Effect Of HNO3 Research Articles

Hydrogen permeation and SCC susceptibility of X70 pipeline steel in CO2-saturated water environment containing acidic impurity

The effect of HNO3 and H2SO4 impurities on hydrogen permeation behavior and stress corrosion cracking (SCC) susceptibility of X70 steel in CO2-saturated water environment was investigated. Concurrently, a method for characterizing the contribution of corrosion-produced hydrogen to SCC was developed. HNO3 and H2SO4 boost the hydrogen permeation through promoting cathodic hydrogen evolution. The hydrogen embrittlement induced by corrosion-produced hydrogen, together with anodic dissolution, dominates the SCC process of X70 steel. The steel has much higher SCC susceptibility in H2SO4-containing environment than in HNO3-containing environment, which is closely related to the much stronger hydrogen embrittlement effect caused by H2SO4 than HNO3.

Study of removing radioactive thorium(IV) from high-purity scandium(III) products with di-(2-ethylhexyl) 2-ethylhexyl phosphonate (DEHEHP) in nitric acid solution

Scandium (Sc) is a critical rare earth element. Its compounds are of great concern due to their excellent properties. However, the application is limited by the presence of radioactive impurity thorium (Th). The study aims to remove the radioactive Th(IV) from high-purity Sc2O3 by DEHEHP. The extraction behavior of Sc(III) from HNO3 solution using DEHEHP was also investigated. The effects of HNO3, extractant and salting-out reagent (LiNO3) concentrations on the Sc(III) extraction were studied. The extraction mechanism and thermodynamic parameters were determined. Among the three extractants: Cyanex 923, TBP and DEHEHP, DEHEHP showed the greatest separation ability for Sc(III) and Th(IV) from HNO3 solution. The effects of HNO3, LiNO3, and initial Sc(III) concentrations as well as phase ratio on the separation factor βTh/Sc were investigated. It was indicated that βTh/Sc reached as high as 196 after separation by 30% (v/v) DEHEHP at 3.0 mol L−1 HNO3. The McCabe-Thiele diagram for Th(IV) was plotted. After the six-stage counter-current extraction experiment, the concentration of Th(IV) in the raffinate decreased to 20 mg L−1 from the solution containing 7.71 g L−1 Sc(III) and 692 mg L−1 Th(IV) without the co-extraction of Sc(III). Finally, Sc2O3 of purity >99.99% was obtained.

Rapid Determination of Sulfur in Sixty Geological Reference Materials by High Resolution Inductively Coupled Plasma‐Mass Spectrometry

In this study, a rapid method for the quantification of sulfur mass fractions in geological materials using high‐resolution sector field‐inductively coupled plasma‐mass spectrometry (SF‐ICP‐MS) was developed. The effects of HNO3, Lefort, aqua regia, and HCl on the recoveries of sulfur in three different geological samples were evaluated. It was found that 0.5‐1 h digestion at 90 °C was enough to completely recover sulfur from BCR‐2 (basalt rock), GSS‐25 (loess), and GSD‐7 (stream sediment) using 2 ml aqua regia in both closed and open vessels. Compared with that of traditional digestion methods (e.g., HF‐HBr‐HNO3 acid digestion method), the efficiency of this proposed aqua regia digestion is improved by a factor of approximately 20. No loss of sulfur was observed because sulfur released from geological materials is directly oxidised to sulfate, which inhibits the volatilisation of sulfur. In addition, the effect of the heating‐condensing system combined with two different skimmer cones on the analytical sensitivity of sulfur was investigated. Compared with that of the normal sampling mode, the signal intensity of sulfur is enhanced by a factor of approximately 22 and 10 at a temperature of 140 °C using the S + X cone combination and S + H cone combination, respectively. This improvement is of importance for the determination of sulfur in samples with low sulfur content. The developed method was successfully applied to the determination of sulfur in geological reference materials. Most of the measured sulfur values of sixty geological materials, using both closed and open vessel digestion, are in good agreement with reference values. Compared with closed vessel digestion, the more flexible open vessel acid digestion is simple, fast, and shows great potential for the rapid quantification of sulfur in a large batch of geological and environmental samples.

Extraction of Uranium in Nitric Media with Novel Asymmetric Tetra-Alkylcarbamide.

