Hydrochloric Acid Medium Research Articles

Spectrophotometric Determination of Curcumin using 3-Methyl-2-benzothiazolinone Hydrazone Hydrochloride Hydrate as Electrophilic Coupling Agent

Introduction: Nutraceuticals are products derived from food sources that provide extra health benefits in addition to the basic nutritional value found in foods. Spectrophotometric methods for the determination of curcumin were developed, which are simple, sensitive, selective, rapid, and reliable. Methods: The methods are based on the reduction of iron (III) to iron (II) by 3-Methyl-2- benzothiazolinone hydrazone hydrochloride hydrate (MBTH), which is an electrophilic coupling agent and subsequent reaction with curcumin in mild hydrochloric acid medium. Spectrophotometric methods for the determination of curcumin were developed, which are simple, sensitive, selective, rapid, and reliable. The methods are based on the reduction of iron (III) to iron (II) by 3-Methyl-2-benzothiazolinone hydrazone hydrochloride hydrate (MBTH), which is an electrophilic coupling agent and subsequent reaction with curcumin in mild hydrochloric acid medium. Result: The reaction produces a bluish–green complex with maximum absorbance at 670 nm. The colour complex can be extracted into chloroform. The methods obey Beer’s law in the range 0.3-7.0 and 0.2-7.0 (μg mL-1). Conclusion: 10 common anions and cations were added, and the method was tested, and no interference was observed. The proposed methods offered the advantages of having good reproducibility and were satisfactorily worked out to estimate the amount of curcumin in various turmeric samples.

Spectrophotometric determination of metoclopramide hydrochloride in pharmaceutical tablets, by diazotization-coupling method with 1-naphthol as the coupling agent

Simple, rapid and sensitive spectrophotometric method was proposed for the analysis of metoclopramide hydrochloride (MPH) in pure form as well as in pharmaceutical tablets. The method is based on the diazotization reaction of MPH with sodium nitrite in hydrochloric acid medium to form diazonium salt, which is coupled with 1-naphthol in sodium hydroxide medium to form azo dye, showing absorption maxima at 550 nm. Beer’s law is obeyed in the concentration range of 0.4 – 18 µg mL-1 of MPH with detection limit 0.5448 µg mL-1. The molar absorptivity and Sandell’s sensitivity are 3.4969 × 104 L mol-1 cm-1 and 0.0101 µg cm-2, respectively. The method was successfully applied to the determination of MPH in pharmaceutical tablets without any interference from common excipients used as additives in tablets. The results agree favorably with the official British Pharmacopoeia method.

Liquid-liquid extraction of selenium (IV) ions from hydrochloric acid solution using Aliquat 336 dissolved in kerosene.

Solvent extraction of selenium(IV) ions from highly concentrated hydrochloric acid using 0.4mol/L Aliquat 336 dissolved in kerosene was investigated. As a modifying agent, 1-octanol (10% v/v) was added to the organic phase to avoid the third phase formation. The effect of different parameters affecting the liquid-liquid extraction of selenium(IV) such as the acid concentration, shaking time, metal ion concentration in the aqueous phase, loading capacity, diluents, and temperature, was studied. The results indicate that selenium(IV) is extracted efficiently by 0.4mol/L Aliquat 336 dissolved in kerosene. It was noticed that the extraction increased with the increase in the acid and Aliquat 336 concentrations, reaching an extraction percentage of about 92% at 8mol/L HCl and 97.1% at 1mol/L extractant. The extracted organic species is postulated to be [H2SeO2Cl2.2R4NCl]org by using the slope analysis method, and the value of Kex for selenium(IV) extraction was found to be 26.17 ± 2 M- 2. The structure of the extracted organic species was confirmed by FT-IR. The effect of diluents using various aliphatic and aromatic diluents indicated that kerosene is the most preferred diluent. This is owing to safety ground purpose, economic consideration, the lower cost, availability, and lower toxicity. Thermodynamic parameters indicate the endothermic nature for the solvent extraction of selenium(IV) for the investigated system according to the positive value obtained of the enthalpy change (ΔH). Depending on the obtained results, the method was used to recover selenium(IV) from a simulated solution synthesized in hydrochloric acid medium, which is expected in anode slime leach liquor solution.

