Sulfuric Acid Solution Research Articles

Spectrophotometric Analysis of Copolyarylene Phthalides and Their Copolymers with Methyl Methacrylate and Styrene

Sulfuric acid solutions of copolyarylene phthalides of the diphenyloxide series and their copolymers with methyl methacrylate and styrene were studied by the photometric method. According to spectral data, regardless of the ratio of single (α) and double (β + γ) phthalide groups in the macrochains of copolyarylene phthalides in their copolymers with methyl methacrylate, there are ~20–26 mol of MMA per 1 mol of phthalide units. The structure of copolyarylene phthalides is a determining factor in the formation of copolymers with styrene, in which either styrene units or phthalide fragments predominate (~15–40 and ~2–5 mol of styrene per mole of phthalide unit).

Study of the Dissolution of Tahoua Natural Phosphate by Mineral Acids: Hydrochloric Acid and Sulfuric Acid

The transformation of natural phosphorus into plant nutrient phosphorus, natural phosphates from Tahoua were dissolved in mineral acids, hydrochloric acid and sulfuric acid. Dissolution was effected at various concentrations (0.01M; 0.1M and 1M) and stirring times (1 hour, 3 hours and 5 hours). The results show that for all two acids (2), the dissolution rate is greater in concentrated acid solutions (1M) and for the 5-hour attack time. These rates are 38.37% and 34.87% respectively for sulfuric and hydrochloric acid solutions. Dissolution of Tahoua natural phosphate depends on the concentration of etching solutions and the etching time. With mineral acids (sulfuric and hydrochloric acid), for example, it increases with concentration. This dissolution offers interesting visions for perfecting phosphate fertilizers.

Valorisation of acid mine drainage through effective recovery of selected rare earth elements using cationic resins

Acid mine drainage (AMD) presents a challenge to the environment if not well managed, but it also presents an opportunity for the recovery of economically valuable products, including rare earth elements (REEs), which are critical for the development of advanced, and green technologies. REE concentrations in AMD samples from coal and gold mines were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES) and their sorption by different cationic resins (CHT4083, CHP4502 and CHP00712) was evaluated. Optimum conditions for the sorption of the REEs by these resins were determined through batch experiments and desorption of the REEs from the resins using different concentrations of sulphuric acid (H2SO4) solutions. Coal mine drainage (CMD), with a low pH of 2.37, had higher amounts of REEs (ΣREE 226.3732 mg/L) than AMD from the gold mines (ΣREE 4.9705 mg/L), with a pH of 3.21. A REE sorption efficiency of up to 98% was obtained with CHP4502 and CHP00712 resins and further optimisation of CHP00712 revealed that a resin volume of 250 mL and a contact time of 10 min were required to successfully remove REEs from 500 mL AMD. The sorption capacities of the resin for the selected REEs were 3.88 mg/g, 0.88 mg/g, 1.37 mg/g, 3.18 mg/g, 0.67 mg/g, 0.01 mg/g and 0.27mg/g for Pr, Gd, Nd, Ce, Sm, Eu and Y, respectively. Elution of the resin with a 0.5 N solution of sulphuric acid desorbed the REEs. AMD from coal mines could be an alternate source of REEs and cationic resins can be used to recover these REEs from the CMD. Further investigations, including impregnation of resin to improve its sorption capacity, and temperature effects on the sorption process, are recommended.

N, S-Codoped Carbon Quantum Dots with High Inhibition Efficiency: Implications for Corrosion Mitigation of Carbon Steel in Acidic Environments.

