Dihydroxybenzene Isomers Research Articles

Corrosion Inhibition Mechanism and Efficiency Differentiation of Dihydroxybenzene Isomers Towards Aluminum Alloy 5754 in Alkaline Media.

The selection of efficient corrosion inhibitors requires detailed knowledge regarding the interaction mechanism, which depends on the type and amount of functional groups within the inhibitor molecule. The position of functional groups between different isomers is often overlooked, but is no less important, since factors like steric hinderance may significantly affect the adsorption mechanism. In this study, we have presented how different dihydroxybenzene isomers interact with aluminum alloy 5754 surface, reducing its corrosion rate in bicarbonate buffer (pH = 11). We show that the highest inhibition efficiency among tested compounds belongs to catechol at 10 mM concentration, although the differences were moderate. Utilization of novel impedance approach to adsorption isotherm determination made it possible to confirm that while resorcinol chemisorbs on aluminum surface, catechol and quinol follows the ligand exchange model of adsorption. Unlike catechol and quinol, the protection mechanism of resorcinol is bound to interaction with insoluble aluminum corrosion products layer and was only found efficient at concentration of 100 mM (98.7%). The aforementioned studies were confirmed with Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy analyses. There is a significant increase in the corrosion resistance offered by catechol at 10 mM after 24 h exposure in electrolyte: from 63 to 98%, with only negligible changes in inhibitor efficiency observed for resorcinol at the same time. However, in the case of resorcinol a change in electrolyte color was observed. We have revealed that the differentiating factor is the keto-enol tautomerism. The Nuclear Magnetic Resonance (NMR) studies of resorcinol indicate the keto form in structure in presence of NaOH, while the chemical structure of catechol does not change significantly in alkaline environment.

Experimental and Theoretical Insights into Molecular and Solid-State Properties of Isomeric Bis(salicylaldehydes).

A series of five bis(salicylaldehydes), including four isomeric compounds based on a benzene scaffold and a closely related naphthalene derivative, were investigated in order to elucidate the impact of resonance effects and intramolecular hydrogen bonds (HBs) on the macroscopic properties of these systems. Density functional theory (DFT) computations revealed important differences between isomers on the molecular level, which was reflected in different charge distributions, aromatic C-C bond orders, and aromaticity characters. The consequences of these features were evidenced by the UV-vis absorption spectra: for 1,3-diformyl-4,6-dihydroxybenzene (2), the longest wavelength absorption band is observed at 285 nm, while its isomers 1,4-diformyl-2,5-dihydroxybenzene (1), 1,4-diformyl-2,3-dihydroxybenzene (3), and 1,2-diformyl-3,6-dihydroxybenzene (4) are characterized by absorption in the visible range (379-407 nm). The specificity of 2 results from simultaneous lowering and elevation of HOMO and LUMO energy levels, respectively. We have found that the HOMO/LUMO energy variations follow trends observed in isomeric dihydroxybenzenes (HOMO) and phthalaldehydes (LUMO), and these effects operate separately to some extent. Furthermore, theoretical calculations indicate that the UV-vis spectral properties of bis(salicylaldehydes) are directly transferable to the corresponding bis(salicylaldimines) and their boron complexes. Finally, the influence of structural and molecular stabilization effects was analyzed by means of X-ray structural analysis and periodic DFT computations.

Simultaneous Determination of Dihydroxybenzene Isomers using Glass Carbon Electrode Modified with 3D CNT-graphene Decorated with Au Nanoparticles

Simultaneous Determination of Dihydroxybenzene Isomers using Glass Carbon Electrode Modified with 3D CNT-graphene Decorated with Au Nanoparticles

Spectroscopic and quantum chemical investigations on structural isomers of dihydroxybenzene

Spectroscopic and structural properties of hydroxyl group based structural isomers such as catechol, resorcinol and hydroquinone have been investigated by FT-IR, FT-Raman, NMR and UV-Vis analytical techniques with the help of quantum chemical calculations. The electronic structure of benzenediol isomers have been optimized with complete relaxations on the potential energy surfaces and structure of these isomers were predicted with different point group symmetries. The intra- and inter-molecular interactions have been studied by natural bond orbital (NBO) and Hirshfeld surface analysis. In addition, the frontier molecular orbital (FMO), nonlinear optical (NLO), potential energy surface (PES) scan, dimer formation, direction of the dipole moment and influences of hydrogen bonding have been analyzed to gain better insight into the benzenediol isomers.

