In this study, for the first time we report a highly selective and sensitive lutetium ions chemical optical sensor based on immobilization of a asymmetrically S–N Schiff’s base, namely N-(thien-2-ylmethylene)pyridine-2,6-diamine (TPD) on a triacetylcellulose membrane. This optode exhibits a linear range of 5.0 ×10-7 –1.0 ×10-5 M of the Lu(III) ion concentration with a detection limit of 9.3 ×10-8 M at a wavelength of 336 nm. The influence of responsible factors for improving sensitivity of the sensor was studied and identified. Response time of the newly designed optode was within 20-30 s depending on the Lu(III) ion concentration. Response of the optical sensor is independent of the pH of the solution in the range of 3.0–9.0. It manifests advantages of fast response time, low detection limit and most significantly, very good selectivity with respect to a number of lanthanide ions. The sensor can readily be regenerated with thiourea solutions and its response was reversible and reproducible. This optode was applied to the determination of Lu(III) in aqueous and CRM samples.
HDPE was functionalized with two different esters in an inert atmosphere at 160°C, under different experimental conditions by thermolysis method. The order of the functionalization and crosslinking reactions was determined. The C=C formation peak is assigned at 1610 cm-1.The percentage of functionalization was determined by FTIR spectroscopy method. Thermogravimetric analysis and differential scanning calorimetric methods were also used to study about the thermal properties of the functionalized HDPE.
An efficient and simple protocol of B-enaminones and B-enamino esters synthesis using nickel oxide under ultrasound sonication has been developed. Ultrasound sonication triggers the formation of enaminones under the mild reaction conditions. Nickel oxide was found to be efficient, heterogeneous, moisture stable, robust and recyclable catalyst.
Superabsorbent hydrogels based on poly(vinyl alcohol) were prepared by a crosslinking technique using glutaraldehyde as a crosslinker. The hydrogel structure was confirmed using scanning electron microscopy (SEM). Results from SEM observation showed a porous structure with smooth surface morphology of the hydrogel. We have systematically optimized the certain variables of hydrogel synthesis (i.e. the crosslinker concentration, poly(vinyl alcohol) content, time and temperature of crosslinking reaction) to achieve a hydrogel with maximum water absorbency. It was concluded that under the optimized conditions, maximum capacity of swelling in distilled water was equal to 231 g/g. The absorbency under load (AUL) of hydrogels was also measured. In addition, swelling ratio in various salt solutions was determined and the hydrogels exhibited salt-sensitivity properties.
In this study the degradation of an azo dye, Methyl Red, which is used in textile industry, using Fenton reaction was studied and optimized by a chemometrics method. Fenton oxidation is one of the Advanced Oxidation Processes (AOPs), in which hydroxyl radicals are generated from Fenton’s reagents (Fe2+, H2O2). The effects of various experimental parameters in this reaction were investigated using Central Composite Design (CCD) method. The experimental design was done at five levels of operating parameters. 28 experiments, with 4 factors and 5 levels for each factor were designed. These factors (or variables) include [Fe2+], [H2O2], [oxalate] and the reaction time. A full-quadratic polynomial equation between the percentage of dye degradation (as the response) and the studied parameters was established. After removing the non-significant terms from the model, response surface method was used to obtain the optimum conditions. The optimum ranges of variables were: 0.1 - 0.4 mM for [Fe2+], 13.5-22 mM for [H2O2], 1.5-2 mM for [Oxalate], and 115-125 min for the reaction time. Also the results of extra experiments showed that these optimized values can be used for real samples and yield to high values for the response.
In traditional spectrophotometric determination of stability constants of complexation, it is necessary to find a wavelength at which only one of the components has absorbance without any spectroscopic interference of the other reaction components. In the present work, a simple multi-wavelength model-based method has been developed to determine stability constants for complexation reaction regardless of the spectra overlapping of components. Also, pure spectra and concentration profiles of all components are extracted using multi-wavelength model based method. In the present work spectrophotometric titration of several cationic metal ions with new synthetic ligand were studied in order to calculate the formation constant(s). In order to estimate the formation constants a chemometrics method, model based analysis was applied.
Silver indium sulfide (AgInS2) nanoparticles were synthesized by microwave method. These nanopartricles were characterized by FT-IR, XRD, DRS, SEM and TEM techniques. The band gap energy of 1.96 eV was determined by UV-Vis diffuse reflection spectrum (DRS). The photocatalytic activity was studied by photodegradation reaction of 2,4-dichlorophenol (2,4-DCP) under visible light irradiation. The influence of initial concentration, initial solution pH on the degradation percentage of 2,4-DCP and also, the kinetics of photodegradation were investigated. The removal efficiency up to 95% proved the superior capability of AgInS2 (AIS) nanoparticles for water purification.
A green and efficient method for the preparation of 5-aryl-4-hydroxy-2-methyl-1H-pyrrole-3-carboxylic acid esters and 6-aryl-3-methylpyridazine-4-carboxylic acid esters via three-component reaction of arylglyoxal hydrates with B-dicarbonyl compounds in the presence of ammonium acetate and hydrazine hydrate using water as solvent under ultrasonic irradiation was reported. The reactions proceeded rapidly and afforded the corresponding pyrroles and pyridazines in good to high yields in very short reaction time.
Kinetic studies were made of the reactions between triphenylphosphine 1 and dialkyl acetylenedicarboxylates 2, in the presence of NH-acids, such as benzotriazole, 5-methylbenzotriazole or 5-chlorobenzotriazole 3 (as a protic/nucleophilic reagent). To determine the kinetic parameters of the reactions, they were monitored by UV spectrophotometry. Useful information was obtained from studies of the effect of solvent, structure of reactants (dialkyl acetylenedicarboxylates and NH-acids) and also concentration of reactants on the reaction rates. First and third steps (k2, k3) of all reactions were recognized as a rate determining and fast steps, respectively. Proposed mechanism was confirmed on the basis of experimental data.
Efficient synthesis of quinoxaline derivatives from the reaction of ?-diketones and o-phenylenediamines in the presence of Keggin-type heteropolyacids (HPA) such as H3PMo12O40, H4SiW12O40, K7PMo2W9O40, H3PW12O40.SiO2 and H3PW12O40 in high yields and short reaction times, and at room temperature is introduced.