Substitution reactions under NH3 chemical ionization conditions in cis-/trans-1,2-dihydroxybenzosuberans

The nucleophilic substitution reaction under NH₃ chemical ionization (CI) conditions in cis- and trans-1,2-dihydroxybenzosuberans (1–4) has been studied with the help of ND₃ CI and metastable data. The results indicate that in the parent diols 1 (cis) and 2 (trans), the substitution ion [M_sH]⁺, is produced mainly by the loss of H₂O from the [MNH₄]⁺ ion (S_Ni reaction) while in their 7-methoxy derivatives 3 and 4, the ion-molecule reaction between [M? OH]⁺ and NH₃ seems to be the major pathway for the formation of [M_sH]⁺. The substitution ion from 1 and 2 and the [MH]⁺ ion from trans-1-amino-2-hydroxybenzosuberan give similar collision-induced dissociation mass-analysed ion kinetic energy spectra. Interestingly, their diacetates do not undergo the substitution reaction.     

Mechanism of N-vinylcarbazole polymerization on Co(II)–13X molecular sieve

Kinetics of polymerization of N-vinylcarbazole over Co(II)-13X molecular sieves in toluene have been studied. The rate of polymerization (R_p) has been found to be second order with respect to percent exchange level of Co(II) and also to the NVC concentration at all the reaction temperatures of 40, 50 and 60°C. The rate increases with decreasing pH of the original exchanging salt solution up to a pH of about 3.5, beyond which it falls. The overall activation energy of polymerization has been found to decrease with increase in monomer concentration, exchange level of Co(II), and the hydrogen ion concentration of the original exchange solution. Average degree of polymerization also follows a similar trend. A mechanism of polymerization involving simultaneous propagation on both metal ion Co(II) and proton on a zeolite surface has been suggested. The two propagation routes are characterized by an average activation energy of 10.36 kcal/mol and 5.40 kcal/mol on the metal ion and proton centers, respectively.     

A sustainable method of mitigating acid corrosion of mild steel using jackfruit pectin (JP) as green inhibitor: Theoretical and electrochemical studies

This study is attempted to develop a green corrosion inhibitor from a waste material of Jack fruit (Artocarpus heterophyllus). This method is therefore quite valuable to health, environment, and economic point of view. Pectin is isolated from the jackfruit peel waste using 0.05 ?N oxalic acid and used as an inhibitor for mild steel corrosion in acidic environment as it is highly water soluble. 250–1000 ?ppm of pectin was used in this study at a temperature range of 303–323 ?K. The protection efficiency of jack fruit pectin (JP) in 0.5 ?M HCl was evaluated by conventional weight loss and electrochemical techniques. The potentiodynamic polarization results revealed that JP could effectively reduce the corrosion of mild steel in acidic medium at 1000 ?ppm concentration with an inhibition efficiency of 89.75% and corrosion rate of 2.392 mpy. The mixed type behavior of the inhibitor is identified from Tafel polarization studies. Electrochemical impedance spectroscopy (EIS) measurements suggest that the corrosion inhibition process is kinetically controlled. adsorption and kinetic behavior of the inhibitor also have been studied. Surface manifestations were followed using FESEM and AFM techniques. DFT calculations and Monte Carlo simulations were also carried out to corroborate the experimental results with theoretical outputs and succeeded to a great extent.     

Thermal performance of stable SiO2 nanofluids and regression correlations to estimate their thermophysical properties

The present work investigates the best mix ratio of Glycerol in Water as a medium to prepare a stable nanofluid. Increasing the proportion of glycerol enhances the aqueous mix's dynamic viscosity and improves the prepared nanofluid's stability. The thermal conductivity and viscosity of the Glycerol and Water mixtures determination were undertaken at various Glycerol ratios. The best percentage of glycerol in the mixture is found to have the least amount of thermal conductivity loss and the optimum viscosity gain. Silica (SiO₂) nanofluid of 0.25%, 0.5%, 1%, and 1.5% weight concentrations was prepared with this optimal mixture of Glycerol and Water. The stability of these SiO₂ nanofluids is evaluated by determining the zeta potential at different time intervals. The nanofluids prepared were observed to be stable for one month. The thermal conductivity and viscosity of the nanofluids are measured between the temperature limits of 30°–70°C. A peak increment of 32.1%and 46.3% in thermal conductivity and viscosity is observed. Furthermore, when the percentage enhancement ratio (PER) and Mouromtseff ratio of these nanofluids is examined, it is observed that they have more excellent thermal performance at higher temperatures. Regression correlations are developed to estimate the thermal conductivity and viscosity of the prepared nanofluids with a maximum deviation of 9%.     

