Sensitive and Simultaneous Determination of Hydroquinone and Catechol in Water Using an Anodized Glassy Carbon Electrode with Polymerized 2-(Phenylazo) Chromotropic Acid
Abstract:Hydroquinone (HQ) and catechol (CT) are considered as environmental pollutants with high toxicity. We have developed a simple electrochemical sensor using an anodized glassy carbon electrode modified with a stable 2-(phenylazo) chromotropic acid- (CH-) conducting polymer (PCH/AGCE). The PCH/AGCE sensor showed good electrocatalytic activity and reversibility towards the redox of HQ and CT in phosphate buffer solution (PBS, pH 7.0). The cyclic voltammetry (CV) in mixed solution of HQ and CT showed that the oxida… Show more
“…e binding mechanism of HQ and R is discussed on the basis of surface properties of CAK-S and modeling results. In general, the surfaces of activated carbons are made of acid functions like carboxyl, hydroxyl, quinones, carbonyl, and lactone groups, as well as basic functions like pyrones and chromenes [4,50,51]. For the case of CAK-S, the FTIR and the Boehm titration results, supplemented by EDX/SEM [28], have shown that it has the chemical functions mentioned above.…”
Section: Mechanism Involving Hydrogen Bonding and π-π And N-πmentioning
confidence: 99%
“…ey mainly come from discharges from textile, petrochemical, petroleum refinery, rubber, dye, plastic, pharmaceutical, and cosmetic industries [2,3]. Several phenolic derivatives such as hydroquinone (HQ) and resorcinol (R) have been recognized as being dangerous pollutants due to their potential toxicity [4]. Wastewater laden with HQ and R is harmful to the environment in general and to the aquatic environment in particular [4,5] because these compounds dissolve and can easily infiltrate the environment.…”
Section: Introductionmentioning
confidence: 99%
“…Several phenolic derivatives such as hydroquinone (HQ) and resorcinol (R) have been recognized as being dangerous pollutants due to their potential toxicity [4]. Wastewater laden with HQ and R is harmful to the environment in general and to the aquatic environment in particular [4,5] because these compounds dissolve and can easily infiltrate the environment. Although the carcinogenic effects of HQ and R in humans are controversial, these compounds cause acute toxicity in several organs such as the kidneys and stomach [1] and are suspected to be endocrine disruptors.…”
The present work demonstrates the adsorption of hydroquinone (HQ) and resorcinol (R) by activated carbon based on shea residue (Vitellaria paradoxa). The adsorbent was prepared chemically by impregnation with sulfuric acid and coded by the acronym CAK-S. The central composite design (CCD) was used to optimize the main factors that influence the adsorption of HQ or R by activated carbon such as the initial concentration, the pH of the solution, the contact time, and the mass of the carbon on the expected response, which is the adsorbed quantity of the target pollutants. The optimal conditions obtained from the statistical analysis are as follows: concentration of 158 mg/L, pH 3, time of 120 min, and mass of 50 mg for the adsorption of HQ and concentration of 180 mg/L, pH 3, time of 86 min, and mass of 118 mg for the adsorption of R. The maximum quantities of HQ and R adsorbed are 45.02 mg/g and 33.65 mg/g, respectively. The analysis of variance (ANOVA) showed a good relationship between the variables involved with the coefficients of determination R2 = 98.69% for the adsorption of hydroquinone and R2 = 90.55% for that of resorcinol, which means that the model is more suitable to express the adsorbed amount according to the four optimized parameters. The experimental data obtained under these optimal conditions were simulated with two and three parameter nonlinear isotherm models as well as kinetic models. The results show that Elovich kinetic model better describes the adsorption of HQ and R, indicating chemisorption with heterogeneous active sites on the surface of CAK-S. Temkin’s two-parameter model shows that adsorption occurs on heterogeneous surfaces with a nonuniform adsorption energy distribution at the surface and Sips’s three-parameter model confirms the heterogeneity of the surface with a localized adsorption of HQ or R by CAK-S. The thermodynamics study has shown that the adsorption is endothermic (
Δ
H
0
>
0
) and spontaneous (
Δ
G
0
<
0
).
