Oxidation Of Hydroquinone Research Articles

Structure–reactivity relationships in the removal efficiency of catechol and hydroquinone by structurally diverse Mn-oxides

Catechol and hydroquinone are widely present hydroxybenzene isomers in the natural environment that induce environmental toxicities. These hydroxybenzene compounds can be effectively removed by manganese (Mn)-oxides via sorption and oxidative degradation processes. In the present study, we investigated the structure–reactivity relationships in the sorption and oxidation of catechol and hydroquinone on Mn-oxide surfaces. Two widely present Mn-oxides, including hydrous Mn oxide (HMO) and cryptomelane, comprised of layer and tunnel structures, respectively, are specifically studied. Effects of Mn-oxide structures and environmental pH conditions on the removal efficiency of these hydroxybenzene compounds, via sorption and oxidative degradation, are investigated. Cryptomelane, which has a higher specific surface area than HMO, possesses a higher sorption and oxidation capacity. The complexation mechanisms of catechol and hydroquinone vary due to their structure-induced difference in reactivity. Catechol reduced and dissolved more Mn from Mn-oxides than hydroquinone, accompanied by a higher C loss of catechol-C, suggesting a higher reactivity of catechol. Structural changes occurred in the Mn-oxides resulting from reaction with catechol and hydroquinone: reduction of Mn(IV), corresponding formation of Mn(III) and Mn(II) in the mineral, and free Mn2+ ions released into the suspension. These insights could help us better understand and predict the fate of hydroxybenzene compounds in Mn-oxide-rich soils and wastewater treatment systems that generate Mn-oxides via Mn removal and the associated environmental toxicity.

Flow injection analysis of hydroquinone using amperometric sensor modified with nanomaterials

Modified carbon paste electrodes (CPE) have been widely used in diverse applications, such as environmental, food, and pharmaceutical analysis, among other applications. In this work, the development of an amperometric sensor modified with functionalized multi-walled carbon nanotubes (CNT) and HY-type zeolite (ZEO) is reported for the analysis of hydroquinone (HQ) in pharmaceuticals. Practical and theoretical studies were carried out regarding the modifiers used. No chemical bond was observed between the modifiers and the analyte, such as HQ and CNT. It is likely that dynamic interactions governed by surface adsorption phenomena, rather than covalent bonding, are occurring. Furthermore, the contribution of modifiers to the improvement of the analytical peak current was elucidated through characterization studies, such as electrochemical impedance spectroscopy. These experiments revealed a 147-fold decrease in charge transfer resistance when CPE was modified with ZEO and CNT, which is likely due to an enhancement in electron transfer. A sample rate of 100 injections per hour, and the limit of quantification (LQ) of 8.99 x 10-7 mol/L were achieved during the oxidation of HQ using amperometry in association with flow injection analysis (FIA). The sensitivity of the proposed sensor was of 0.0186 mol/L cm−2. Determinations of pharmaceutical samples were in good agreement with results obtained by High Performance Liquid Chromatography.

A highly sensitive sandwich-type electrochemical sensor for detection glypican-3 based on H-rGO-CMC@Pt NPs and aptamers

Glypican-3 (GPC3), which is a surface heparan sulfate proteoglycan, has been widely known the ideal biomarker for diagnosis and treatment of hepatocellular carcinoma (HCC). Accurate and sensitive detection of serum GPC3 level is an important and challenging task. In this paper, a sandwich electrochemical aptasensor was designed to specifically detect serum GPC3 level through aptamer-target-aptamer recognition. A GPC3 aptamer (GPC3Apt) immobilized on the surface of gold nanoparticles@reduced graphene oxide modified screen-printed electrode (Au NPs@rGO/SPCE) was used as the capture probe. Hemin-reduced graphene oxide-carboxymethyl chitosan@platinum nanoparticles (H-rGO-CMC@Pt NPs), with good mimicking peroxidases activity, were labeled with amination GPC3 aptamer, which was employed as the signal probe. Once the target GPC3 was anchored on the surface of GPC3Apt/Au NPs@rGO/SPCE, the H-rGO-CMC@Pt NPs-GPC3Apt was further specifically bound to the GPC3, forming the aptamer-target-aptamer sandwich structure, which can catalyze the oxidation of hydroquinone (HQ) to benzoquinone (BQ) and lead the oxidation current of HQ recorded by DPV to changing. The linear relationship between the current signal of oxidation of HQ and GPC3 concentration range of 0.0001–3.0 µg/mL and 3.0–60.0 µg/mL, with a low detection limit (LOD) of 0.0685 ng/mL. Additionally, the electrochemical aptasensor was successfully applied for the detection of GPC3 in human serum samples with the recovery of 99.95–104.06 % and relative standard deviation (RSD) of 1.31–5.22 %. Thus, the sandwich aptasensor could provide a new strategy for detection of serum GPC3 level and improve the early diagnosis rate of HCC.

