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In recent years, hydrogels have been employed to fabricate flexible capacitors (FCs) and wearable sensors. However, achieving a balance between the electrochemical and mechanical properties of hydrogels remains a challenge. Herein, polyacrylamide/sodium alginate (PAM/SA) dual-network hydrogels with good mechanical properties and high electrochemical properties were obtained by nitric acid (HNO3) mediation. The –COO– groups on the SA network inside the hydrogel are partially acidified to –COOH under the action of HNO3, which increases the hydrogen bond density of the hydrogel. The PAM/SA hydrogel exhibited a maximum mechanical strength of 83.4 KPa and a maximum elongation at break of 471.3%. Furthermore, the conductivity (σ) of PAM/SA dual-network hydrogels increased from 36.48 mS cm−1 to 96.4 mS cm−1, and the specific capacitance of the flexible capacitor (FC) composed of the hydrogels increased by about 142.1%. Finally, the hydrogel was prepared as a wearable motion sensor, which is capable of accurately detecting the different motion states of a person. Consequently, the hydrogel has a multitude of applications in the field of FCs and wearable sensors. [ABSTRACT FROM AUTHOR]

The Ostwald process, which is producing HNO3 for commercial use, involves the catalytic oxidation of NH3 and a series of chemical reactions conducted under severe operating conditions. Due to their energy‐intensive nature, these activities play a major role in greenhouse gas emissions and global energy consumption. In response to the urgent requirements of the global energy and environmental sectors, there is an increasingly critical need to develop novel, highly efficient, and environmentally sustainable methods. Herein, CoPc/C3N4 electrocatalyst, integrating CoPc nanotubes with C3N4 nanosheets, is shown. The CoPc/C3N4 electrocatalyst demonstrates yield rate of 871.8 µmol h−1 gcat−1 at 2.2 V, with corresponding Faradaic efficiency (FE) of 46.4% at 2.1 V, which notably surpasses that of CoPc. Through a combination of experimental investigations and density functional theory (DFT) calculations, this study shows that CoPc anchored on C3N4 effectively simplifies the adsorption and activation of chemically inactive nitrogen molecules. The improved catalytic activity for composite system may be the reason of re‐distribution of charges over the CoPc, tuning the valence orbital of Co center due to the presence of 2D layer of C3N4. This mechanism significantly lowers the energy barrier required for critical breaking of inert N2, ultimately leading to a significant improvement in N2 oxidation efficiency. [ABSTRACT FROM AUTHOR]

Recently, an unusual method of home burglary has emerged in several European countries. Nitric acid is used to attack the tumbler lock of the front door. The aim of this study is to gain insights into the technical functioning of this method and to evaluate the advantages and disadvantages of this modus operandi. For this purpose, four pin‐tumbler locks were attached to a custom‐made holder and 65% nitric acid was successively injected into the key channel using a syringe. The locks were checked manually and using a CT scanner to see whether the lock was overcome and how the acid did affect the pins and springs. In three out of four cases the lock was overcome. The shortest time was 22 min until the pin pairs could be removed and it was possible to turn the core with a screwdriver. Overall, the results show that the modus operandi works with standard locks. According to the authors, the long duration and the high health risk are significant disadvantages in relation to other overcoming methods. [ABSTRACT FROM AUTHOR]

N,N-diethylhydroxylamine (DEHA) is a new salt-free reducing agent applied in the separation of Pu from U in the reprocessing of irradiated fuel from nuclear power plants. The effect of monomethylhydrazine (MMH) on the γ-rays radiolysis of DEHA-HNO3 solution is presented in this paper. MMH can effectively enhance DEHA stability against radiation, and the main radiolytic products are H2, CH4, CH3CHO, CH3COOH and HNO2. The content of H2, CH4, CH3CHO and CH3COOH is raised with the dose. The amount of H2, CH4 and CH3CHO enhances with the MMH concentration, but CH3COOH concentration is reduced when MMH concentration is raised. [ABSTRACT FROM AUTHOR]

The density of aqueous solutions containing actinide nitrates is an important parameter for process design, equipment design, and remote operation/control. It is also significantly important for the estimation of atom densities during criticality calculations and related experiments involving actinide solutions. Using a massive database of 1353 points consisting of in-house-generated data as well as data published in the literature, a robust estimation of the coefficients of a re-parameterized and dimensionally consistent form of density equation was performed in the following range of parameters: U(VI) concentration 0 to 1330 g/L, Pu(IV) concentration 0 to 1201 g/L, HNO3 concentration 0 to 15.8 M, and temperature range of 283.15 to 373.15 K. This paper lists the details of the new database, the newly estimated coefficients, and the performance evaluation of the proposed re-parameterized dimensionally consistent equations. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The gamma radiolytic degradation behavior of n‐dodecane (n‐DD) was investigated under conditions both with and without the presence of nitric acid. The physicochemical property alterations due to radiolysis were quantified and compared against an unirradiated system. Compositional changes in n‐DD post radiolysis was measured, and the degraded n‐DD was characterized using Fourier‐transform infrared (FT‐IR) spectroscopy, gas chromatography (GC), and gas chromatography–mass spectrometry (GC–MS) analysis. The presence of nitric acid was observed to accelerate the radiolytic degradation of n‐DD. The extent of diluent degradation caused by gamma irradiation was assessed through the retention behavior of uranium [U(VI)], plutonium [Pu(IV)], and zirconium [Zr(IV)] in 1.1 M tri‐n‐butyl phosphate (TBP) in irradiated diluent. Furthermore, the effectiveness of hydrazine carbonate (HC) as a solvent wash reagent for the removal of diluent degradation products was evaluated. [ABSTRACT FROM AUTHOR]