“…e binding mechanism of HQ and R is discussed on the basis of surface properties of CAK-S and modeling results. In general, the surfaces of activated carbons are made of acid functions like carboxyl, hydroxyl, quinones, carbonyl, and lactone groups, as well as basic functions like pyrones and chromenes [4,50,51]. For the case of CAK-S, the FTIR and the Boehm titration results, supplemented by EDX/SEM [28], have shown that it has the chemical functions mentioned above.…”
Section: Mechanism Involving Hydrogen Bonding and π-π And N-πmentioning
confidence: 99%
“…ey mainly come from discharges from textile, petrochemical, petroleum refinery, rubber, dye, plastic, pharmaceutical, and cosmetic industries [2,3]. Several phenolic derivatives such as hydroquinone (HQ) and resorcinol (R) have been recognized as being dangerous pollutants due to their potential toxicity [4]. Wastewater laden with HQ and R is harmful to the environment in general and to the aquatic environment in particular [4,5] because these compounds dissolve and can easily infiltrate the environment.…”
Section: Introductionmentioning
confidence: 99%
“…Several phenolic derivatives such as hydroquinone (HQ) and resorcinol (R) have been recognized as being dangerous pollutants due to their potential toxicity [4]. Wastewater laden with HQ and R is harmful to the environment in general and to the aquatic environment in particular [4,5] because these compounds dissolve and can easily infiltrate the environment. Although the carcinogenic effects of HQ and R in humans are controversial, these compounds cause acute toxicity in several organs such as the kidneys and stomach [1] and are suspected to be endocrine disruptors.…”
The present work demonstrates the adsorption of hydroquinone (HQ) and resorcinol (R) by activated carbon based on shea residue (Vitellaria paradoxa). The adsorbent was prepared chemically by impregnation with sulfuric acid and coded by the acronym CAK-S. The central composite design (CCD) was used to optimize the main factors that influence the adsorption of HQ or R by activated carbon such as the initial concentration, the pH of the solution, the contact time, and the mass of the carbon on the expected response, which is the adsorbed quantity of the target pollutants. The optimal conditions obtained from the statistical analysis are as follows: concentration of 158 mg/L, pH 3, time of 120 min, and mass of 50 mg for the adsorption of HQ and concentration of 180 mg/L, pH 3, time of 86 min, and mass of 118 mg for the adsorption of R. The maximum quantities of HQ and R adsorbed are 45.02 mg/g and 33.65 mg/g, respectively. The analysis of variance (ANOVA) showed a good relationship between the variables involved with the coefficients of determination R2 = 98.69% for the adsorption of hydroquinone and R2 = 90.55% for that of resorcinol, which means that the model is more suitable to express the adsorbed amount according to the four optimized parameters. The experimental data obtained under these optimal conditions were simulated with two and three parameter nonlinear isotherm models as well as kinetic models. The results show that Elovich kinetic model better describes the adsorption of HQ and R, indicating chemisorption with heterogeneous active sites on the surface of CAK-S. Temkin’s two-parameter model shows that adsorption occurs on heterogeneous surfaces with a nonuniform adsorption energy distribution at the surface and Sips’s three-parameter model confirms the heterogeneity of the surface with a localized adsorption of HQ or R by CAK-S. The thermodynamics study has shown that the adsorption is endothermic (
Δ
H
0
>
0
) and spontaneous (
Δ
G
0
<
0
).
“…Also, the redox peaks become prominent on increasing the pH of the solution. At low pH hydroxyl groups of catechol are protonated which decreases its adsorption at the electrode surface due to which decrease in the current is observed 56 . Figure 7 Effect of variable pH (4.0–9.0) solutions of ( a ) 500 µM catechol ( b ) 500 µM hydroquinone (0.1 M PBS) at CNCs/Zn-TPP/GCE electrode.…”
Non-enzymatic electrochemical detection of catechol (CC) and hydroquinone (HQ), the xenobiotic pollutants, was carried out at the surface of novel carbon nanocoils/zinc-tetraphenylporphyrin (CNCs/Zn-TPP) nanocomposite supported on glassy carbon electrode. The synergistic effect of chemoresponsive activity of Zn-TPP and a large surface area and electron transfer ability of CNCs lead to efficient detection of CC and HQ. The nanocomposite was characterized by using FT-IR, UV/vis. spectrophotometer, SEM and energy dispersive X-ray spectroscopy (EDS). Cyclic voltammetry, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy were used for the electrochemical studies. CNCs/Zn-TPP/GCE nanosensor displayed a limit of detection (LOD), limit of quantification (LOQ) and sensitivity for catechol as 0.9 µM, 3.1 µM and 0.48 µA µM−1 cm−2, respectively in a concentration range of 25–1500 µM. Similarly, a linear trend in the concentration of hydroquinone detection was observed between 25 and 1500 µM with an LOD, LOQ and sensitivity of 1.5 µM, 5.1 µM and 0.35 µA µM−1 cm−2, respectively. DPV of binary mixture pictured well resolved peaks with anodic peak potential difference, ∆Epa(CC-HQ), of 110 mV showing efficient sensing of CC and HQ. The developed nanosensor exhibits stability for up to 30 days, better selectivity and good repeatability for eight measurements (4.5% for CC and 5.4% for HQ).
In this work, an HB pencil electrode (HBPE) was electrochemically
modified by amino acids (AAs) glycine (GLY) and aspartic acid (ASA)
and designated as GLY-HB and ASA-HB electrodes. They were used in
the detection of dihydroxybenzene isomers (DHBIs) such as hydroquinone
(HQ), catechol (CC), and resorcinol (RS), by cyclic voltammetry (CV),
and by differential pulse voltammetry. HBPE was characterized by scanning
electron microscopy and energy-dispersive X-ray spectroscopy. These
three electrodes showed a linear relationship of current with concentration
of DHBIs, and the electrochemical processes were diffusion controlled
in all cases. In simultaneous detection, the limit of detection, based
on signal-to-noise ratio (S/N = 3), for HQ, CC, and RS was 12.473,
16.132, and 25.25 μM, respectively, at bare HBPE; 5.498, 7.119,
and 14.794 μM, respectively, at GLY-HB; and 22.459, 25.478,
and 38.303 μM, respectively, at ASA-HB. The sensitivity for
HQ, CC, and RS was 470.481, 363.781, and 232.416 μA/mM/cm
2
, respectively, at bare HBPE; 364.785, 282.712, and 135.560
μA/mM/cm
2
, respectively, at GLY-HB; and 374.483,
330.108, and 219.574, respectively, at ASA-HB. The interference studies
clarified the suitability and reliability of the electrodes for the
detection of HQ, CC, and RS in an environmental system. Real sample
analysis was done using tap water, and the proposed electrodes expressed
recovery with high reproducibility. Meanwhile, these three electrodes
have excellent sensitivity and selectivity, which can be used as a
promising technique for the detection of DHBIs simultaneously.
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