Ultrafast Self‐Charging in Acid–Base Free Aqueous Rechargeable Zinc–Quinhydrone Batteries

AbstractIn the field of energy technologies, self‐charging batteries are receiving extensive attention. However, the existing technologies are highly dependent on the available sources of O2, have long self‐charging duration, and have complex architectures. Herein, a novel ultrafast chemical self‐charging Zn‐quinhydrone polymer gel (QPG) battery, composed of acid/base free quinhydrone as a cathode material is reported. The prepared Zn–QPG battery exhibits a specific capacity of 209.7 mAh g−1 at 10C rate and maintains 86.4% of the initial discharge capacity even after 3000 cycles with a high coulombic efficiency of 99.4%. The aqueous amphiphilic block co‐polymer‐driven selective oxidation of hydroquinone (HQ) to benzoquinone (BQ) compels the chemical self‐charging feature wherein the device attains ≈1.1 V within ten minutes of complete discharge. The chemical self‐charging generated a high specific capacity of 197.8 mAh g−1 at 10C rate with a capacity retention of 91.2% after 100 cycles. Moreover, a flexible Zn–QPG battery also demonstrates excellent rechargeability and power‐delivering ability even in a wrist‐bend geometry. This work paves the way to develop ultrafast energy storage systems, which are not dependent on an external power supply and broaden the horizon of aqueous zinc–organic batteries.

Employing conductive porous hydrogen-bonded organic framework for ultrasensitive detection of peanut allergen Ara h1

Peanut allergy has garnered worldwide attention due to its high incidence rate and severe symptoms, stimulating the demand for the ultrasensitive detection method of peanut allergen. Herein, we successfully developed a novel electrochemical aptasensor for ultrasensitive detection Ara h1, a major allergenic protein present in peanuts. A conductive nickel atoms Anchored Hydrogen-Bonded Organic Frameworks (PFC-73-Ni) were utilized as excellent electrocatalysts toward hydroquinone (HQ) oxidation to generate a readable current signal. The developed electrochemical aptasensor offers wide linear range (1–120 nM) and low detection limit (0.26 nM) for Ara h1. This method demonstrated a recovery rate ranging from 95.00% to 107.42% in standard addition detection of non-peanut food samples. Additionally, the developed electrochemical method was validated with actual samples and demonstrated good consistency with the results obtained from a commercial ELISA kit. This indicates that the established Ara h1 detection method is a promising tool for peanut allergy prevention.

Reactions between ferric oxyhydroxide mineral coatings and a dimethoxyhydroquinone: A source of hydroxyl radicals

Quinones are organic molecules that facilitate electron-transfer reactions in terrestrial environments. The reduced forms, hydroquinones, are powerful reductants that can trigger non-enzymatic radical-based decomposition of organic matter and contaminants by simultaneous reduction of iron and oxygen. Iron oxides often occur as coatings on other minerals, thus our study investigated the reactions between the ferric oxyhydroxide (FeO(OH)) surface coatings on gibbsite (Al(OH)3) and 2,6-dimethoxy-1,4-hydroquinone (2,6-DMHQ). The main aim was to investigate the oxidation of 2,6-DMHQ and the generation ∙OH in the presence of O2 at low Fe concentrations in a novel setup that allows local structural characterization. The heterogeneous redox reactions between 2,6-DMHQ and the FeO(OH) coatings were studied at pH 5.0 as a function of the amount of Fe present on the gibbsite surfaces, including the effect of aging of the FeO(OH) coatings. The results showed that reactions between 2,6-DMHQ and FeO(OH) coated gibbsite under ambient conditions can generate substantial amounts of ·OH, comparable with amounts generated on pure ferrihydrite surfaces. The ·OH is the product of two sequential reactions: hydroquinone oxidation by O2 and degradation of the formed H2O2. The calculated rate constant of the former reaction is the same regardless of amount of FeO(OH) coating suggesting a surface catalytic process where 2,6-DMHQ is oxidized by O2 resulting in formation of H2O2. Subsequently, the observed induction period, the low Fe2+ (aq) concentrations in solution and the dependency of FeO(OH) coating amount influencing ·OH formation suggest that the pathway for ∙OH is through H2O2 decomposition by the surface sites on the FeO(OH) coating. Overall, this study shows that co-existence of oxygen, FeO(OH) and organic reductants, possibly secreted by soil microorganisms, creates favorable conditions for generation of ·OH contributing to decomposition of organic matter and organic pollutants in soil environments.

