Sulfuric Acid Solution Research Articles

The influence of carbon imperfections on the physicochemical characteristics of coal gangue aggregates

In order to promote the development of coal gangue aggregate concrete and the resource utilization of coal gangue solid waste, the coal gangue samples were crushed into aggregates, and then the macroscopic characteristics and microscopic structures of the aggregates were characterized through methods such as calcination, sulfuric acid solution dry-wet cycle, XRD, TG-DTG, and SEM-EDS, based on the Chinese national aggregate standard, the key influencing factors of the physicochemical properties of coal gangue aggregates were analyzed. The results show that coal gangue with lower loss on ignition and carbon content has smaller crushing value, lower water absorption rate, and stronger soundness. The carbon content and carbon distribution significantly affect the macroscopic physicochemical properties of coal gangue aggregates. Carbon, as a defect, is uniformly distributed in coal gangue, which increases the crushing value of coal gangue aggregates and greatly reduces their soundness, leading to the “second-order adverse effect” and “opening window effect”, which are detrimental to the durability of coal gangue aggregate concrete. The composition and physicochemical properties of a large number of coal gangue samples were determined, and the correlation between composition overlay effects on physicochemical properties were analyzed using a “three-dimensional surface”. This analysis confirms the adverse effects of carbon defects on the physicochemical properties of coal gangue aggregates. Carbon content can be used as the primary control index for coal gangue in resource utilization.

Feasibility of CO2 desorption and electrolytic regeneration of potassium carbonate solution in an anion exchange membrane cell

In this work, an electrolytic process was introduced for coupled regeneration of potassium carbonate (K2CO3) solution and water electrolysis by using an anion exchange membrane cell. The process made the CO2 separation from O2 much easier with respect to the existing cationic exchange membrane process. The solution of K2CO3 was used in the cathode chamber to simulate the solution after absorbing CO2. The solution of sulfuric acid (0.1 mol/L H2SO4) was charged in the anode chamber. The feasibility of the process was discussed. The effects of various operation parameters, including temperature, current density, and electrolysis time, were studied. The results indicate that both the yield rate of CO2 and the current efficiency increase initially and decrease afterward with temperature. The yield rate of CO2 increases while the current efficiency decreases with the current density. A low current density can reduce the energy consumption for producing the same amount of CO2. The processes using anion exchange membrane electrolysis can regenerate the absorbent solution to achieve 89% current efficiency, and the simultaneous production of three pure gases, CO2, H2, and O2, makes this method promising.

Acid dissolution of LiF/(NH4)3AlF6 mixtures obtained in the fluorination of α-spodumene with NH4HF2: Modeling and optimization

Lithium is an essential element in the current energy paradigm shift. Therefore, Li extraction from mineral sources has become a scientific and technological priority. Industrially, the mineral α-spodumene is heated to 1100 °C to obtain phase β and then digested with concentrated sulfuric acid at 250 °C. As an alternative, the extraction of Li from α-spodumene with molten NH4HF2 has been proposed as an efficient alternative method at low temperature (∼160 °C). However, the LiF obtained requires an acid leaching step to be solubilized and to separate the Li from other products. This research presents the modeling and optimization of the acid leaching operating parameters of the LiF/(NH4)3AlF6 mixture. This mixture was obtained by processing α-spodumene with NH4HF2 at low temperatures. The solids were characterized by XRD, SEM/EDS, and the Rietveld method. The leaching operating parameters investigated were solid/liquid ratio, sulfuric acid concentration, and leaching time. (NH4)3AlF6 dissolution and Li extraction were analyzed and modeled separately using artificial neural networks and least squares, respectively. The optimization stage of the process leads to (NH4)3AlF6 dissolution of 99% and Li extractions of 93%, working with 6% (v/v) sulfuric acid solution and an S/L ratio of 30 g/L for 24 min

Electrochemical behavior and passive film properties of Ce-added AlCoCrFeNi2.1 eutectic high-entropy alloys in sulfuric acid solution

