Dihydroxybenzene Isomers Research Articles

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.

Poly(quercetin)-bismuth nanowires as a new modifier for simultaneous voltammetric determination of dihydroxybenzene isomers and nitrite.

Dihydroxybenzene isomers and nitrite, NO2−, are present in the environment as highly toxic compounds and cause human cancer. In this study, for the first time poly(quercetin) (PQ) was synthesized from the reaction between quercetin (Q) and hydroquinone (HQ) as a linker. Bismuth nanowires (BNWs) were synthesized using a solvothermal technique and then the BNWs and PQ were used for preparation of a novel modified graphite paste electrode (GPE/PQ–BNWs) for simultaneous determination of dihydroxybenzene isomers; HQ, catechol (CC), resorcinol (RS) in the presence of NO2−. The product was characterized using X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. The electrochemical response characteristics of the modified GPE toward mix HQ, CC, RS and NO2− were investigated by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. Under the optimum conditions, detection limits of 0.12, 0.2, 0.82 and 4.5 μM were obtained for HQ, CC, RS and NO2−, respectively. Moreover, the GPE/PQ–BNWs were applied to determine HQ, CC, RS and NO2− in water samples with satisfactory results.

Tea quality testing using 6B pencil lead as an electrochemical sensor

Isomers of dihydroxy benzene (DHB) such as 1,2-DHB, 1,3-DHB and 1,2,3-trihydroxy benzene (1,2,3-THB) are the functional electro-active constituents of tea polyphenols.

A carbon nanofibers–Sm2O3 nanocomposite: a novel electrochemical platform for simultaneously detecting two isomers of dihydroxybenzene

In this report, a CNFs-Sm2O3 nanocomposite modified glassy carbon electrode (CNFs-Sm2O3/GCE), comprising CNFs with a large specific surface area and Sm2O3 with excellent catalytic activity, is prepared as a novel sensor for simultaneously detecting hydroquinone (HQ) and catechol (CC) in an aqueous environment.

Improved effect of deep eutectic solvents on polymeric film of surfactant: application in determination and discrimination of dihydroxybenzene isomers as model molecules

The simultaneous determination of hydroquinone and catechol with different deep eutectic solvents (DESs) employed in the polymerization step of cetyltrimethylammonium bromide (CTAB) on an oxidized glassy carbon electrode is studied.

A glassy carbon electrode modified with poly(2,4-dinitrophenylhydrazine) for simultaneous detection of dihydroxybenzene isomers.

2,4-Dinitrophenylhydrazine (DNPH) was electropolymerized on the surface of an anodized glassy carbon electrode by cyclic voltammetry. The anodized electrode has a highly electroactive surface due to the creation of chemically functionalized graphitic nanoparticles, and this facilitates the formation of poly-DNPH via radical polymerization. Poly-DNPH displays excellent redox activity due to the presence of nitro groups on its backbone. These catalyze the electro-oxidation of hydroquinone (HQ) and catechol (CT). The peak-to-peak separation is around 109mV, while a bare GCE cannot resolve the peaks (located at 165 and 274mV vs. Ag/AgCl). Sensitivity is also enhanced to ∼1.20 and 1.19μA·cm-2·μM-1, respectively. The sensor has a linear response that covers the 20-250μM concentration range for both HQ and CT, with 0.75 and 0.76 μM detection limits, respectively, at simultaneous detection. Commonly present species do not interfere. Graphical abstract A novel conducting poly(2,4-dinitrophenylhydrazine)-modified anodized glassy carbon electrode (pDNPH/AGCE) was developed by electrochemical method. The electro-catalytic activity of pDNPH/AGCE sensor was investigated for the selective and simultaneous electrochemical detection of hydroquinone (HQ) and catechol (CT), which revealed high sensitivities and low detection limits with excellent stability.