New Benzimidazole derivatives as efficient organic inhibitors of mild steel corrosion in hydrochloric acid medium: Electrochemical, SEM/EDX, MC, and DFT studies

The corrosion of mild steel (MS), a widely used material in industry, represents a significant global challenge. In order to extend the durability of equipment, the use of corrosion inhibitors proves to be an effective solution, particularly in corrosive environments. In this research, two newly synthesized benzimidazole derivatives, namely 1-(cyclohex-1-en-1-yl)-3-[(3-phenyl-1,2-oxazol-5-yl)methyl]-2,3-dihydro-1H-1,3-benzodiazol-2-one (Benz1) and 1-(cyclohex-1-en-1-yl)-3-[(3-phenyl-4, 5-dihydro-1,2-oxazol-5-yl)methyl]-2,3-dihydro-1H-1,3-benzodiazol-2-one (Benz2), were evaluated as corrosion inhibitors for MS in 1 M hydrochloric acid solution. This study was conducted using both experimental methods and computational approaches. Potentiodynamic polarization diagrams (PDP) indicate that, depending on concentration effects, Benz1 and 2 function as mixed-type inhibitors, with a predominance of cathodic inhibition. The results of electrochemical impedance spectroscopy (EIS) show that the compounds tested offer high inhibition efficiencies of 96.32 % and 98.30 % at 10−⁴ M for Benz1 and 2, respectively. Inhibitor adsorption follows the Langmuir isotherm and involves chemisorption. SEM/EDX analyses confirm the presence of a protective film on the metal. In addition, DFT and Monte Carlo simulations reveal significant adsorption of the compounds on the MS surface, underlining their high potential as effective corrosion inhibitors.

Lycium barbarum extract as an environmentally friendly corrosion inhibitor for AISI 52100 bearing steel in hydrochloric acid medium

This study reports the use of Lycium barbarum extract (LBE), a green and environmentally friendly additive, to inhibit the corrosion of AISI 52100 bearing steel in 1 M hydrochloric acid (HCl) solutions. Corrosion inhibition was experimentally investigated via the weight loss method and electrochemical analyses. The surface morphologies were evaluated by scanning electron microscopy (SEM), and the chemical compositions were analyzed via energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The experimental electrochemical and weight loss results demonstrated that LBE has excellent inhibitory properties, with the highest inhibition efficiencies of 92.68 % and 92.31 % when the concentration is 500 ppm, for steel immersed in HCl solutions. Surface coverage studies revealed that the data for the adsorption of LBE on steel were consistent with the Langmuir isotherm. The initial process was investigated via polarization analysis, and the LBE adsorption process was found to be a hybrid of physical and chemical adsorption. To investigate the effectiveness of LBE in preventing corrosion, the corrosion inhibition mechanism was analyzed via a wettability study, high performance liquid chromatography (HPLC) measurements and theoretical quantum chemical calculations. The results indicated that Ara, Rha, Man and Glu played significant effect on the protection of bearing steel in 1 M HCl solution.

Novel bisbenzoxazole derivative as an effective corrosion inhibitor for C38 steel in hydrochloric acid medium: experimental and theoretical investigations

ABSTRACT This study examines the inhibitory capacity of synthesised bis-benzoxazole (BBOSZ) for C38 steel, in hydrochloric acid medium, using electrochemical techniques (EIS and PDP methods), as well as spectroscopic methods. The polarisation results reveal the mixed character of the BBOSZ inhibitor's properties. The obtained efficiency is about 96.89% at 5.10−4 M BBOSZ. The isotherm of adsorption indicates that the inhibitor adsorbs onto the surface via the Langmuir model, with ΔG°adsorption around −41.12 (kJ mol–1), this suggests the inhibitor reduces corrosion via chemical and physical adsorption. Scanning electron microscopy analysis confirms the adsorption mechanism. The interaction between the inhibitor, hydrochloric acid, water, and the iron surface was analysed using theoretical methods such as DFT, MC, and MD simulation. The provided results by theoretical calculations and experimental data proved highly consistent. The data reveals that the adsorption of bis-benzoxazole provides a barrier layer onto the metallic surface, contributing to corrosion prevention.