Eutectic high-entropy alloys (EHEAs), represented by AlCoCrFeNi2.1, are considered to be promising materials. However, the study of the corrosion behavior of EHEAs remains limited, which hinders further development. This study investigated the effect of Ce addition on the electrochemical behavior and passive film properties of AlCoCrFeNi2.1 EHEAs in H2SO4 solutions. The results show that the addition of Ce changed the properties of the passive film formed on the alloys, resulting in reduction in the proportion of Cr2O3, and thereby reduced the corrosion resistance. Moreover, a higher Ce content in the EHEAs was found to correspond to a more pronounced deterioration in corrosion resistance. Compared with the film formed at 0.2 Vvs SCE, the film formed at 0.5 Vvs SCE exhibited more optimal physicochemical properties, leading to a decrease in the passive current density. Notably, Ce was absent in the film formed at 0.2 Vvs SCE, but present at 0.5 Vvs SCE.

Enhancing concrete performance using protective coating fabricated by recycled waste material

The motivation behind this research is to enhance concrete using a coating fabricated from waste materials. Polyethylene terephthalate (PET) was added to asphalt (AP) cement of 60/70 penetration grade at different percentages. Scanning electron microscope (SEM) images show that 6% PET is the optimum mix proportion, and then ternary blends were done by mixing the prepared AP/PET with nano silica (nS) at different ratios (0.5, 1, 1.5, 2, and 2.5) wt./wt. The prepared coatings were evaluated by determining drying time, dry film thickness (DFT), adhesion strength, impact resistance, and flexibility. The formulated coatings were applied to concrete substrates, and the performance of coated concrete cubes was examined by determining water absorption, contact angle, and chloride diffusion. The durability of coated concrete was evaluated by measuring the changes in compressive strength after immersion in both sulfuric acid and sodium chloride solutions separately. The study proved the eco-efficient use of PET waste bottles in protective coating preparation, and the experimental results detected that nS has a significant mechanism for improving coating performance as follows; drying time of AP/PET-2 reduced with 61% as compared to AP/PET, the increment of DFT of AP/PET-2 was 25%, and adhesion strength was improved by 90%. On the same time, silica nano particles are mainly contributes for enhancing coated concretes. Where water absorption reduced with 75%, contact angle increased by 55%, and chloride permeability resistance enhanced to 40%. Finally, improvement durability of coated concrete was 25% and 20% after immersion for 28 d in both sulfuric (3%) acid and sodium chloride (5%) solutions, respectively.

H2SO4 assisted hydrothermal conversion of biomass with solid acid catalysis to produce aviation fuel precursors

With hydrothermal reaction, lignocellulosic biomass can be efficiently converted into furfural (FF) and levulinic acid (LA), both of which are key platform compounds that can be used for the subsequent preparation of aviation fuels. In order to reduce the acid concentration in traditional hydrolysis and provide a reaction system with good catalytic activity, we propose a biomass conversion route as dilute acid hydrolysis coupled with solid acid catalysis. Firstly, at different temperatures, the hemicellulose and cellulose in corn stover were step-hydrolyzed by sulfuric acid solution with a concentration of 0.9 wt.% to produce xylose and glucose, with conversion reaching 100% and 97.3%, respectively. Subsequently, a new resin-derived carbon-based solid acid catalyst was used to catalyze the aforementioned saccharide solutions to obtain FF with yield of 68.7 mol% and LA of 70.3 mol%, respectively. This work provides a promising approach for the efficient production of bio-aviation fuel precursors.