AbstractResins impregnated with organic extractants regarded as effective adsorbent materials due to their ability for selective sorption. These resins consist of a polymeric material that is infused with accessible organic extractants. Furthermore, these resins merge the unique properties and the distinctive characteristics of both liquid-liquid extraction and solid-liquid sorption processes. In this work, the impregnation of Styrene divinyl benzene beads (SM-2 beads) with triisobutylphosphine sulfide (TIBPS = CYANEX 471X) was prepared. A SM-2 bead functionalized with CYANEX 471X (SM-2-TIBPS beads) was characterized using scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FT-IR) techniques and investigated for recovery and separation of palladium ions from a 3 M nitric acid solution. Various parameters were studied, as shaking time effect, nitric acid concentration, SM-2-TIBPS beads weight, Pd(II) concentration and temperature. The Pd(II)/SM-2-TIBPS sorption system has an endothermic nature and was fitted with a Langmuir isotherm model with a 0.9860 regression factor. The kinetics modeling was fitted with PSO and IPD models with regression factors of 0.9889 and 0.9959, respectively. The maximum monolayer sorption capacity of SM-2-TIBPS was found to be 17.47 ± 0.9 mg/g. The sorption of Pd(II) from different media at 3 M takes the following sequence: HNO3 > HCl > H2SO4. Desorption of about 76.38 ± 2.4% was achieved with (1 M + 1 M) of thiourea + HCl after one desorption stage. Effect of other interfering ions, as Pt(II), Pb(II), Eu(III), Cu(II), Mo(VI), Co(III), Zr(IV), Fe(III), Cd(II), and Ce(III), indicates high separation factors between Pd(II) and other investigated metal ions, which ranged from 9.4 to 35. [ABSTRACT FROM AUTHOR]

Hydrazine and its derivatives have served as a conventional bipropellant fuel for several decades. However, their extremely acute toxicity and carcinogenicity, high volatility, and environmental impact have attracted significant attention. In order to synthesize green bipropellant fuels with high density, high specific impulse, and good thermal stability, three novel N -alkyl-1,2,4-triazole–borane complexes were successfully synthesized by reacting alkylated 1,2,4-triazole coordinated with sodium borohydride in the presence of ammonium sulfate. During the droplet test with white fuming nitric acid, there was a relatively short ignition delay time of 98 ms. Additionally, these hypergolic fuels possessed a high density exceeding 1.10 g cm–3 , and the specific impulse is ranging from 187 to 199 s, and the highest decomposition temperature reaches 153.4 °C. These results demonstrate their great potential as hypergolic fuels or hypergolic ionic liquid additives in the field of hypergolic materials. [ABSTRACT FROM AUTHOR]

An online graphite crystal pre‐diffraction x‐ray fluorescence technique was developed for accurate real‐time detection of trace uranium concentrations in spent‐fuel reprocessing streams. Online analysis for determining uranium concentrations was established. The device was equipped with measurement windows in both the flow cell and a side wall of the glove box. X‐ray tubes and detectors were arranged outside the glove box, and the process stream flowing through the flow cell was measured through the measurement window. A cylindrical highly oriented pyrolytic graphite crystal was located in front of the detector to improve detection efficiency and to provide monochromatic uranium‐characteristic x‐rays. At the same time, the device could perform remote online automatic calibration. The uranium detection limit in a kerosene solution was 0.08 mg/L, and the quantitative limit was 0.27 mg/L. The detection limit in a nitric acid solution was 0.11 mg/L, and the quantitative limit was 0.37 mg/L. The relative standard deviation of measuring 0.5 mg/L uranium was less than 10%, which greatly improved online monitoring of trace uranium in spent‐fuel reprocessing samples. [ABSTRACT FROM AUTHOR]

The production of nitric acid represents the primary source of nitrous oxide (N2O) emissions. During pilot-scale studies of N2O reduction on a low-temperature catalyst on nitric acid plants, it was observed that increasing the concentration of NH3 resulted in a decrease in the degree of N2O decomposition. This suggested that N2O was formed by the oxidation of NH3. Measurements at different temperatures, conducted after the N2O reduction trials, resulted in the N2O concentration at the inlet equal to the concentration at the outlet, indicating catalyst deactivation. To identify the causes of deactivation, the physicochemical properties of the catalyst were investigated. XRF analysis revealed the presence of sulfur. The results suggest the necessity of removing sulfur from the raw gas before the reduction of N2O on the low-temperature catalyst in practical applications. [ABSTRACT FROM AUTHOR]

Thermal ignition of radioactive waste within a 55-gallon drum was simulated by using a pressure-dependent waste decomposition model (Hobbs et al. in Process Saf Environ Prot https://doi.org/10.1016/j.psep.2022.09.047, 2022) calibrated with data from full-scale drum experiments (Parker et al. in The thermolytic response of a surrogate RNS waste mixture at the drum scale. Los Alamos National Laboratory Report LA-UR-16-21760, 2016) and validated with experiments from multiple laboratories (Hobbs et al. in Thermal analysis of aged nitric acid-soaked kitty litter in TRU waste drums-23370.WM2023 Conference, Phoenix, AZ, 2023). The acceleration of nitric acid chemistry reacting with an organic cat litter leading to thermal ignition was likely triggered by a restricted vent in the drum. Here, we address whether the form of the rate equation in (Hobbs et al. in Process Saf Environ Prot https://doi.org/10.1016/j.psep.2022.09.047, 2022) is sufficient to extrapolate thermal ignition within aged drums of similar content that have been stored in Texas for over nine years by investigating four different reaction rate forms for waste decomposition. A critical reaction rate reduction analysis is performed on each of these models to determine if delayed thermal runaway within vented aged waste is possible after nine years. We found that a pressure-dependent first-order rate expression not only predicted the accidental ignition of the waste drum, but the form also matches multiple experiments from different laboratories. Even though the waste composition decreases over time, the model predicts that acceleration leading to thermal runaway is possible if the waste is confined, even after 9 years. Waste containing oxidizers such as nitric acid should not be mixed with organic adsorbents, especially if the waste is confined. [ABSTRACT FROM AUTHOR]