In-depth study of a newly synthesized imidazole derivative as an eco-friendly corrosion inhibitor for mild steel in 1 M HCl: Theoretical, electrochemical, and surface analysis perspectives

The present study is concerned with the corrosion inhibition and adsorption behaviour of a series of novel imidazole derivatives. The compounds under investigation are 5,5-diphenyl-3-propyl-2-(propylthio)-3,5-dihydro-4 H-imidazol-4-one (AM3) and 3-allyl-2-(allylthio)-5,5-diphenyl-3,5-dihydro-4 H-imidazol-4-one (AM6). The objective of this study is to evaluate the efficacy of 5,5-diphenyl-3,5-dihydro-4 H-imidazol-4-one (AM6) as a corrosion inhibitor on mild steel immersed in a 1.0 M hydrochloric acid medium. This comprehensive study assesses the efficacy of these derivatives through a range of electrochemical and spectroscopic analysis techniques. Additionally, polarisation curves, electrochemical impedance spectroscopy and advanced computer simulations were employed to evaluate the efficacy and inhibition mechanism of imidazole derivatives, thereby facilitating a more profound understanding of their anticorrosive capacity. The results obtained from potentiodynamic polarisation (PDP), electrochemical frequency modulation (EFM) and electrochemical impedance spectroscopy (EIS) measurements demonstrate that the inhibition efficiency increases with increasing imidazole derivative concentration. Conversely, an inverse relationship is observed between inhibition efficiency and temperature. The thermodynamic parameters ΔG°_ads and ΔH°_ads corroborate the conclusion that the adsorption process is predominantly chemical in nature. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were employed to characterise the surface morphology. The maximum protection afforded by imidazole derivatives was 95.2 % and 93 % for compounds AM3 and AM6, respectively. Polarisation curves indicated that imidazole derivatives exhibited mixed inhibition behaviour. Surface analysis demonstrated that imidazole derivatives were effectively adsorbed onto the carbon surface, thereby significantly reducing acid damage. This finding was corroborated by DFT calculations, as well as Monte Carlo (MC) and molecular dynamics (MD) simulations. These simulations provided a comprehensive insight into the adsorption of imidazole and its protonated form onto the carbon surface, offering valuable insight into the corrosion inhibition mechanism.

Syzygium polyanthum (Wight) Walp. leaf extract as a sustainable corrosion inhibitor for carbon steel in hydrochloric acidic environment

This study focuses on an investigation of the corrosion inhibition behavior of Syzygium polyanthum (Wight) Walp. leaf extract (SPWE) of carbon steel in 1.0 M hydrochloric acid medium. Electrochemical methods demonstrated a corrosion inhibition efficiency of 94.65 ± 0.94 % when 2000 ppm extract is added to the corrosive solution. Furthermore, surface analysis results indicated that with the absence of an inhibitor, the steel surface suffered severe corrosion, while the corrosion density was slow, and a film was observed on the surface after applying the SPWE into a corrosive environment. The film formed by the chemical and physical adsorption of compounds such as polyphenol, flavonoid, alkaloid, and tannin onto the carbon steel surface has been qualitatively and quantitatively analyzed in this study. Notably, increased immersion time and reaction temperature led to significant desorption of molecules, reflecting characteristic of physical adsorption. However, the corrosion inhibition efficiency of SPWE remained effective, particularly within the temperature range of 25–35 °C. Therefore, this study provides an efficient inhibitor for carbon steel corrosion in 1.0 M hydrochloric acidic environment that could be possibly added to the corrosion inhibitor system.

Influence of Potentiostat Hardware on Electrochemical Measurements.

We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems.

Enhanced antimicrobial activity of photocatalytic titanium oxide upon formation of composites with polyaniline via an eco-friendly and facile microwave synthesis approach