The use of tetra-alkylcarbamides as novel ligands: N,N-butyl-N’,N’-hexylurea (L1: ABHU), and N,N-butyl-N’,N’-pentylurea (L2: ABPU), for the solvent extraction and complexation behaviors of uranium(VI) was synthesized and investigated in this study. The effects of HNO3 and NO3− concentrations in the aqueous phase on the distribution ratio of U(VI) were examined. Under 5 mol/L HNO3 concentration, DU reached 5.02 and 4.94 respectively without third-phase formation. During the extraction, slope measurements and IR spectral analysis revealed that the U(VI) complexes are a form of UO2(NO3)2·2L for both ligands. In addition, thermodynamic studies showed that the uranium extraction reaction was a spontaneous exothermic reaction. The deep structural analysis of the complexes was realized with DFT calculation. The bond length, bond properties, and topology of the complexes were discussed in detail to analyze the extraction behavior. This study enriches the coordination chemistry of U(VI) by tetra-alkylcarbamides, which may offer new clues for the design and synthesis of novel ligands for the separation, enrichment, and recovery of uranium in the nuclear fuel cycle.

Effect of HNO3 and FeCl3 Additives on the Pickling Ability of Fayalite-Containing Oxide Film from Si-Containing Steels

The present work discusses the morphology and pickling behavior of tertiary oxide scale formed on 4 types of hot-rolled steels (0.008 Si-0.019 Cr, 0.43 Si-0.017 Cr, 0.35 Si-0.525 Cr and 0.034 Si-0.72 Cr (wt.% basis)) in four successive tanks of acid containing 4, 6, 8 and 12% HCl solution, respectively, with the addition of strong oxidizer like FeCl3 and HNO3 along with inhibitor. The presence of fayalite (Fe2SiO4) in oxide scale of 0.43 Si-0.017 Cr and 0.35 Si-0.525 Cr steels was confirmed. This fayalite layer is difficult to be removed by pickling. Therefore, pickling was done at room temperature and at 80 ± 3 °C with different strong oxidants, such as FeCl3 and HNO3 added to the pickling liquor and it was found that even at room temperature, the addition of 0.1N FeCl3 and 0.1N HNO3 could remove the oxide scale completely for the high Si-containing steel too. However, only the addition of 0.1N FeCl3 was sufficient to remove the fayalite layer when pickled at 80 ± 3 °C. Additionally, an inhibitor helped to restrict the over-pickling.

Effect of HNO3 and H2SO4 on the Paddy Ecosystem: A Mesocosm Study with Exposure at PNEC and HC50 Levels.

Paddy mesocosms comprising of rice (Oryza sativa), snail (Pomacea canaliculata), and worm (Tubifex tubifex) were used to assess the damage caused by two acids (HNO3 and H2SO4) at predicted no-effect concentration (PNEC) and hazardous concentration for 50% of species (HC50) levels. In the fourth week, the fresh weight and shoot height of O. sativa at H2SO4-HC50 were reduced by 83.2% and 30.3%, respectively. Wilted leaves (%) at HC50 were approximately twice that at PNEC. No P. canaliculata and T. tubifex were recovered at HC50. At H2SO4-PNEC, the length and weight of P. canaliculata were reduced by 7.4% and 25.9%, respectively, whereas fewer adult (46.5%) and juvenile (84%) T. tubifex were recovered. In the 20th week, rice growth and productivity were correlated with initial pH (pHi) and nitrogen levels. Poor correlation with chlorophyll at the active tillering stage suggests the disturbance of nutrient uptake by roots. Partial least squares path modeling (PLS-PM) results further supported that the pHi directly affects grain yield and quality, as well as plant growth. The indirect effect via intervening fourth-week-variables was also substantial. Therefore, it is important to measure initial pH upon acid spill to estimate the risk to the paddy ecosystem. Information on the change in soil properties associated with acidity will also aid in predicting the yield and quality of grain to be harvested.

TEPA impregnation of electrospun carbon nanofibers for enhanced low-level CO2 adsorption

The CO2 adsorption selectivity of plain activated carbon nanofibers (ANF) is generally low. For enhancement, nitrogen functionalities favorable for CO2 adsorption are usually tethered to the ANF. In the current study, we adopted chemical impregnation using 0.5 wt% tetraethylenepentamine (TEPA) solution as an impregnant. To enhance the impregnation of TEPA further, preliminary oxidation of the nanofibers with 70% HNO3 was conducted. The effects of HNO3 and TEPA treatments on the modified ANFs were investigated for physical (using N2 monosorb, thermogravimetric analyzer, scanning electron microscopy) and chemical (X-ray photoelectron spectrometer) changes. From the results, we found that although TEPA impregnation reduced the specific surface area and pore volume of the ANFs (from 673.7 and 15.61 to 278.8 m2/g and 0.284 cm3/g, respectively), whereas the HNO3 pre-oxidation increased the number of carboxylic groups on the ANF. Upon TEPA loading, pyridinic nitrogen was tethered and further enhanced by pre-oxidation. The surface treatment cumulatively increased the amine content from 5.81% to 13.31%. Consequently, the final adsorption capacity for low (0.3%) and pure CO2 levels were enhanced from 0.20 and 1.89 to 0.33 and 2.96 mmol/g, respectively. Hence, the two-step pre-oxidation and TEPA treatments were efficient for improved CO2 affinity.