The extraction of rare earth elements (REEs) from mineral resources is of significant global importance due to their critical role in modern technologies. This study focuses on the leaching behavior of artificial cerium and lanthanum phosphates using nitric, sulfuric, and hydrochloric acids under varying conditions of acid concentration and temperature. Our experiments demonstrated that the maximum extraction efficiency of lanthanum and cerium was achieved with nitric acid solutions at concentrations of 12.5 mol/dm3, with 85.0% and 79.1% extraction efficiency, respectively. The leaching mechanism involved the protonation of phosphate anions, which disrupted the phosphate matrix, facilitating the dissolution of lanthanum and cerium into solution. Sulfuric acid, although less effective at room temperature, proved to be the most thermodynamically favorable leaching agent at higher temperatures due to the formation of stable sulfate complexes. Additionally, hydrochloric acid displayed high selectivity for cerium extraction, although its applicability is limited by complexation and environmental concerns. This study offers new insights into optimizing REE recovery from phosphates, demonstrating the advantages of sulfuric acid for industrial-scale leaching processes due to its economic and thermodynamic benefits. The novelty of this work lies in its systematic comparison of the three acids' effects on REE extraction, providing a comprehensive framework for selecting optimal leaching agents based on specific operational conditions. [ABSTRACT FROM AUTHOR]

The rapid formation of secondary nitrate (NO3−) contributes significantly to the nocturnal increase of PM2.5 and has been shown to be a critical factor for aerosol pollution in the North China Plain (NCP) region in summer. To explore the nocturnal NO3− formation pathways and the influence of ozone (O3) on NO3− production, the WRF-CMAQ model was utilized to simulate O3 and PM2.5 co-pollution events in the NCP region. The simulation results demonstrated that heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) accounts for 60% to 67% of NO3− production at night (22:00 to 05:00) and is the main source of nocturnal NO3−. O3 enhances the formation of NO3 radicals, thereby further promoting nocturnal N2O5 production. In the evening (20:00 to 21:00), O3 sustains the formation of hydroxyl (OH) radicals, resulting in the reaction between OH radicals and nitrogen dioxide (NO2), which accounts for 48% to 64% of NO3− formation. Our results suggest that effective control of O3 pollution in NCP can also reduce NO3− formation at night. [ABSTRACT FROM AUTHOR]

Solvent extraction behaviors of Se (VI) from nitric acid solutions were investigated with multiple extractants used for uranium, plutonium, minor actinides, and rare earth elements separation processes from high-level liquid waste. During the processes, Se remained in the residual aqueous solutions, as all extractants showed distribution ratios < 1. In contrast, Se showed distribution ratios > 1 with o-phenylenediamine in dilute nitric acid (< 2 M HNO3), octanol as the organic phase, and concentrated nitric acid (8 M HNO3) for back extraction, suggesting a potential new single separation process and recovery of Se. [ABSTRACT FROM AUTHOR]

Yttrium-90 (90Y) microsphere radioembolization is a promising internal therapy for treatment of hepatic tumors. Development of a precise method for measuring the activity of 90Y in blood samples is needed to facilitate preclinical safety assessment of drugs. This paper presents the development of a triple-to-double coincidence ratio (TDCR) Cherenkov counting method for quantifying blood 90Y activity. The impact of heating temperature and the quantities of nitric acid and H2O2 on wet oxidation of blood were studied for rapid sample preparation. Elevated heating temperatures and the addition of concentrated nitric acid expedited blood decolorization and effectively suppressed chemiluminescence interference. The addition of H2O2 also accelerated blood decomposition while mitigating sample color quenching. The digested samples were counted using a Hidex 300SL liquid scintillation counter for 5 minutes, and a minimum detectable activity of 0.31 kBq/L was achieved with the region of interest (ROI) analysis window set at 80–300 channels. The method was validated using whole blood samples spiked with varying activities of 90Y in the range of 3.37–51.15 kBq/L. [ABSTRACT FROM AUTHOR]

Four chromatographic supports were functionalized with bis-(2-ethylhexyl) phosphoric acid (HDEHP) and examined for radiation stability when used for f-element separations after exposure to high levels of ionizing gamma radiation. Changes in Eu(III) partitioning were evaluated and compared to an analogous solvent extraction system using HDEHP in n-dodecane. The solvent extraction system showed an increase in Eu(III) uptake with increasing γ irradiation dose to the solvent in the presence of nitric acid. The Eu(III) distribution profiles indicate that the functionalized chromatographic support materials are less affected by γ irradiation, when exposed in a radiation environment of up to 2.5 MGy in the presence of nitric acid. [ABSTRACT FROM AUTHOR]

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acid digestion is the most ideal detection method for the determination of copper in copper concentrate, which is commonly treated with hydrochloric acid and nitric acid. However, for some insoluble copper-containing material samples, there is always black residue that cannot be treated in the later stage of dissolution, and adding saturated ammonium fluoride after adjusting acidly before titration can produce dark purple flocculent precipitation, witch seriously affect the titration analysis, resulting in large deviation and inaccurate analysis results. In this study, copper-containing material waste dissolved by acid dissolution, insoluble material was filtered and separated, and the residue was analyzed and corrected. The conditions such as the amount of hydrofluoric acid and the amount of nitric acid used in the dissolution of filtered filter residue were optimized by experiments, and the final experimental method was established. The determination results were consistent with the results of laboratory outsourcing, and the relative standard deviation (RSD) was 0.060% -- 0.16%, which showed that this method was accurate, rapid, stable and reliable for the determination of copper content in copper materials in the range of 12.5%--24.5%. [ABSTRACT FROM AUTHOR]