Paper-based immunosensor integrated with bioinspired Cu-polydopamine nanozyme for voltammetric detection of CA-15-3 tumor marker

This manuscript describes the fabrication and characterization of a highly conductive paper-based nanoplatform for immobliztion of anti-CA 15-3 antibodies. For this purpose, cellulosic filter paper (FP) was first coated with Cu nanosponges (CuNSs) through ion beam sputtering deposition (IBSD) method and then covered with Cu-doped polydopamine nanospheres (Cu-PDA). Polydopamine doped with copper exhibited laccase (multi-copper oxidase)-mimicking properties. Bioinspired by the structure of the active site and the electron transfer mechanism of laccase, Cu-PDA nanozyme catalyzed the oxidation of hydroquinone (HQ) signal probe. In this design, CA-15-3, a prognostic biomarker in the breast cancer, was chosen as a model target. To the best of our knowledge, this is the only paper on the design of an electrochemical biosensor based on dense and uniform CuNSs produced by IBSD. More importantly, Cu-PDA is biocompatible and biodegradable, which makes it a potential competitor in the point-of-care (POC) biosensing applications. Thus, this paper-based sensing strategy can be used in designing cost-effective flexible chips consisting of electrodes printed on paper for in-situ and real-time monitoring biomarkers under clinical conditions. In addition to these outstanding features, the LOD (1.3 mU mL 1) and LOQ (4.3 mU mL 1) of the Ab/HQ/Cu-PDA/CuNSs/FP-based immunosensor was significantly lower than the clinically relevant cut-off level (30 U mL 1). In the practical applications, one of the key superiorities of this immuosensor is the wide DLR (5 mU mL 1–280 U mL 1) which covers the ultimate value of healthy and patient individuals.

"Two-in-One" PtPdCu Trimetallic Multifunctional Nanoparticles-Mediated Dual-Signal-Integrated Aptasensor for Ultradetection of Enrofloxacin.

Balancing the accuracy and simplicity of aptasensors is a challenge in their construction. This study addresses this issue by leveraging the remarkable loading capacity and peroxidase-like catalytic activity of PtPdCu trimetallic nanoparticles, which reduces the reliance on precious metals. A dual-signal readout aptasensor for enrofloxacin (ENR) detection is designed, incorporating DNA dynamic network cascade reactions to further amplify the output signal. Exploiting the strong loading capacity of PtPdCu nanoparticles, they are self-assembled with thionine (Thi) to form a signal label capable of generating signals in two independent modes. The label exhibits excellent enzyme-like catalytic activity and enhances electron transfer capabilities. Differential pulse voltammetry (DPV) and square-wave voltammetry (SWV) are employed to independently read signals from the oxidation-reduction reaction of Thi and the catalytic oxidation of hydroquinone (HQ) to benzoquinone (BQ) by H2O2. The introduced DNA dynamic network cascade reaction modularizes sample processing and electrode surface signal generation, avoiding electrode contamination and efficiently increasing the output of the catalyzed hairpin assembly (CHA) cycle. Under optimized conditions, the developed aptasensor demonstrates detection limits of 0.112 (DPV mode) and 0.0203 pg/mL (SWV mode). Additionally, the sensor successfully detected enrofloxacin in real samples, expanding avenues for designing dual-mode signal amplification strategies.

