Electrochemical Behavior Of Hydroquinone Research Articles

Voltammetric examination of hydroquinone at ordinary and nano-architecture platinum electrodes

The electrochemical behavior of hydroquinone was examined experimentally using cyclic voltammetry, convolution transform, and deconvolution transform at clean ordinary and nanostructured mesoporous platinum electrodes in 1 mol/l HClO4. The cyclic voltammogram of hydroquinone (HQ) at an ordinary Pt electrode displays an anodic peak at 0.610 V and a cathodic peak at 0.117 V, with a scan rate of 50 mV·s–1. Excellent linearity was recorded between the anodic or cathodic peak currents of hydroquinone and the square root of the scan rate (υ1/2). The anodic and cathodic peak potential separation (∆Ep) was found to be 463 ± 3 mV vs. the saturated calomel electrode (SCE). It was noted that the value of peak potential separation increased with increasing the scan rate. The type of electrode reaction at both platinum electrodes in 1 mol/l HClO4 was examined and discussed. The electrochemical parameters and the nature of the mechanistic pathway of the investigated HQ were determined experimentally and ascertained via a numerical simulation method.

Investigation of the Electrochemical Behavior of Hydroquinone at Some Conducting Polymer Electrodes and Amperometric Detection

In this paper, a rapid and sensitive modified electrode for the determination of hydroquinone (HQ) is proposed. In this study, active compound HQ was determined from commercial drug form based on electrochemical oxidation properties at various electrodes by voltammetric methods. Electrodes modified by the electrodeposition of conducting organic polymers such as poly(3-methylthiophene, PMT), polypyrrole (PPY) and polyaniline (PAN) were used as chemical sensors for voltammetric analysis and flow injection detection of HQ. The electrochemical behavior of HQ at conducting polymer electrodes was compared and the effects on behavior of electrolyte type and its pH and the film thickness were systematically examined. The results showed that the proposed modified surface catalyzes the oxidation of HQ. Electrocatalytic efficiency decreases in order of PMT > PPY > PAN. Voltammetric peak positions were affected by the nature of the electrolyte and its pH. Also, the effect of increasing film thickness was to observe increased peak heights for oxidation potential of HQ. The best results for the determination of HQ were obtained by DPV in Na2SO4 (pH 2.0) and PMT electrodes. Polymer coated electrodes were also used in an amperometric detector for flow injection analysis of HQ. The responses of the polymer electrode were 5–15 times larger as compared to those of bare platinum. PMT showed improved performance as an amperometric detector for flow injection analysis systems over other types of polymer electrodes. Detection limits as low as 1 × 10–9 M were achieved using the PMT, compared to 1 × 10–6 M using platinum electrodes.

Enhancement Effect of Cetyltrimethylammonium Bromide on Electrochemical Determination of Chlorophenols using a Carbon Paste Electrode

The electrochemical responses of chlorophenols can be effectively enhanced by using the surfactant cetyltrimethylammonium bromide (CTAB) in combination with a carbon paste electrode (CPE). The influence of CTAB on the electrochemical behavior of hydroquinone, phenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, p-chloro-m-cresol and pentachlorophenol at the CPE was investigated in the phosphate buffer solution (pH 7). The concentration of CTAB affecting the electrochemical reaction of phenols was examined and the optimal concentration was 0.2 mM. In this research we have applied electrochemical methods, such as cyclic voltammetry and differential pulse voltammetry (DPV). The CPE modified with CTAB in DPV increased signal intensity for chlorophenols by around 5 to 13 times and was successfully applied to determination of chlorophenols in soil samples.

A study on the electrochemical behavior of hydroquinone at a nanometer cobalt/l-glutamate-modified electrode.

