Sulfuric Acid Research Articles

Exploring protective mechanisms with triazine ring and hydroxyethyl groups: Experimental and theoretical insights

The current study investigates the protective mechanisms of a novel triazine-based compound, 2,2′,2''-((1,3,5-triazine-2,4,6-triyl)tris (azanediyl))triethanol (TATTE) (for carbon steel protection in 0.5 M sulfuric acid) were investigated. Potentiodynamic polarization and electrochemical impedance spectroscopy analyses unveiled that TATTE serves as a protective agent with a dual inhibitory mechanism, showcasing exceptional efficiency exceeding 96%. Scanning electron microscopy (SEM) observations demonstrated the formation of a protective layer by TATTE on the surface of carbon steel. Density functional theory (DFT) calculations offered valuable insights into the favorable adsorption of both the neutral and protonated forms of TATTE through interactions between their functional groups and the steel surface. Molecular dynamics simulations further substantiated this, revealing that the neutral molecule exhibits physical adsorption, while the protonated form engages in stronger chemical adsorption, as evidenced by binding energies and radial distribution functions. The superior protective mechanism performance observed in our experiments can be attributed to the synergistic adsorption of TATTE, facilitated by the presence of the triazine ring and multiple hydroxyl groups.

Development of the technology for producing isopropyl alcohol by the sulfuric acid method

Development of the technology for producing isopropyl alcohol by the sulfuric acid method

Enhanced decoupling of conductivity relaxation from structural relaxation in non-stoichiometric protic ionic liquids involving triflic acid and 2-aminoethyl hydrogen sulfate.

The glass transition dynamics and conductivity relaxation are studied for a series of non-stoichiometric protic ionic liquids (PILs) based on 2-aminoethyl hydrogen sulfate and triflic acid with varying molar ratios (denoted as AT-55, AT-46, AT-37, AT-28, and AT-19) by broadband dielectric spectroscopy in a wide frequency (10-1-107Hz) and temperature range (173-353K). The results indicate that the addition of acid lowers the glass transition temperature, as confirmed by the activation energy fine structure analysis and a crossover in the conductivity relaxation time. Notably, samples with higher acid content deliver markedly increased conductivity. In addition, detailed analysis of the permittivity and modulus spectra reveals enhanced decoupling between the structural (α-process) and conductivity relaxation in samples with a higher acid content. Remarkably, nano-phase separation in AT-28 and AT-19 samples is observed, resulting in a second glass transition temperature indicating a more mobile phase. Based on the above-mentioned findings, we infer that increased acid content disrupts strong ionic interactions within the IL fraction, resulting in a decrease in the glass transition temperature and leading to nano-phase separation into distinct acid-rich and IL-rich phases with varying Tg values. This phase separation alters the long-range ionic pathways, shifting from being solely governed by IL cluster dynamics to a scenario where charge transport becomes largely decoupled from the dynamics of IL-rich clusters. Hence, modulating the stoichiometry of PILs appears a promising approach to enhance the conductivity together with widening the usable temperature range for applications.

Sulfuric acid effects in seed dormancy break of Ipomoea batatas evaluated by enzymatic, anatomic and physiological approaches

ABSTRACT The recommended method to overcome seed coat dormancy in sweet potato seeds is exposure to sulfuric acid, which can damage the embryo and affect seedling development depending on exposure time. This study aimed to determine the ideal immersion period using physiological, anatomical, and enzymatic analyses. Seeds were scarified with concentrated sulfuric acid for nine immersion periods. Physiological analyses included germination tests, germination speed index, first germination count, emergence test, and emergence speed index. Image analysis quantified the primary root length, root-to-hypocotyl ratio, and seedling length. Catalase and superoxide dismutase enzyme activities were analysed. Seed coat anatomy, including thickness, wear, and colour, was also assessed. Exposure to sulfuric acid for 30 min effectively broke dormancy without impacting the antioxidant system or seedling development. Thermal chambers confirmed that chemically scarified seeds absorb water and activate metabolism faster. Plant anatomy helped illustrate how sulfuric acid breaks dormancy by eroding physical barriers.