This study proposes inexpensive antimicrobial polyaniline-titanium oxide (PANI-TiO2) samples prepared through eco-friendly enhanced microwave (MW) synthesis with 93 W applied over 10 min in aqueous 1.25 M hydrochloric acid media (HCl) using potassium iodate (KIO3) as oxidising agent, an approach suitable for industrial scale up production of PANI polymers at room temperature. The PANI-TiO2 samples are produced in the presence of 5–20 wt% of TiO2 in the initial reaction mixture along with aniline monomer by both the enhanced MW method and a classical chemical synthesis (CS) method at room temperature. The nanocomposites showed lower conductivity than pure PANI, slightly higher conductivity was observed in the MW prepared PANI-TiO2 in comparison to CS prepared PANI-TiO2. This result can be correlated with the observation that the optical absorbance of MW PANI-TiO2 samples were notable higher than for CS PANI-TiO2, which may be due to the presence of a greater amount of polarons present in the samples prepared by the enhanced MW method. MW PANI-TiO2 samples were equally active against both Gram-negative E. coli and Gram-positive S. aureus bacteria, in contrast to the CS PANI-TiO2 samples, which could be due to presence of short-chain fragments in the CS samples as confirmed by Fourier-transform infrared (FTIR) spectroscopy. The incorporation of PANI particles in TiO2 showed enhanced antimicrobial activity compared to pure TiO2, with greater antifungal activity. Our study indicates that a facile, low-cost, and green enhanced MW method can be used for preparation of the advanced antimicrobial PANI-TiO2 nanocomposites for biomedical applications.

Experimental and Theoretical Investigation of the Inhibitor Efficiency of Eucalyptus globulus Leaf Essential Oil (EuEO) on Mild Steel Corrosion in a Molar Hydrochloric Acid Medium.

As a corrosion inhibitor for mild steel in a molar hydrochloric acid medium, we investigated the potential of Eucalyptus globulus essential oil (EuEO). Through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves, and theoretical methods, including DFT/B3LYP 6-31G (d, p) and Monte Carlo simulations, the interactions between the EuEO components and the steel surface were analyzed. D-Allose, Betulinaldehyde, and Uvaol were identified as the major active compounds in the GC-MS analysis. The experimental results showed that EuEO reached an inhibitory efficiency as high as 97% at a 1 g/L concentration. The findings suggest that EuEO operates as a mixed-type inhibitor, reducing both cathodic and anodic reactions, as well as building up a protective coating on the steel surface. Simulations also confirmed that EuEO molecules function as electron donors and acceptors, enhancing corrosion resistance.

Excellent inhibition performance of an imidazole based ionic liquid on steel-N80 in 15 % hydrochloric acid medium

Imidazoline phenyl thiourea iodized n-butane quaternary ammonium salt (IMSQ) is synthesized from oleic acid, diethylenetriamine, iodinated n-butane, and n-phenylthiourea. The corrosion inhibition performance is studied by electrochemical test. The experimental findings underscored a pronounced positive correlation between the concentration of IMSQ and its corrosion inhibition efficacy on N80 steel. Notably, at a concentration of 0.07 mM, IMSQ attained a corrosion inhibition efficiency of 99.1 %, exhibiting exceptional protective capability for N80 steel in hydrochloric acid environments. By studying the adsorption isotherm equation, it is judged that the type of adsorption includes physical adsorption and chemical adsorption. The characterization analysis results indicate that IMSQ can adsorb on the surface of steel-N80, providing effective protection for the metal.

Corrosion mitigation of 6061 aluminium alloy hybrid metal matrix composite using a green inhibitor: experimental and theoretical investigations

Carbohydrate compounds are recognized potent green corrosion inhibitors owing to their structural properties and eco-friendliness. This study showed the effectiveness of glucosamine sulfate (GAS), an eco-friendly green inhibitor, in mitigating the deterioration of 6061 aluminium alloy reinforced with 2% SiC and 2% B4C hybrid composite (6061AA-HMMC) material in 0.1 M hydrochloric acid (HCl) medium. Electrochemical measurements were carried out to quantify the corrosion rate in the absence and presence of the GAS. The results were included in an acceptable adsorption isotherm model, and a suitable mechanism for the corrosion inhibition process was discussed in detail. To comprehend the method of adsorption, the Freundlich isotherm model was applied. Different characterization techniques were used to verify the adsorption of the investigated inhibitor. The optimized structure of the GAS was analysed using density functional theory to provide further insight into its interaction with the metal surface. The infrared (IR) and UV-visible (UV) spectra for the adsorption of the inhibitor molecule were compared with the IR and UV spectra calculated by B3LYP/6-311++G(d, p).