A new electrochemical sensor for hydroquinone (HQ) was prepared. The electrochemical sensor was modified by electrodeposition and electrochemical polymerization to modify nanometer cobalt (nano-Co) and poly-l-glutamic acid (poly-l-glu) on the surface of a glassy carbon electrode (GCE). Then, the electrochemical behavior of hydroquinone on the electrochemical sensor was investigated by cyclic voltammetry (CV). The experimental conditions were optimized from the aspects of electrolyte type, concentration, acidity, enrichment time and scanning speed. The experimental results showed that under optimized conditions the oxidation peak current has a good linear relationship with the concentration of hydroquinone in the range of 3.85 × 10−6 to 1.30 × 10−3 mol L−1 (R2 = 0.9998). Moreover, there was a low detection limit of 4.97 × 10−7 mol L−1. When the sensor was used for the analysis of hydroquinone in water samples, the recoveries with satisfactory results were in the range of 97.2–102.6%.

Electroorganic synthesis of disulfonamide substituted p-benzoquinone by hydroquinone electrochemical oxidation

This study illustrates electrochemical behavior of hydroquinone and 4-amino-6-chloro­benzene-1,3-disulfonamide in the phosphate buffer solution evaluated by cyclic voltammetry. It was found that the peak of the hydroquinone oxidation potential in the presence of 4-amino-6-chlorobenzene-1,3-disulfonamide is shifted to more positive values compared to hydroquinone alone. Based on these results, the electrochemical synthesis of new disulfonamide substituted p-benzoquinone is proposed and carried out via electro­chemical oxidation of hydroquinone in the presence of 4-amino-6-chlorobenzene-1,3-di­sulfonamide in the electrolytic cell. It has been concluded that hydroquinone is converted into disulfonamide substituted p-benzoquinone via an ECE mechanism. The successful electrochemical synthesis was conducted in the water/ethanol mixture under green conditions without any toxic reagents or solvents and with high atom economy.

New cathodic peak of quinone caused by the ultrafast diffusion of protons in unbuffered aqueous solution

The electrochemical behavior of hydroquinone in unbuffered aqueous solution was investigated using cyclic voltammetry. Subsequent cathodic scan showed a new cathodic peak at the negative potential and another similar cathodic peak for catechol. The peak current increased with the increasing pH of the bulk solution and concentration of hydroquinone. We observed that only the new cathodic peak increased, whereas the other peaks remained constant with the addition of quinone to the test solution. This new cathodic peak was caused by the ultrafast diffusion of proton from the electrode surface to the bulk solution. The results can help us understand the unique characteristics of hydroquinone in unbuffered solution.

Sensitive detection of hydroquinone using exfoliated graphene-Au/glassy carbon modified electrode

Graphene nanosheets (EGr) were electrochemically prepared through one-step exfoliation of a graphite rod in a mixture of H2SO4:HNO3 (3:1) at low bias (4 V). Subsequently, gold nanoparticles were attached to the graphene surface (EGr−Au) by the reduction of the metal precursor (HAuCl4) in aqueous solution containing dispersed graphene sheets. According to the XRD investigation, the synthesized material consists of a mixture of few-layer (86%) and multi-layer (14%) graphene. The interlayer distance was found to be in the range of 0.466–0.342 nm, which is larger than the interlayer distance in graphite (0.335 nm). The average size of gold nanoparticles in the EGr−Au sample was 24 nm, in excellent agreement with the TEM results. The synthesized material was then employed to modify a glassy carbon (GC) substrate, in order to obtain a modified electrode (GC/EGr−Au). Next, the electrochemical behavior of hydroquinone (HQ) in the presence and absence of interfering species, catechol (CAT) and bisphenol A (BPA) was studied and the corresponding calibration curves were plotted. Thus, in solutions without interfering species, the GC/EGr-Au electrode has a wide linear range (3 × 10−7–10−4 M), high sensitivity (0.089 A M−1) and low detection limit (LOD = 10−7 M; S/N = 3). The presence of either catechol or bisphenol A leads to the increase of LOD to 2 × 10−7 M, and in addition changes the electrode sensitivity, up to 0.146 A M−1.