Selective Leaching for the Recycling of Lithium, Iron, and Phosphorous from Lithium-Ion Battery Cathodes’ Production Scraps

The market for lithium iron phosphate (LFP) batteries is projected to grow in the near future. However, recycling methods targeting LFP batteries, especially production scraps, are still underdeveloped. This study investigated the extraction of iron phosphate and lithium from LFP production scraps using selective leaching, considering technical and economic aspects. Two leaching agents, sulfuric acid (0.25–0.5 M, 25 °C, 1 h, 50 g/L) and citric acid (0.25–0.5 M, 25 °C, 1 h, 70 g/L) were compared; hydrogen peroxide (3–6%vv.) was added to prevent iron and phosphorous solubilization. Sulfuric acid leached up to 98% of Li and recovered up to 98% of Fe and P in the solid residues. Citric acid leached 18–26% of Li and recovered 98% of Fe and P. Totally, 28% of Li was precipitated for sulfuric acid process, while recovery with citric acid did not produce enough precipitate for a characterization. Sulfur is the main impurity present in the precipitates. The total operative costs associated with reagents and energy consumption of the sulfuric acid route were below 3.00 €/kg. In conclusion, selective leaching provided a viable and economic method to recycle LFP production scraps, and it is worth further research to optimize Lithium recovery.

Molecular Mechanisms of Aerosol Nucleation: from CLOUD Chamber Experiments to Field Observations

Atmospheric aerosol particles contribute to over four million premature deaths annually and play a critical role in modulating Earth’s climate. Most atmospheric particles and more than 50% of the cloud condensation nuclei are formed through a secondary process named new particle formation involving unique precursor vapors. This article summarizes current knowledge of how new atmospheric particles form, based on experiments at the CERN CLOUD chamber. While the role of sulfuric acid has long been known, other vapors like highly oxygenated organic molecules and iodine oxoacids are also important, along with stabilizers like ammonia, amines, and ions from cosmic rays. We explain how findings from CLOUD experiments help us understand particle formation in various atmospheric conditions and improve air quality and climate models.

Synthesis and characterization of nano-Plaster of Paris from Babylonia japonica, Oliva sayana, and Conasprella bermudensis

In this study, Plaster of Paris (POP, CaSO4.0.5H2O) was successfully synthesized from the shells of marine mollusks, specifically Conasprella bermudensis, Babylonia japonica, and Oliva sayana, highlighting the potential of utilizing marine resources for material production. The synthesis process was accelerated through a chemical reaction between the mollusk shells and sulfuric acid, which provided calcium and sulfate ions, respectively. Various model equations were employed to assess the crystallite size, which was less than 200 nm; notably, all models except the Halder-Wagner technique yielded significant estimations for the synthesized products. The calculated energy density ranged from 1.32×10² to 2.38×10³ J/m³, with stress values between 5.02×10⁵ and 2×10⁶ and strain values from 5×10⁻⁴ to 1.7×10⁻³. The preferred growth calculation indicated that the (200), (400), and (020) planes are the most thermodynamically stable for the synthesized POP. Additionally, FTIR analysis confirmed the presence of sulfate and hydroxyl functional groups in the products. This research advances the understanding of nano-Plaster of Paris (POP) derived from marine sources, promotes sustainable practices in material synthesis, and explores new applications in construction and biomedical fields.

High Proton Conductivity of Acid Impregnated COFs Stabilized by Post-Oxidation.

The investigation of proton conduction processes within artificial nanopores using phosphoric acid (H3PO4) and sulfuric acid (H2SO4) not only sheds light on the mechanisms of proton conduction for these strong acids in confined environments, while also provides critical insights into the proper understanding of biological transmembrane proton transport. However, the synthesis of stable and acid-resistant host frameworks is yet a major challenges. By following that, the present study is conducted with the aim of improving the chemical stability of an imine-based COF (CPOF-10) by converting it into an amide-linked COF (CPOF-11) via a post-oxidative approach. In which, the integration of an appropriate amount of imidazole groups into the framework facilitates the efficient impregnation of liquid proton-conducting acids. The obtained results indicate the ten times greater proton conductivity of H3PO4@CPOF-11 than that of H3PO4@CPOF-10, thereby, successfully achieving 8.63 × 10-2 S cm-1 at 160°C, under nitrogen (N2) atmosphere. Moreover, the highly stable CPOF-11 tolerated H2SO4 doping, delivering a high proton conductivity of up to 1.70 × 10-1 S cm-1 at 140°C, with a significantly low activation energy of 0.05 eV. To the best of the knowledge, this activation energy (0.05 eV) of H2SO4@CPOF-11 is found to be one of the lowest value among all the reported proton-conducting materials. Thus, this study will provide new understanding for the fabrication of advanced porous organic materials in fuel cells application.