Investigations of corrosion inhibition of ethanolic extract of Dillenia suffruticosa leaves as a green corrosion inhibitor of mild steel in hydrochloric acid medium

The utilization of plant extracts as environmentally friendly corrosion inhibitors has garnered considerable interest in the field of metallic corrosion protection. The primary objective of this study was to explore a new approach for utilizing Dillenia suffruticosa leaves extract (DSLE) to provide corrosion protection for mild steel (MS) in a molar hydrochloric acid solution. The phytocompounds responsible for corrosion prevention were extracted using ethanol with Soxhlet apparatus. The effectiveness of the extract as a corrosion inhibitor was evaluated through gravimetric and electrochemical methods, along with surface analysis of the corroded steel samples. This analysis involved the use of scanning electron microscopy (SEM) and Fourier-transformed infrared spectroscopy (FTIR) to examine the specimens with and without addition of the extract as inhibitor. The findings demonstrate that DSLE exhibits notable efficacy as a corrosion inhibitor for MS in an acidic environment. The inhibition efficiency (IE) demonstrates a positive correlation with the concentration of the extract, ultimately reaching a maximum value of 81.4 % at the optimum concentration of 1000 mg/L of the extract investigated. Potentiodynamic polarization data revealed that the DSLE functions as a mixed-type inhibitor.

A Novel Approach for Tailoring of a Corrosion Inhibitor for Mild Steel in 1 M Hydrochloric Acid Medium: Combined Advanced Computational and Experimental Studies for Developing a Novel Quinoline Based Corrosion Inhibitor

A Novel Approach for Tailoring of a Corrosion Inhibitor for Mild Steel in 1 M Hydrochloric Acid Medium: Combined Advanced Computational and Experimental Studies for Developing a Novel Quinoline Based Corrosion Inhibitor

Citrullus colocynthis fruit extract as effective eco-friendly corrosion inhibitor in a hydrochloric acid pickling medium for carbon steel by using both experimental and theoretical studies.

The present study focuses on an environmental approach based on the use of an eco-friendly corrosion inhibitor from the Citrullus colocynthis fruit extract for enhancement corrosion resistance of carbon steel (C-S) in acid medium as an alternative to various organic and non-organic chemical inhibitors. The evaluation of the inhibition properties of the fruit methanolic extract of Citrullus colocynthis (CCE) were performed in molar hydrochloric acid (1M HCl) medium using gravimetric and electrochemical (potentiodynamic polarization and AC impedance) techniques as well as surface analyses. CCE is rich in amino acids, mainly citrulline and β-(pyrazo-1-yl)-L-analine molecules. Based on the weight loss evaluation, the results demonstrated that this plant extract acts as an effective corrosion inhibitor and a protection level of 93.6% was attained at 500ppm of CCE after 6h of metal exposure at 303K. According to polarization curves, CCE functions as a mixed-type inhibitor. In addition, AC impedance analyses have shown that the incorporation of CCE into the corrosive solution leads to a decrease in load capacity, while improving the charge/discharge function at the interface. This suggests the possibility of the formation of an adsorbed layer on the C-S surface. In addition, scanning electron microscope (SEM) observation, contact angle measurements, and Fourier-transform infrared spectroscopy (FTIR) analyses supported the development of a protective film over CS substrate surface afterwards addition of CCE. Langmuir and/or Temkin isotherms can be used to characterize the adsorption of this organic inhibitor on the C-S surface. X-ray photoelectron spectroscopy (XPS) has revealed that the inhibiting effect of CCE on the corrosion of C-S in 1M HCl solution is mainly controlled by a chemisorption process and the inhibitive layer is composed of an iron oxide/hydroxide mixture where CCE molecules are incorporated. In order to understand the relationship between the molecular structure and anti-corrosion effectiveness of these inhibitor molecules, quantum chemical studies were carried out using density functional theory (DFT) and molecular dynamics (MD) simulation.

Retardation of the C-Steel Destruction in Hydrochloric Acid Media Utilizing an Effective Schiff Base Inhibitor: Experimental and Theoretical Computations.