Self-template synthesis of biomass-derived 3D hierarchical N-doped porous carbon for simultaneous determination of dihydroxybenzene isomers

Nitrogen doped hierarchical porous carbon materials (HPCs) was achieved by the successful carbonization, using pig lung as biomass precursor. Three-dimensional HPCs constituted with sheets and lines were synergistically inherited from original pig lung. Such structure provided a large specific surface area (958.5 g−1 m2) and rich porous, effectively supported a large number of electro-active species, and greatly enhanced the mass and electron transfer. High graphitization degree of HPCs resulted in good electrical conductivity. Furthermore, the different electronegativity between nitrogen and carbon atoms in HPCs could affect the electron cloud distribution, polarity and then the electrochemical oxidation kinetics of dihydroxybenzene isomers. Based on these characteristics of HPCs, the electrochemical sensor for dihydroxybenzene isomers exhibited high sensitivity, excellent specificity and stability. Quantitative analysis assays by differential pulse voltammetry (DPV) technology showed that the sensor has wide linear ranges (0.5–320, 0.5–340 and 1–360 μmol L−1) and low detection limits (0.078, 0.057 and 0.371 μmol L−1) for the catechol, resorcinol and hydroquinone, respectively. This proposed method was successfully applied for simultaneous detection of dihydroxybenzene isomers in river water.

Hierarchical Self-Assembly of Cyclodextrin and Dimethylamino-Substituted Arylene-Ethynylene on N-doped Graphene for Synergistically Enhanced Electrochemical Sensing of Dihydroxybenzene Isomers.

An electrochemically active sensing nanomaterial (denoted as CD-MPEA-NG) has been successfully constructed by an hierarchical self-assembly of cyclodextrin (CD) and N,N-dimethyl-4-(phenylethynyl)aniline (MPEA) on N-doped graphene (NG) in a low-temperature hydrothermal process. The unique nanostructure of the high-performance CD-MPEA-NG was confirmed by utilizing Fourier transform infrared spectra, an X-ray diffractometer, and differential pulse voltammetry (DPV), etc. In particular, the method of density functional theory with dispersion energy (DFT-D) of wB97XD/LanL2DZ was employed to optimize and describe the face-to-face packing structure of heterodimers of NG and MPEA. The CD-MPEA-NG sensor exhibits highly sensitive performance toward dihydroxybenzene isomers, without relying on expensive noble metal or a complicated preparation process. The experimental results demonstrate that given the synergistic effect of NG and MPEA as a coupled sensing platform, CD as a supramolecular cavity can significantly enhance the electrochemical response. The detection limits (S/N = 3) for catechol (CT), resorcinol (RS), and hydroquinone (HQ) are 0.008, 0.018, and 0.011 μM by DPV, respectively. Besides, the CD-MPEA-NG sensor shows a superb anti-interference, reproducibility, and stability, and satisfactory recovery aimed at detecting isomers in Nanjing River water. The encouraging performance as well as simplified preparation approach strongly support the CD-MPEA-NG sensor is a fascinating electrode to develop as a seamless and sensitive electroanalytical technique.

Electrochemically reduced graphene oxide as modified electrode material for determination of dihydroxybenzenes

A simple and green method was introduced to fabricate the electrochemical sensor based on the electrochemically reduced graphene oxide (ERGO) modified electrode. It was found that the ERGO modified electrode exhibited an excellent catalytic activity toward the oxidation of dihydroxybenzenes isomers. Under the optimum conditions, in the simultaneous determination of the dihydroxybenzene isomers, the currents were linear with the concentrations of the isomers from 5 to 550 μmol/L for hydroquinone (HQ), from 6 to 400 μmol/L for catechol (CT) and from 5 to 350 μmol/L for resorcinol (RS), respectively. In addition, the proposed sensor has good stability and reproducibility. The developed method has been applied to the simultaneous determination of dihydroxybenzene isomers in real samples with a satisfactory recovery from 98% to 103%.

Modified Glassy Carbon Electrode with Galvanized Copper Nanowires by Palladium and Carbon Nanotubes for Speciation of Dihydroxybenzene Isomers

Modified Glassy Carbon Electrode with Galvanized Copper Nanowires by Palladium and Carbon Nanotubes for Speciation of Dihydroxybenzene Isomers

Isothermal Titration Calorimetry to Probe the Coil-to-Globule Transition of Thermoresponsive Polymers.

