferes somewhat by producing a faint yellow color. Certain reducing agents (Fe 2+, S 2-, S 2O 3 2-, and SCN -) cause low results by reducing the nitrate in the strong sulfuric acid solution, while some oxidizing agents (Mn 7+, Cr 6+, V 5+, and ClO 3 -) cause low results by inactivating or destroying the 2,4-xylenol. Persulfate and small amounts of H 2O 2 produce a slight deepening of the color; larger amounts of H 2O 2; cause low results, as do Cl -, Br -, I -, and metals. The recommended maximum permissible limits (mg per 10-ml aliquot) for the original method are NO 2 --N, Fe 2+, S 2-, SCN -, V 5+, ClO 3 -, Cl -, I -, 0.2; Mn 7+, Cr 6+, S 2O 8 2-, 5; H 2O 2, 0.02; S 2O 3 2-, Br -, 0.1; metals, none. Procedures for the elimination of most of the interferences are described. Nitrite is destroyed with sulfamic acid. The interferences of reductants (Fe 2+, S 2-, S 2O 3 2-, and SCN -) and oxidants (Mn 7+ and Cr 6+) are eliminated with hydrogen peroxide, the excess of which (and S 2O 8 2-) is destroyed by boiling in the presence of Fe 3+. The interference of Cl -, Br -, and I - is eliminated by precipitation with silver sulfate. An alternative to the sulfamic acid procedure is to oxidize nitrite to nitrate with peroxide and deduct NO 2 --N from the total NO 3 --N. After elimination of interferences, a 10-ml aliquot of sample solution is treated with 17.0 ml of sulfuric acid and 2,4-xylenol, the 6-nitro-2,4-xylenol is steam-distilled into an ammonia—water—isopropanol mixture, and the yellow color is measured.

Reduction of arsenic acid with aqueous sulfur dioxide

The reduction of arsenic acid with aqueous sulfur dioxide in sulfuric acid solutions is presented. First order kinetics with respect to arsenic acid and sulfur dioxide concentrations are observed. Appreciable reduction occurs only when tetravalent sulfur is present as sulfur dioxide. The protonation of arsenic acid in strong sulfuric acid solutions decreases the rate of pentavalent arsenic reduction.

Orientation in the Wallach Rearrangement for the Naphthyl Azoxy Series

The acid-catalyzed Wallach rearrangement of azoxybenzenes has been extended to the naphthyl azoxy series in order to evaluate the effect of annelation of benzene rings on the course of rearrangement. The six known azoxy derivatives containing the α-naphthyl, β-naphthyl, and phenyl moieties, in various combinations, have been examined with respect to product orientation in moderately strong sulfuric acid solutions. The course of rearrangement (eqs. 2–6) is discussed on the basis of current mechanisms.

Determination of ethanol in fingertip quantities of blood

A simple procedure has been described which involves the use of the Conway cell for the “isothermal distillation” of ethanol into an oxidizing scrubber of a strong sulfuric acid solution of dichromate. The residual dichromate is then reacted with brucine which yields a stable, sensitive chromophore. The increased sensitivity enables the technique to be performed on amounts of blood easily obtainable from the fingertip.

The standardization of Ammonium vanadate solutions with Sodium Oxalate .

The results of a study of the reaction between ammonium m-vanadate and sodium oxalate in strong sulfuric acid solution are given. It has been found that the latter is a suitable and convenient primary standard for solutions of quinquevalent vanadium.

Electrolytic investigations: New method for the electrolytic separation of copper and antimony from tin

Copper can be separated from tin by elcctrolysis from a strong sulfuric acid solution. The method is advantageous because tin can be determined directly on the copper electrolyte without the necessity of fuming with sulfuric acid to drive off nitric acid. Small amounts of antimony plate quantitatively with the copper and can be determined by difference.

Destruction of Phenylalanine by Ultraviolet Radiant Energy

The following changes have been observed to occur when dl-phenylalanine is exposed to ultraviolet radiant energy:1. Spiegel-Adolf1 reported that solutions of phenylalanine exposed to ultraviolet rays become pigmented. Pigment formation was most marked in neutral solution, but acid and alkaline solutions also became red-brown after prolonged irradiation. During the present investigation, these findings were confirmed. Moreover, when dilute sulfuric acid or hydrochloric acid solutions of the amino acid were exposed to the ultraviolet rays, a small amount of dark brown material precipitated; this material formed colloidal solutions in dilute sodium hydroxide solution, but was insoluble in dilute acid solution. Much of the soluble pigment of the irradiated solutions could be removed by alternate additions of strong sodium hydroxide and sulfuric acid solutions; or by extraction from strongly acid solution with butyl alcohol.2. Irradiated neutral, acid, or alkaline solutions of phenylalanine were found in the p...