Electrochemical sensor based on PEDOT/CNTs-graphene oxide for simultaneous determination of hazardous hydroquinone, catechol, and nitrite in real water samples

Hydroquinone (HQ), catechol (CC) and nitrite (NT) are considered aquatic environmental pollutants. They are highly toxic, harm humans’ health, and damage the environment. Thus, in the present work we introduce a simple and efficient electrochemical sensor for determination of HQ, CC, and NT simultaneously in wastewater sample. The sensor is fabricated by modifying the surface of a glassy carbon electrode (GCE) by two successive thin films from poly(3,4-ethylenedioxythiophene) (PEDOT) and a mixture of carbon nanotubes-graphene oxide (CNT-GRO). Under optimized conditions the HQ, CC, and NT are successfully detected simultaneously in wastewater sample with changing their concentrations in the ranges (0.04 → 100 µM), (0.01 → 100 µM) and (0.05 → 120 µM), the detection limits are 8.5 nM, 3.8 nM and 6.1 nM, respectively. Good potential peak separations: 117 mV and 585 mV are obtained between the HQ-CC, and CC-NT. The sensor has an excellent catalytic capability toward the oxidation of HQ, CC, and NT due to good synergism between its composite components: PEDOT, GRO and CNTs. The features of the sensor are large active surface area, good electrical conductivity, perfect storage stability, good reproducibility, anti-interference capability and accepted recovery rate for HQ, CC, and NT determination in wastewater sample.

New Isoxazole‐Substituted Aryl Iodides: Metal‐Free Synthesis, Characterization and Catalytic Activity

AbstractA series of new isoxazole‐substituted aryl iodides 1 a–1 d have been synthesized by DIB‐mediated [3+2] cycloaddition reaction of 2‐iodo‐1,3‐bis(prop‐2‐yn‐1‐yloxy) benzene (4) with corresponding benzaldehyde oximes 5 a–5 d. Structure of the synthesized aryl iodides 1 were characterized by IR, 1H NMR, 13C NMR and HRMS. The structure of 1 a was also confirmed by single‐crystal X‐ray crystallography. Further, catalytic activity of iodoarenes 1 a–1 d was screened for the oxidation of hydroquinones and sulfides. On oxidation using aryl iodides 1 with m‐CPBA as terminal oxidant, hydroquinones afforded benzoquinones while sulfides gave corresponding sulfoxides in good to excellent yields. Iodoarene 1 b showed the best catalytic activity for the oxidation of sulfides and hydroquinones. Moreover, iodoarene 1 b, was also utilized for α‐oxytosylation of acetophenones.

Study of molecular mechanism and extraction performance evaluation for separation of phenolics from alkaline wastewater through synergistic extraction

ABSTRACT Phenols were a kind of pollutant in coal chemical wastewater with high concentration and difficult to decompose and have a significant impact on the subsequent biochemical treatment of the wastewater. In addition, phenols were a kind of weak electrolytes that partially dissociation oxidation under weakly alkaline conditions, making recovery more difficult. In order to solve this problem, phenols were extracted from weak alkaline wastewater with a synergistic solvent. First, the interaction between solvents and phenols and the solvent effect of solvents were calculated by quantum chemistry and the synergistic extractant cyclohexanone/1-pentanol was determined to have significant advantages. Moreover, the synergistic extractant was further analyzed through independent gradient model based on Hirshfeld partition analysis, atoms in molecule topology analysis, electrostatic potential analysis. Results indicated that the synergistic extract can provide multiple hydrogen bond interactions with phenol due to the double action sites of the C=O group of ketone and the -OH group of alcohol. In addition, the efficacy of the extractant was validated by multistage extraction, indicating partial dissociation oxidation of hydroquinone to benzoquinone under weakly alkaline conditions, with removal rates of 99.5% and 99.2% for phenol and hydroquinone, respectively. In general, the synergistic extractant can effectively remove phenols.

Boosting the charge for the selective photoelectrochemical oxidation of hydroquinone in hazardous environments using a fine-tuned heterojunction catalyst

A heterojunction semiconductor PEC is used to boost the charge for HQ oxidation and H2O2 formation under visible light. The composite is successfully employed for the sensitive and selective determination of HQ in different environments.

An electrochemical aptasensor based on Ce-MOF@COF to detect carcinoembryonic antigen

In the presence of H2O2, Au@Ce-MOF@COF-HRP can effectively promote the oxidation of hydroquinone (HQ) to benzoquinone (BQ), and the electrochemical reduction signal of BQ was significantly amplified.