INVESTIGATION OF THE POSSIBILITY OF PROCESSING KAOLIN CLAYS OF THE SUVOROV DEPOSIT TO OBTAIN COAGULANTS

The mineral and chemical compositions of the Suvorov depositkaolin clay have been studied using X-ray phase and atomic emission spectrometry with induction plasma. The conditions of thermal calcination and decomposition of kaolin clay with sulfuric and hydrochloric acids are optimized: the calcination temperature is 650-700 °C; the calcination duration is 60-90 minutes. The extraction degree of Al2O3 from calcined clay into sulfuric acid solutions was 92-94%, into hydrochloric acid solutions — 76-78%. The effect of different flocculants on the separation of liquid and solid phases is investigated. It is shown that the use of polyacrylamide increases the filtration rate by 1.5—2 times. The coagulating properties of aluminum sulfate and hydroxochlorides were studied: oxidizability, color, concentration of aluminum and iron in the treated water. The tested coagulants can be effectively used in the purification of drinking and wastewater at low and high temperatures in a wide pH range of treated waters.

One Pot Synthesis of Calcium Sulfate Hemihydrate from Fishbone-derived Carbon

Calcium Sulfate Hemihydrate (CSH) with uniform morphology and high crystallinity were successfully prepared by a precipitation-hydrolysis method in a concentrated sulfuric acid solution containing fishbone-derived carbon. The CSH was produced by carbonization of fishbone powder at 500 °C for 2 h, followed by sulfonation with concentrated sulfuric acid for 3 h. The solid mixture was washed until the pH of 2, then left at room temperature for 3 days. Physical properties of synthesized CSH were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), wavelength dispersive X-ray fluorescence (WDXRF), Scanning Electron Microscope (SEM), nitrogen adsorption-desorption isotherm, and melting point test. It is concluded that the CSH were formed due to hydrolysis of fishbone-derived carbon in a moderately concentrated sulfuric acid solution of carbon-derived fishbone and crystallization into a fibrous octa calcium phosphate (OCP) form. In this research, effect of crystal growth time, effect of pH during the crystal growth, and effect of volume of the solution were also investigated. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Electrochemical Exfoliation of Graphene Oxide: Unveiling Structural Properties and Electrochemical Performance.

An electrochemical exfoliation method for the production of graphene oxide and its characterization by electrochemical techniques are presented here. Graphite rods are used as working electrode in a three-electrode electrochemical cell, and electro-exfoliation is achieved by applying anodic polarization in a sulfuric acid solution. The electrochemical process involved two steps characterized by an intercalation at lower potential and an exfoliation at higher potential. The electrochemical behavior of the produced GO is studied through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). X ray Photoelectronic Spectroscopy (XPS), Raman spectroscopy, Transmission Electron Microscopy (TEM), and Atomic Force Microscopy (AFM) are employed to characterize the structural and chemical properties of the exfoliated GO. The results demonstrate that the electrochemical exfoliation method yields GO materials with varying degrees of oxidation, defect density, and crystallite size, depending on the applied potential and acid concentration. The graphene oxide samples exhibited distinct electrochemical properties, including charge transfer resistance, interfacial capacitance, and relaxation times for the charge transfer, as revealed by CV and EIS measurements with a specifically selected redox probe. The comprehensive characterization performed provides valuable insights into the structure-property relationships of the GO materials synthesized through electrochemical exfoliation of graphite.

Investigation of corrosion inhibition performance of expired fluconazole drug on mild steel in 0.5M H2SO4 medium

Fluconazole is a pharmaceutical drugused for the treatment of fungal infections.The disposal of the expired Fluconazoledrug threatens the environment, but still, it contains active components. The potentiality of the active components of the expired Fluconazole drug was utilized to guard the mild steel corrosion in0.5 M sulphuric acid medium. Electrochemical and mass loss studies were used to evaluate the drug's capacity to protect mild steel surfaces against corrosion. The outcomes of the studies demonstrate that Fluconazole effectively inhibits the corrosion of mild steel in sulphuric acid solution at various temperatures.The maximum inhibition efficiency obtained by the mass loss method was 93.75% at 110 ppm drug concentration. Fluconazole molecules have been determined to follow the Langmuir adsorption isotherm model. The SEM images visualized that, in the presence of drug molecules th mild steel surface was least affected by the acid solution compared to the blank solution. The water contact angle data revealed that the adsorption of Fluconazole molecules builds mild steel surfaces that are more hydrophobic in nature. The inhibitor molecules retard both anodic and cathodic reactions in an acid medium and act as a mixed-type inhibitor. DFT calculations and Molecular dynamics simulations further elucidated the chemical interactions between Fluconazole and the mild steel surface.