Isothermal titration calorimetry (ITC) is introduced as a new way to study the effect of cosolutes on the coil-to-globule transition of thermoresponsive polymers. From isothermal titrations, critical cosolute concentrations can be identified, at which a coil-to-globule transition occurs. The concept of a temperature-dependent critical cosolute concentration is proven employing different isomers of dihydroxybenzene (DHB) and one isomer of hydroxy benzaldehyde (mHBA) in solutions of two thermoreversible polymer, namely poly(N-isopropylacrylamide) (PNiPAM) and poly(N,N-diethylacrylamide) (PDEAM). It is shown that the temperature-dependent critical cosolute concentration, determined by ITC, and the cosolute concentration-dependent critical temperature, probed via differential scanning calorimetry (DSC), yield the same phase diagram. The advantage of employing ITC is the ability to probe even critical concentrations at very low temperatures, whereas the corresponding critical temperatures are not easily accessible in DSC. In addition, kinetic information about the coil-to-globule transition in different systems is obtained, and the effect of the DHB isomers on the transition temperature is found to scale as ortho > para > meta.

Gold Nanoparticle Decorated Multiwall Carbon Nanotubes/Ionic Liquid Composite Film on Glassy Carbon Electrode for Sensitive and Simultaneous Electrochemical Determination of Dihydroxybenzene Isomers

Gold nanoparticles stabilized with ionic liquid 1-dodecyl-3-methylimidazolium bromide ([C12mim]Br) as protecting agent was successfully anchored to acid treated multiwall carbon nanotubes (MWCNTs) by simple electrostatic interaction. A thin film of hybrid nanocomposite (MWCNTs-Au) was then successfully formed on glassy carbon electrode with the aid of ionic liquid N-octyl-pyridinium hexafluorophosphate. The application of the electrode for electrooxidation of dihydroxybenzene isomers was studied by cyclic voltammetry. Well-defined voltammetric peaks were obtained for a mixture of hydroquinone (HQ), catechol (CC), and resorcinol (RS) in 0.1-M PBS (pH 7.0) with a peak potential separation of 0.112 V between HQ and CC, and 0.329 V between CC and RS. Under the optimized experimental conditions, the differential pulse voltammetry current response on the fabricated electrode was linear over the wide concentration range of 0.5–110.0 $\mu \text{M}$ for HQ, 0.5–200.0 $\mu \text{M}$ for CC, and 2.0–200.0 $\mu \text{M}$ for RS. Low detection limits of 0.2, 0.2, and 0.8 $\mu \text{M}$ were obtained for HQ, CC, and RS, respectively. The developed electrochemical sensor was successfully used for the determination of dihyroxybenzene isomers in tap water sample.

Facile preparation of a cellulose microfibers–exfoliated graphite composite: a robust sensor for determining dopamine in biological samples

A simple and robust dopamine (DA) sensor was developed using a cellulose microfibers (CMF)–exfoliated graphite composite-modified screen-printed carbon electrode (SPCE) for the first time. The graphite-CMF composite was prepared by sonication of pristine graphite in CMF solution and was characterized by high-resolution scanning electron microscopy, Fourier transform, infrared, and Raman spectroscopy. The cyclic voltammetry results reveal that the graphite-CMF composite modified SPCE has superior electrocatalytic activity against oxidation of dopamine than SPCE modified with pristine graphite and CMF. The presence of large edge plane defects on exfoliated graphite and abundant oxygen functional groups of CMF enhance electrocatalytic activity and decrease potential to oxidize DA. Differential pulse voltammetry was used to quantify DA using the graphite-CMF composite-modified SPCE and demonstrated a linear response for DA detection in the range of 0.06–134.5 µM. The sensor shows a detection limit at 10 nM with an appropriate sensitivity and displays appropriate recovery of DA in human serum samples with good repeatability. Sensor selectivity is demonstrated in the presence of 50-fold concentrations of potentially active interfering compounds including ascorbic acid, uric acid, and dihydroxybenzene isomers.

