Journal of Applied Research in Chemistry
Year:2010 | Volume:3 | Issue:12|Papers Count:11

In this paper, micro and nanosized flower-like ZnO were successfully prepared by a microwave route without assistance of surfactant and template, employing zinc acetate and sodium hydroxide or ammonia as the starting materials. Nanosized flower-like was obtained when ammonium hydroxide solution was used.X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra were employed to characterization of the as synthesized ZnO. The photocatalytic activity of micro and nanosized flower-like ZnO was compared by photocatalytic decolorization of Congo red azo dye. Results show that the photocatalytic efficiency of micro sized flower-like ZnO to be remarkably greater than that nanosized flowerlike ZnO.

Today, in developing countries like Iran heavy metals are present everywhere which threatens the health of the people. The analysis of human hair is useful in monitoring the levels of certain trace elements in the body and assessing heavy metals environmental exposure.In the present work, we propose uncertainty estimation for the analytical results we obtained from determination of cadmium, lead and nickel in human hair by electro thermal atomic absorption spectrometry (ETAAS).Prior to analysis, hair samples were washed with 1% (w/v) sodium diethyldithiocarbamate (DDTC), and 0.1M HCl. The hair samples were digested afterward in a mixture of HNO3, and H2O2. To estimate the uncertainty of analytical result obtained, we propose assessing trueness by employing spiked sample. Two types of bias are calculated in the assessment of trueness: a proportional bias and a constant bias. We applied Nested design for calculating proportional bias and Youden method to calculate the constant bias. The results we obtained for proportional bias are calculated from spiked samples. In this case, the concentration found is plotted against the concentration added and the slop of standard addition of curve is an estimate of the method recovery. Estimated method of average recovery in human hair is: (1.019±0.026), (0.918±0.014) and (1.0597±0.017) for Cd, and Ni, respectively.

The main natural source of pentosans is lignocellulose that exists in biomass. Pentosans are hydrolyzed to pentoses in dilute mineral acid hydrolysis. Product of pentoses dehydrolysis is furfural. It can also be produced from different fruit shells as agricultural residues. The pistachio green hulls (PGH) from Pistachio vera as agricultural residues are abundant and low-cost lignocellollosic material and they have good potential for furfural production. In this study, the factors affecting on acid-hydrolysis of PGH such as reaction temperature (from 425 to 545 K), sulfuric acid concentration (from 0.5 to 4.0 mol/l) and reaction times (from 30 to 600 s) have been investigated. The reaction yields have been obtained on the basis of lignocellulose, pentoses and furfural.

The study of dendritic molecules, such as dendrimers, hyperbranched and dendronized polymers, and molecular "bottle brushes" has received increasing interests in recent years. They are essential building blocks for both covalent and supramolecular assemblies and have promising technological and biomedical applications. In this report several aspects of dendrimers are collected, including definition of dendrimers and dendrons, synthesis, characterization, and their properties and applications.

The solubilization of multi-walled carbon nanotubes (MWNTs) had been a research goal for the past few years. Carbon nanotubes could be solubilized in different solvents to promote their potential applications in the form of polymers, copolymers, ceramics, and gasoline, etc. In this work, solubility of the functionalized carbon nanotubes were studied in different solvents such as THF, dichloromethane, ethanol, deionized water and n-hexane. Carboxylic acid groups and amide groups were applied for functinalization of multi-walled carbon nanotubes. Octadecylamine and dodecylamine were used for functionalization of carbon nanotubes to study solubility of them in gasoline, for the first time, and compared the results with those of the other solvents. The results showed that amido-functionalized carbon nanotubes had the best solubility in the dichloromethane, ethanol, and gasoline. In addition it was observed that the solubility of these carbon nanotubes was stable for several days. The resulting materials were characterized by Fourier-transform infrared spectroscopy (FT-IR), and thermal gravimetry analysis (TGA).

Reaction of phthalic acid with 1-methylimidazole and Co (NO3) 2.6H2O in aqueous solution give rise to a three-dimensional complex [Co (Pht) (1-MeIm) 2] n (Pht-2=dianion of o-phthalic acid; 1-MeIm=1- methylimidazole).The product has been characterized by infrared spectroscopy (IR), and single crystal X-ray diffraction. The complex crystallizes in the Pccn space group with a=17.2402 (19) Å, b=25.712 (3) Å, c= 16.1672 (18) Å, a=90o, b=90º, g=90o, V=7166.6 (14) Å, Z=8. In this three-dimensional complex two independent metal atoms are tetrahedrally (N2O2) coordinated to a pair of Pht ligands and a pair of 1-MeIm molecules.

Silane coupling agent has long been used to enhance degree of reinforcement of silica in rubber matrix. Recently various types of these coupling agents have been developed and commercialized. In the present study, two new silane coupling agents were introduced as decyloxytriethylsilane and 5, 11, 17-Tritertbutyl- 23-trimethylsilylethynyl-25, 26, 27, 28-tetrapropoxy calix (4) aren to compare the effect of generating Van der waals interaction between filler and polymer matrix that was originated by decyloxytriethylsilane in comparison with p-p interactions that was due to 5, 11, 17-Tritertbutyl-23-trimethylsilylethynyl-25, 26, 27, 28- tetrapropoxy calix (4) aren. Cure characteristics and physicomechanical properties of a nano-silica filled NR/ SBR polymer based compounds using these two agents were investigated and compared with commercialized Si69. Distribution of the filler in the rubber matrix was considered by scanning electron microscopy. These two suggestions were presented coupling agent effects. Decyloxytriethylsilane was shown better results due to the reduction of curative absorption and van der waals interactions between filler and polymer matrix in comparison with p-p interactions that was originated by the other coupling agent.

The UV-spectrophotometric method of analysis was proposed for simultaneous determination of sulfamethoxazole and trimethoprim. Considering the strong spectral overlap among UV-vis spectra of these compounds, a previous separation should be carried out in order to determine them by conventional spectrophotometric techniques. Here, full-spectrum multivariate calibrations PLS and PCR methods are developed. The experimental calibration matrix was constructed with 26 samples. The concentration ranges considered were 2-15mgml-1 sulfamethoxazole and 0.4-6mgml-1 trimethoprim. Absorbance data of the calibration standards were taken between 200-400nm with UV-vis spectrophotometer. For achieving the best model, related parameters of the model were evaluated. The optimum number of factors was selected by using the cross-validation method. The relative errors in each step were calculated. The PLS and PCR calibrations based on the raw data matrix were utilized to illustrate successfully the application of the proposed methods for analysis of the drugs in synthetic mixtures and pharmaceutical tablet. The errors obtained in the PLS method were slightly better.The errors were less than 0.1% for sulfamethoxazole and 0.9% for trimethoprim in PLS method, respectively.