Sulfuric Acid Research Articles

Computational exploration of the electrochemical oxidation mechanism of thiocyanate catalyzed by cobalt-phthalocyanines.

In this study, we focused on the mechanism of the electrocatalytic oxidation of thiocyanate, which in traditional electrodes typically requires high overpotentials. As models for reducing these overpotentials and catalyzing the reaction, we used a set of modified cobalt phthalocyanines (CoPc), known as electrocatalysts. Using DFT calculations, we explored how modifications to CoPc by adding electron-donating and withdrawing groups and the coordination of 4-amino thiophenol impact the oxidation process. The reaction mechanism for the electrooxidation of thiocyanate has remained elusive, where only the reaction products have been properly identified, including hydrogen cyanide and sulfate ions at pH 4. The approach for understanding the reaction was considering the formation of an (SCN)2 dimer as an intermediate that is a suitable precursor of the products of the reaction. Our findings showed that electron-donating groups and 4-amino thiophenol coordination lowered oxidation potentials, enhancing electrocatalytic efficiency and promoting thiocyanate radical formation and release before dimerization occurs. In contrast, electron-withdrawing groups facilitated dimerization while attached to cobalt, albeit with lower electrocatalytic proficiency. This study highlights the crucial role of CoPc modifications in thiocyanate oxidation, demonstrating the potential for improved electrocatalytic processes through tailored catalyst design.

Optimizing Recycling Processes for Mixed LFP/NMC Lithium-Ion Batteries: A Comparative Study of Acid-Excess and Acid-Deficient Leaching

This study explores the optimization of hydrometallurgical processes for recycling lithium-ion batteries (LIBs) containing a mixture of lithium iron phosphate (LFP) and nickel–manganese–cobalt (NMC) cathodes. Two approaches were investigated: acid-excess leaching and acid-deficient leaching with residue recirculation. A design of experiments (DoE) framework was applied to assess the impact of key parameters, including sulfuric acid and hydrogen peroxide concentrations, as well as solid-to-liquid (S/L) ratios, on the dissolution yields of target metals (Ni, Mn, Co, and Li). Acid-excess leaching achieved nearly complete dissolution of target metals but required additional purification steps to remove impurities. Acid-deficient leaching with a 60% recirculation of leaching residue improved dissolution yields by up to 12.5%, reduced reagent consumption, and minimized operational complexity. The study also evaluated separation strategies for manganese and cobalt through solvent extraction. Results indicate that while acid-excess leaching offers higher yields, acid-deficient leaching with residue recirculation is more cost-effective and environmentally friendly. These findings provide valuable insights for developing sustainable LIB recycling technologies.

Short-Time Peeling of Large Anodic Porous Alumina Membranes from Al Substrates by Two-Layer Anodization Using Concentrated Sulfuric Acid

Short-Time Peeling of Large Anodic Porous Alumina Membranes from Al Substrates by Two-Layer Anodization Using Concentrated Sulfuric Acid

Modeling the Nucleation and Growth of Lead Sulfate Particles on Lead Electrodes

Abstract Lead-acid batteries (LABs) play a pivotal role in the energy storage sector with applications spanning from starting-lighting-ignition batteries to grid energy storage. Passivation of lead negative electrodes by PbSO4 particles is a fundamental mechanism limiting the performance of LAB. In this regard, an electrochemical model is developed that simulates the nucleation and growth (N&G) dynamics of PbSO4 particles on a flat lead electrode, responsible for its passivation. The model considers the electrochemical reactions between lead electrode and sulfuric acid, N&G of PbSO4 particles, passivation of the lead surface, and the ternary transport of PbSO4 (aq), bisulfate, and protons in H2SO4 electrolyte. The model is validated with a dataset of cyclic voltammetry (CV) responses collected at several scan rates and H2SO4 concentrations. The model shows remarkable qualitative and quantitative agreement with the experimental data including CV peak features, discharge capacity, and particle size. The model was employed to explore key N&G quantities, such as supersaturation, nucleation rate, particle count, growth rate, particle size, and surface coverage, and to examine how their interactions influence electrode utilization. Parametric studies were also conducted to evaluate how scan rates and acid concentrations influence the previously mentioned N&G quantities and, subsequently, the utilization of the electrode.