Highly selective extraction of Pu (IV) and Am (III) by N,N′-diethyl-N,N′-ditolyl-2,9-diamide-1,10-phenanthroline ligand: An experimental and theoretical study

The group actinide extraction ligand, N,N′-diethyl-N,N′-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) has been successfully developed in our laboratory recently. In this work, the extraction behaviors of the tetradentate Et-Tol-DAPhen toward Am(III) and Pu(IV) by using 1-(trifluoromethyl)-3-nitrobenzene as the diluent were systematically explored. The effects of HNO3 and ligand concentration as well as temperature were studied in detail. In addition, the selectivity of this ligand towards actinides and the stripping performance of the extraction system were also investigated to assess its potential application for group actinide separation over trivalent lanthanides (Ln(III)). According to our results, Et-Tol-DAPhen exhibits large distribution ratios for both Am(III) and Pu(IV) with high separation factors over Pm(III) in a wide range of acidity. Moreover, Am(III) and Pu(IV) can be efficiently stripped into the aqueous phase via three stages of batch back extraction. In addition, density functional theory (DFT) calculations suggest that the ligand selectivity towards actinides over Ln(III) probably results from the higher covalency of An-N bonds. The consistency between calculated thermodynamic parameters and experimental observations demonstrates the reasonability of the proposed extraction mechanism. Our findings afford insightful extraction parameters of Et-Tol-DAPhen towards actinides with different oxidation states and justify its versatile coordination abilities with respect to group actinide separation over lanthanides.

A Study on DSLM Transporting the Rare Earth Metal La (III) with a Carrier of PC-88A.

This paper studies transmission behavior of La (III) in dispersed supported liquid membrane (DSLM) of dispersed phase constituted by dispersed supported liquid membrane solution and HCl solution with polyvinylidene fluoride membrane (PVDF) as support and kerosene as membrane solvent, with 2-ethyl hexyl phosphonic acid-single-2-ethyl hexyl ester (PC-88A) and two-(2-ethyl hexyl) phosphoric acid (D2EHPA) as mobile carrier. It also investigates the influence of La (III) transmission by the material liquid acidity, initial concentration of La (III), HCI concentration, membrane solution, and HCI solution volume ratio, resolving agent and carrier concentration, as well as concluding that the optimal transmission and separation conditions are dispersed phase of 4.00 mol/L HCl concentration, 30:30 volume ratio of membrane solution, and HCl solution, within 0.160 mol/L controlled carrier concentration and 4.00 pH value of material liquid. Under the optimal conditions, the La (III) initial concentration of material liquid phase is 8.00 × 10–5 mol/L mol/L, 125 min, and 93.9% migration rate. Under the condition of unchanged acidity of resolving phase, HCL, H2SO4, and HNO3 as resolving agent, at 125th min, the migration rates of La (III) are 93.9%, 94.0%, and 87.8%, respectively. HCl solution, H2SO4 solution, and HNO3 solution have a certain effect on the La (III) resolution, of which 4.00 mol/L HCl solution and 2.00 mol/L H2SO4 solution are better. The effect of HNO3 is slightly lower than HCl and H2SO4.

Extraction and sorption preconcentration of rhenium with the use of 2-phosphorylphenoxyacetamides

Interfacial distribution of micro amount of ReO4 - between aqueous solutions of mineral acids and solutions of 2-phosphorylphenoxyacetamides in dichloroethane has been studied. Stoichiometry of extracted complexes has been determined; the effect of HNO3, HCl, and H2SO4 concentration in aqueous phase, extractant structure, and organic solvent nature on the efficiency of ReO4 - ions transfer into organic phase has been considered. It has been shown that Re(VII) can be selectively recovered and concentrated with complexing sorbent obtained by the noncovalent binding of 2-[2-(diphenylphosphoryl)-4-ethylphenoxy]-N,N-dioctylacetamide on the surface of macroporous polymer Amberlite XAD7HP.