Sensitive and Simultaneous Electrochemical Sensing for Three Dihydroxybenzene Isomers Based on Poly(L-arginine) Modified Glassy Carbon Electrode.

The simultaneous and sensitive electrochemical detection of dihydroxybenzene isomers (hydroquinone, HQ; catechol, CC; resorcinol, RS) is of great significance because such isomers can be awfully harmful to the environment and human health. In this paper, by preparing poly(L-arginine) modified glassy carbon electrode (P-L-Arg/GCE) with a simple method, a highly sensitive electrochemical sensor for simultaneously detecting HQ, CC and RS was constructed successfully due to the large surface area, good electronic properties and catalytic ability of P-L-Arg/GCE and the electrostatic action between P-L-Arg (positive) and targets (negative). Under the optimized conditions, the results show that the P-L-Arg/GCE has a wide linear range from 0.1 to 110.0 μM for HQ ,CC and RS. The detection limits for HQ, CC and RS are 0.01, 0.03 and 0.1 μM, respectively. Finally, the proposed sensor was successfully applied in real sample analysis.

Selective amperometric and flow injection analysis of 1,2-dihydroxy benzene isomer in presence of 1,3- and 1,4-dihydroxy benzene isomers using palladium nanoparticles-chitosan modified ITO electrode

Amongst various isomers of dihydroxy benzene, 1,2-dihydroxy benzene (Catechol, CA) isomer and its derivative based natural compounds are considered to be the key functional group for various health benefits. In electrochemistry, pulse voltammetric techniques combined with chemically modified electrodes (CMEs) have been often reported for simultaneous detection of 1,2- (CA); 1,3- (Resorcinol, RE) and 1,4-dihydroxy benzene (hydroquinone, HQ) isomers at discreet potentials, ∼0.1, ∼0.2 and ∼0.4V vs Ag/AgCl, respectively, in a neutral pH condition. Indeed, the above technique and the reported CMEs were not suitable for selective amperometric i-t based detection of CA without interference from HQ and RE. In fact, at CA detection potential, ∼0.2V, HQ also got co-detected. Herein, we report a palladium nanoparticles-Chitosan indium tin oxide modified electrode (ITO/CHIT@Pdnano) as a selective amperometric sensor system for CA isomer detection without any interference of HQ and RE. A specific interaction between Pd2+ and CA as {Pd2+-CA complex} is proposed as a key factor for the selectivity achieved in this work. As a proof of concept, flow injection analysis of CA functional group in wine and tea real samples was demonstrated.

Formation of Au Nanoparticles at the Counter Electrode During the Oscillatory Oxidation of Methionine on a Gold Electrode

Oscillatory behavior was uncovered during the electrochemical oxidation of methionine in a potassium chloride solution on a gold electrode. Linear sweep voltammograms illustrate that it is Au rather than Au oxide which facilitates the oxidation of methionine. The passivation of Au electrode surface due to its oxidation causes the development of a negative differential resistance in the system, which consequently leads to the emergence of oscillations in current. Under certain conditions more complicated reaction behavior in the form of bursting oscillations could be seen. Gold dissolution was found to occur during the oscillatory process, which led to coating of the platinum counter electrode by gold nanoparticles, as confirmed with elemental analysis studies and scanning electron microscopy measurements. The as-prepared gold nanoparticle modified electrode is able to differentiate dihydroxybenzene isomers in their electrochemical analysis, a great improvement over flat Au electrode.

Simultaneous and sensitive electrochemical detection of dihydroxybenzene isomers with UiO-66 metal-organic framework/mesoporous carbon

The zirconium-based MOF (UiO-66)/mesoporous carbon (MC) composite was synthesized using conventional hydrothermal method for the first time. The surface morphology and structure of UiO-66/MC composite were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A novel electrochemical sensor based on UiO-66/MC was constructed for simultaneous and sensitive determination of dihydroxybenzene isomers (DBIs) of hydroquinone (HQ), catechol (CT) and resorcinol (RS). The proposed sensor displays excellent electrocatalytic activity toward the oxidation of HQ, CT and RS. The peak-to-peak potential separations between CT and HQ, and RS and CT are 0.130V and 0.345V, respectively. Under the optimized conditions, the electrochemical sensor shows a wide linear response in the concentration range of 0.5–100μM, 0.4–100μM and 30–400μM with a detection limit of 0.056μM, 0.072μM and 3.51μM (S/N = 3) for HQ, CT and RS, respectively. In addition, the sensor has superior sensitivity and electrochemical stability along with good reproducibility and anti-interference properties. The fabricated sensor was also applied for the determination of DBIs in the real water samples with satisfying results.