Revisiting the Metabolism of Donepezil in Rats Using Non-Targeted Metabolomics and Molecular Networking

Background/Objectives: Although donepezil, a reversible acetylcholinesterase inhibitor, has been in use since 1996, its metabolic characteristics remain poorly characterized. Therefore, this study aims to investigate the in vivo metabolism of donepezil using liquid chromatography–high-resolution mass spectrometry (LC-HRMS) based on a molecular networking (MN) approach integrated with a non-targeted metabolomics approach. Methods: After the oral administration of donepezil (30 mg/kg) in rats, urine, feces, and liver samples were collected for LC-HRMS analysis. Chromatographic and spectrometric data were processed through MN and multivariate data analysis to identify the in vivo metabolites of donepezil. Results: A total of 50 metabolites were characterized, including 23 newly identified metabolites. Donepezil was biotransformed by O-demethylation, N-debenzylation, and hydroxylation, and these metabolites are further conjugated with glucuronic acid and sulfurous acid. N-Desbenzyldonepezil (M4), didesmethyldonepezil (M5), and N-desbenzyldonepezil (M4) were identified as the most abundant metabolites in urine, feces, and liver samples, respectively. Conclusions: The metabolic characteristics of donepezil in rats were comparable to those in humans, indicating that a rat is a reliable model for studying donepezil metabolism. This study indicates that a MN approach combined with a metabolomics approach is a reliable tool to identify unknown metabolites of drugs and drug candidates.

Microstructure and Corrosion Resistance of Composite Based on Ultra-High Molecular Weight Polyethylene in Acidic Media

In this work, the effect of an acidic environment on the structure of composite samples based on ultra-high molecular weight polyethylene (UHMWPE) modified with mineral filler in the form of diabase (DB) is studied. The stability of samples was investigated in solutions of sulfuric (H₂SO₄) and hydrochloric (HCl) acids with concentrations of 10 vol% and 20 vol% at room temperature for 16 weeks. It was found that the introduction of 10 wt% DB into the UHMWPE matrix significantly increases the resistance of the composite sample to aggressive media, which is confirmed by the minimum degree of swelling compared to pure UHMWPE and composites with higher filler content. Scanning electron microscopy (SEM) demonstrated a uniform distribution of DB in the sample structure and the absence of defects such as agglomeration and cracks. The methods of infrared spectroscopy (IRS) and X-ray structural analysis (XRD) revealed a decrease in the degree of crystallinity of the samples after acid exposure, but no significant changes in the chemical structure of the materials were recorded, which confirms their resistance to chemical degradation. The best chemical resistance was demonstrated by composites containing 10 wt% DB, which is associated with the formation of a barrier structure preventing the diffusion of acids. The obtained results indicate the promising application of UHMWPE with DB filler to create samples resistant to aggressive media.

A Study on the Mechanism of Cellulose Nanocrystals to Enhance the Stability of Hydrophobic Phthalocyanine Green in Water and the Functional Characteristics of Colour Pastes

Cellulose nanocrystals (CNCs) prepared by sulfuric acid hydrolysis were added to phthalocyanine green colour pastes with a surfactant to improve stability. The particle size, zeta potential, absorbance, and microstructure of the colour pastes were analyzed and characterized. The mechanism of CNCs to enhance the stability of hydrophobic phthalocyanine green in water was investigated. The functionalized application of the colour pastes was explored by mixing colour pastes with coating-forming substances to prepare phthalocyanine green paint. The results show that CNCs could enhance the stability of phthalocyanine green in water and form a binary system with non-ionic surfactants in colour pastes. The system could make phthalocyanine green colour pastes have very good dispersion and stability and mix well with coating-forming substances. The phthalocyanine green paint had excellent performance. As a renewable and naturally degradable biomass resource, CNCs have the potential to be applied for the dispersion and stabilization of hydrophobic pigments by compounding with surfactants.

New particle formation dynamics in the central Andes: contrasting urban and mountaintop environments