The corrosion inhibition of (N 1 E)-N 1,N 2-bis(4-(dimethylamino)benzylidene)-ethane-1,2-diamine, DMAB, against the destruction of C-steel in dilute HCl media (1.0 M) was examined. The techniques of gravimetry, gasometry, potentiodynamic, and electrochemical impedance spectroscopy are utilized. The rate of corrosion is found to decrease with more additions of the DMAB compound. The inhibition efficacy increases with concentrations to reach 97.7% at 5.0 mM and 298 K. The protection of metal destruction is controlled by the adsorption of the DMAB molecules on the metallic surface obeying Langmuir's pattern. The computed ΔG°ads values are characterized by negative sign, explaining the spontaneity of the adsorption process. These values vary between -38.70 and -35.13 kJ mol-1 depending on the temperature, which proves the physio- and chemisorption mechanisms. The reduction in K ads values with T can be attributed to the desorption of some DMAB molecules from the electrode surface. Theoretical quantum computation confirms the adsorption of the DMAB compound in concurrence with the data obtained by practical techniques.

Methanol extract of Murraya koenigii stem as green inhibitor for mild steel corrosion in 1 M HCl solution

In this work, methanol extract of Murraya koeginii stem has been studied as an ecofriendly inhibitor against mild steel corrosion in 1 M hydrochloric acid medium. Ultraviolet–visible and Fourier transform infrared spectroscopic tools were employed to characterize the extract. Corrosion inhibition efficacy of the extract against mild steel was studied in terms of weight loss method and electrochemical measurement method. Weight loss measurement shows the inhibition efficiency of 94.95 % for the first 6 h of immersion time and maximum efficiency of 96.39 % for 24 h immersion time using 1000 ppm inhibitor solution. Electrochemical measurement shows that for the same concentration of inhibitor, inhibition efficiency is 81.54 % in as-immersed condition whereas it is 85.76 % in 1 h immersed condition. Free energy of the adsorption reflected the physisorption followed by chemisorption. Similarly, thermodynamic parameters revealed the feasibility and spontaneity of the adsorption. Obtained results showed that the methanol extract of Murraya koeginii stem can be a potential corrosion inhibitor.

Properties Enhancement of Cu2O/TiO2 Heterostructure Film Using Two-step Hydrothermal and Potentiostatic Deposition Method

Two-steps hydrothermal were demonstrated to create a high efficiently interfacial layer of TiO2 thin film. The first hydrothermal was conducted to synthesize a well-aligned and compact structure of TiO2 nanorods on FTO substrate. Etching treatment in an acidic medium of hydrochloric acid (HCl) as a second hydrothermal favors increasing the surface area prior to any deposition to be a heterostructure film. The morphology of nanorods changed while the electrical resistivity decreased, demonstrating that the etching treatment had a substantial effect on the TiO2 thin film properties. Cyclic voltammetry (CV) was conducted prior deposition. The electrodeposition of Cu2O on the TiO2 thin film was fabricated by using copper acetate-based solution with pH value of 12.0 at bath temperature of 60°C. The finding revealed that the pyramidal structure of Cu2O film was deposited uniformly, which is believed that the properties of TiO2 interfacial layer were excellently improved.

Study of the Adsorption and Separation Behavior of Scandium and Zirconium by Trialkyl Phosphine Oxide-Modified Resins in Sulfuric and Hydrochloric Acid Media.

Zirconium is recognized as one of the main impurities of the rare earth element scandium during purification. It presents significant challenges due to its similar chemical properties, making separating it difficult. This study used trialkyl phosphine oxide (TRPO) as a functional ligand, and the effects of carrier type and acidity on adsorption performance were first investigated. Among these, the novel extraction resin SiO2-P as a carrier for TRPO demonstrated more prominent separation performance in 0.2 M H2SO4 and 5 M HCl solutions. The kinetic and isotherm data were consistent with the pseudo-secondary kinetics and Langmuir model, respectively, and the adsorption process could be regarded as homogeneous monolayer adsorption subject to the dual effects of chemisorption and internal diffusion. In addition, thermodynamic analysis showed that the adsorption process of zirconium under the experimental conditions was a spontaneous endothermic process. Combined with the results of SEM-EDS, FT-IR, and XPS analyses, scandium and zirconium were successfully adsorbed by the resin and uniformly distributed on its surface, and the greater affinity of the P=O groups on the resin for zirconium was the critical factor contributing to the separation of scandium and zirconium. Finally, scandium and zirconium in sulfuric acid and hydrochloric acid media were extracted and separated by column experiments, and the purity of scandium could reach 99.8% and 99.99%, respectively.