Electrolytic destruction of organic matter in urine

A novel electrolytic method has been developed for destroying organic matter in urine. A combination of potassium permanganate, sulfuric acid and nitric acid has yielded about 99% destruction in initial organic content of urine within two hours when electrolysis is carried out with an applied voltage of about 2.5 V, while maintaining a current density of 8.23 mA/cm² at 373 K.     

Solution-processed electrochemical synthesis of ZnFe2O4 photoanode for photoelectrochemical water splitting

Journal of Solid State Electrochemistry - Herein, we report the synthesis of ZnO nanorod films onto FTO (fluorine-doped tin oxide) substrates using the solution-processed electrodeposition method....     

Ultrafast Excited State Relaxation Dynamics of New Fuchsine- a Triphenylmethane Derivative Dye

An all-inclusive investigation of the ultrafast excited state relaxation dynamics of a triphenylmethane derivative molecule, New Fuchsine (NF), using a combined approach of density functional theory (DFT), femtosecond transient absorption spectroscopy (fs-TAS), and photoluminescence spectroscopy is presented in this work. The DFT calculations confirmed the formation of twisted molecular structure in the excited state of NF in ethanol solution with bond rotation of ≈86°. TAS measurements of NF solution exhibited ultrafast ground state-recovery pathway via a conical intersection confirming an ultrafast structural reorientation. On the contrary, TAS measurements of NF thin-film exhibited a longer excited-state lifetime suggesting a hindered molecular twisted state formed as an intermediate step. Photophysical kinetic models are proposed to globally fit the fs-TAS data establishing the twisted intramolecular charge transfer (TICT) state mediated ground state recovery for NF in solution and thin film, respectively. Temperature-dependent photoluminescence study of NF film provided a clear insight into the effect of rotational motion of phenyl rings in NF molecules over the TICT mediated emission.     

Nickel and Tungsten Bimetallic Nanoparticles Modified Pencil Graphite Electrode: A High-performance Electrochemical Sensor for Detection of Endocrine Disruptor Bisphenol A

In this work, an economically viable, very low cost, indigenous, ubiquitously available electrochemical sensor based on bimetallic nickel and tungsten nanoparticles modified pencil graphite electrode (NiNP-WNP@PGE) was fabricated for the sensitive and selective detection of bisphenol A (BPA). The NiNP-WNP@PGE sensor was prepared by a facile electrochemical one step co-deposition method. The prepared nanocomposite was morphologically characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), electrochemically by cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The proposed sensor displayed high electrocatalytic activity towards electro-oxidation of BPA with one irreversible peak. The fabricated sensor displayed a wide detection window between 0.025 μM and 250 μM with a limit of detection of 0.012 μM. PGE sensor was successfully engaged for the detection of BPA in bottled water, biological, and baby glass samples.     

Development of Pen-type Portable Electrochemical Sensor Based on Au-W Bimetallic Nanoparticles Decorated Graphene-chitosan Nanocomposite Film for the Detection of Nitrite in Water,Milk and Fruit Juices

The development and fabrication of a simple, portable, and sensitive detection tool to precisely monitor nitrite level is of growing importance in electrochemistry research, given the strong interest in the protection of drinking water quality, treatment of wastewater, food production, and control of remediation processes. This work describes the fabrication of a simple, cost-effective, pen-type electrochemical sensor based on bimetallic gold and tungsten nanoparticles electrochemically decorated on graphene-chitosan modified pencil graphite electrode (PGE) for the trace detection of nitrite in real samples. The prepared nanocomposite was characterized using XRD, SEM, and EDS. The electrochemical behavior of the sensor was evaluated by cyclic voltammetry (CV) and impedance electrochemical spectroscopy (EIS). Results revealed that the proposed sensor displayed excellent electrocatalytic activity towards electro-oxidation of nitrite with an irreversible redox reaction. The AuNPs-WNPs@Gr-Chi/PGE sensor exhibited excellent analytical performance with a wide linear range from 10 to 250 μM towards nitrite. The LOD and LOQ were calculated to be 0.12 μM and 0.44 μM, respectively. The designed electrochemical sensor was successfully applied for the detection of nitrite in water, milk, and natural fruit juice samples.