Facile electrochemical preparation of NaOH nanorods on glassy carbon electrode for ultrasensitive and simultaneous sensing of hydroquinone, catechol and resorcinol

A simple and efficient electrochemical sensing platform for simultaneous detection of hydroquinone (HQ), catechol (CC) and resorcinol (RC) based on in-situ prepared sodium hydroxide (NaOH) nanorods was reported for the first time. Sodium hydroxide (NaOH) nanorods on glassy carbon electrode (GCE) was synthesized via one electrochemical deposition step in NaOH solution using constant current. The affecting factors including content of NaOH solution, deposition current and deposition time were investigated. The obtained electrodes were also examined by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The electrochemical behaviour analysis and dynamic study indicated that the three dihydroxybenzene isomers can be catalytically oxidized and discriminated simultaneously on the proposed electrode. Using square wave voltammetry (SWV), the ultrasensitive and simultaneous detection of HQ, CC and RC was realized with wide linear range from 0.03 to 1500 μM and low detection limit of 0.01, 0.01, 0.09 μM, respectively. The detection of them in real water samples was also successfully performed and good recovery was obtained.

Unusual pH - Dependent Electrochemical Activity of Nitrogen Doped Graphene Oxide Towards Selective and Simultaneous Determination of Hydroquinone and Catechol

Hydroquinone (HQ) and Catechol (CC) are the two important dihydroxybenzene isomers that have found widespread usage in dyes, pesticides, cosmetics and pharmaceuticals manufacturing industries as synthetic intermediates [1]. However, due to their toxicity and low degradability, they have been declared as important environmental pollutants to be monitored [2]. Therefore, it is imperative to develop a rapid and facile analytical method for the simultaneous determination of HQ and CC. In this regard, electroanalytical techniques have been preferred over conventional analytical techniques because of their cost–efficiency and high–speed analysis [3]. Unfortunately, due to the presence of same electroactive groups, the redox peaks of both these isomers overlap together, thereby resolution of them at conventional working electrodes has been rendered impossible without chemical or electrochemical modifications. In the past few years, the doping of atoms such as Nitrogen, Boron and Sulfur into graphene or graphene oxide lattices have evoked lot of interest [4]. These doped graphene oxides have large amount of edge sites, high surface area and electrical conductivity which in turn leads to superior electrochemical and catalytic activities [5]. In the present work, a simple, facile and one – pot hydrothermal strategy is presented for the synthesis of Nitrogen–doped graphene oxide (NGO) by employing Amitrole (AMT) as the nitrogen source. The successful N–doping into the graphene oxide lattices have been confirmed through FT–IR, FT–Raman and XPS techniques while, other characteristic properties were investigated using powder XRD, SEM, TEM and TGA. As an application, an electrochemical sensor based on the NGO–AMT modified glassy carbon electrode (NGO–AMT/GCE) has been developed for the sensitive and simultaneous determination of HQ and CC. Interestingly, the NGO–AMT/GCE exhibited a pH–dependent electrochemical activity towards the simultaneous sensing of these two dihydroxybenzene isomers in 0.1 M PBS. Moreover, the characteristic twin oxidation peaks of HQ and CC were observed at pH = 7.08 with a peak separation of about 110 mV using DPV technique. On the other hand, at pH = 5.08 and pH = 9.08 the corresponding oxidation peaks of CC and HQ were alone observed. This unusual behavior has been rationalized through the protonation of pyridinic nitrogen at lower pH and de-protonation of carboxylic acid active sites at higher pH (Fig.1). The proposed sensor was thus examined at pH 7.08 and found to have a linear range from 1 to 500 μM. The limits of detection (LOD, S/N = 3) were 15 and 20 nM, respectively for HQ and CC. Furthermore, the interference analysis has been carried out with some typical interfering agents and the performance of NGO–AMT/GCE was found to be satisfactory. As a practical application, the developed sensor was utilized for analyzing these isomers in tap water and exhibited reliable and stable recovery results.