The high-field-strength elements in diorite mainly occur in insoluble minerals (hornblende, zircon, etc.). The recoveries of high-field-strength elements, especially zirconium and hafnium, are low due to the conventional sealed acid digestion method. To solve this problem, according to the occurrence state of high-field-strength elements, this study added the pre-digestion process, and deigned three factor and three--level orthogonal experiment including the amount of reagents (hydrofluoric acid, nitric acid) and the digestion lime. According to the experiment, the optimal reagent addition amount was 2 mL hydrofluoric acid and 1 mL nitric add, and the digestion lime was 36 hours. The most important factor affecting the recoveries of high field strength elements-was hydrochloric aid. This study added 0.1% hydrochloric add (volume ratio) to the dissolved solution to ensure the stability of high field strength elements. High-field-strength elements contents of diorite in the Beishan area were determined by the method, which was consistent-with the results determined by alkali fusion and X-ray fluorescence methods. Detection Units of the method were in the range of 0.004 -- 2.5 µg/g with relative standard deviations of 1.5%-8.4% and recoveries of 93.0%-108%.As a result, accurate analysis of high-field-strength elements in diorite is realized. [ABSTRACT FROM AUTHOR]

Mutual separation of Y(III) and Sr(II) from their waste solution has been an emerging research domain due to their various industrial applications. In this investigation, we emphasize the feasibility of selective separation of Y(III) from Sr(II) present in nitric acid medium using undiluted cyphos nitrate ionic liquid (IL): trihexyl(tetradecyl)phosphonium nitrate ([P66614][NO3]) as the ligating phase. The set experimental parameters were the feed phase acidity, initial nitrate ion concentration, initial feed metal ion concentration, equilibration time and temperature to unveil the efficacy of the proposed system. Efficient extraction of Y(III) selectively in presence of Sr(II) using only a salting agent in aqueous phase without additional extractant in IL phase was highlighted. A remarkable separation factor (SF) obtained for Y(III) over Sr(II) explored the efficacy of the proposed IL system. Y(III) loading in IL phase both in unirradiated and irradiated conditions was compared to evaluate the coordination behavior of irradiated moieties. In addition, a most important advantage of the proposed system is that it employs Milli‐Q water for the back extraction (stripping) of the loaded Y(III) from IL phase and does not demand any complexing agent (water soluble). This undoubtedly corroborates the economic and environmental benefits of the proposed IL system. [ABSTRACT FROM AUTHOR]

The article "Collision of liquid drops: bounce or merge?" delves into the intricate physics behind determining whether liquid drops will bounce or merge upon collision. It reveals that nanoscale phenomena, such as gas-kinetic and disjoining pressure effects, play a significant role in these outcomes. Through simulations, the study offers new predictions that align well with past experiments and examines the impact of gas pressure on drop behavior. By focusing on drop collisions in a gaseous environment, the research sheds light on the factors influencing bouncing and merging, emphasizing the importance of additional experimental validation. [Extracted from the article]

This work is an attempt to understand and optimize the rare earth elements leaching from Moroccan phosphogypsum using a nitric acid solution. The Plackett–Burman statistical design was used to identify the statistically significant factors responsible for the optimum leaching conditions. With this purpose, the following seven variables were studied: nitric acid concentration (X1), solid‐to‐liquid ratio (X2), temperature (X3), leaching time (X4), stirring speed (X5), drying (X6), and particle size (X7). Given that the leaching recovery of rare earth elements is limited by the quantity of dissolved phosphogypsum, we examined two simultaneous responses, namely, the leaching efficiency of rare earth elements YREEs and the leaching efficiency of calcium YCa (dissolution rate of phosphogypsum). The predicted values of the two fitted models were in good agreement with the experimental values by a coefficient of determination (R2) equal to 98.6% and 96.50%, respectively. In the model of YREEs, only the effect of drying was found to be statistically insignificant with a p‐value greater than 0.05. Nitric acid concentration, solid‐to‐liquid ratio, and temperature are the only variables having a statistically significant effect in the model of YCa. At a dissolution rate of phosphogypsum equal to 30.13%, the leaching efficiency of rare earth elements from our sample has reached a maximum of 87.55%. The optimal experimental conditions are a nitric acid concentration of 3.3 M, a solid‐to‐liquid ratio of 1/9, a temperature of 75°C, a leaching time of 20 min, a stirring speed of 200 rpm, and d ≤ 100 µm as a particle size. [ABSTRACT FROM AUTHOR]

We report a generalized route for synthesizing pure SnO2 and Cu (1 and 3 at%) doped SnO2 at room temperature with crystallite size in a nanometer range of 1.0–3.0 nm using CuCl2, nitric acid and Sn metal. The structural properties of these samples were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The open system was used to monitor heat generation. Thin films of SnO2 and SnO2:xCu nanocrystallites were prepared using a mixture of surfactant (docusate sodium salt), SnO2, water and cyclohexane. H2S sensing at room temperature was performed. The Cu-doped SnO2 sample showed higher sensitivity than pure SnO2, and its sensitivity was more than that of the reported ones. [ABSTRACT FROM AUTHOR]

Photocatalytic nitrogen oxidation reactions has emerged as promising techniques for air‐based nitrate synthesis, bolstering sustainable nitrogen fixation in industrial chains centered around nitrates. However, significant disparities in orbital energy levels impose constraints on N2 conversion, highlighting the pivotal role of nitrogen activation, particularly in oxygen‐rich environments. Herein, a novel Ir‐WO3 catalyst with cation vacancy chains is fabricated and utilized as a highly efficient catalyst for thermal‐assisted nitrogen oxidation under an innovative discontinuous light illumination strategy. Remarkably, an unexpected NO3− yield of 381.21 µmol g−1 h−1 is achieved, marking a 10.4‐fold increase compared to regular continuous light illumination. This exceptional performance is attributed to the unique structure and discontinuous light illumination, which lowered the energy barrier of the rate‐determining step for forming *NN(OH) intermediates and enhanced the abundance of •OH. Furthermore, a novel •OH assisted nitrogen activation mechanism is proposed based on the identification of crucial N2O intermediate and operando experiments. This work offers novel insights into free radicals‐based photocatalytic conversion processes and also presents a potential nitrate synthesis pathway for nitrates‐centric industrial nitrogen fixation chains. [ABSTRACT FROM AUTHOR]

