نشریه شیمی کاربردی روز
پیاپی 53 (زمستان 1398)

Polyurethane elastomers are an important polymer in many applications which attach many interest. In this research, novel macro-diamines were synthesized successfully and used as chain extenders for the improvement of mechanical properties and thermal stability of poly(urethane-urea)s (PUUs). Structural characteristics of synthesized macro-diamines investigated by FT-IR. Also, thermal stability of prepared copolymers studied by DSC, TGA and DTG. As well, mechanical characteristics all of the PUUs investigated. Thermal melting (Tm) of copolymers hard segment appears in DSC curves. Furthermore, DSC curves don’t show any peak in measured area; It’s mean glass transition temperature (Tg) is less than (-80) °C. TGA curves displays that synthesized PUUs improvement thermal stability of polyurethane system. Mechanical test results show that mechanical properties of synthesized copolymers are improved

In this work, ZnO with a nanorod morphology loaded on activated carbon (ZnO NRs-AC) was synthesized using the co-precipitation method for the photo-degradation of malachite green (MG) under the UV light. The photo-catalyst was characterized using various analytical techniques including XRD and FE-SEM. The Box-Behnken design (BBD) combined with the response surface methodology (RSM) was applied for the optimization of the influential parameters. The optimum values for the parameters involved were as follow: photo-catalyst dosage,16 mg; MG concentration, 30 mg L-1; and reaction time was 46 min. Studying the effect of foreign ions on the performance of the photo-catalytic process indicated the stability of ZnO NRs-AC in the photo-catalytic degradation of MG. According to the Langmuir–Hinshelwood (L–H) kinetic model, the kinetic degradation of MG followed a pseudo-first order kinetic model.

The main objective of the present work is the investigation of the efficacy of a combination of Fenton chemistry and high-frequency sonochemistry for wastewater treatment, including p-nitrophenol (PNP) as a model pollutant. These methods have been used to degrade PNP in a batch system under different operating conditions based on ultrasound process, Fenton reaction, ultrasound/hydrogen peroxide, and ultrasound/Fenton process. The reactor consisted of six ultrasonic transducers with a frequency of 1.7 MHz. Three transducers were located in the bottom, and the other three were embedded in the wall of the reactor. The results showed that the PNP decomposition follows a pseudo-first-order reaction. The degradation rate constant was determined for various operating parameters including pH, input electric power to transducers, and concentrations and volumes of H2O2 and FeSO4. In optimum conditions, the highest PNP degradation rate constant was obtained for the combination of 1.7 MHz ultrasound and Fenton reaction (0.166 min-1 ) with a synergistic coefficient of 1.165. Next priorities were related to Fenton, ultrasound/hydrogen peroxide and ultrasound with degradation rate constant of 0.137, 0.0107, and 0.005 min-1, respectively. Therefore, the ultrasound/Fenton process had the highest ability to degrade PNP, because ultrasound could intensify Fenton reaction to produce more hydroxyl radicals.

The interaction between an ionic liquid (1-dodecyl-3-methylimidazolium bromide or IL) and cationic surfactant (dodecyltrimethylammonium bromide (DTAB)) in aqueous solution has been investigated at various mole fractions and temperature 30 ˚C using experimental and theoretical methods. The critical micelle concentration (CMC) of pure components and their binary mixtures, mixed micellar composition at ideal state( and ) and real state( and ), interaction parameter ( ), activity coefficients of components in mixed micelles ( and ), the standard Gibbs energy of micellization ( ) values and the degree of counterion binding(α) have been calculated and discussed. It has been found for the DTAB/IL mixture that depending on the ionic liquid bulk concentration (y1), repulsive or attractive interactions (positive or negative value of ) are produced in mixed micelle formation. The unique role of IL in changing behaviors of aqueous surfactant mixtures is described. In the theoretical section, the molecular interaction energy of the pure IL, pure DTAB, and mixed IL-DTAB have been estimated using density functional theory (DFT) calculations. The value of interaction energy parameter ( ) has also been calculated at mole fraction of 0.5 and a good agreement with the experimental results was observed.