Isomorphic MOF-derived porous carbon materials as electrochemical sensor for simultaneous determination of hydroquinone and catechol

It is needed to speed up the development of a sensitive detection platform for simultaneous determination of dihydroxybenzene isomers with harmful properties. Here, two isomorphic Metal–organic frameworks (MOFs) [Zn(Trz)(R-BDC)1/2] (FJU-40-R, R = H or NH2; Trz = 1,2,4-Triazole; H-BDC = terephthalic acid) were selected to derive two N-doping porous carbon (NPC) materials. Further, a strategy for constructing electrochemical sensors for simultaneous determination of hydroquinone (HQ) and catechol (CT) was proposed by the MOF-derived NPC modifying glass carbon electrode (GCE). It was found that HQ and CT had good responses on NPC-FJU-40-H/GCE, but had no obvious responses on NPC-FJU-40-NH2/GCE. NPC-FJU-40-H/GCE displayed excellent reproducibility, stability, and anti-interference. Under the optimal conditions, the linear ranges of HQ and CT on NPC-FJU-40-H/GCE were 1 ~ 70 µmol L−1 and 1 ~ 100 µmol L−1 with the detection limits of 0.18 µmol L−1 for HQ and 0.31 µmol L−1 for CT, respectively. Although the porous carbon (PC) derived from MOFs has been applied in electrochemical sensing, the effect of the ligand functional groups of isomorphic MOFs on the electrochemical properties of the derived PC materials is still lack of relevant research. Our research provided an idea that the electrocatalysis properties of MOF-derived porous carbon materials could be tuned by changing the functional groups in ligands of isomorphic MOFs in electrochemical sensing field. A feasible strategy was proposed by changing the ligands of the two isomorphic MOFs (FJU-40-H and FJU-40-NH2) to tune the electrocatalysis properties of MOF-derived N-doped porous carbon materials for the simultaneous determination of dihydroxybenzene isomer.

An Ultrasensitive Electrochemical Sensor Based on Multiwalled Carbon Nanotube@Reduced Graphene Oxide Nanoribbon Composite for Simultaneous Determination of Hydroquinone, Catechol and Resorcinol

Three dihydroxybenzene isomers, hydroquinone (HQ), catechol (CC) and resorcinol (RS), were determined simultaneously by an ultrasensitive electrochemical sensor based on a glassy carbon electrode modified by multiwalled carbon nanotube@reduced graphene oxide nanoribbon (MWCNT@rGONR) composite. The material was synthesized via hydrothermal method and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). We used cyclic voltammetry (CV) to study the electrochemical performance of the three isomers and differential pulse voltammetry (DPV) to optimize the experimental parameters. Based on the optimal experimental condition, our electrochemical sensor displayed a good linear relationship with the concentration range of 15 to 921 μM, 15 to 1101 μM, and 15 to 1301 μM and detection limit of 3.89 μM, 1.73 μM and 5.77 μM for HQ, CC and RS respectively. The electrochemical sensor based on MWCNT@GONR composite showed outstanding ability of reproducibility, stability and anti-interference. In addition, this sensor was also used successfully for simultaneous determination of HQ, CC and RS in real samples with satisfactory result.

In situ construction of hollow carbon spheres with N, Co, and Fe co-doping as electrochemical sensors for simultaneous determination of dihydroxybenzene isomers.

Control of the active sites/centers plays an important role in the design of novel electrode materials with unusual properties and achievement of sensors with high performance. In this study, three-dimensional (3D) freestanding multi-doped hollow carbon spheres (N-Co-Fe-HCS) with a layer thickness of 30 nm, which contained multiple active sites of the heteroatom N and transition metals (Co and Fe), were synthesized via a simple template method (with SiO2 as the template) and cost-efficient in situ self-polymerization, self-adsorption/reduction and carbonization strategies. Moreover, a series of hollow carbon sphere composites of the same family (N-HCS, N-Co-HCS and N-Fe-HCS) were prepared by this sensible process using the same method and precursors but different doping elements. These differences lead to different active sites/centers from hollow carbon spheres and improved electrocatalytic activities for dihydroxybenzene isomers. Furthermore, N-Co-Fe-HCS as an electrochemical sensor exhibited excellent simultaneous qualitative and quantitative determination performance for catechol (CC) and hydroquinone (HQ). The detection limit and the linear range were 75 nmol L-1 and 0.5-500 μmol L-1 for CC and 80 nmol L-1 and 0.5-1500 μmol L-1 for HQ, respectively. The interference from the components coexisting in river water on the detection of CC and HQ was not observed. These results indicate that high-performance electrochemical sensors can be constructed by in situ multi-element doping into electrode materials to achieve multi-active sites.