Enzyme immobilization can offer a range of significant advantages, including reusability, and increased selectivity, stability, and activity. In this work, a central composite design (CCD) of experiments and response surface methodology (RSM) were used to study, for the first time, the L‐asparaginase (ASNase) immobilization onto functionalized carbon xerogels (CXs). The best results were achieved using CXs obtained by hydrothermal oxidation with nitric acid and subsequent heat treatment in a nitrogen flow at 600 °C (CX−OX‐600). Under the optimal conditions (81 min of contact time, pH 6.2 and 0.36 g/L of ASNase), an immobilization yield (IY) of 100 % and relative recovered activity (RRA) of 103 % were achieved. The kinetic parameters obtained also indicate a 1.25‐fold increase in the affinity of ASNase towards the substrate after immobilization. Moreover, the immobilized enzyme retained 97 % of its initial activity after 6 consecutive reaction cycles. All these outcomes confirm the promising properties of functionalized CXs as support for ASNase, bringing new insights into the development of an efficient and stable immobilization platform for use in the pharmaceutical industry, food industry, and biosensors. [ABSTRACT FROM AUTHOR]

Gaseous air pollutants emitted primarily by anthropogenic sources form secondary products through photochemical reactions, complicating the regulatory analysis of anthropogenic emissions in the atmosphere. We used an environmental chassis dynamometer and a photochemical smog chamber to conduct a parameter sensitivity experiment to investigate the formation of secondary products from a gasoline passenger car. To simulate the mitigation of ammonia emissions from gasoline vehicle exhausts assuming future emission controls and to allow photochemical oxidation and aging of the vehicle exhaust, ammonia was selectively removed by a series of five denuders installed between the vehicle and photochemical smog chamber. Overall, there were no differences in the formation of secondary organic aerosols and ozone with or without ammonia mitigation. However, the potential for ammonium nitrate particle formation was significantly reduced with ammonia mitigation. In addition, ammonia mitigation resulted in increased aerosol acidity due to nitric acid in the gas phase not being neutralized by ammonia and condensing onto the liquid particle phase, indicating a potentially important secondary effect associated with ammonia mitigation. Thus, we provide new insights into the effects of ammonia mitigation on secondary emissions from gasoline vehicle exhaust and into a potentially useful experimental approach for determining primary and secondary emissions. [ABSTRACT FROM AUTHOR]

The paper presents the results of processing niobium-containing fluoride cinders to obtain niobium concentrate from them. The material composition of the cinder was studied by chemical and X-ray methods. X-ray phase analysis showed the presence of ammonium aluminium fluoride, ammonium iron fluoride, ammonium titanium fluoride, as well as niobium-containing sodium niobium fluoride. Leaching of the fluoride cinder was carried out with ammonia water at temperatures of 60 - 80°C until a precipitate was formed at pH = 9 with vigorous stirring at 300 rpm, for 90 min. Nitric acid purification of the sludge was performed with a nitric acid solution within 4 - 10 %, at 60°C, with a S:L ratio of 1:5 and an agitation time of 120 min. 8 % HNO3 was chosen as the optimum concentration of nitric acid. After washing the obtained cake was calcined at 500°C for 120 min. The niobium concentrate containing 57.5 % Nb2O5 was obtained according to the study results. [ABSTRACT FROM AUTHOR]

In this work, with the aim of increasing the monomer conversion rate in the styrene-graphite in situ polymerization system, graphite modification methods have been investigated. Modification of the graphite in the presence of nitric acid, sodium hydroxide or sodium dodecyl benzene sulfate (SDBS) was investigated with five different methods in order to reduce its adverse effects on the polymerization rate of styrene. The most effective modification approach was determined using quantitative data such as polymerization conversion and graphite dispersion in organic phase. Compared to other modified samples and unmodified graphite, graphite modified in sodium hydroxide solution with SDBS showed the most compatibility with the polymerization system and caused a significant increase in the monomer conversion rate. Monomer conversion increases by 22% and 29% respectively in the presence of 0.5% and 2% of the best modified graphite compared to non-modified graphite. Also, the results showed that this modification method stabilizes the suspension of graphite particles in styrene for a longer period of time than other methods. [ABSTRACT FROM AUTHOR]

This article discusses the use of lignocellulose, a renewable source of chemical products, for the production of high-value compounds. The authors focus on the nitration of lignin-derived monomeric products, such as vanillin, to produce 5-nitrovanillin. They explore the use of acetyl nitrate as a nitrating agent and highlight its advantages over other methods. The study demonstrates that the nitration of vanillin is highly selective and can be carried out in a simple and efficient manner. The authors hope that this research will contribute to the practical applications of lignin-derived structures and enhance our understanding of their reactivities. [Extracted from the article]