The environmental friendliness, economic feasibility, and high efficiency of carbon quantum dots (CQDs) render them as highly promising candidates for corrosion inhibitors. The present study proposed the fabrication of nitrogen- and sulfur-codoped CQDs via an one-step hydrothermal method using l-cysteine and 4-aminosalicylic acid as precursors. The structure, particle size, and surface ligands of the prepared CQDs were determined through spectroscopy and transmission electron microscopy characterization. Subsequently, the inhibition performance of the CQDs on carbon steel in a 0.5 M sulfuric acid solution was evaluated through weight loss measurement, electrochemical methods, and surface analysis. The CQDs exhibited remarkable inhibition efficiencies of 97.9% at 293 K and 98.9% at 313 K, with a concentration of 150 ppm. In addition, the obtained CQDs demonstrated a combined physisorption and chemisorption adsorption behavior, which complied with the Langmuir adsorption isotherm. These findings provide insight into the inhibition mechanism and highlight the potential of codoped CQDs for corrosion mitigation applications in acidic environments.

One-step synthesis of short columnar α-calcium sulfate hemihydrate from titanium white waste acid

The waste sulfuric acid solution emerged as a main emission substance from titanium dioxide production is called titanium white waste acid (TWWA). The disposal of TWWA has been a concern due to its potential impact on the environment. A green way including one-step preparation and purification stages of α-calcium sulfate hemihydrate (α-HH) from TWWA and lime mud via a neutralization reaction in the hydrothermal pressure apparatus was developed. The preferred experimental conditions were obtained, i.e., lime mud/TWWA/sodium citrate ratio: 16/16/1, 140 ℃, 0.5 MPa, reaction time: 10 min. The recovery rate of α-HH in the whole process was 89.5%. The method presented high efficiency and selectivity in conversion to a short-columnar-shaped α-HH under addition of 3.40 × 10−2 mol/L sodium citrate as a crystal modifier. The structure and composition of the obtained α-HH products were confirmed by XRD, TGA, and SEM. Compared with titanium gypsum, the obtained short columnar α-HH with hexaprismatic morphology showed excellent mechanical properties. According to GB/T 9776 − 2008 “Calcined gypsum”, the compressive strength of 7 days of the cemented short-columnar α-HH was about 6.35 MPa, which it meets the strength requirements for building gypsum.

Corrosion inhibition performance of protein derived carbon quantum dots as corrosion inhibitors on low carbon steel in sulfuric acid solution

Protein derived carbon quantum dots (PCQDs) were successfully fabricated via a hydrothermal method with shrimp meat as the precursor. Subsequently, their corrosion-inhibiting performance on mild steel (L-steel) in a 0.5 mol/L H2SO4 solution was evaluated. Electrochemical impedance spectroscopy (EIS) tests demonstrated that at a concentration of 250 mg/L, the corrosion inhibition efficiency of PCQDs exceeded 90 %. Potentiodynamic polarization (PDP) tests indicated that when the concentration of PCQDs reached 500 mg/L, the corrosion inhibition efficiency was as high as 97.45 %. Comprehensive characterizations of the PCQDs, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible spectroscopy (UV–Vis), verified the existence of functional groups such as carboxyl, hydroxyl, and aromatic rings within the PCQDs. These groups are conducive to forming a strong adsorption force on the surface of L-steel and creating a protective layer. Surface morphology analyses carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the surface of L-steel treated with PCQDs was significantly smoother in comparison to untreated samples exposed to acidic conditions. Adsorption studies disclosed a mixed physical and chemical adsorption behavior, and theoretical calculations showed that the N and S atoms in PCQDs preferentially adsorb in a parallel direction. The addition of PCQDs led to a reduction in the diffusion coefficient, indicating that the diffusion of corrosive ions was effectively hindered. The distribution function of PCQDs was 3.48 Å, which suggested that the chemisorption mechanism played a dominant role in the inhibition process.

Investigation of the high temperature leaching of a zinc sulphide concentrate in sulphuric acid solutions

Investigation of the high temperature leaching of a zinc sulphide concentrate in sulphuric acid solutions

Proton transport mechanisms in aqueous acids: Insights from abinitio molecular dynamics simulations.