Effect of Nature and Charge of Counterions and Co-Ions on Electrotransport Properties of Heterogeneous Anion Exchange Membranes

A comprehensive characterization of heterogeneous anion exchange MA-40 and MA-41 membranes, differing in the nature of functional groups and the exchange capacity (3.32 and 1.41 mmol/gdry, respectively), was carried out. The MA-40 membrane contains low basic secondary and tertiary amino groups, while the MA-41 membrane contains predominantly quaternary ammonium bases. Concentration dependences of conductivity and diffusion permeability, current-voltage curves were obtained, and the transport and structural parameters of a microheterogeneous model of membrane in solutions of different natures (salts and acids) containing singly and doubly charged cations and anions (sodium and calcium chlorides, sodium sulfate and sulfuric acid). The influence of counter- and co-ions on the electrical transport properties of the studied membranes was revealed and it was shown that changes in their properties are determined not only by the nature of the electrolyte, but also by the value of the exchange capacity of the samples, as well as the nature of their functional groups.

Microwave-assisted esterification of oleic acid using pyrrolidonium-based bronsted-acidic ionic liquids catalyst

Biodiesel is a liquid fuel obtained by the transesterification reaction of triglycerides and the esterification reaction of free fatty acids. In this study, pyrrolidonium-based Brønsted-acidic ionic liquids (ILs) were applied as catalysts for the production of biodiesel by microwave-assisted esterification of oleic acid with methanol. The effects of reaction temperature, catalyst amount, methanol/oleic acid molar ratio, and reaction time on the oleic acid conversion were investigated. Under optimal conditions, the results demonstrated that N-methyl-2-pyrrolidonium hydrogen sulfate (IL1) and 2-pyrrolidonium hydrogen sulfate (IL2) can achieve conversion rates exceeding 98 %. A comparative analysis with other IL catalysts showed the superior performance of pyrrolidonium-based ILs, especially in terms of Turn Over Frequency (TOF) values. To investigate the effects of different heating methods on the esterification of oleic acid, the esterification reaction was carried out using both conventional and microwave methods. The microwave method is more effective than the conventional method. The reusability of the IL catalyst was investigated, and the recovered catalyst showed excellent stability when it was reused for five consecutive runs without significant loss of activity.

Innovative research on one-step regeneration and reduction of saturated desulfurization coke: Reactivating desulfurization performance and sulfur recovery

Current advancements in flue gas desulfurization have highlighted the efficacy of activated coke (AC) as an SO2 adsorbent, leveraging sulfur resources. Despite its success, challenges such as lengthy processing and logistics for sulfuric acid storage and transport limit its widespread use. This research explores an innovative approach: powder saturated AC (SAC) achieves rapid temperature rise and one-step regeneration coupled reduction in a drop-tube reactor. Findings reveal that SAC undergoes primary regeneration at 450–650 ℃, converting adsorbed sulfur compounds into gaseous SO2. However, issues like incomplete active site recovery and surface oxidation reduce the re-adsorption capacity of regenerated AC. At 750–950 ℃, a concurrent regeneration and reduction phase converts desorbed SO2 into elemental sulfur. Carbothermal reduction during this phase enhances microporous structure development, lowers oxygen content, increases edge defects, promotes sulfur doping, and boosts SO2 re-adsorption efficiency. This study provides practical insights and a conceptual framework to refine desulfurization processes and optimize resultant products.