Extraction of lanthanide ions with N,N,N′,N′-tetrabutyl-3-oxa-diglycolamide from nitric acid media

Extractability and extraction mechanism of lanthanide ions were investigated by using a new extractant, N,N,N′,N′-tetrabutyl-3-oxa-diglycolamide (TBDGA), in toluene from nitric acid media. The effects of HNO3 and TBDGA concentrations, and temperature, on extraction of lanthanide ions were studied. Stoichiometries of the main extracted species were HNO3·TBDGA and M(NO3)3·3TBDGA (M = Er, Dy, Tb, Gd, La, Ce, Nd, Sm and Eu). The extracted species for metal ions were established to be ionic complex. In this complex, nitrate anion was not coordinated to the central ion. The extraction pattern increased gradually across the lanthanide ions series, showing enhanced affinity of TBDGA toward heavy lanthanide ions. Thermodynamic parameters were investigated for the exothermic extraction reaction.

Extraction of rare earth elements from nitrate solution using novel unsymmetrical diglycolamide

ABSTRACTA novel unsymmetrical diglycolamide (DGA), namely N,N-dihexyl-N’,N’-didecyldiglycolamide (DHD2DGA), was synthesized for the extraction of Nd(III), Sm(III), Gd(III), Dy(III), Ho(III) and Er(III) in nitric acid solutions. The effects of HNO3, HCl or H2SO4 on the distribution ratio of the investigated metal ions were investigated. A systematic investigation was carried out using DHD2DGA in n-dodecane from nitric acid solutions. The main extracted species of Nd(III), Sm(III), Gd(III), Dy(III), Ho(III) and Er(III) were studied at different nitric acid concentrations by the slope analysis method and the enthalpy change of the extraction reactions was determined. The IR spectra of the extracted species were also investigated. The values of thermodynamic functions for the extraction of the lanthanides were calculated. The obtained results indicated that the effective separation of Ln(III) from Fe(III), Ni(II), Co(II) and Cs(I) can be obtained.

Lead Removal from Industrial Waste

As time goes on technology is developing very fast. With these developments, there is also contamination coming from the establishments producing these technologies, especially metal manufacturer. People are suffering from environmental and water contamination in heavy metal aspects. In this study, the heavy metal removal performance of poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine methyl ester), poly(HEMA-MAH) cryogel, a known polymer, in HNO3 was investigated. The effect of HNO3 on the adsorption process, especially for metals, is found very effective even in trace amounts. The characterization studies using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, water swelling tests and surface area analysis methods. At the end of the optimum conditions (time, concentration, etc.), to determine the heavy metal removal performance of cryogel, the real wastewater was used as obtained from an inorganic material manufacturer factory. Keywords: Cryogel; Heavy Metal; Removal; Wastewater. DOI: 10.17350/HJSE19030000041 Full Text: Research Article

Thermal stability and radiation resistance of trifluoromethyl phenyl sulfone in the presence of nitric acid

The effect of HNO3 on the thermal stability and radiation resistance of trifluoromethyl phenyl sulfone (FS-13) used as extractant diluent in high-level waste partitioning was studied. Heating of FS-13 in the presence of 14 M HNO3 is not accompanied by exothermic effects up to 160°С. The amount of gaseous products released in the course of heating the system consisting of FS-13 and HNO3 and the composition of the major radiolysis products of the system components at irradiation doses of up to 0.5 MGy were determined.

Extractive and sorption preconcentration of rhenium(VII) with the use of phosphoryl-containing podands

Interphase distribution of micro amounts of ReO 4 − between aqueous solutions of mineral acids and solutions of phosphoryl-containing mono-, di-, and tripodands, derived from 1-(methoxydiphenylphosphoryl)-2-diphenylphosphorylbenzene in dichloroethane was studied. The stoichiometry of extracted complexes was determined, the effect of HNO3, HCl, and H2SO4 concentration in aqueous phase and the nature of organic solvent on the efficiency of transition of ions into organic phase was considered. The growth of the number of phosphoryl groups in podand molecule enhances its extraction ability toward Re(VII). The possibility of selective recovery and preconcentration of Re(VII) with complexing sorbent obtained by noncovalent binding of phosphoryl-containing podand on the surface of macroporous polymer Amberlite XAD7HP was shown.