Abstract. In this study, we investigate atmospheric new particle formation (NPF) across 65 d in the Bolivian central Andes at two locations: the mountaintop Chacaltaya station (CHC, 5.2 km above sea level) and an urban site in El Alto–La Paz (EAC), 19 km apart and at 1.1 km lower altitude. We classified the days into four categories based on the intensity of NPF, determined by the daily maximum concentration of 4–7 nm particles: (1) high at both sites, (2) medium at both, (3) high at EAC but low at CHC, and (4) low at both. These categories were then named after their emergent and most prominent characteristics: (1) Intense-NPF, (2) Polluted, (3) Volcanic, and (4) Cloudy. This classification was premised on the assumption that similar NPF intensities imply similar atmospheric processes. Our findings show significant differences across the categories in terms of particle size and volume, sulfuric acid concentration, aerosol compositions, pollution levels, meteorological conditions, and air mass origins. Specifically, intense NPF events (1) increased Aitken mode particle concentrations (14–100 nm) significantly on 28 % of the days when air masses passed over the Altiplano. At CHC, larger Aitken mode particle concentrations (40–100 nm) increased from 1.1 × 103 cm−3 (background) to 6.2 × 103 cm−3, and this is very likely linked to the ongoing NPF process. High pollution levels from urban emissions on 24 % of the days (2) were found to interrupt particle growth at CHC and diminish nucleation at EAC. Meanwhile, on 14 % of the days, high concentrations of sulfate and large particle volumes (3) were observed, correlating with significant influences from air masses originating from the actively degassing Sabancaya volcano and a depletion of positive 2–4 nm ions at CHC but not at EAC. During these days, reduced NPF intensity was observed at CHC but not at EAC. Lastly, on 34 % of the days, overcast conditions (4) were associated with low formation rates and air masses originating from the lowlands east of the stations. In all cases, event initiation (∼ 09:00 LT) generally occurred about half an hour earlier at CHC than at EAC and was likely modulated by the daily solar cycle. CHC at dawn is in an air mass representative of the regional residual layer with minimal local surface influence due to the barren landscape. As the day progresses, upslope winds bring in air masses affected by surface emissions from lower altitudes, which may include anthropogenic or biogenic sources. This influence likely develops gradually, eventually creating the right conditions for an NPF event to start. At EAC, the start of NPF was linked to the rapid growth of the boundary layer, which favored the entrainment of air masses from above. The study highlights the role of NPF in modifying atmospheric particles and underscores the varying impacts of urban versus mountain top environments on particle formation processes in the Andean region.

Design, Scale‐Up, and Dynamic Simulation of a Patented Bayonet Reactor for Commercial Hydrogen Production via Sulfur‐Iodine Water Splitting

ABSTRACTThe sulfuric acid decomposition reactor is a key component of the iodine‐sulfur thermochemical cycle process. The design of the sulfuric acid decomposition reactor requires excellent corrosion resistance and mechanical strength performance. In this work, a patented reactor on a pilot scale was scaled up to an industrial scale. A plant equipment design for an industrial‐scale reactor was performed. Based on an integrated inherent safety design approach, it was determined that the optimal thickness was 110 mm, and the design passed all stress analysis tests. With a minimum targeted hydrogen production rate of 1000 kg/h, the process design yielded a reactor with a diameter of 7 m and a height of 30 m, while silicon carbide was chosen as the construction material. The scaled‐up reactor was dynamically simulated in MATLAB. Simulink demonstrated that both the reactor temperature and product flow rates successfully produced a stable response within 1.8 and 4 h of operation, respectively.

Leaching of Copper and Zinc from Copper-Zinc Sulfide Ore Activated by Sulfuric Acid with Water

Leaching of Copper and Zinc from Copper-Zinc Sulfide Ore Activated by Sulfuric Acid with Water

Insights into the Corrosion Inhibition Performance of Plant Extracts of Different Genera in the Asteraceae Family for Q235 Steel in H2SO4 Medium

Nowadays, the development of plant extracts as corrosion inhibitors to protect metals from corrosion is a popular research direction. However, given the vast diversity of plant species in nature, it is imperative to explore effective methods to improve screening efficiency in order to quickly identify the corrosion inhibition potential of plants. In this work, a new strategy for developing plant-extracted eco-friendly corrosion inhibitors based on the family and genus of plants is proposed. Three plants of different genera in the Asteraceae family, including Artemisia argyi extract (AAE), Chrysanthemum indicum extract (CIE), and Centipeda minima extract (CME), were selected and successfully prepared as novel corrosion inhibitors for Q235 steel in a sulfuric acid solution. The corrosion inhibition behavior and corresponding mechanism were systematically investigated by using some electrochemical tests (open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy) and surface characterizations (Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy). The experimental results illustrated that the main components of the three extracts were similar and that when combined with KI as mixed-type corrosion inhibitors, they could dramatically slow down the metal corrosion rate. The maximum value of the corrosion inhibition efficiency reached 96.29%, 96.50%, and 97.52%, respectively, at 200 mg/L and could increase to 98.64%, 97.65%, and 99.06%, respectively, with a prolonged immersion time. A synergistic effect exists between the three plant extracts and KI, leading to the firm adsorption of the three plant extract molecules onto a Q235 steel surface, thereby forming a robust protective film. This work demonstrated that plants of different genera in the Asteraceae family possessed similar corrosion inhibition capabilities, providing a novel way to select potential corrosion inhibitors from numerous plants based on family and genus classification.