The solvation and transport of protons in aqueous solutions of phosphoric acid (PA), sulfuric acid (SA), and nitric acid (NA) were studied using abinitio molecular dynamics simulations. Systems with acid-to-water ratios of 1:1 and 1:3 were examined to understand the similarities and differences in transport mechanisms. The solvation structure of H3O+ in these systems is similar to that in slightly acidic water, with variations in the strength of hydrogen bonds (H-bonds) accepted by acid molecules. In aqueous PA systems, strong H-bonds between PA molecules are slightly affected by water, leading to significantly greater H3O+ diffusion compared to aqueous SA and NA systems. This enhanced diffusion is attributed to the participation of PA molecules in H3O+ transport, where the PA molecule can shuttle a proton for H3O+, facilitating a large displacement via collective proton hopping. This shuttling mechanism is prominent in aqueous PA but rare in aqueous SA and absent in aqueous NA. Moreover, the decomposition of H3O+ diffusion into vehicular and structural components indicates that the higher diffusion in aqueous PA is primarily due to the structural mechanism with the aid of PA molecules. In the aqueous NA systems, the vehicular diffusion is dominant at low water contents and the increase in water content improves the structural diffusion by forming connected H-bonds within water molecules. Our findings elucidate the role of acid molecules in proton transport within their aqueous solutions, thereby advancing the fundamental understanding of proton transport mechanisms.

Removal of Impurities from Nickel and Cobalt in Mixed Hydroxide Precipitate with Solvent Extraction Using Di(2-Ethylhexyl) Phosphoric Acid

ABSTRACT This study investigates the removal of major impurities, namely Fe, Al, Zn, and Mn, in a solution produced by sulfuric acid leaching of mixed hydroxide precipitate from the Ni and Co via solvent extraction using di(2-ethylhexyl) phosphoric acid (D2EHPA). The results of extraction experiments showed that the extracted Ni, Co, Fe, Al, Zn, Mn, and Mg increased as the equilibrium pH, D2EHPA concentration, and O/A ratio increased. The optimum extraction condition was achieved at a pH of 3.5, a 20% (v/v) D2EHPA concentration, and an O/A ratio of 1, with a complete (>99.9%) extraction of Al, Fe, Zn, and 97.33% Mn with co-extracted Ni and Co of 22.32% and 29.13%, respectively, in a single extraction stage. Complete Mn removal can be achieved in two extraction stages. Co-extracted Ni and Co can be scrubbed out using a mild sulfuric acid solution at a pH of 1.2 with only less than 2% of the Al, Fe, Zn, and Mn co-scrubbed. McCabe-Thiele diagrams of the scrubbing processes were constructed, and the results showed that Ni and Co can be scrubbed out using a mild acidic solution at a pH of 1.2, O/A ratio of 1, and temperature of 40°C for 10 min of mixing. Zn and Mn can be stripped completely using 0.5 M sulfuric acid solution at an O/A of 1 and temperature of 40°C for 10 min of mixing, while Fe and Al remained unstripped. Fe and Al can subsequently be stripped via reductive stripping.

In Situ STM Study of Roughening of Au(111) Single-Crystal Electrode in Sulfuric Acid Solution during Oxidation–Reduction Cycles

In Situ STM Study of Roughening of Au(111) Single-Crystal Electrode in Sulfuric Acid Solution during Oxidation–Reduction Cycles

Electrodeposition of Cu 3D structures suitable for CO2 reduction

Porous Cu foam electrodes, suitable for cathodic CO2 reduction, were deposited in an acidic sulphate solution with different additives to obtain structures with a high real surface area and an adequate mechanical stability. The influence of the electrodeposition time and solution composition on the porosity parameters, microstructure and stiffness of Cu 3D structures was evaluated. Neither ammonium acetate nor polyethylene glycol were found to be effective additives to the Cu sulphate electrolyte to achieve the main objectives. Only the presence of Cl– ions in the deposition solution resulted in a threefold increase in the real surface area and the achievement of a sufficient mechanical stability of the Cu 3D structure. The latter effect is related to the specific influence of Cl– ions during the electrodeposition process on the microstructural characteristics, such as the size of micropores in the walls of holes and crystallite aggregates that form dendritic branches. These structural changes, in contrast to the Cu samples deposited in a solution without additives, resulted in larger real surface areas, while the denser structures deposited in the presence of Cl– ions ensured the mechanical stability of the 3D structure.