Effect of HNO<sub>3</sub> and H<sub>3</sub>PO<sub>4</sub> on Ion Exchange of Natural Zeolite for Making Agricultural Cultivation Solution from Seawater

Effects of HNO3 and H3PO4 on ion exchange of natural zeolite in a new-simple process, which is a twostep process using calcined hydrotalcite and natural zeolite, for making agricultural cultivation solution were examined. The anion-reduced solution obtained by the treatment of seawater with calcined hydrotalcite (CHT-solution) was neutralized with phosphoric (CHT-solution-H3PO4) or nitric acids (CHT-solutionHNO3), and each four solutions (seawater, CHT-solution, CHT-solution-H3PO4 and CHT-solution-HNO3) was treated with natural zeolite to compare the ion exchange behaviors among these solutions. The pH of the all solutions can be neutralized to 5.5 by zeolite treatment, and the Na+ content can be removed from the all solution. The tendencies of Na+ removal in all solutions are almost same, and percentages of Na+ removal from all solutions are above 95% over 8 times zeolite treatment. The amounts of supplies for K+, Mg2+ and Ca2+ to the CHT-solution-HNO3 is higher than those of other solutions up to 6 times treatment. While almost PO43- was removed, NO3- was remained in the solution, over 6 times treatment with natural zeolite. Therefore, NO3- is possible to be supplied to the solution as nutrient in the two-step process, but PO43- isn't possible.

The nature of nitrate at the ice surface studied by XPS and NEXAFS

Trace contaminants such as strong acids have been suggested to affect the thickness of the quasi-liquid layer at the ice/air interface, which is at the heart of heterogeneous chemical reactions between snowpacks or cirrus clouds and the surrounding air. We used X-ray photoelectron spectroscopy (XPS) and electron yield near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Advanced Light Source (ALS) to probe the ice surface in the presence of HNO(3) formed from the heterogeneous hydrolysis of NO(2) at 230 K. We studied the nature of the adsorbed species at the ice/vapor interfaces as well as the effect of HNO(3) on the hydrogen bonding environment at the ice surface. The NEXAFS spectrum of ice with adsorbed HNO(3) can be represented as linear combination of the clean ice and nitrate solution spectrum, thus indicating that in the presence of HNO(3) the ice surface consists of a mixture of clean ice and nitrate ions that are coordinated as in a concentrated solution at the same temperature but higher HNO(3) pressures.

A role of HNO3 on transparent conducting film with single-walled carbon nanotubes

There is some controversy regarding the effects ofHNO3 on filmsof single-walled carbon nanotubes (SWCNTs). In this study we examined the change in sheet resistanceof an HNO3-modified SWCNT film after different drying times at85 °C using various analytical techniques. The shift and suppression in the Raman spectra,bleaching of the transition peaks related to van Hove singularities and a shift in the originalpeak in the C 1s XPS spectra provided evidence for p-type doping. A decrease in sheetresistance was also observed in the SWCNTs films due to the removal of residualN-methylpyrrolidone solvent on the surface and bundle of SWCNTs. These results suggestthat p-type doping has a larger effect on the sheet resistance than the removal of residualN-methylpyrrolidoneby an HNO3 treatment.

Effect of HNO3 on crystalline phase evolution in lithium silicate powders prepared by sol–gel processes

An interesting observation is reported on the dramatic effect of HNO3 on crystalline phase evolution in the 33.3 mol% Li2O–SiO2 glass–ceramic (stoichiometric composition of lithium disilicate Li2Si2O5, LS2) prepared by sol–gel processes from tetraethylorthosilicate (TEOS) and lithium ethoxide precursors. Nitric acid (65%), in molar ratio HNO3/TEOS = 0.1, was added either to the precursor sol or to 95 °C dried gel. The product, which is amorphous at temperatures below 450 °C, transforms into crystalline lithium metasilicate (Li2SiO3, LS) at around 550 °C (starting temperature ∼450 °C), instead of forming crystalline LS2. Phase separation in the glassy phase may be responsible for the formation of lithium metasilicate. XRD, 29Si MAS, and 7Li static NMR were used to follow the crystallization evolution and network structures of the materials heat-treated at various temperatures.

Influence of nitric acid on atmospheric corrosion of copper, zinc and carbon steels

In this study, the effects of subppm levels of nitric acid (HNO3) on corrosion of copper, zinc and carbon steels are studied and compared with other reported data on corrosion of the same materials exposed to sulphur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3). The deposition velocity Vd of HNO3 on the specimens, the corrosion rates and corrosion products of metals are determined by gravimetry, ion chromatography, X-ray diffraction and Fourier transform infrared (FTIR) microspectroscopy. The effect of HNO3 contaminated air on the corrosion rate of metals is far above that of SO2, NO2 or O3. This is mainly attributed to the relatively high sticking coefficient, water solubility and reactivity of HNO3. Despite the fact that ambient SO2 levels are still much higher than HNO3 levels, the results show that HNO3 plays a significant role for corrosion of copper and zinc, but not for carbon steel.