In situ synthesis of sandwich MOFs on reduced graphene oxide for electrochemical sensing of dihydroxybenzene isomers

A novel type of sandwich MOF was successfully synthesized on reduced graphene oxide (denoted as M@Pt@M-rGO) by an in situ synthesis method. The obtained M@Pt@M-rGO possesses excellent electrochemical properties. The surface morphology and structure of M@Pt@M-rGO were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), etc. By using M@Pt@M-rGO, a novel electrochemical sensor was constructed and successfully used for the simultaneous and sensitive detection of three isomers: hydroquinone (HQ), catechol (CT) and resorcinol (RS), with wider linear ranges of concentrations of 0.05-200 μM, 0.1-160 μM and 0.4-300 μM and lower detection limits of 0.015 μM, 0.032 μM and 0.133 μM (S/N = 3) for HQ, CT and RS, respectively. Besides, the proposed electrochemical sensor showed excellent anti-interference capability, high stability, good reproducibility, and satisfactory recovery for determination of isomers in river and lake water.

Facile synthesis of cellulose microfibers supported palladium nanospindles on graphene oxide for selective detection of dopamine in pharmaceutical and biological samples

The cost-effective synthesis of novel functional nanomaterials has received significant attention in the physical and chemical sciences due to their improved surface area, high catalytic activity along with unique morphological features. This paper reports a facile and eco-friendly synthesis of spindle-like palladium nanostructures (PdSPs) on graphene oxide-cellulose microfiber (GO-CMF) composite for the first time. The GO-CMF/PdSPs composite was synthesized by an electrochemical method without the use of additional surfactants and capping agents. The synthesized materials were characterized and confirmed by using transmission electron microscopy, high-resolution scanning electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy and Fourier-transform infrared spectroscopy. As-synthesized GO-CMF/PdSPs composite modified electrode was used as a selective electrocatalyst for the oxidation of dopamine (DA). The electrochemical redox behaviors of DA were investigated using cyclic voltammetry (CV). The CV results revealed that the GO-CMF/PdSPs composite modified electrode has 10 folds enhanced oxidation current response to DA than GO, PdSPs and GO-CMF modified GCEs. Under optimized conditions, the GO-CMF/PdSPs composite sensor exhibits a linear response to DA in the concentration range from 0.3 to 196.3 μM with the lower detection limit of 23 nM. The nanocomposite electrode also shows promising features towards the reliable and selective detection of DA, which includes high stability, reproducibility and high selectivity towards the commonly interfering species such as ascorbic acid, uric acid, and dihydroxybenzene isomers. The sensor was successfully tested for the real-time detection of DA in the commercial DA injections and human serum samples.

Poly (Evans blue) sensor for catechol and hydroquinone: A voltammetric study

Poly (Evans blue) modified carbon paste electrode was prepared by electropolymerization method. The electrochemical determination of two major phenolic moieties namely catechol (CC) and hydroquinone (HQ) was performed at poly (Evans blue) modified carbon paste electrode (Evans blue/MCPE) by cyclic voltammetry in the PBS (0.2M) at pH7.4, with the sweep rate of 50mV/s. The sensor showed good electrocatalytic activity towards the oxidation of dihydroxybenzene isomers. The effect of variation of sweep rate and pH on voltammograms of CC and HQ was studied. The lower limit of detection of CC and HQ was found to be 2.0 and 2.1μM, respectively, and simultaneous determination was possible. The separation of oxidation peak potential of CC and HQ on this modified electrode was 212mV in CV. The interference studies showed that the modified electrode exhibits excellent selectivity and sensitivity. Finally, the fabricated sensor was successfully applied for the determination of CC and HQ in lake water sample with satisfactory recovery.

Simultaneous determination of dihydroxybenzene isomers at nitrogen-doped graphene surface using fast Fourier transform square wave voltammetry and multivariate calibration

In this paper, a highly sensitive electrochemical method, which is based on the combination of fast Fourier transform square wave voltammetry and multivariate calibration techniques, was developed for simultaneous determination of dihydroxybenzene positional isomers, including catechol, hydroquinone, and resorcinol, in environmental samples. An electrochemical sensor was constructed by the deposition of nitrogen-doped graphene on a glassy carbon electrode to apply as a new approach for the multicomponent analysis. Partial least squares was applied, as a multivariate calibration method, to deconvolute the highly overlapping electrochemical signals from the analytes. Using the simplex experimental design with the degree of 4, 19 ternary mixture solutions of the cited analytes were prepared in the established linear ranges of the analytes. The developed multivariate model was validated by predicting the concentration of 8 independent solutions. The root mean square error values of validation values were between 0.04230 and 0.06549 μM, respectively. The applicability of the proposed method was checked using water samples (collected from both the surface and waste water) and human urine, and the obtained recovery values were between 89.3 and 107.1%. The limits of detection and relative standard deviations for catechol, hydroquinone, and resorcinol were 0.046, 0.046, and 0.045 μM, and 3.6, 3.4 and 3% (N = 5), respectively.