Potentiodynamic Polarization Study of PH3 Electrochemical Oxidation

ABSTRACTIn this study, the electrochemical behaviour of phosphine in sulphuric acid solutions on the surface of various electrode materials was conducted by voltammetric investigations. The effects of electrode materials such as lead, copper, and platinum electrodes on the PH3 anodic oxidation were investigated. Polarization curves were recorded by saturating the sulphuric acid solution with phosphine. The results received show that the electrochemical oxidation of phosphine on the lead electrode is accompanied by an oxygen evolution potential and, on the copper electrode, copper (II) ions show catalytic effects. The maximum anodic oxidation of phosphine on a platinum electrode was observed at the potential range of 0.8–1.0 V, and in the presence of copper (II) ions on the polarogram a maximum of phosphine oxidation is recorded at a potential of approximately 0.1–0.2 V.

Effects of Strontium Modification on Corrosion Resistance of Al-Si Alloys in Various Corrosive Environments.

This study investigates the impact of strontium (Sr) additions on the corrosion resistance of an LM6 (A413) aluminium alloy. By incorporating varying concentrations of Sr (0.01 wt.% and 0.05 wt.%), the morphological and corrosion behaviours of the alloy were analysed under different corrosive environments, including sulphuric acid, sodium hydroxide, and sodium chloride solutions. The results demonstrate that Sr modifications significantly enhance the alloy's corrosion resistance, with the most substantial improvement observed at 0.05 wt.% Sr. The analysis revealed that the weight loss of the alloy in sulphuric acid decreased by 2.5% with 0.05 wt.% Sr after 10 days of immersion, due to the formation of a stable passive oxide layer. In sodium hydroxide, however, the weight loss was reduced by 5% with 0.05 wt.% Sr after 10 days, indicating aggressive uniform corrosion. In the 3.5% sodium chloride solution, the corrosion rates remain relatively low, and the 0.05 wt.% Sr alloy showed a decrease in corrosion product formation over time, suggesting enhanced resistance. Detailed surface analyses, including 3D profiling and morphology assessments, revealed that Sr additions refine the eutectic silicon phase, transforming it from a coarse to a more desirable fibrous or lamellar structure, thus improving the alloy's overall performance. The innovative findings underscore the potential of Sr as an effective microstructural modifier for enhancing the durability and longevity of Al-Si alloys in corrosive environments.

Determination of saturated dissolved oxygen concentration in iron sulfate solutions containing iron oxidizing microorganisms

Iron sulfate solutions and the extremophile lifeforms that can live within them are industrially and environmentally important in many applications and require proper assessments of solution properties. Determination of saturated dissolved oxygen concentration is an important parameter for monitoring iron biooxidation processes. However, its determination is not so straight forward using commercially available dissolved oxygen meters. Such meters utilize internal calculation models based on the saline properties of seawater which can be easily overlooked. A method for determination of the saturated dissolved oxygen concentration in acidic iron sulfate solutions with the inclusion of other inorganic salts is proposed in this work using the biooxidation of ferrous iron as an indicator measured with redox potential and converted to oxygen concentration through bioreaction stoichiometry. The technique was tested on a BioGenerator system over the course of four days and proved satisfactory in establishing a value for the saturated dissolved oxygen concentration of the bioreactor broth. Study of the lifespan properties of the microorganisms in absence of ferrous iron substrate was briefly examined to determine the effective handling period of solutions for assessment.

