Here, an electrochemical detection approach (differential pulse voltammetry) was employed to develop a 2-nitrophenol (2-NP) sensor probe using a glassy carbon electrode (GCE) coated by wet-chemically synthesized nanorods (NRs) of BaO. The prepared BaO NRs were characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD) analysis. The peak currents by differential pulse voltammetric (DPV) analysis of 2-NP are plotted against the concentration to obtain the calibration curve of the 2-NP detection. It was found to be linear from 1.5 to 9.0 μM, defined as the dynamic range (LDR) for 2-NP detection in phosphate buffer solution. The sensor sensitivity was calculated from the slope of LDR by considering the active surface area of NRs coated on GCE (0.0316 cm<sup>2</sup> ) and found as 17.6 μAμM<sup>-1</sup> cm<sup>-2</sup> . The limit of detection (LOD) was calculated as 0.50±0.025 μM from the signal/noise (S/N) ratio of 3. Moreover, the sensor analytical parameters such as reproducibility, long-term performing ability (stability), response time and validity in real environmental samples were found acceptable and to give satisfactory results. The development of a nanomaterial-based electrochemical chemical sensor might be an effective approach to sensor technology to detect carcinogenic and hazardous toxins for environmental safety and healthcare fields in a broad scale.
This work presents the fabrication and investigation of the multiwalled carbon nanotubes (MWCNTs) and graphene pristine powders based multifunctional pressure, displacement and gradient of temperature sensors. The effect of pressure on the resistance, Seebeck coefficient, thermoelectric voltage and current of the sensors was measured by changing pressure from 0 to 1.65 kgf/cm2, while the effect of temperature gradient on the resistance, thermoelectric voltage and current of the sensors was measured up to the temperature gradient of 34–36°C. Dependence of the resistance on longitudinal compressive displacement up to 100 μm was investigated. It was found that the resistance, Seebeck coefficient and thermoelectric voltage of the CNT and graphene powders decreased with increasing pressure, while the thermoelectric current increased with pressure. Moreover, with increasing temperature gradient and average temperature a considerable increase was observed in thermoelectric current and voltage, while the increase in resistances was moderate. The increase in longitudinal displacement resulted in the compression of the samples that caused to decrease the resistances of the samples, especially in the case of samples made from CNT and graphene both. The simulation of the experimental results was carried out by using of linear functions and the results of simulations were in good agreement with experimental results.
Abstract On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the effect of medium acidity and photoreactivity of 3‐(4‐dimethylamino‐phenyl)‐1‐(2,5‐dimethyl‐thiophen‐3‐yl)‐propenone (DDTP) has been investigated in dimethylformamide and in chloromethane solvents such as methylenechloride, chloroform and carbon tetrachloride. The dye solution ( ca . 5×10 −4 mol·L −1 in DMF) gives a good laser emission in the range 470–560 nm with emission maximum at 515 nm upon pumping by nitrogen laser ( λ ex =337.1 nm). The laser parameters such as gain coefficient ( α ), emission cross section ( δ e ) and half life energy ( E 1/2 ) at maximum laser emission are also determined.
The particle size and nickel-doping effect on pure nanocrystalline WO3 powders are addressed through X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. A brief review of different structure types of tungsten oxides is also given. Stable and metastable crystallographic structures, resulting from oxygen deficiency, metal doping, or low-temperature synthesis, are discussed. The focus is put on the topology of the structures and notably on the structural features allowing ion intercalation. Small particle size WO3 powders were synthesized by two different wet chemical methods to determine the impact of particle size on the crystal symmetry: in the first method, a freeze-drying technique was utilized, whereas the second technique was based on a reverse micelle method. Both methods yielded similar powders with an average size of approximately 10 nm. However, the first method yielded single-phase rhenium oxide structured particles, whereas the latter method produced a mixture of hexagonal tungsten bronze and rhenium oxide structures. In the case of single-phase rhenium oxide structure powders, the crystal symmetry was found to increase from monoclinic P21/n to orthorhombic Pbcn when particle size decreased below 20 nm. The effect of nickel doping (≈1 wt %) and synthesis conditions on WO3 powders were studied. Ni-doped WO3 was spatially inhomogeneous: the most abundant phase was monoclinic WO3, whereas the minority phase was either perovskite tungsten bronze (annealing temperature below 500 °C) or wolframite (annealing temperature 500 °C or higher) showing that annealing conditions are a way to selectively produce different crystal structures. The wolframite and tungsten bronze structures are very different with different applications. The results are discussed in the context of thin film synthesis and sensor applications.
Abstract Here ZnTiO 3 @TiO 2 heterostructure nanomaterial was prepared through a simple sonochemical strategy using TiO 2 (P25) with zinc nitrate as a precursor and then calcined the obtained sample at 700 °C in 2h for the photocatalytic degradation of Congo red dye solution. XRD result confirms that the diffraction patterns related to the ZnTiO 3 and TiO 2 as heterostructure with high purity. SEM confirms that particles are irregular in shape with high agglomeration and HRTEM reveals that ZnTiO 3 @TiO 2 is highly crystalline with a lattice spacing of 0.37 nm. The calculated band gap of as‐synthesized ZnTiO 3 @TiO 2 heterostructure nanomaterial is found to be 3.07 eV. The photocatalytic degradation of as prepared ZnTiO 3 @TiO 2 heterostructure was investigated for the degradation of Congo red dye by varying the effect of catalyst amount and initial dye concentration. The ZnTiO 3 @TiO 2 heterostructure nanomaterial exhibited 96% degradation efficiency of Congo red in 4h under visible light illumination. Moreover, the photodegradation mechanism of Congo red was studied with various scavengers such as EDTA, IPA, and Benzoquinone. Further, the detection of OH radicals during photocatalytic processes was confirmed by luminescence technique using terephthalic acid (TA) as a test molecule.
In this study, the fabrication, performance characteristics and application of a Cu(II) ion selective pyridine based thorium(IV) phosphate membrane electrode are studied. The membrane electrode exhibited a fast response time of 10 s, the wide linear response in the concentration of 1 × 10–1 to 1 × 10–7 M of Cu (II) ions with a slope of 27.60 mV/decade change in concentration and a lifetime of 4 months. The potentiometric response revealed that the potentials are independent of pH in the wide range of 3.0–6.5. It was also used as an indicator electrode in the potentiometric titration of Cu(II) ions using ethylenediamine tetraacetic acid, disodium salt.
Abstract The interaction between the amphiphilic drug amitriptyline hydrochloride (AMT) and the nonionic surfactants used in drug delivery has been investigated. Herein, we report the micellization behavior of AMT in presence of ethoxylated alkyl phenols in aqueous medium and the clouding phenomenon in the absence and presence of different nonionic surfactants in buffer solution. The values of critical micelle concentration (CMC) of AMT obtained using the conductivity method, decrease as nonionic surfactant concentration increases. With an increase in temperature, the CMC first increases and then decreases. At 303.15 K, the maximum CMC values were obtained with or without nonionic surfactant. The results obtained indicate attractive interactions (synergism) between the two mixing amphiphiles in solution. The experimentally obtained critical micelle concentration (CMC) values are always lower than ideal CMC values. Micellar mole fraction ( X 1 ) values, calculated by different proposed models, show the contribution of nonionic surfactant concentration. At a fixed drug concentration (50 mmol kg −1 ) and pH (=6.7) nonionic surfactants show continuous increase in cloud point (CP). Increase in drug concentration and pH, in the presence of fixed amounts of nonionic surfactant, increases and decreases the CP, respectively.