Mechanochemical hydroquinone regeneration promotes gold salt reduction in sub-stoichiometric conditions of the reducing agent.

Bottom-up mechanochemical synthesis (BUMS) has been demonstrated to be an efficient approach for the preparation of metal nanoparticles (NPs), protected by surface agents or anchored on solid supports. However, there are limitations, such as precise size and morphological control, due to a lack of knowledge about the mechanically induced processes of NP formation under milling. In this article, we further investigate the BUMS of AuNPs. Using SiO2 as a solid support, we studied the effect of typical reducing agents, namely NaBH4, L-ascorbic acid, and hydroquinone (HQ), on the conversion of a AuIII source. XANES showed that HQ is the strongest reducing agent under our experimental conditions, leading to the quantitative conversion of gold salt in a few minutes. Interestingly, even when HQ was used in sub-stoichiometric amounts, AuIII could be reduced to ratios higher than 85% after two minutes of milling. Investigations into the byproducts by 1H NMR and GC-FID/MS enabled the identification HQ regeneration and the formation of its derivatives. We mainly focused on benzoquinone (BQ), which is the product of the oxidation of HQ as it reduces the gold salt. We could demonstrate that HQ is regenerated from BQ exclusively under milling and acidic conditions. The regenerated HQ and other HQ-chlorinated molecules could then reduce gold-oxidized species, leading to higher conversions and economy of reactants. Our study highlights the intriguing and complex mechanisms of mechanochemical systems, in addition to fostering the atom and energy economy side of mechanochemical means to produce metal nanoparticles.

Chain Oxidation of Hydroquinone by Water Activated by Pulsed Hot-Plasma Radiation

Chain Oxidation of Hydroquinone by Water Activated by Pulsed Hot-Plasma Radiation

Synergistic catalysis of graphitic carbon nitride and dichromate for augmented oxidative polymerization of hydroquinone leading to enhanced humic-like substance formation

BackgroundHumic substances (HS) originate from organic matter decomposition, primarily through polyphenol polymerization (known as the browning reaction). The slow reaction kinetics have posed challenges in studying the catalytic oxidation of polyphenols by metal oxides. A substantial knowledge gap persists regarding the role of metal oxides and other catalysts in polyphenol polymerization. MethodHerein, we focused on the oxidative polymerization of hydroquinone (HQ) using potassium dichromate (Cr2O72−) to accelerate reaction rates and gain insights into HS formation. Moreover, graphitic carbon nitride (g-C3N4) was introduced as an N-doping compound with a substantial surface area and Lewis base properties, enriching the N source and promoting π-π interactions. Significant findingsThe addition of g-C3N4 to the metal oxide systems tripled reaction rates, enhanced browning reactions, and complex stability. Furthermore, it improved HS surface morphology and particle size, with g-C3N4's electron transfer capabilities facilitating the in-situ HQ oxidation. Empirical data and theoretical calculations demonstrated that the g-C3N4…HQ…Cr2O72− complex exhibits greater binding energy than HQ… Cr2O72−, explaining the accelerated reaction kinetics. Post-reaction 13C NMR spectra confirmed the predicted HS spectra. This work highlights g-C3N4's catalytic role in HQ oxidative polymerization and HS generation, shedding light on abiotic humification and environmental implications.

Chain Oxidation of Hydroquinone by Water Activated by Pulsed Hot-Plasma Radiation

The interaction of hydroquinone with water activated by hot-plasma pulsed radiation has been studied. In the reactions of hydroquinone with products accumulated in water during irradiation (nitrous and peroxynitrous acids), hydroquinone undergoes chain oxidation to benzoquinone. The mechanism of chain oxidation is analyzed. The decomposition of hydroquinone by corona discharge cold plasma (OH• radicals) was studied. Benzoquinone is not produced by the action of corona discharge; hydroquinone immediately decomposes into smaller molecules. The hydroquinone oxidation process considered can be used to create hydrogen elements based on the hydroquinone ↔ benzoquinone couple.