Research on the technology and mechanism of direct acidification of phosphogypsum and deeply solidify impurities with lime

Phosphogypsum (PG) is a solid waste generated during the wet production of phosphoric acid, noted for causing significant environmental pollution due to low pH and contamination with phosphorus-fluorine impurities. This work proposes an innovative method of acid treatment to acidify PG by directly adding of sulfuric acid at suitable temperatures. Initially, this acid treatment process is employed to convert and remove phosphorus-fluorine impurities, followed by PG after acid treatment incorporation with lime for safe solidification. The conversion mechanisms of phosphorus-fluorine impurities during acidification and solidification are elucidated. Results demonstrate that the direct acidification method converts most fluoride into H2SiF6 and HF, which are subsequently released from the PG system after a temperature of 175 °C treatment. Phosphorus is wholly transformed into water-soluble forms (H3PO4/H2PO4-/HPO42-), especially as eutectic phosphorus is released and converted when CaSO4·2H2O crystals dissolve to II-CaSO4. Following acidification to achieve a high water-soluble phosphorus/fluorine ratio, lime is added to convert phosphorus-fluorine impurities into Ca5(PO4)3F, ensuring harmlessness. The addition of 3.7% lime to acidified PG, an acid amount of 2-times the theoretical requirement, yields a treatment solution with pH=8.65, ρ(P)=0.05mg/L and ρ(F-)=1.11mg/L, meeting Class V water discharge standards (GB 3838-2002). The solidified PG filter residue contains ω(P2O5) ≤ 0.01% and ω(F-) ≤ 0.0061%, suitable for safe storage. This work indicates that this process can separate phosphorus impurities with lower energy consumption, providing a harmless PG treatment. Furthermore, the treated PG can hydrate to gain strength, potentially enhancing its utility as a resource.

Cellulose nanocrystals from rice bran as excellent emulsifiers for independently stabilizing Pickering emulsions

Rice bran as a kind of agricultural waste is anattractive and promising source of cellulose. In this paper, cellulose nanocrystals (CNC) from rice bran were prepared by the hydrolysis of sulfuric acid under ultrasonic treatment. CNC was explored as the stabilizer for Pickering emulsion. The morphological features, chemical structure, crystal property, particle size, surface charge, and thermal stability of CNC were investigated. The CNC with typical cellulose I structure produced by acidic treatment exhibited high thermal stability (>200°C). To evaluate the emulsion capability of CNC, the visual distribution and stability properties of Pickering emulsions were characterized. It was noted that Pickering emulsions stabilized by CNC exhibited excellent storage, oxidative, and environmental stability. This work provides evidence for the valuable utilization of CNC from rice bran. It could be used as a new kind of stabilizer for Pickering emulsions in biomedicine, cosmetics, and food.

Advancing biorefineries with ultrasonically assisted ionic liquid-based delignification: Optimizing biomass processing for enhanced bio-based product yields

Encouraging sustainable business needs utilization of bio-based substrate for green manufacturing of chemicals and fuels to achieve sustainable development goals set by the United Nations. One of the abundantly available bio-based substrates is lignocellulosic (LC) biomass, which requires effective pretreatment to fractionate into its structural biocomponents to maximize biorefinery potential. This study addresses the use of an inexpensive ionic liquid (triethylammonium hydrogen sulfate) [T2220][HSO4] in an ultrasound-assisted process as an environmentally acceptable pretreatment method for the delignification of LC biomass, specifically rice straw (RS). Using ionic liquid (IL)-assisted (IL, acid-IL, and alkali-IL) pretreatment procedures, the effects of IL volume, sonication time, and temperature were methodically examined for RS delignification. To evaluate the compositional changes in pretreated and raw RS, instrumental analyses were carried out. The maximum rates of 47 %, 55 %, and 64 % for the only IL, acid-IL, and alkali-IL treatments demonstrated the effect of temperature, operating time, and IL concentration on the delignification efficiency. The alkali-IL pretreatment was noteworthy for achieving a 64 % delignification rate under optimum values of IL volume (8.65 mL), sonication time (123 min), and temperature (82 °C). Artificial neural networks (ANN) and response surface methodology (RSM) were used for process modeling and optimization. With an accuracy of 0.989 in correlation coefficient, the ANN model outperformed the RSM regression model regarding forecasting delignification performance. Biorefinery of renewable biomass resources ensures the sustainable supply of materials, chemicals, and fuels. The delignification and downstream product recovery technologies are major limiting factors in the commercialization of biomass processing. The suggested [T2220][HSO4]-based ultrasonic approach provides a viable way to boost biomass valorization efficiency, which in turn improves economical and sustainable biorefinery and aids in the shift to green bio-based production.