Biosorption of rare earth elements from luminophores by G. sulphuraria (Cyanidiophytina, Rhodophyta)

Lanthanides are indispensable constituents of modern technologies and are often challenging to acquire from natural resources. The demand for REEs is so high that there is a clear need to develop efficient and eco-friendly recycling methods. In the present study, freeze-dried biomass of the polyextremophile Galdieria sulphuraria was employed to recover REEs from spent fluorescent lamps (FL) luminophores by pretreating the freeze-dried biomass with an acid solution to favour ion exchange and enhance the binding sites on the cell surface available for the metal ions. Lanthanides were extracted from the luminophores using sulfuric acid solutions according to standardised procedures, and the effect of biosorbent dosage (0.5–5 mg/ml) and biosorption time (5–60 min) were evaluated. The content of individual REEs in the luminophores and the resulting algal biomass were determined using inductively coupled plasma mass spectrometry (ICP-MS). The most abundant REE in the luminophores was yttrium (287.42 mg/g dm, 91.60% of all REEs), followed by europium (20.98 mg/g, 6.69%); cerium, gadolinium, terbium and lanthanum was in trace. The best biosorption performances were achieved after 5 min and at the lowest biosorbent dosage (0.5 mg/mL). The highest total metal amount corresponded to 41.61 mg/g dried mass, and yttrium was the most adsorbed metal (34.59 mg/g dm, 82.88%), followed by cerium (4.01 mg/g); all other metals were less than 2 mg/g. The rapidity of the biosorption process and the low biosorbent dosage required confirmed this microalga as a promising material for creating an eco-sustainable protocol for recycling REEs.

Benzene Sulfonamide Derivatives as Inhibitors for Steel Dissolution in Sulfuric Acid Solution

Benzene Sulfonamide Derivatives as Inhibitors for Steel Dissolution in Sulfuric Acid Solution

Impact of magnesia and titania nanoparticles on characteristics of alkali-activated slag mortars exposed to sulfuric acid solution and elevated temperatures

Nanotechnology is being employed as potential solution to alleviate limitations of alkali-activated slag mortars (AASMs). The current study investigated the impact of prepared magnesia (NMg) and titania nanoparticles (NT) at various dosages (0, 1, 3 and 5 wt%) on mechanical and durability characteristics of AASMs. Specimens were either fully immersed in an aqueous solution of sulfuric acid (1 wt% concentration) or subjected to elevated temperatures (250, 500 and 750℃). Microstructural development and densification were analyzed by XRD, FTIR, and SEM with EDX technique to determine the primary improvement mechanism imparted as a result of employing nanoparticles to AASMs systems. Optimum performance prior to and after exposures was achieved for specimens containing 3% NMg and 1% NT in terms of compressive strength, water absorption for unexposed specimens, and weight loss and compressive strength retention for specimens exposed to sulfuric acid solution and elevated temperature. Nanoparticles produced more densified mixtures imparted by their ability to accelerate geopolymerization processes, filling effect and formation of voluminous compounds that further block available spaces in the microstructure.