The acid-leaching process and structural changes of lizardite, chlorite and talc in sulfuric acid medium

The acid-leaching process and structural changes of lizardite, chlorite and talc in sulfuric acid medium

Gaseous Sulfuric Acid Contributions to Sulfate Formation in Urban Atmosphere

Gaseous Sulfuric Acid Contributions to Sulfate Formation in Urban Atmosphere

Design Principles for Efficient Hydrothermal Relithiation of Spent Lithium Iron Phosphate.

Direct regeneration, which involves replenishing lithium in spent cathode materials, is emerging as a promising recycling technique for spent lithium iron phosphate (s-LFP) cathodes. Unlike solid-state regeneration, the aqueous relithiation method consumes less energy, ensures even lithium replenishment, and significantly recovers the capacity of s-LFP. However, liquid-phase lithium replenishment formulations are generally less standardized. In this study, we propose designing principles for hydrothermal relithiation recipes to achieve efficient relithiation while ensuring a high yield of relithiated LFP products, assisted by various electrochemical techniques. This led to the discovery of an economical hydrothermal relithiation approach. Specifically, using sulfurous acid (H2SO3) as the reducing agent and LiOH as the lithium source in the hydrothermal precursor, we achieved complete relithiation at a mild hydrothermal temperature of 90 °C with a high yield (only 3.1% mass loss) of relithiated LFP products. The regenerated LFP recovers approximately 29% of its capacity and exhibits remarkable capacity retention (98.9%). This research highlights a significant advancement in the efficient hydrothermal regeneration of s-LFP, presenting a green and economically viable method for LFP recycling and setting a benchmark for sustainable battery recycling technologies.

Corrosion Inhibition of E24 Carbon Steel in Sulfuric Acid by PMDA: Experimental and Theoretical Insights

Corrosion Inhibition of E24 Carbon Steel in Sulfuric Acid by PMDA: Experimental and Theoretical Insights

Extraction of aluminium from mudstone using a two-step acid leaching method

Laboratory studies were conducted to produce a 44.29 g/L aluminum sulfate solution by leaching mudstone (coal mine waste), with an 83% recovery rate. This was achieved through two steps: firstly, roasting and leaching the roasted material, and secondly, roasting the residue mixed with sodium carbonate, followed by leaching the roasted material. The favorable operating conditions included a 1:1 mixing ratio, 1-h roasting time at 800 °C, leaching temperature of 100 °C, agitation speed of 200 rpm, a solid-to-liquid ratio of 1:4, 60% sulfuric acid concentration, and 3 h of agitation time. This study is significant because it yielded a novel high recovery percentage and produced aluminum sulfate solution, which can be crystallized to alum and purified to water.

Miscible Polymer Blend Membranes Bearing Pyrrolidone for Fractioning Sulfuric Acid and Sulfates

ABSTRACTIon exchange membranes of new chemistry based on polymer blends are proposed through a convenient solution‐blending process using the hydrophobic commodity polymer polyvinyl chloride (PVC) and the hydrophilic polyvinylpyrrolidone (PVP), which are completely miscible. The pyrrolidone groups can be protonated to form oxonium ions, functioning as transient fixed positive charges for fractioning sulfuric acid and sulfates via diffusion. The influence of PVC molecular weight and the membrane composition on the physical, chemical properties, and mass transfer performance of PVC‐PVP blend membranes was systematically investigated. After equilibrium in 2.68 mol/L sulfuric acid, the sulfuric acid, and water contents in the blend membranes increase with the increase of the membrane PVP contents (20–75 wt%). The permeability coefficients of sulfuric acid and ferrous sulfate for the blend membranes also exhibit a gradual increase. Membranes of mass transfer properties comparable to commercial ones can be easily obtained by tuning the membrane PVP contents. It is proved that the larger sulfuric acid permeability over sulfates (FeSO4 as an example) is due to both larger solubility and diffusion coefficient of sulfuric acid in the membrane phase. The optimal PVC‐PVP blend membranes have shown nice performance in fractioning sulfuric acid from sulfates, when treating titania waste acid. This study provides valuable guidance for the design of high‐performance yet low‐cost ion exchange membranes with pyrrolidone chemistry from commodity polymers for resource recovery.