Influence of C6H4(OH)2 isomers on water disinfection by photocatalysis: a computational study

Solar disinfection by photocatalysis is one of the promising methods used for drinking water disinfection. It leads to the destruction of bacteria like $Escherichia$ $Coli$ ($E.$ $Coli$). In this paper, we compare our theoretical results with experimental ones done previously by A.G. Rinc\'on and his colleagues concerning the order of decay of C$_{6}$H$_{4}$(OH)$_{2}$ isomers in the presence of titanium dioxide TiO$_{2}$, and show the influence of optical properties of those molecules on $E.$ $Coli$ inactivation. According to the adsorption energy parameter, we find that catechol has the highest adsorption degree on titanium dioxide, followed by resorcinol, and finally hydroquinone. Three dihydroxybenzene isomers absorb photons belonging to ultraviolet (UV) range. The lowest absorption energies of resorcinol, catechol and hydroquinone are respectively 3.42, 4.44 and 4.49 eV.

Poly(4-vinylphenylboronic acid) functionalized polypyrrole/graphene oxide nanosheets for simultaneous electrochemical determination of catechol and hydroquinone

Novel poly(4-vinylphenylboronic acid) (P4VPBA) functionalized polypyrrole/graphene oxide (PPy/GO) nanosheets, which combined the advantages of GO, PPy and PBA groups, were successfully prepared by a simple polymerization of 4-vinylphenylboronic acid (4VPBA) on the surface of pre-treated PPy/GO containing vinyl groups. Because of the synergistic effects of GO with excellent 2D structures and large surface area, PPy with good electronic conductivity and PBA with high recognition capability, P4VPBA/PPy/GO modified glassy carbon electrode presented excellent electrochemical sensing capabilities toward catechol (CC) and hydroquinone (HQ) with good stability, high sensitivity and selectivity, especially giving a large anodic peak potential difference between CC and HQ enough to well distinguish and simultaneously determine the two dihydroxybenzene isomers in their mixture. It is found that PBA groups on the surface of P4VPBA/PPy/GO nanosheets played an essential role for the discrimination and simultaneous electrochemical determination of CC and HQ, which may be due to the selective formation of stable cyclic esters by the covalent interaction between PBA groups and related molecules with a cis-diol in an alkaline aqueous solution. Therefore, P4VPBA/PPy/GO nanosheets can act as a good electrode material for building a steady electrochemical sensor for detecting the two dihydroxybenzene isomers with high sensitivity and selectivity.

Copper nanoparticles modified nitrogen doped reduced graphene oxide 3-D superstructure for simultaneous determination of dihydroxybenzene isomers

Copper nanoparticles modified nitrogen doped reduced graphene oxide 3-D superstructure was successively prepared via a two-step reaction. Polydopamine was used as nitrogen source for the fabrication of nitrogen doped reduced graphene oxide and reducing agent for in-situ reduction of CuCl2. After calcination under nitrogen protection, the conductivity, electron transfer ability and electrocatalytic activity of nanocomposites were substantially improved. The enhanced redox property could be attributed to the difference in the electronegativity of carbon and nitrogen atoms of the 3-D superstructure. By using this composite material, an electrochemical sensor was constructed for the detection of dihydroxybenzene isomers, which exhibited excellent sensitivity (with limit of detection at 81•131nmolL∧1 levels), wide linear ranges (0.5•720α/4molL∧1) and good selectivity. Hence it was directly applied for the simultaneous determination of dihydroxybenzene isomers in contaminated samples (e.g., waste waters).