The development of efficient recovery methods for waste printed circuit boards (WPCBs) not only tackles the environmental risks of disposal but also promotes the conservation of resources within the electronics industry. This study proposes a two-step leaching approach for recovering metals from WPCBs. Initially, transition metals are leached using nitric acid, followed by the recovery of precious metals with thiourea in the second stage. In the first stage, dissolution rates exceeding 90 wt% were achieved for transition metals, including Cu, Fe, Ni, Pb, and Sn. In this stage, the dissolution of precious metals (i.e., Au and Pd) was insignificant. In the second stage, the effect of four parameters was investigated, including the impact of temperature, concentrations of ferric ions, sulfuric media, and thiourea on the recovery of Au and Pd. Precise control over sulfate concentration played a vital role in achieving maximum Au recovery. The optimal acid concentration was 0.2 M, resulting in a recovery rate of ~50 wt%. Ferric ion concentration positively affects Au recovery, whereas, in extracting Pd, optimal conditions imposed the absence of ferric ions. Thiourea concentration positively impacted Au and Pd recovery rates, peaking at 49 wt% for Au at 1 M and 44 wt% for Pd at 1.5 M. Prolonged leaching resulted in declining Au recovery rates, indicating a decrease in reagent concentration. Temperature variation yielded similar outcomes, with 50 °C resulting in peak recovery rates of 53 wt% for Au and 54 wt% for Pd. Metal dissolution kinetics during leaching were analyzed using pseudo-first-order and pseudo-second-order models. The second-order model proved suitable for transition metals in the first stage, while only for Au and Pd in the second stage (with R2 = 0.99). [ABSTRACT FROM AUTHOR]

This study aims to develop a liquid-liquid equilibrium model to predict the Ce distribution in the extraction system based on experimental laboratory data. Extraction feed solution (Ce hydroxide in nitric acid media) and solvent (Tri Butyl Phosphate (TBP) in kerosene diluent) with a volume ratio of 1:1 at various concentrations of feed and solvent were contacted using a mechanical shaker at 150 rpm for 15 minutes. The solution was settled for 30 minutes to separate the aqueous and organic phases. Cerium concentration in the aqueous phase was analyzed using XRF, while cerium concentration in the organic phase was calculated using a mass balance. The results showed that the extraction of Ce from the Ce-hydroxide concentrate was successfully carried out using TBP 0.92 M in kerosene diluent so that the Ce extraction efficiency of 70% was obtained. The equilibrium model that has been developed was able to represent the phenomenon of the liquid-liquid equilibrium distribution in the extraction system, which was carried out with an average relative error of 8.53%. Five stages of extraction unit need to apply to achieve 90% of extraction efficiency. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Anopheles arabiensis, a highly adaptable member of the Anopheles gambiae complex, poses a challenge for control efforts due to its outdoor biting and resting behaviour. Consequently, indoor insecticide‐based control methods are ineffective against An. arabiensis. Furthermore, An. arabiensis are adapting to breeding in polluted waters, and may be contributing to residual malaria and malaria in urban areas. There have been some advances in understanding the effect of rural pollutants on Anopheles mosquitoes, but the effect of urban pollutants is poorly understood. Thus, in this study, the effect of acidic pollutants [nitric acid (HNO3) and hydrochloric acid (HCl)] and alkaline pollutants (phosphate‐free and phosphate‐containing detergent) on two laboratory‐reared An. arabiensis strains – an insecticide susceptible strain (SENN) and an insecticide‐resistant strain selected from SENN (SENN‐DDT) – were determined. RESULTS: The median lethal concentration (LC50) and larval exposure on larval development, adult longevity and insecticide tolerance were evaluated. Nitric acid and phosphate‐containing detergent were found to be more toxic than HCl and phosphate‐free detergent in terms of LC50 values. Detergent exposure (both phosphate‐containing and phosphate‐free) increased adult longevity of both strains. Nitric acid reduced larval development time in both SENN and SENN‐DDT, whereas HCl reduced larval development time in SENN only. By contrast, both phosphate‐containing and phosphate‐free detergents increased larval development time of both strains. Furthermore, HNO3 and phosphate‐containing detergent increased insecticide tolerance the most. CONCLUSION: The two An. arabiensis strains responded to urban pollutants differently. Thus, this study provides insight into the adaptation of An. arabiensis to acidic and alkaline urban pollutants. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Phosphate rocks, as well as their derivatives and by-products, are complex minerals that make elemental analysis very complicated. Iodine is commonly found in these matrices, and its concentration must be controlled. The present work describes the development of a novel rapid digestion protocol based on ultrasonic-assisted acid digestion for the determination of iodine in phosphate rock and phosphogybsum samples by Iodometric titration. The developed method occurs at low digestion temperature and uses a dilute nitric acid 5% (v/v) solution instead of concentrated acid. The investigated parameters influencing UAD, were completely optimised using experiments design methodology (DOE). Iodine recoveries from dilute nitric acid digestion without sonication were generally lower overall when compared to UAD results, illustrating the effect of ultrasound on iodine dissolution. This technique effectively addresses iodine volatilisation and sample losses problem encountered while using classical digestions. Method validation included: defining the detection and quantification limit of iodine using this method were about 2.2 and 8 mg.kg−1, respectively, and it's suitable for the proposed application. Moreover, the repeatability and reproducibility, expressed as RSD for phosphogybsum sample was 7%, 8.3% respectively, while for phosphate samples is tacked as the mean of relative standard deviation 3.4%, 3.8%. Additionally, accuracy of the method was assessed by analysing a certified reference material and the iodine concentration was found to be in good agreement with the indicative values for this CRM. Thus, the mean recoveries in fortified sample were between 96% and 107%.The developed method is fast, accurate, and it is applicable to the monitoring of iodine in the phosphate industries. [ABSTRACT FROM AUTHOR]

Power components under corrosive environmental conditions are subjected to the double damage of corrosion and wear, and the reciprocating action of the load makes the passivation layer on the metal surface fail and accelerates the damage. Amorphous carbon-based films show the excellent protection in the areas of corrosion and friction. For studying the effect of load on the corrosion and wear properties of amorphous carbon-based thin films, and clarifying the relationship of the each loss component with the change of the load, thin films of a-C, a-C:Cr and a-C:Si were prepared on the surface of 304 stainless steel by magnetron sputtering. Meanwhile, the static corrosion behavior of three films under 5.0 mol/L HNO3 was tested by kinetic potential polarization, and the effect of load on each component of the corrosion friction process was also analyzed and studied by combining the wear amounts of the three films under different loads in deionized water and 5.0 mol/L HNO3 environments. Results showed that Si doping reduced the corrosion current density of a-C films from 1.11×10-6 A/cm2 to 3.96×10-7 A/cm2, while Cr doping slightly decreased the corrosion current density. As the load increased, the corrosion damage component of the three films decreased and the mechanical wear component increased accordingly, corresponding to a weakening of the damage effect on the films due to the corrosion-wear interaction.