Selective leaching mechanisms of zinc from industrial waste using hybrid acids: Sustainable synthesis of Nano-ZnO

Zinc-containing dust (ZCD) has received extensive attention because it is a hazardous waste rich in various metals. This study innovatively proposed a hybrid acid leaching agent based on malic acid (MA) and sulfuric acid to selectively extract Zn from ZCD and successfully prepare nano-ZnO materials. The leaching experiments show that among the combinations of various organic acids and sulfuric acid, MA and sulfuric acid are superior in the selective leaching of Zn. Under optimal conditions, the leaching ratios of Zn, Pb, and Fe are 97.70%, 0.88%, and 2.95%, respectively. In addition, the use of hybrid acids can reduce sulfuric acid consumption by more than 46%. The Molecular dynamics simulation indicate that the interaction between the hybrid acid with ZnO and PbO was stronger (PbO > ZnO > Fe2O3). The radial distribution function (RDF) reveals that Zn and Pb ions form strong coordination structures with some oxygen atoms in MA, thereby confirming that MA plays a crucial role in preventing the dissolution of Fe. Finally, spherical nano-ZnO with a purity of 98.14% and an average particle size of 68.60 nm is obtained from the leaching solutions by precipitation method. This study provides a green and sustainable alternative for the selective recovery of Zn from ZCD.

Evaluation of scarification in seed germination and characterization of the early stages of seedling development of Rubus erythroclados.

The shrub Rubus erythroclados Mart. ex Hook.f. is endemic to Brazil and has high nutritional and medicinal potential. The objective of this study was to test scarification methods in the seed germination of R. erythroclados and to characterize the early stages of seedling development. The seeds were submitted to four treatments: 1) distilled water; 2) sodium hypochlorite (5% NaOCl); 3) sulfuric acid (80% H2SO4) and 4) sulfuric acid (98% H2SO4). The experimental design used was completely randomized. Each treatment (150 seeds) contained three replications with 50 seeds each, totaling 600 seeds. The seedling phase was also monitored weekly, from emergence to the loss of cotyledons. Furthermore, young plants were monitored until they acquired 5-leaflets. Seed germination had a general average of 46.3%. The treatment 5% NaOCl showed the highest mean germination (88.7%), followed by 80% H2SO4 (66.7%), both higher than the distilled water (30.0%). No seeds germinated in the 98% H2SO4 treatment. The seedling emergence time in the substrate was, on average, 54.4 days, ranging from 22.3 to 107.3 days, after sowing. The 5% NaOCl and 80% H2SO4 treatments increased the percentage of seed germination by scarification and reduced the seedling emergence time, being indicated for the cultivation of R. erythroclados. On the other hand, the 98% H2SO4 treatment is not indicated, as it possibly damaged the seeds. In the seedling phase, the growth in height was slow and the average number of leaves increased over the weeks. This phase lasted on average 107.9 ± 14.3 days. Pentafoliate leaves were observed on average 398.5 ± 54.7 days and lateral sprouting on average 435.7 ± 54.7 days, both after seedling emergence. These results indicate that plants produced by seeds may take some years to become sexually reproductive.

Helical magnetism in poly(aniline-co-ferrocene): structure and magnetism.

This study reports the synthesis and characterisation of a ferrocene-based conjugated polymer and a chiral composite. The precursor copolymer was synthesised from 1,3-phenylenediamine and 1,1'-dibromoferrocene via Buchwald-Hartwig polycondensation. This polymerisation process increased the effective conjugation length and led to magnetic spin interactions along the main chain, resulting in a ground triplet spin state at 25 °C. Furthermore, the polymer was oxidised with m-chloroperoxybenzoic acid and doped with sulfuric acid. A chiral polymer blend was also prepared by combining the copolymer with hydroxypropyl cellulose to form helical polymer liquid crystals. The physical properties of these polymers were analysed using superconducting quantum interference devices, optical spectroscopy, electron spin resonance, and X-ray fluorescence spectroscopy. The resulting polymer blend exhibits helical magnetism. This approach to fabricating a chiral magnetic material from an achiral polymer via supramolecular chirality introduces a new method for preparing chiral magnets.