Studies of the electrochemical reduction of 4-nitrophenol in dimethylformamide: evidence for a change in mechanism with temperature

The electrochemical studies of 4-nitrophenol were carried out in acidic, neutral and basic buffer media at bare glassy carbon (GC) and nanosize polyaniline (PANI) modified GC electrodes. In all pH, 4-nitrophenol exhibits three oxidation peaks in forward scan and three reduction peaks in reverse scan in the CV. The peak current reached its maximum value at pH 7.0. The effect of scan rate was studied between 25 and 500 mVs-1 at pH 7. CV results revealed the diffusion-controlled reaction at the electrode surface. The atomic force microscopy used for studies of morphological behavior of nanosize polyaniline and compound adsorbed on PANI surface. Under optimum DPSV experimental conditions, the influence of concentration on the stripping signal was studied A linear relationship between peak current and concentration is obtained in the range 100 to 500 ppb, with lower detection limit of 50 ppb on PANI/GCE. The relative standard deviation of 1.76% for a 250ppb 4-nitrophenol concentration and relative error of 2.6% were also obtained.

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“…The broad peak between 2θ = 22° and 28° is the characteristic peak of PANI. Same behavior was reported by many researchers [17,18].…”

Section: Electrode Surface Characterizationsupporting

confidence: 81%

Quantification of 4-Nitrophenol on Nanosize Polyaniline Modified Glassy Carbon Electrode through Electrochemical Method

Manikandan¹,

Shoba²,

Kumar³

2018

JNST

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“…However, the electrochemical reduction of nitro-aromatic compounds is complicated as a consequence of the various chemical transformations involved in the process, which are strongly dependent on pH, solvent and catalytic nature. [42][43][44][45] Nonetheless, in protic media, the predominant reduction product is either aminophenol and/or aniline, depending upon the strength of the acidic medium, [46][47][48] while in aprotic media it is 4-hydroxylaminophenol. For example, in an acidic electrolyte (10% H 2 SO 4 ), nitrophenol is reduced to aminophenol in a virtually quantitative yield.…”

Section: Resultsmentioning

confidence: 99%

Highly efficient electrochemical and chemical hydrogenation of 4-nitrophenol using recyclable narrow mesoporous magnetic CoPt nanowires

et al. 2016

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“…For example, the conversion at 25 °C reaches 65% in 200 s, and the reduction can be finished in 460 s. In comparison, the reduction rate is relatively fast, and the conversion is high;22 this suggests that the hydrogel/gold nanocomposite is an efficient catalyst below the LCST. However, when the temperature is above the LCST of the hydrogel/gold nanocomposite, the rate of the reduction of 4‐nitrophenol greatly decreases, and the conversion at 75 °C is just at about 10% in 600 s. Usually, the reduction rate of 4‐nitrophenol catalyzed with a common catalyst increases with the increase in temperature 23, 24. However, when the present catalyst of the thermoresponsive hydrogel/gold nanocomposite is used, the case is just the converse.…”

Section: Resultsmentioning

confidence: 99%

“…However, when the temperature is above the LCST of the hydrogel/gold nanocomposite, the rate of the reduction of 4-nitrophenol greatly decreases, and the conversion at 75 8C is just at about 10% in 600 s. Usually, the reduction rate of 4-nitrophenol catalyzed with a common catalyst increases with the increase in temperature. 23,24 However, when the present catalyst of the thermoresponsive hydrogel/gold nanocomposite is used, the case is just the converse. Therefore, it can be concluded that the resultant thermoresponsive hydrogel/gold nanocomposite is a smart catalyst, the activity of which can be modulated by the solubility of the thermoresponsive hydrogel.…”

Section: Characterization Of the Hydrogel/gold Nanocompositementioning

confidence: 99%

Thermoresponsive hydrogel of poly(glycidyl methacrylate‐co‐N‐isopropylacrylamide) as a nanoreactor of gold nanoparticles

Jiang

Xiong

et al. 2007

J. Polym. Sci. A Polym. Chem.

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The synthesis of a thermoresponsive hydrogel of poly(glycidyl methacrylate-co-N-isopropylacrylamide) (PGMA-co-PNIPAM) and its application as a nanoreactor of gold nanoparticles are studied. The thermoresponsive copolymer of PGMA-co-PNIPAM is first synthesized by the copolymerization of glycidyl methacrylate and N-isopropylacrylamide using 2,2 0 -azobis(isobutyronitrile) as an initiator in tetrahydrofuran at 70 8C and then crosslinked with diethylenetriamine to form a thermoresponsive hydrogel. The lower critical solution temperature (LCST) of the thermoresponsive hydrogel is about 50 8C. The hydrogel exists as 280-nm spheres below the LCST. The diameter of the spherical hydrogel gradually decreases to a minimum constant of 113 nm when the temperature increases to 75 8C. The hydrogel can act as a nanoreactor of gold nanoparticles because of the coordination of nitrogen atoms of the crosslinker with gold ions, on which a hydrogel/gold nanocomposite is synthesized. The LCST of the resultant hydrogel/gold nanocomposite is similar to that of the hydrogel. The size of the resultant gold nanoparticles is about 15 nm. The hydrogel/gold nanocomposite can act as a smart and recyclable catalyst. At a temperature below the LCST, the thermoresponsive nanocomposite is a homogeneous and efficient catalyst, whereas at a temperature above the LCST, it becomes a heterogeneous one, and its catalytic activity greatly decreases.

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Studies of the electrochemical reduction of 4-nitrophenol in dimethylformamide: evidence for a change in mechanism with temperature

Cited by 21 publications

References 17 publications

Quantification of 4-Nitrophenol on Nanosize Polyaniline Modified Glassy Carbon Electrode through Electrochemical Method

Quantification of 4-Nitrophenol on Nanosize Polyaniline Modified Glassy Carbon Electrode through Electrochemical Method

Highly efficient electrochemical and chemical hydrogenation of 4-nitrophenol using recyclable narrow mesoporous magnetic CoPt nanowires

Thermoresponsive hydrogel of poly(glycidyl methacrylate‐co‐N‐isopropylacrylamide) as a nanoreactor of gold nanoparticles

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