Highly selective and sensitive detection of catechol by one step synthesized highly fluorescent and water-soluble silicon nanoparticles

Because the chemical properties and structures of catechol and its analogues (hydroquinone and resorcinol) are similar, it still is a great challenge to detect catechol from other hydroxybenzene isomers with high accuracy and reliability. Herein, a selective and sensitive method based on the water soluble silicon nanoparticles (Si NPs) was established for catechol detection, and to the best of our knowledge, this is the first time using Si NPs for catechol measurement. The synthesis of Si NPs was very cheap and simple, no time-consuming, and no need for high temperature processing, or special instrument. The as-synthesized Si NPs, with high salt and temperature stabilities emitted yellow-green fluorescence (540 nm). A good linear relationship was observed from 0.06 to 40 μM and the limit of detection (based on 3s/k) was calculated as 20 nM, and the sensor displayed a significant selectivity toward catechol over other dihydroxybenzene isomers. Moreover, the Si NPs were applied in tap water, human serum samples and Yellow River water for catechol measurement.

MOF-derived binary mixed carbon/metal oxide porous materials for constructing simultaneous determination of hydroquinone and catechol sensor

It is a top priority to simultaneously and accurately detect hydroquinone (HQ) and catechol (CC). Here, a new strategy for constructing simultaneous determination of HQ and CC sensor was proposed by one-step pyrolysis of MIL series metal-organic frameworks materials (MIL-125 (Ti), MIL-101 (Cr), and MIL-101 (Fe)) to obtain uniform-mixed carbon/metal oxide porous materials (TiO2/C900, Cr2O3/C900, and Fe2O3/C900, respectively). And, cyclic voltammetry (CV) was utilized to investigate the electrochemical behavior of the composite materials. It was found that the simultaneous detection of catechol (CC) and hydroquinone (HQ) could be achieved by the sensor consisted of TiO2/C900 with the superior BET-specific surface area and micro-mesoporous characteristics. And, the linear range and detection limit of HQ and CC for the TiO2/C900 sensor were further studied. In addition, it was also found that the pyrolysis temperature and metal centers would affect the internal structures and component of the materials, thus affecting the properties of materials. The experiment provides a new idea for optimizing the simultaneous detection of the dihydroxybenzene isomers.

Microwave-assisted synthesis of Bi2WO6 flowers decorated graphene nanoribbon composite for electrocatalytic sensing of hazardous dihydroxybenzene isomers

Abstract A microwave-assisted synthesis is described for the preparation of bismuth tungstate/graphene nanoribbons (Bi2WO6@GNRs) nanocomposite as cost-effective alternative to existing hydrothermal method. HR-TEM, XRD, XPS, EDX, BET and Raman characterizations reveal the incorporation of Bi2WO6 flowers on GNRs. The electrochemical and interfacial properties of the composite were probed by voltammetry and impedance studies. The electrocatalytic ability of the composite was assessed by studying the redox reactions of hazardous dihydroxybenzene isomers. Bi2WO6@GNRs modified screen-printed electrode was found to distinguish the voltammetric signals of catechol and hydroquinone (separation gap of 140 mV, vs. Ag|AgCl), minimizes reaction overpotentials, and amplifies the electrochemical current signal. The effects of concentration scan rate and cross-reactivity are studied. Bi2WO6@GNRs incorporated sensor displayed detection limits of 5.31 nM and 7.24 nM for catechol and hydroquinone, respectively. The method was found to be practically applicable in the determination of catechol and hydroquinone in water samples and face cream sample, respectively.