Investigating the synergistic effect of fish waste extract and KI on the corrosion inhibition of carbon steel in sulfuric acid solution

Biowaste has become a serious problem that can lead to serious environmental pollution and waste of resources if not handled properly. Waste materials are often high in proteins, which are easily extracted and hydrolyzed to provide an adequate quantity of amino acids. This indicates that biowastes can be used as green and efficient corrosion inhibitors (CIs). This work aimed to prepare fish waste extract (FWE) by acid hydrolysis with alkaline leaching using fish waste as the raw material. The results of the characterization analysis identified the presence of 17 amino acids, with Leucine, Phenylalanine, Methionine, and Alanine being the most abundant. FWE was then tested as a corrosion inhibitor (CI) for carbon steel in 0.5 mol/L H2SO4. Further, the effect of KI on the corrosion inhibition performance of FWE for carbon steel in 0.5 mol/L H2SO4 was systematically investigated by the weight loss method, electrochemical method, and surface analysis. The maximum corrosion inhibition efficiencies were 88.7 % and 63.9 % for the FWE and KI alone, and 97.10 % for the combination of FWE and KI. The synergistic coefficient study confirmed that the synergistic coefficients of the FWE and KI exceeded 1 across all concentration conditions, indicating a synergistic effect between them. The surface analysis results showed that the deterioration of carbon steel after adding the compounded CI was mild, and pitting and crevice corrosion was not observed. Theoretical calculations revealed the active reaction sites of four major amino acid molecules via quantum chemical and molecular dynamics simulations. The effect of different types of side chains and heteroatoms of amino acid molecules on their corrosion inhibition performance was elucidated to provide theoretical guidance for designing biowaste CIs.

On the corrosion resistance of the CoCrFeMnNi high entropy alloys in chloride-containing sulfuric acid solutions

The electrochemical reactivity of the high entropy Cantor alloy (CoCrFeMnNi) was investigated via potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and surface analysis as a function of chloride content, in sulfuric acid solutions. The results revealed that corrosion mechanism of the CoCrFeMnNi alloy at the corrosion potential, is a two-step mechanism, involving one adsorbed intermediate, similar to that of pure iron in the H2SO4, and this model provided a good description of the impedance data. X-ray photoelectron spectroscopy (XPS) surface characterization and impedance data fitting revealed that chloride ions do not alter the corrosion mechanism or the thickness of the surface oxide film. Instead, they affect the corrosion resistance by changing the composition of the oxide film. Additionally, this work demonstrated that the corrosion mechanism of the CoCrFeMnNi alloy varies with the applied potential, as evidenced by impedance measurements under potentiostatic polarization. Surface observations using scanning electron microscopy (SEM) and XPS analysis provided insights into the morphology and composition of the surface oxide film at different applied potentials, explaining the observed changes in impedance.

Impact of Aging on Tensile Properties of EPDM, TPV, and eco-TPV: A Comparative Study Across Diverse Environments

Abstract This study examines the effects of aging on the tensile characteristics of Ethylene Propylene Diene Monomer (EPDM), Thermoplastic Vulcanizates (TPV), and Eco-friendly Thermoplastic Vulcanizates (Eco TPV) in different conditions. The samples underwent thermal aging at a temperature of 90°C and were immersed in sulfuric acid solutions with varying concentrations (1M, 0.1M, and 0.001M) for a duration of 1000 hours at the same temperature. The findings revealed that EPDM demonstrated the maximum tensile strength and a moderate level of elongation and breakage. Furthermore, it retained substantial mechanical integrity after undergoing aging, thereby establishing it as the most resilient material among those evaluated. The thermoplastic vulcanizate (TPV) exhibited intermediate tensile strength and elongation, but experienced significant deterioration when exposed to very acidic environments while Eco TPV had lower tensile strength but good chemical stability. The stress-strain behavior and compression set tests emphasized EPDM’s exceptional durability and ability to recover elastically. The pH measurements of the immersion solutions indicated an elevation caused by the release of alkaline chemicals from the rubber components, especially in the 1M solution.

Functionalization of High-Density Polyethylene Capillaries for Open Tubular Ion Chromatography.