Corrosion protection of mild steel using calcined cattle bone waste powder coating in sulphuric acid solution

Corrosion protection of mild steel using calcined cattle bone waste powder coating in sulphuric acid solution

Electrochemical Exfoliation and Thermal Deoxygenation of Pristine Graphene for Various Industrial Applications

The transition of graphene from the lab to consumer goods is still a challenging job that necessitates efficient and cost-effective large-scale graphene production. This study combines electrochemical exfoliation in an aqueous solution of sulfuric acid (1M H2SO[Formula: see text] and hydrogen peroxide (3% H2O[Formula: see text] followed by thermal deoxygenation at a temperature of 800[Formula: see text]C within the ambient environment. This method allows the inexpensive synthesis of pristine graphene for various industrial applications. X-Ray diffraction (XRD) results for pristine graphene showed a distinct peak at 2[Formula: see text] with a corresponding interplanar distance ([Formula: see text] of 3.3754 Å and a crystallite size of 18 nm. XRD statistics indicated that the crystal structure of the original graphene was preserved. The crystalline structure was recovered and the interplaner distance was decreased following the high temperature thermal reduction. According to Raman spectroscopy, the impurity degree (I[Formula: see text]/I[Formula: see text] region fraction of pristine graphene was 0.211. This indicates that the original graph produced by the current method has little distortion. Raman analysis shows that there is a linear red shift in peaks D-band (D), G-band (G), and second order of the D-band (2D) due to the increase in phonon–phonon nonlinear interactions with increasing temperature, so that peaks (D), (G) and (2D) shifts are shown. The majority of the functional groups were discovered to be eliminated after high temperature thermal treatment. The three-dimensional graphene sheet is highly defined and intricately coupled in the microstructure analysis, resulting in a laxer and porous structure. When treated at a temperature below 800[Formula: see text]C, there was only minor damage to the reduced graphene oxide (RGO) microstructure. The results of the Atom Force Microscope (AFM) demonstrated that the flaws spread over time from the layer boundaries and pores to the edges and eventually resulted in a separate RGO archipelago. According to TGA analysis, at temperatures up to 800[Formula: see text]C, the RGO sheet loses up to 45% of its weight.

Study of the process of obtaining water glass from silica gel for use in metallurgy

This study explores the possibility of producing a sodium silicate solution (liquid glass) using industrial raw materials for subsequent use in metallurgical practice. The object of the study was industrial waste from the production of aluminium fluoride, i.e., silica gel, which comprises a fine powder of silicon dioxide with a moisture content of over 55 wt %. Silica gel was purified using a low-concentration solution of sulfuric acid. The synthesis of liquid glass was carried out using the HEL Auto-Mate Reactor System. The silicon content in the solution was determined by X-ray fluorescence method using the Shimadzu EDX-7000P analyzer. To determine the alkali content in the resulting product, a titrimetric analysis method was used. The preliminary purification process allowed silica gel with an amorphous silica content of over 98 wt % to be obtained. The optimal parameters of the liquid glass production were defined: temperature – 100°C, process time – 4.5 hours, mixing speed – 300 rpm, and the concentration of the initial alkaline solution – from 10 to 17.5 wt %. The resulting liquid glass solution had a mass content of silicon dioxide from 16.65 to 23.77 wt % and a silicate module from 2.72 to 3.16, which meets the requirements of marketable products for various industries. Based on the experimental results, optimal parameters for the production of liquid glass using industrial raw materials, i.e., silica gel, are proposed. Liquid glass with the defined characteristics can be further used as a binder in metallurgical processes.

The Blue Molybdenum Reaction for the Determination of Phosphate in Natural Water and Detergent Samples

