Electrochemical Oxidative Determination and Electrochemical Behavior of 4‐Nitrophenol Based on an Au Electrode Modified with Electro‐polymerized 3,5‐Diamino‐1,2,4‐triazole Film

Determination of optimum operating parameters of MWCNT-doped ethanol fueled HCCI engine for emission reduction

Carbon based metallic additives were widely researched to improve combustion charecteristics of spark ignition and compression ignition engines. It was proven that carbon nanotube additive shortens ignition delay period and improves combustion characteristics especially in diesel engines. HCCI is a lean burn combustion mode which provides high thermal efficiency and simultaneously low NOx and soot emission. However it has drawbacks such as misfire at leaner mixtures and knocking at high loads. Carbon nanotube could be used to improve combustion for HCCI engines as well. The aim of this study is to investigate the effects of multi-walled carbon nanotube addition to ethanol and n-heptane blends on HCCI engine performance, combustion and emission by experimentally and statistically. During the experiments, the mixed fuels formed with %25 ethanol, %75 n-heptane and 100, 150 and 200 ppm MWCNT additives were used. The experiment of these mixed fuels was carried out at different lambda and engine speed values. Response Surface Method was implemented to determine optimal additive amount and operation parameters of the engine. The variable parameter values to be used in the experiments were created with the central composite design, and a total of 20 experiments were performed. According to the obtained results, IMEP, ITE, BSFC, MPRR, COVimep, SOC, CA50, CO and HC response parameter values were obtained. Response parameter values were entered into the RSM environment and optimization studies were carried out depending on the response parameters targets. Among the optimum variable parameter values, the MWCNT ratio was determined as 102.16 ppm, lambda 2.7 and engine speed 1124.439 rpm. Response parameter values after optimization were determined as IMEP 4.988 bar, ITE 45.988 %, BSFC 227.846 g/kWh, MPRR 2.544 bar/CA, COVimep 1.722 %, SOC 4.445 CA, CA50 7 CA, CO 0.073 % and HC 476.452 ppm.

Electrochemical preparation and the characterizations of poly(3,5-diamino 1,2,4-triazole) film for the selective determination of pyridoxine in pharmaceutical formulations

This work describes the synthesis and characterization of a polymeric film of 3,5-diamino 1,2,4-triazole on a pencil graphite electrode for the selective sensing of pyridoxine (PY). The PGE was modified using the electropolymerization process by the potentiodynamic method. The polymerized electrode (PDAT/PGE) was characterized by IR, SEM, AFM, cyclic voltammetry, and electrochemical impedance spectroscopy. PY undergoes irreversible oxidation at 0.79 V on PDAT/PGE in phosphate buffer of pH 5. Using the differential pulse voltammetric technique (DPV), PY showed a linear range from 5 to 950 μM with a lower detection limit of 2.96 μM. The PDAT/PGE was applied for the analytical determination of PY in pharmaceutical tablets with good recovery.

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Supplementary Information

The online version contains supplementary material available at 10.1007/s11696-023-02777-5.

Eco-friendly non-conjugated polymer dots for chemiluminometric determination of 4-nitrophenol

Polymer dots (PDs) are a new family of quantum dots which their behavior and potential applications have not yet been completely explored. In this study, non-conjugated PDs were synthesized via a simple pyrolysis method and used for the chemiluminescence (CL) assay of 4-nitrophenol (4-NP). PDs increase the CL signal of the Ce (IV)-Na₂ SO₃ reaction 39-fold. Using the CL spectrum, it was concluded that the emission at 434 nm was generated by the excited PDs (PDs^* ), which are produced via energy transfer from SO₂ ^* to PDs. Our experiments showed that 4-NP enhanced the CL signal of the Ce (IV)-Na₂ SO₃ -PDs reaction. The mechanism of this effect was explored by obtaining CL, UV-Vis and FT-IR spectra. Due to the high sensitivity and selectivity of the CL system to 4-NP, a probe was designed to determine 4-NP in the linear range of 1.0-500 nmol/L with a detection limit of 0.33 nmol/L. Different spiked real samples were successfully analyzed by this probe.

Electrochemical Sensors Based on Conducting Polymers for the Aqueous Detection of Biologically Relevant Molecules

Electrochemical sensors appear as low-cost, rapid, easy to use, and in situ devices for determination of diverse analytes in a liquid solution. In that context, conducting polymers are much-explored sensor building materials because of their semiconductivity, structural versatility, multiple synthetic pathways, and stability in environmental conditions. In this state-of-the-art review, synthetic processes, morphological characterization, and nanostructure formation are analyzed for relevant literature about electrochemical sensors based on conducting polymers for the determination of molecules that (i) have a fundamental role in the human body function regulation, and (ii) are considered as water emergent pollutants. Special focus is put on the different types of micro- and nanostructures generated for the polymer itself or the combination with different materials in a composite, and how the rough morphology of the conducting polymers based electrochemical sensors affect their limit of detection. Polypyrroles, polyanilines, and polythiophenes appear as the most recurrent conducting polymers for the construction of electrochemical sensors. These conducting polymers are usually built starting from bifunctional precursor monomers resulting in linear and branched polymer structures; however, opportunities for sensitivity enhancement in electrochemical sensors have been recently reported by using conjugated microporous polymers synthesized from multifunctional monomers.

Voltammetric determination and electrochemical behavior of vanillin based on 1H-1,2,4-triazole-3-thiol polymer film modified gold electrode

Poly(1H-1,2,4-triazole-3-thiol) (poly(T3T)) conductive film was coated successfully on the gold electrode (Au). The electrochemical behavior of vanillin (VAN) was studied on the 1H-1,2,4-triazole-3-thiol-Au (T3T-Au) electrode. The determination of VAN was performed on the T3T-Au electrode using a differential pulse voltammetry (DPV) technique. In order to detect the concentration of VAN, suitable supporting electrolyte solution and pH value were determined. At pH 3 in HClO₄ solution, the anodic peak current of VAN obtained with the T3T-Au electrode is 4.3 times greater than the bare Au electrode. The response oxidation peak current and concentration of VAN showed a good linear relationship in the range of 0.1-11.3 µM. The limit of detection was found as 0.04 µM. Besides, the reproducibility, repeatability, stability, and interference measurements were also assayed. This sensor was applied successfully for the detection of VAN in synthetic samples and various food samples.