An electrochemical sensor based on copper-based metal-organic frameworks-graphene composites for determination of dihydroxybenzene isomers in water

A highly and simply sensitive electrochemical sensor was presented for the simultaneous determination of hydroquinone (HQ) and catechol (CT) in the water based on copper centered metal-organic framework-graphene composites (Cu-MOF-GN) [Cu-MOF = Cu3(BTC)2 (BTC = 1, 3, 5-benzenetricarboxylicacid)] modified glassy carbon electrode (Cu-MOF-GN/GCE). The modification procedure was carried out through casting metal-organic framework-graphene oxide composites (Cu-MOF-GO) on the bare glassy carbon electrode and followed by the transformation of Cu-MOF-GO to Cu-MOF-GN by an electrochemical reduction. The electrochemical behavior of HQ and CT at Cu-MOF-GN/GCE was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, the modified electrode had excellent electrocatalytic activity and high selectivity toward HQ and CT. The electrochemical sensor exhibited a linear response in the same range of 1.0 × 10−6 to 1.0 × 10−3M with the detection limits of 5.9 × 10−7M for HQ and 3.3 × 10−7M for CT (S/N = 3). Four samples of tap water spiked with different concentrations of HQ and CT were considered. The method has been applied to the analysis of these isomers in spiked tap water with recoveries from 99.0 ~ 102.9% and relative standard deviations (RSDs) for 5 successive measurements less than 5% were also acceptable. This method was successfully applied to detect target analytes in the real samples with satisfying results. The MOFs-based sensors in the field of electrochemical sensing held a great promise for routine sensing applications.

Simultaneous determination of hydroquinone and catechol at gold nanoparticles mesoporous silica modified carbon paste electrode

A new electrochemical sensor based on gold nanoparticles mesoporous silica modified carbon paste electrode (AuNPs-MPS) was developed for simultaneous determination of hydroquinone and catechol. Morphology and structure of the AuNPs-MPS were characterized by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The electrochemical behavior of hydroquinone and catechol were investigated using square wave voltammetry and the results indicate that the electrochemical responses are improved significantly at the modified electrode. The observed oxidative peaks separation of about 120mV made possible the simultaneous determination of hydroquinone and catechol in their binary-mixture. Under the optimized condition, a linear dynamic range of 10.0μM–1.0mM range for hydroquinone with the detection limit of 1.2μM and from 30.0μM–1.0mM for catechol with the detection limit of 1.1μM were obtained. The applicability of the method was demonstrated by the recovery studies of hydroquinone and catechol in spiked tap water samples.

Electrochemical behavior of hydroquinone and catechol at glassy carbon electrode modified by electropolymerization of tetraruthenated oxovanadium porphyrin

This work presents the simultaneous determination of catechol (CC) and hydroquinone (HQ), employing a modified glassy carbon electrode with tetraruthenated oxovanadium (IV) porphyrin. The GCE was modified by electropolymerization of {VOTPyP[RuCl3(dppb)]4} porphyrin, onto the GCE surface, by cyclic voltammetry. The modified electrode, labeled as VOTPRu-GCE, showed two pairs of well-defined redox peaks for the electrochemical processes of catechol and hydroquinone. In bare GCE, the potential difference (ΔEp) of CC and HQ were 469mV and 457mV, respectively, while with VOTPRu-GCE the potential difference decreased to 29mV and 30mV, indicating that the redox processes were reversible onto the VOTPRu-GCE surface. With differential pulse voltammetry, it was possible to simultaneously determine the CC and HQ, with peak-to-peak potential separation of 129mV, in 0.1mol L−1 acetate buffer (pH 4.75). Under the optimized conditions, the calibration curves were obtained in the linear concentration ranges of 2–38μmolL−1 for both isomers using the VOTPRu-GCE, which showed high sensitivity in the determination of CC and HQ, 12.73 and 15.91μAμmolL−1cm−2, respectively. The detection limits were 0.41 and 0.55μmolL−1 for CC and HQ, respectively.