Enzyme-catalyzed electrochemical aptasensor for ultrasensitive detection of soluble PD-L1 in breast cancer based on decorated covalent organic frameworks and carbon nanotubes

BackgroundSoluble programmed death-ligand 1 (sPD-L1) is critically involved in breast cancer recurrence and metastasis. However, the clinical application of highly sensitive sPD-L1 assays remains a challenge due to its low abundance in peripheral blood. To address this issue, for the first time, an enzyme-catalyzed electrochemical aptasensing platform was devised, incorporating covalent organic frameworks-gold nanoparticles-antibody-horseradish peroxidase (COFs-AuNPs-Ab-HRP) and polyethyleneimine-functionalized multiwalled carbon nanotubes (MWCNTs-PEI-AuNPs) for the highly specific and ultrasensitive detection of sPD-L1. ResultsMWCNTs-PEI-AuNPs possessed an extensive specific surface area and exhibited excellent electrical conductivity, facilitating the immobilization of aptamer and amplifying the signal. COFs modified with AuNPs not only amplified the electrical signal but also proffered a loading platform for the Ab and HRP. The favorable biocompatibility of COFs contributed to the preservation of enzyme activity and stability. HRP acted in synergy with hydrogen peroxide (H2O2) to catalyze the oxidation of hydroquinone (HQ) to benzoquinone (BQ). Subsequently, BQ underwent electrochemical reduction to HQ, inducing an enzymatic redox cycle that amplified the electrochemical signal and enhanced the sensitivity and selectivity of the detection method. The developed aptasensor displayed a liner range for sPD-L1 identification from 1 pg mL−1 to 100 ng mL−1 and the detection limit reached 0.143 pg mL−1 (S/N = 3). SignificancePaving the way for clinical application, this strategy detected differences in sPD-L1 in cell supernatants and peripheral blood of breast cancer patients with higher sensitivity compared to commercial sPD-L1 ELISA kit. This work demonstrates significant potential in offering reference information for early diagnosis and disease surveillance of breast cancer.

Synthesis and Characterization of Ruthenium(II) Carbonyl Complexes of Substituted Quinazoline Derivatives and their Catalytic Activity

A series of ruthenium(II) carbonyl complexes of the types [RuCl2(CO)2L]2·nH2O {n = 1, L = L1, L3}; [RuCl2(CO)2(L)(H2O)]·nH2O {n = 1, L = L2, L4, L6 and n = 2, L = L7}; [RuCl(CO)2(L-H)(H2O)]2 {L = L5}; [RuCl2(CO)2]3(L)2 {L = L8} were synthesized where L is 6R-5,6- dihydrobenzoimidazo[1,2-c]quinazoline (R-Diq; R = phenyl: L1/furyl: L2/thiophenyl: L3/o or p-hydroxyphenyl: L4, L5/o or p- hlorophenyl: L6, L7/dimethylaminophenyl: L8). The Ru(II) complexes were characterized by elemental analyses, conductivity measurements, TGA, infrared, electronic, NMR and mass spectral techniques. An octahedral geometry around the metal ion was proposed for all the complexes and monomeric, dimeric and trimeric stereochemistry was suggested. The catalytic activity for few ruthenium(II) complexes towards oxidation of benzyl alcohol, hydroquinone and cyclohexanol was also investigated.

Promotion of the catalytic polymerization of hydroquinone towards humic-like substances by graphitic carbon nitride

The utilization of graphitic carbon nitride (C3N4) to enhance the oxidative polymerization of hydroquinone (HQ) within manganese dioxide (MnO2) systems was investigated. C3N4, a Lewis base enriched with nitrogen, acted as a bridge through π − π interactions between metal oxides and polyphenols. These interactions increased the affinity of the reactants, resulting in an enhanced reaction rate of six-fold, accelerated browning, and improved complex stability of C3N4. HQ.MnO2 complex. As a result, a humic-like substance (HS) was rapidly formed with improved surface morphology and larger particle sizes. Electron transfer of HQ.MnO2 promoted by C3N4 played a crucial role in HQ oxidation, expanding atomic distance and composite morphology. Theoretical calculations supported the experimental results, indicating strong affinity and higher binding energies in the C3N4. HQ.MnO2 complex. The complex had a more stable structure with a narrower HOMO-LUMO gap, facilitating HS formation. 13C and 1H NMR spectra confirmed the experimental-theoretical agreement.