Novel technology of electric combustion of pulverized coal and prospects of its use with small additions of hydrogen to ensure ignition of low-grade fuels

Coal-fired generation has long been, and still is, one of the leaders in global power generation. According to the International Energy Agency at the moment the share of coal-fired generation is about 39%.Despite the global trend of decarbonization, global coal-fired power generation is steadily growing. In 2019, coal-fired generation grew by about 1.5%. As of 2019, the world's proven coal reserves are concentrated in the United States (23%), the Russian Federation (15%), Australia (14%), and China (13%), amounting to about 1070 billion tons. In 2020, due to the pandemic of a new coronavirus infection, coal-fired power generation has been slightly reduced. Low-grade coals such as brown coals or lignite make up more than 40% of the world's reserves [4–6]. Which suggests the need to switch to burning these types of coals. Consumption of high-sulfur viscous fuel oils as starting, reserve or main fuel leads to emissions of such harmful substances as benz(a)pyrene and vanadium pentoxide in addition to toxic sulfur oxides, nitrogen and carbon. When sulfur oxides are formed, the dew point temperature of flue gases increases, which leads to the formation of sulfuric acid and, as a consequence, to frequent repairs of tail parts of boiler units due to their corrosion. Composition of flue gases at oil combustion also depends on its quality: its content of sulfur, nitrogen, metals, polycycloarenes, etc. The same replacement of liquid fuel at start-ups of pulverized coal-fired boiler units and maintenance of pulverized coal flare combustion will reduce the fire hazard of the production process, the operating costs of TPP, the environmental hazards of gaseous products of co-combustion of liquid and solid fuels. The article presents a review of modern technologies for firing up pulverized coal-fired boiler units, as well as presents the original technology of electric ignition and the results of tests on the laboratory bench.

Ethylene glycol pretreatment of softwood coupled with fast pyrolysis for sugar production: Solvent recycling and regeneration

Organosolv pretreatment of biomass with high-boiling solvents like ethylene glycol (EG) can overcome biomass recalcitrance for improving its fast pyrolysis performance. However, solvent recovery and recycling are challenging, hindering the economic feasibility of this technology. This study proposes a novel process combining sulfuric acid-assisted EG pretreatment of pine with fast pyrolysis, investigating the effects of EG recovery and regeneration on pyrolytic product distribution. The results showed that both initial and recovered EG solution effectively deconstructed pine into hemicellulosic monosaccharides, cellulose-rich fraction, and high-purity organosolv lignin, facilitating subsequent pyrolytic saccharification into levoglucosan. After five pretreatment cycles, the EG recovery rate decreased to 86.4 wt%, and the pretreatment effect declined linearly. However, during the sixth pretreatment, adding sulfuric acid to restore the initial pH kept the EG recovery rate above 85.0 wt% and maintained its initial deconstruction effectiveness, yielding 16.89 wt% hemicellulosic monosaccharides and 44.53 wt% levoglucosan. Pretreatment of pine with recycled and regenerated EG solution facilitates the targeted breakage of cellulose glycosidic bonds to form levoglucosan at lower activation energy (136.66 kJ·mol−1) than the raw feedstock (177.71 kJ·mol−1). This study provides an efficient method for recycling and regenerating high-boiling solvents for the pretreatment of recalcitrant softwood and efficient pyrolytic sugar production.

Efficacy of Andrographis paniculata leaf extract as a green corrosion inhibitor for mild steel in concentrated sulfuric acid: Experimental and computational insights

The rising demand for eco-friendly corrosion inhibitors has intensified efforts to find sustainable alternatives to hazardous chemical inhibitors widely used in industry. Mild steel, although commonly utilized in acidic environments, is prone to significant corrosion, necessitating effective solutions to prevent structural degradation. This study investigates the potential of Andrographis paniculata leaf extract (APLE) as a sustainable, green corrosion inhibitor for mild steel in concentrated sulfuric acid, a condition representative of harsh industrial environments. Using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods, APLE demonstrated a high inhibition efficiency of 95.14% at a concentration of 4000 ppm, effectively reducing both anodic and cathodic corrosion reactions. Scanning electron microscopy (SEM) revealed a protective layer formation on the steel surface, significantly reducing corrosion. The adsorption of APLE followed the Langmuir isotherm, indicating monolayer coverage, while quantum chemical calculations validated APLE's electron-donating capability, enhancing surface stability through physisorption. These findings underscore APLE as a viable, eco-friendly alternative to conventional inhibitors, offering promising applications in various acidic environments.