SYNTHESIS AND CHARACTERIZATION OF POLYCARBAZOL - POLYANILINE COPOLYMER IN DICHLOROMETHANE SOLUTION

Conductive polymers can be synthesized in solution or on the electrode surface by oxidation of aromatic heterocyclic organic molecules. Polypyrrole, polythiophene, polyaniline, polyfuran, polyphenylenevinylene, polytionaphtene, polycarbazole, polyindole and polyazulene are the most well-known conductive polymers. Although less studied among the conductive polymers, carbazole polymers have many advantages such as cheap, environmental and chemically stable because of aromatic structure, optic with nitrogen atom in structure, electrical properties, can give polymers having a lower band gap than p-phenylene polymers because occur from biphenyl group. During the polymerization, poly (2,7-carbazole) derivatives can be obtained by binding from 2- and 7- positions while poly (3,6-carbazole) polymers obtained by binding from 3- and 6- positions. Features and applications area of these polymers are different [1,2]. In previous studies, electrochemical synthesis of Polyaniline was carried out in dichloromethane medium and it was used as modified surface for determination of some phenolic compounds [3,4]. In this study, electropolymerization of polycarbazole- polyaniline (PC - PANI) copolymer was firstly studied using polymerization solution containing dichloromethane / 100 mM tetrabutylammonium perchlorate (TBAP) / 1.0 mM carbazole / 50.0 - 200 mM aniline and optimum polymerization conditions were determined. Aqueous and non-aqueous medium behaviors of prepared PC –PANI modified electrode were investigated. The best electroactive film was determined. Characterization of the synthesized copolymer film was carried out by UV-vis, FT-IR, Raman, SEM and EDS techniques. Electrochemical behavior of hydroquinone was investigated in NaHSO4 / Na2SO4 medium over obtained modified electrode and it was compared with its homopolymers.

An electrochemical sensor based on polyaniline for monitoring hydroquinone and its damage on DNA

A dsDNA/PANI/CTS/GCE biosensor was constructed by using the biocompatible chitosan (CTS) and the polyaniline (PANI) with excellent electric catalytic properties and large specific surface areas. The electrochemical behavior of hydroquinone on biosensor and its DNA-damaging mechanisms were investigated. Results showed that the redox peak current was remarkably increased after glassy carbon electrode (GCE) was modified by PANI/CTS. The dsDNA damage by hydroquinone was concentration dependent, and increased along with the increase of hydroquinone oxidation peak current and the reduction of dsDNA guanine oxidation peak current. The linear detection range of hydroquinone with dsDNA/PANI/CTS/GCE was 1.25×10−6–3.2×10−4M, and the detection limit was 9.65×10−7M. It was confirmed by the UV method that applying dsDNA/PANI/CTS/GCE to monitor hydroquinone was accurate and reliable. In addition, it could be deduced that the mode of interaction between the hydroquinone and dsDNA was intercalation. The electrochemical oxidation of hydroquinone on the dsDNA/PANI/CTS/GCE electrode was an adsorption-controlled irreversible and a two-electron two-proton transfer process.

Preparation of Copper Doped L-Threonine Modified Electrode and its Application in Determination of Hydroquinone

A copper doped L-threonine modified electrode was prepared by cyclic voltammetry (CV), and the electrochemical behavior of hydroquinone at the modified electrode had been studied. A novel determination method of hydroquinone using CV, chronoamperometry and differential pulse voltammetry (DPV) was established, and the scan rate and supporting electrolyte factors on catalytic oxidation of hydroquinone in modified electrodes were discussed. The results revealed that the modified electrode had showed obvious electrocatalytic activity for hydroquinone, and anodic peak current increased linearly with the concentration of hydroquinone in the range of 0.8-150 μmol/L with the detection limit of 0.4 μmol/L (S/N=3). The method has been applied to the determination of hydroquinone in water sample with satisfactory results.the recovery ranged from 95.9 % to 105.2 %.