5‐Hydroxymethylfurfural (HMF) was transformed into 2,5‐diformylfuran (DFF) with nitric acid as the oxidant. The initial HMF content was as high as 12.5 wt %, and water was the sole solvent. This is an intensely exothermic reaction along with the emission of NO2 gas. A high DFF yield of 83.2 % was achieved if the oxidation ability of nitric acid matched with the requirement of target oxidation reaction while mismatched those of side reactions by regulating the initial concentration of nitric acid (59.5 wt %) and reaction temperature (50–60 °C). The oxidation reaction of HMF, overoxidation of HMF, and skeleton‐cracking reaction of FDCA preferred concentrated HNO3, hot HNO3, and concentrated or hot HNO3, respectively. After liquid‐liquid extraction, filtration, and column chromatography, light‐yellow DFF powders with purity of 92.1 wt % and isolated yield of 40.2 % were obtained and confirmed by NMR, FTIR, UV‐Vis, and elemental analysis. HMF was the dominant impurity due to its affinity to DFF. In addition, chromogenic substances were obtained as a byproduct, and they were potential pH indicators. These chromogenic substances had highly conjugated molecular structures, and they were generated via successive β‐protonation‐based ring‐opening reaction of HMF, aldol reaction, and dehydration reaction. [ABSTRACT FROM AUTHOR]

A continuous flow metal‐free protocol for the synthesis of sulfonyl chlorides from thiols and disulfides in the presence of nitric acid, hydrochloric acid and oxygen was developed. The influence of the reaction parameters was investigated under batch and flow conditions. Online 19F NMR was successfully implemented to investigate different reaction conditions within a single experiment. The sulfonyl chlorides were isolated (mostly in 70–81 % yield) after performing a simple aqueous washing procedure. In particular, the protocol was successfully operated for >6 hours to convert diphenyl disulfide to its corresponding sulfonyl chloride, achieving a throughput of 3.7 g h−1. The environmental impact of the protocol was assessed and compared to an existing continuous flow protocol using 1,3‐dichloro‐5,5‐dimethylhydantoin (DCH) as reagent. The process mass intensity (PMI) for the newly‐developed flow protocol (15) compared favorably to the DCH flow process (20). [ABSTRACT FROM AUTHOR]

The thermal stability of dibenzo-21-crown-7 (DB21C7) and its solution in 1,2-dichloroethane (DCE) after contact with nitrogen dioxide, which is a product of nitric acid degradation, was studied. It is shown that exothermic processes accompanied by the release of gaseous products are observed in inert and oxidizing atmosphere. The compounds formed after contact with nitrogen dioxide were determined by gas chromatography–mass spectrometry. Differences in gaseous products in the temperature range of 300℃ were defined for the initial crown ether and for DB21С7 and its solution in DСE after contact with NO2. [ABSTRACT FROM AUTHOR]

The effect of the ionic liquid, 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, on the extraction of lanthanides(III) from nitric acid solutions with phosphoryl-containing podands (2-(2-diphenylphosphoryl)-4-ethylphenoxy)methyl)diphenylphosphine oxide (1), (2-(2-diphenylphosphoryl)-4-ethylphenoxy)ethyl)diphenylphosphine oxide (2), and 2-[2-(diphenylphosphoryl)-4-ethylphenoxy]-N,N-dioctylacetamide (3) was studied. The stoichiometry of the extracted complexes was determined. The efficiency of extraction of lanthanides(III) with solutions of compounds 1–3 in dichloroethane from nitric acid solutions increases in the order 3 < 2 < 1. It has been established that, when replacing dichloroethane with an ionic liquid as a diluent, the extraction efficiency enhances. The magnitude of this effect decreases in the series of compounds 3 > 2 > 1. In the case of compound 1, the replacement of dichloroethane with an ionic liquid as a solvent is accompanied by a decrease in the extraction of lanthanides(III) at [HNO3] > 1.5 M. [ABSTRACT FROM AUTHOR]

Background: There are multiple conservative treatment options for plantar warts, but none have proven to be universally effective. Nitric acid is often used empirically by podiatrists in the treatment of plantar warts. A novel medical device or topical solution of nitric–zinc complex solution (NZCS) could potentially offer an effective and safe alternative for the targeted treatment of plantar warts. Objective: To observe the rate of complete healing of NZCS in a series of plantar wart cases and to establish the minimum number of product applications and time needed for healing. This will help standardize and protocolize its use. Methods: A descriptive study was conducted involving 72 patients who exhibited symptoms of plantar warts. These patients underwent chemical treatment using a nitric–zinc complex. Results: The cure rate with NZCS was 59.2%. The average number of NZCS applications was 5.9 ± 3.0 and the mean duration of treatment was 9.4 ± 7.1 weeks. A recurrence rate of 6.7% was observed. Conclusions: The topical solution of the nitric–zinc complex is an effective treatment for plantar warts, which can be considered a first-line treatment option in the general population. [ABSTRACT FROM AUTHOR]