Hyperelastic and Stacked Ensemble-Driven Predictive Modeling of PEMFC Gaskets Under Thermal and Chemical Aging.

This study comprehensively investigates the stress distribution and aging effects in Ethylene Propylene Diene Monomer (EPDM) and Liquid Silicone Rubber (LSR) gasket materials through a novel integration of hyperelastic modeling and advanced machine learning techniques. By employing the Mooney-Rivlin, Ogden, and Yeoh hyperelastic models, we evaluated the mechanical behavior of EPDM and LSR under conditions of no aging, heat aging, and combined heat- and sulfuric-acid exposure. Each model revealed distinct sensitivities to stress distribution and material deformation, with peak von Mises stress values indicating that LSR experiences higher internal stress than EPDM across all conditions. For instance, without aging, LSR shows a von Mises stress of 24.17 MPa compared to 14.96 MPa for EPDM, while under heat and sulfuric acid exposure, LSR still exhibits higher stress values, showcasing its resilience under extreme conditions. Additionally, the ensemble learning approach achieved a classification accuracy of 98% for LSR and 84% for EPDM in predicting aging effects, underscoring the robustness of our predictive framework. These findings offer practical implications for selecting suitable gasket materials and developing predictive maintenance strategies in industrial applications, such as fuel cells, where material integrity under stress and aging is paramount.

Effect of Change in Sulfuric Acid Concentrations and Different Temperatures on Corrosion of Heat-Treated Moderate Carbon Steel

This study looked at the effects of successive heat treatments (first quenching, first tempering, second quenching, and second tempering) on the corrosion rate of moderate carbon steel in a methodical manner. Using distilled water, the specimens were cooled at 10 oC following the initial quenching and at different temperatures (0, 10, 20, 30 oC) following the second quenching. Based on the results of repeated heat treatment experiments and corrosion rate experiments in these models, the moderate carbon specimens that underwent the heat treatments have a high corrosion resistance compared to the original models (prior to the application of the heat treatments). At different temperatures (298, 303, and 313 K) and concentrations (0.2, 0.3, and 0.4 N–H2SO4), in an acidic moderate. The study also showed that corrosion resistance decreases with concentration and with increasing corrosion-moderate temperature in heat-treated models. Another finding is that the models with the best corrosion resistance were those that underwent a second quench and cooling process. Another finding shows that the models with the highest corrosion resistance were those that experienced a second quench and were cooled in water at zero oxygen content.

Low-Acid Leaching for Preferential Lithium Extraction and Preparation of Lithium Carbonate from Rare Earth Molten Salt Electrolytic Slag

In this work, lithium was preferentially recovered through the low-acid leaching from rare earth molten salt electrolytic slag (REMSES) with a leaching temperature of 60 °C. The influence on lithium extraction was investigated in detail in different leaching conditions. The optimal conditions were as follows: liquid-to-solid ratio (10 mL/g), sulfuric acid concentration (0.8 mol/L), leaching time (60 min) and leaching temperature (60 °C). This yielded a lithium extraction rate of 98.52% and a lithium carbonate purity of 99.5%. It was fitted using an empirical model; the kinetics showed that internal diffusion control conformed to the low-acid leaching reaction, which had an apparent activation energy of 10.81 kJ/mol for lithium. The total profit from the whole process was USD 0.2576 when dealing with 1.0 kg of REMSES. Moreover, in the sulfuric acid system, the leaching reaction mechanism was carefully investigated between 30 and 90 °C. An innovative process of recovering lithium from REMSES was achieved with environmental friendliness and good economic returns. Compared to traditional leaching using concentrated sulfuric acid, this cleaner recycling method conforms to the concept of green, low-carbon sustainable development, with high lithium selectivity, low impurity content in the filtrate and low acid consumption.