Here in a dispersive liquid- liquid microextraction based on solidification of floating organic drop method was developed for simultaneous pre-concentration and trace determination of cadmium, lead and cobalt ions based on their complexes with dithizone and preprocessing spectrophotometric data by net analyte signal based method. The affecting parameters on extraction were investigated and optimized simultaneously. The optimum conditions for pH, extraction solvent, extraction solvent volume, dispersive solvent, dispersive solvent volume, contact time, centrifugation time, solidification time and freezing temperature were 8, 1-ndecanol, 150 microliter, ethanol, 350 microliter, 10 min, 6 min, 5min and 4 oC, respectively. Under these conditions and using a sample containing 15 ml of the cations, the detection limits were 1.1 µg L-1, 3 µg L-1 and 5.4 µg L-1 for cadmium, lead and cobalt, respectively. Because of spectra sever overlapping of complexes throughout studied pH and spectra regions, the net analyte signal ratio spectra method was used to resolve the problem perfectly. Hence, the determination of studied cations can be conducted in the presence of other complexes and unknown interferences. Ultimately, the modified method was successfully applied for determination of aforementioned cations in real samples.

Covalently bonded third generation dendrimer to magnetized graphene oxide nanosheets (DMGO), with high adsorption capacity, were synthesized and efficiently used for simultaneous removal of reactive red 195 (RR) and reactive yellow 145 (RY) dyes. The important parameters like initial concentrations of dyes, sorbent mass and sonication time was optimized using central composite design (CCD) combined with response surface methodology (RSM). Because of the severe overlapping spectra of the dyes, at each removal condition, the dyes concentration were obtained by application partial least squares (PLS) as a powerful multivariate calibration method. The optimized parameters were found to be 12.5 min sonication time, 15 mg of sorbent, RR concentration 20.0 mg L-1 and RY concentration 45.0 mg L-1. These optimal condition were achieved the removal percentage of 99.20 and 98.80 % for RR and RY, respectively. In order to evaluate sorption performance, isotherms and kinetics studies were carried out under batch adsorption experiments. The adsorption process follows pseudo-second order reaction kinetic, as well as Langmuir isotherm. The results showed that the sorbent had a maximum adsorption capacity of 53.76 and 73.53 mg g-1 corresponds to RR and RY, respectively.

The new trans-[Pt(4-mpy)2Cl4] (1) complex (4-mpy is 4-methylpyridine) was prepared from the reaction of H2PtCl6.6H2O with 4-methylpyridine in methanol. Synthesized complex was thoroughly characterized by elemental analysis, IR and 1H-NMR spectroscopy.Elemental analysis data (C, H, N) support the general composition of the title complex and the structure have been established by single-crystal X-ray diffraction study. In this complex the geometry platinum(IV)cation is octahedral, formed by two nitrogen atoms from two 4-mpy ligands and four chloride anions. Also, in this complex the strong π…π interactions between pyridine rings are effective on the stabilization of the crystal packing. Furthermore, the luminescence properties of the free 4-mpy ligand as well as the complex 1were investigated in solution. Luminescence emission of complex 1 was red shifted and is weaker than that of the free 4-mpy ligand.

In the present study, the interaction between water-soluble cationic asymmetric porphyrin, 5-(1-Hexadecyl pyridinium-4-yl)-10, 15, 20-tris (1-Butyl pyridinium-4-yl) Porphyrin Chloride, and its copper (II) derivative with calf thymus DNA (CT-DNA) were studied by means of spectroscopic techniques, viscosity measurements and molecular docking. The monitoring of the changes in visible absorbance spectra showed a small red shift and a little hypochromicity in the Soret band. Also, insignificant changes were appeared in the viscosity of DNA with increasing of the porphyrins. These results suggested that these porphyrins bound to DNA through the groove binding mode. Then, multivariate curve resolution-alternating least squares (MCR-ALS) method was employed on UV–visible spectral data matrix to resolve the spectral and concentration profiles of the components involved in the interaction and the binding constant was estimated by the combination of bard equation and MCR-ALS approach. Furthermore, molecular docking studies confirmed experimental results obtained by spectral techniques and provide deeper insight into the porphyrin-DNA interaction.