Investigation on Electrochemical Redox of Hydroquinone-Fourier Transform Infrared Spectroelectrochemistry Techniques

Abstract The electrochemical behavior of hydroquinone (QH2) was studied and the reasonable electrochemical oxidation mechanisms were proposed in acetonitrile, neutral unbuffer and basic solutions based on the techniques of cyclic voltammetry (CV), in situ FT-IR spectroelectrochemistry (FT-IR), cyclic voltabsorptometry (CVA), derivative cyclic voltabsorptometry (DCVA) and reconstructed i-E curves. In acetonitrile solution, the electrochemical behavior of hydroquinone shows a couple of irreversible redox peaks in cyclic voltammogram. One negative-going band at 1510 cm−1 and three positive-going bands at 1656, 1595 and 1318 cm−1, which respectively corresponded to QH2, Q, were observed in FT-IR 3D map. The results suggested that the oxidation of QH2 was 2e-2H+ process and the final oxidation product was benzoquinone (Q). In neutral unbuffer solution, it displayed an anodic peak (A1) and two cathode peaks (C1, C2) for one cycle. For continuous three cycles, a new oxidation peak (A2), corresponding to the negative potential reduction peak (C2), appeared. In IR 3D map, six IR absorption peaks, 1510 cm−1 for QH2; 1656 and 1318 cm−1 for Q; 1341 cm−1 for Q−.; 1495 and 1272 cm−1 for Q2− were observed, respectively. The results indicated that the final oxidation product was also Q. In reduction process, one part of Q was reduced to QH2 at more positive potential (C1) and the other was to Q2− at more negative potential (C2). When 2 equiv of OH− were added to the solution, only a couple of redox peaks (Q2−/Q) appeared. In addition, a change of hydrogen bond by the negative-going bands at 2140 cm−1 was observed, which was due to the absorption of Q2−…D2O or Q−.…D2O. So the results indicated that this process is H–bonding coupled-electron transfer. Based on reconstructed current-potential (i-E) curve, we can confirm that the electron transfer of Q2− shows two-step one-electron transfer process.

Comparing the Hydrogen-Bonding Effect of Brönsted Bases in Solution and When They Are Covalently Bound to the Surface of Glassy Carbon Electrodes in the Electrochemical Behavior of Hydroquinone

Mono- and dibasic phthalate bases (HP– and P2–) interact with 1,4-hydroquinone (1,4-H2Q) in acetonitrile through hydrogen bonding to form molecular complexes that oxidize at easier (less positive) potentials than pure 1,4-H2Q. The relatively large decrease in the oxidation overpotential for 1,4-H2Q, observed upon introducing these Bronsted bases, is an example of thermodynamic control of a PCET achieved with weak bases. The favoring effect occurs because the bases accept the protons released by 1,4-H2Q during its two-electron oxidation. Similar effects are observed when the phthalate bases were attached to the electrode surface. The hydrogen bonding was verified and measured by determining diffusion coefficients using 1H NMR spectroscopy. The modification of glassy carbon electrodes with phthalate diazonium salts was monitored by X-ray photoelectron spectroscopy. The experimental electrochemical responses by cyclic voltammetry were fitted to simulations following mechanisms previously reported and using t...

Electrochemical behavior of hydroquinone at multi-walled carbon nanotubes and ionic liquid composite film modified electrode

The electrochemical behavior of hydroquinone (HQ) was studied by cyclic voltammetry at a glassy carbon electrode (GCE) modified by a gel containing multi-walled carbon nanotubes (MWNTs) and room temperature ionic liquid (RTIL) of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF 6). At the modified electrode, HQ showed a pair of quasi-reversible redox peaks. The cathodic peak current value ( I pc) of HQ was 9.608 × 10 −4 A, which is 43 times larger than the one at the GCE, and 11 times larger than that of I pc at the MWNTs/GCE. Furthermore, the capabilities of electron transfer on these three electrodes were also investigated by electrochemical impedance spectroscopy (EIS), and the similar conclusion as cyclic voltammetry has drawn. Besides, we also characterized the surface morphology of the prepared composite film using the scanning electronic microscopy (SEM). The MWNTs were pulled away from the tangle in RTIL. The solvent effect of RTIL may be the reason of higher adsorption amount.