Background:
 The ideal reaction conditions for the quantitative detection of phosphate in various natural water and detergent samples were carefully researched in order to produce and preserve the colored complex product. The blue complex was identified using a simple and accurate UV-VIS spectrophotometer with a maximum wavelength of 870 nm.
 Even though phosphate is an essential ingredient for the development of aquatic species, it is important to know exactly how much is present because an excess amount of phosphate can eutrophic water. Since detergents are one of the sources of phosphate in natural water, determining the concentration of phosphate in detergent samples is also essential.
 Materials and Methods:
 The method is based on the addition of sodium molybdate, which causes the interaction of orthophosphate with molybdate to produce an intense, stable, and water-soluble phosphomolybdate blue complex. Then, this combination is reduced using hydrazine hydrate in a sulfuric acid solution.
 Results:
 With a correlation coefficient of 0.9944, the system complies with Lambert-Beer's law at 870 nm in a concentration range of (0.05-9) ppm. Molar absorptivity was determined to be 12.16x103 L mol-1 cm-1 and Sandell's sensitivity was found to be 0.0156 g cm-2. Water samples were collected from Warte, Choman, Jundeyan, and Bexal in Kurdistan's vicinity of Soran. Further, detergent samples that were obtained from the market and their phosphate level were examined. The Bexal waterfall had the lowest concentration of phosphate, 0.18 ppm, while the Warte and Jundeyan water samples had the highest concentrations, 3.31 ppm, and 3.04 ppm, respectively. Moreover, similar phosphate concentrations in the two detergent samples were discovered to be at 20.43 and 24.76 ppm.
 Conclusion:
 The molybdenum blue reaction has been successfully employed to provide a sensitive and quick measuring method to quantify the phosphate content in various water and detergent samples using UV-VIS spectrophotometry by applying the right reaction conditions and reagent quantities.

Electrotransport Characteristics of Polyaniline-Modified Cations-Exchange Membranes in Solutions of Sulfuric Acid and Nickel and Chromium Sulfates

Electrotransport Characteristics of Polyaniline-Modified Cations-Exchange Membranes in Solutions of Sulfuric Acid and Nickel and Chromium Sulfates

A Flexible Self-Supported Silver Wire with Nanoporous Skeleton for Electrochemical Sensing of Trichloroacetic Acid

The content of chloroacetic acid in water is mandatory, so rapid and accurate detection is of great significance for environmental health. Silver has a strong specific interaction with chloridion and its three-dimensional interconnected ligaments are proved to have higher activity. Herein, a self-supported nanoporous skeleton was constructed on the surface of silver wire by directly electrochemical alloying in ZnCl2–glycol solution at 140 °C and subsequently dealloying in sulfuric acid solution. AgZn and AgZn3 alloys are formed by electrodeposition process, and the nanoporous skeleton of elemental silver is formed after dealloying. The interconnected ligaments are uniform and the pore size is about 10–200 nm. The cyclic voltammetry showed that the self-supported nanoporous skeleton of the silver wire electrode exhibited high electrocatalytic activity for trichloroacetic acid. Detected by chronoamperometry, the results show that the detection limit is 70 nM (S/N = 3) in the concentration range of 0.14–549 μM, and the sensor has high sensitivity, good reproducibility and anti-interference. And by detecting the recovery rate of trichloroacetic acid in the tap water, river water and industrial wastewater, the sensor proves the practicality of the prepared electrode.

TiO2 Microparticles Incorporation in Coatings Produced by Plasma Electrolytic Oxidation (PEO) on Titanium

This research describes the influence of two types of particles, namely rutile and anatase microparticles (average d < 5 µm), on the morphology, structure, and anticorrosive properties of PEO coatings on titanium produced in an alkaline solution based on NaOH and sodium metasilicates. The paper reports the experimental results relating to the study of the influence of the electrical regime and working frequency of the anodizing treatment on the interaction between the particles, the substrate, and the oxide to determine the optimal conditions that favour the incorporation of the particles and the production of a thick oxide. PEO coatings are characterized by using a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) analysis, and X-ray diffraction (XRD) testing. The electrochemical behaviour is evaluated by free corrosion potential monitoring and electrochemical impedance spectroscopy analysis (EIS) performed in a sulphuric acid solution. The particles are successfully incorporated into the coating under any electrical condition and at any frequency. However, only treatments carried out at 1000 Hz allow the production of coatings that combine a large thickness (up to 50 µm) and improved anticorrosion behaviour. In contrast, oxide layers produced at 20 Hz and in DC show a quite damaged structure, affecting their anticorrosion behaviour and resulting in lower corrosion potential and impedance values.