Ion chromatography is the anion analysis benchmark. A miniature form, Open Tubular Ion Chromatography (OTIC), has attractive attributes for efficient ion separations. Here, we fabricate and characterize high-density polyethylene (HDPE) open tubular anion exchange columns (OTCs). We attach positively charged latex particles onto negatively charged capillary surfaces. For efficient OTIC, column diameters need to be < ∼20µm; functionalizing the bore is challenging. Methods to introduce acid groups to an HDPE capillary bore, e.g., sulfonation using chlorosulfonic or sulfuric acid solutions, with or without grafting of an aromatic ring through photo- or chemical grafting first, are explored. Following quaternary ammonium latex attachment, the ion exchange capacity and separating abilities of each OTC were measured as an index of OTC performance. Gradual loss of capacity was observed for many of these; high-resolution mass spectrometry confirmed the leaching of detached oxidized/sulfonated oligomeric fragments and consequent poisoning of the latex sites. Ways to ameliorate this and/or to rejuvenate the columns are also described.

Study of the proton transfer during acidification of sodium salicylate based on ReaxFF molecular dynamics simulation

Salicylic acid(SA) is known for its pain-relieving and fever-reducing abilities and has a very broad range of applications, being an important ingredient in a wide variety of products such as pharmaceuticals, skin care products, agrochemicals, dyes, colorants, preservatives, and more. SA is mainly synthesized by the Kolbe-Schmitt method in industrial production, but there is still no standardized description of the mechanism of this reaction. The Kolbe-Schmitt reaction mechanism is divided into three steps, and the reaction mechanism of the first two steps has been fully investigated, while the reaction mechanism of Sodium salicylate (SS) acidification, as the last step in the synthesis of SA by the Kolbe-Schmitt process, has not been investigated, so we used the Reactive force-field molecular dynamics simulation (ReaxFF MD) method to simulate and reveal the reaction mechanism of the mixed solution of SS and sulfuric acid, followed by an orthogonal design to explore the effects of different factors on the yield of SA. Through the investigation, it was found that the reaction of SS with sulfuric acid mixed solution was divided into the following four stages in total: hydration reaction, proton transfer reaction, association reaction and dissociation reaction, respectively. It is concluded that the SA yield in SS acidification reaction is affected by the factors in the following order: concentration > pressure > time > temperature, where concentration and pressure significantly affect the SA yield. It is hoped that the present study can supplement the relevant understanding of the reaction mechanism of the Kolbe-Schmitt process, and at the same time have some practical significance and application value for the improvement and optimization of the synthetic SA process.

Corrosion mitigation of carbon steel in sulfuric and hydrochloric acid solutions by Syzygium polyanthum (Wight) Walp. leaf extract

It is widely recognized that corrosion has been a persistent issue throughout human history. Over time, various effective strategies have been suggested and successfully employed to combat this problem. Among them, the utilization of inhibitors stands out as a promising, versatile, and easily applicable method. Considering the drawbacks associated with previous substances such as environmental concerns and high operational expenses, plant extracts have emerged as an effective alternative. In there, Syzygium polyanthum (Wight) Walp. stands out as a popular species characterized by a high concentration of polar compounds that is crucial for the formation of a protective film layer on carbon steel. Consequently, this work centers on investigating the corrosion inhibition behavior of Syzygium polyanthum (Wight) Walp. leaf water-extract (SPWE) for carbon steel in different solutions, including 1.0 M HCl, 0.5 M H2SO4, and co-volume acidic mixture, by employing electrochemical and surface techniques. The findings reveal that 2000 ppm of SPWE proved inhibition efficiency exceeding 94.24, 66.27, and 95.02% (estimated by Tafel extrapolation) for carbon steel in 1.0 M HCl, 0.5 M H2SO4, and acidic mixture solutions, respectively. High inhibition performance was also ensured by high polarization resistances (Rp) observed on electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR). Increasing corrosion resistance could be due to the protective layer formed on the inhibited samples, while severe corrosion occurred on the uninhibited steel due to extensive damage across the entire surface. Hence, the study underscores the noteworthy impact of chloride and sulfate ions on corrosive inhibition process of SPWE.