Electrochemical study of 1,4-benzoquinone on gold surface modified

The electrochemical behavior of 1,4-benzoquinone has been studied immobilizing this molecule on a gold electrode modified with 1-propanethiol (1-PT), 2-propene-1-thiol (2-P-1-T) and 1,3-propanedithiol (1,3-PDT). In the method used (self-assembled techniques) for the surface modification we control the exposure time of gold surface in the modifier/ethanol solution. This study was followed by cyclic voltammetry (CV) analysis. We demonstrated that the gold surface was modified by 1-PT, 2-P-1-T and 1,3-PDT compounds. Also, shown was the electrochemical detection of 1,4-benzoquinone (BQ) on these surface and electrochemical behavior of hydroquinone (H 2Q) moiety formed after the Michael addition reaction between the BQ and the thiol (-SH) group on gold surface (see Scheme 1). The better system was Au/2-P-1-T/1,3-PDT/H 2Q.

Voltammetric Determination of Hydroquinone using β‐Cyclodextrin/Poly(N‐Acetylaniline)/Carbon Nanotube Composite Modified Glassy Carbon Electrode

An electrochemical sensor for hydroquinone (HQ) using β‐cyclodextrin/poly(N‐acetylaniline)/carbon nanotube composite (β‐CD/PAA/MWNTs) modified glassy carbon electrode has been successfully developed. Based on the synergistic effect of MWNTs and conducting PAA polymer and the accumulation effect of β‐CD, the analytical response of the β‐CD/PAA/MWNTs film to the electrochemical behavior of HQ was better than that of a β‐CD/PAA film, a PAA/MWNTs film, a PAA film, or a bare glassy carbon (GC) electrode. Under the conditions chosen, the anodic currents increased linearly with HQ concentration from 1×10−6 to 5×10−3 mol l−1 and the detection limit was 8×10−7 mol l−1. This electrochemical sensor showed excellent reproducibility, stability and recovery for the determination of HQ.

Comparative investigation on electrochemical behavior of hydroquinone at carbon ionic liquid electrode, ionic liquid modified carbon paste electrode and carbon paste electrode

Ionic liquid, 1-heptyl-3-methylimidazolium hexafluorophosphate (HMIMPF6), has been used to fabricate two new electrodes, carbon ionic liquid electrode (CILE) and ionic liquid modified carbon paste electrode (IL/CPE), using graphite powder mixed with HMIMPF6 or the mixture of HMIMPF6/paraffin liquid as the binder, respectively. The electrochemical behaviors of hydroquinone at the CILE, the IL/CPE and the CPE were investigated in phosphate buffer solution. At all these electrodes, hydroquinone showed a pair of redox peaks. The order of the current response and the standard rate constant of hydroquinone at these electrodes were as follows: CILE > IL/CPE > CPE, while the peak-to-peak potential separation was in an opposite sequence: CILE < IL/CPE < CPE. The results show the superiority of CILE to IL/CPE and CPE, and IL/CPE to CPE in terms of promoting electron transfer, improving reversibility and enhancing sensitivity. The CILE was chosen as working electrode to determine hydroquinone by differential pulse voltammetry, which can be used for sensitive, simple and rapid determination of hydroquinone in medicated skin cosmetic cream.

Cobalt hydroxide film deposited on glassy carbon electrode for electrocatalytic oxidation of hydroquinone

The electrodeposition of cobalt hydroxide film on glassy carbon electrode was prepared by electrochemical method in an alkaline aqueous solution. The electrochemical behavior of hydroquinone on cobalt hydroxide film electrode has been investigated by using cyclic voltammetry and linear sweep voltammetry. The results showed that the film electrode has good electrocatalytic ability for the oxidation of hydroquinone to p-quinone. The recovery of hydroquinone from sample ranged from 94.7% to 102.9% and a rectilinear analytical curve for hydroquinone concentration from 5.0 × 10 −6 to 1.25 × 10 −4 mol/L was obtained. The detection limit was 5.0 × 10 −7 mol/L and the relative standard deviation was 2.63%. Various factors affecting the electrocatalytic activity of cobalt hydroxide film were investigated.