Contrastive study for coadsorption of copper and two dihydroxybenzene isomers by a multi-amine modified resin

Coadsorption of Cu(II) and two dihydroxybenzene isomers (hydroquinone, HQ and catechol, CAT) onto a multi-amine modified resin (CEAD) were comparatively studied. The presence of Cu(II) promoted adsorption of both HQ and CAT by a maximum of 25.8% and 41.6%, respectively. However, two diphenols exerted a very different influence on Cu(II) uptake. Higher concentrations of HQ consistently suppressed Cu(II) adsorption while the coexistence of CAT facilitated it, especially at lower CAT concentrations. The interactions among solutes and adsorbents were revealed by means of kinetic tracking, sequential adsorption experiments, and characterizations/calculations (FTIR, XPS, MINTEQ and DFT). Cu(II) and HQ/CAT competed for amine sites with the order of adsorption affinity as HQ > Cu(II) > CAT. The bridging effect of Cu(II) forming ternary complexes (amine-Cu-CAT/HQ) on the resin phase was the dominant mechanism for the enhanced adsorption of diphenols. The [Cu-CAT] complex species showed a lower affinity to bind directly to amine sites compared with free Cu2+. Instead, the complex could be attracted by the polyphenyl matrix of CEAD, contributing to the increase of Cu(II) adsorption. Additionally, Cu(II) and diphenols were successively recovered, and CEAD could be stably reused. The findings will guide adsorbent applications and the environmental fate of concurrent heavy metals and phenolic compounds.

Copper oxide and carbon nano-fragments modified glassy carbon electrode as selective electrochemical sensor for simultaneous determination of catechol and hydroquinone in real-life water samples

The fabrication of robust sensors for the monitoring of emerging contaminants in real-life water samples has received much attention. In this study, copper oxide and carbon nano-fragment modified glassy carbon electrode (CuO-CNF/GCE) based electrochemical sensor was developed for the simultaneous monitoring of dihydroxybenzene isomers such as catechol (CC) and hydroquinone (HQ). The structural and morphological characterization of CuO-CNF/GCE was done by scanning electron microscopy - energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The electrochemical oxidation of HQ and CC was investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CuO-CNF/GCE exhibited high current sensitivity for CC and HQ. The oxidation peak currents of CC at the CuO-CNF/GCE were linear function of concentration 0 μM to 150 μM, with detection limit of 2 μM (at a signal-to-noise ratio of 3) (R2 = 0.997) and the oxidation peak currents of HQ were linear function of concentration 3 μM to 80 μM, with 1 μM detection limit (S/N = 3) (R2 = 0.995). The CuO-CNF/GCE was successfully used for detecting the two dihydroxybenzene isomers in real-life water samples with high selectivity.

Modification of glassy carbon electrode with poly(hydroxynaphthol blue)/multi-walled carbon nanotubes composite and construction a new voltammetric sensor for the simultaneous determination of hydroquinone, catechol, and resorcinol

A novel voltammetric sensor is developed based on a poly(hydroxynaphthol blue)/multi-walled carbon nanotubes-modified glassy carbon electrode for the simultaneous determination of the dihydroxybenzene isomers hydroquinone (HQ), catechol (CC), and resorcinol (RS). The preparation and basic electrochemical performance of the sensor are investigated in details. The electrochemical behavior of the dihydroxybenzene isomers at the sensor is studied by the cyclic and differential pulse voltammetric techniques. The results obtained show that this new electrochemical sensor exhibits an excellent electro-catalytic activity towards oxidation of the three isomers. The mechanism of this electro-catalytic activity is discussed. Using the optimum parameters, limit of detection obtained 0.24, 0.24, and 0.26 μmol L−1 for HQ, CC, and RS, respectively. The modified electrode is also successfully applied to the simultaneous determination of dihydroxybenzene in water samples.

Interference free detection of dihydroxybenzene isomers at pyrogallol film coated electrode: A voltammetric method

A carbon paste electrode was modified with pyrogallol red film using a cyclic voltammetric method (CV) and the influence of number of sweep segments on the surface area of was examined. The fabricated film coated electrode exhibited excellent electrocatalytic performance for the electro-oxidation of 1, 2- dihydroxybenzene and 1, 4-dihydroxybenzene. To know the kinetics of electrode process, scan rate study was conducted and it confirms the adsorption controlled electrode kinetics. The redox potentials were dependents on pH and witnessed an identical number transfer of protons and electrons. Also a linearity was observed for the peak current and concentration of both HQ and CC by using differential pulse voltammetric technique (DPV) and gave a detection limit of 0.018 and 0.021 μM respectively. Furthermore, successful selective separation of phenolic isomers was achieved in a binary mixture. A good analytical results were observed towards the quantification of CC and HQ in a tap water sample.