In order to obtain a mechanism which is suitable for numerical simulation of combustion process in EAN thruster, a detailed combustion mechanism for EAN is presented based on the existing mechanism containing EAN evaporation products nitric acid and ethylamine, and a skeletal mechanism for EAN combustion consisting 82 species and 291 reactions is obtained by simplifying the detailed mechanism through an integrated reduction method that contains rate of production (ROP) analysis and sensitivity analysis. The ignition delay time, species profiles in premixed laminar flames and shock tubes for ethylamine reaction and species profiles in shock tubes for nitric acid reaction are simulated by using detailed mechanism and skeletal mechanism. Validations for two mechanisms are presented by comparing their simulation results and experimental datas. The validations show that simulation results of skeletal mechanism are in agreement with experimental datas and predictions of detailed mechanism, which proves that the skeletal mechanism is credible. The obtained skeletal mechanism provides a reaction mechanism model for numerical simulation of combustion process in EAN thruster. [ABSTRACT FROM AUTHOR]

Here we review the 400-year history of hydroponic culture and describe a unique management approach that does not require leaching or discarding solution between harvests. Nutrients are maintained at a low and steady concentration by daily additions of a dilute solution that replaces the transpired water along with the nutrients that were removed in growth each day. A stable pH and a low steady-state concentration of ammonium are maintained through automated additions of a solution of nitric acid and ammonium nitrate. Ample solution volume (at least 20 cm deep) stabilizes nutrient concentrations, reduces root density, and improves uniformity. Gentle aeration at ≈100 mL·min-1·L-1 maintains dissolved oxygen near saturation and increases uniformity throughout the rhizosphere. These practices facilitate a uniform, closed, root zone with rigorous pH control that provides the micromolar nutrient concentrations of N and P that are representative of field soils. [ABSTRACT FROM AUTHOR]

Carbon fibres (CF) are commonly used as carriers in biofilm-based wastewater treatment. The surface properties of the CF are herein modified using a combination of nitric acid oxidation and urea to optimise the carrier to immobilise bacterial cells. The capacity of the CF carriers to immobilise bacterial cells and activated sludge is evaluated using bacterial cell adhesion and sludge immobilisation tests. The total interaction energy profiles between the CF supports and bacterial cells were calculated according to the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory to explain the mechanism by which these modifications enhance this immobilisation capacity. CF-U has a high capacity for immobilising bacterial cells and activated sludge (3.7 g-sludge/g-CF supports) owing to its low total interaction energy. Nitric acid oxidation reduced the diiodomethane contact angle of CF from 55.1° to 38.5°, which reduced the Lifshitz-van der Waals interaction energy, while urea modification further increased the zeta potential of CF from 12.8 mV to −0.7 mV, thereby reducing the electrostatic interaction energy. Experiments and DLVO theory both determined that a combination of nitric acid oxidation and urea modification significantly enhanced the ability of CF to immobilise microorganisms. [ABSTRACT FROM AUTHOR]

Constructing heterojunctions with vacancies has garnered substantial attention in the field of piezo‐photocatalysis. However, the presence of interfacial vacancies can serve as charge‐trapping sites, leading to the localization of electrons and hindering interfacial charge transfer. Herein, dual oxygen vacancies in the NiFe‐layered double hydroxide and Bi2MoO6−x induced interfacial bonds have been designed for the piezo‐photocatalytic N2 oxidation to NO3−. Fortunately, it achieves sensational nitric acid production rates (7.23 mg g−1 h−1) in the absence of cocatalysts and sacrificial agents, which is 6.03 times of pure Bi2MoO6 that under ultrasound and light illumination. Theoretical and experimental results indicate that interfacial bonds act as "charge bridge" and "strain center" to break the carrier local effect and negative effects with piezocatalysis and photocatalysis for promoting exciton dissociation and charge transfer. Moreover, the strong electronic interaction of the interfacial bond induces internal reconstruction under ultrasound for promoting the local polarization and adsorption of N2, which accelerates the fracture of the N≡N bonds and reduces the activation energy of the reaction. The research not only establishes a novel approach for optimizing the combined effects of piezo‐catalysis and photocatalysis, but also achieves equilibrium between the synergistic impacts of vacancies and heterojunctions. [ABSTRACT FROM AUTHOR]

Background. Promising raw materials for obtaining calcium and calcium nitrate are marble and limestone from the Zarbant deposit, containing CaO above 52.16%. Purpose. Determination of the composition and decomposition coefficient of the Zarbant mine marble with nitric acid. Methodology. The CaO content was determined by the complexometric method with Trilon B, and nitrogen - by the Kjeldahl method. Originality. It was found that the decomposition coefficient of the Zarbant marble components depends on the concentration, temperature, and decomposition time. Optimum conditions for the process of marble decomposition with nitric acid were found. Findings. It was found that an increase in the concentration of nitric acid to 49.21% and an increase in the rate to 100% contribute to an increase in the yield of calcium nitrate to 90%, an increase in temperature and time increases nitrogen losses by 2%; conditions: concentration and acid feed rate - 49.21% and 100%, temperature - 25-30°C, time - 2 hours. [ABSTRACT FROM AUTHOR]

The aim of this study was to measure consequences of the arsenic pollution released from a sewage treatment plant into the seawater in Jazan province in the southwest of Saudi Arabia. The impact of the release of arsenic on the ecosystem is the adsorption of arsenic by sea plants. To do so, samples were collected alongside a distance of seven kilometers from the treatment plant. The algae samples: Sargassum sp., Cladophora sp., and seagrasses: Halodule uninervis and Cymodocea rotunda were digested in nitric acid, and the assays of arsenic levels were taken by ICPAES according to EPA methods. The results showed that algae are more efficient than seagrass with absorbing arsenic. Also, the treatment plant was not the only source of arsenic contamination, as ships and boats were adding more arsenic to the ecosystem. [ABSTRACT FROM AUTHOR]