Iranian Journal of Analytical Chemistry
Volume:8 Issue: 2, Summer and Autumn 2021

In this study, hierarchical NaP zeolite was prepared for dehydration of a wet nitrogen gas stream using an adsorption system. Hierarchical NaP zeolite was synthesized via an easy hydrothermal process and characterized using several techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area analysis and Fourier transform infrared (FT-IR) spectroscopy. An adsorption system comprising a desiccant packed column, humidity analyzer, and dry and wet gas cylinders was designed to evaluate the adsorption behavior of the synthesized NaP zeolite. Results indicated that hierarchical structure of NaP zeolite made a high surface area for water removal from a non-corrosive gas stream at ambient condition as it could reduce the water content of the gas from an initial concentration of 53 ppmv to approximately 5 ppmv after just one minute of the experiment.

Computational and experimental approach on standard redox potential of dobutamine was developed in aqueous media. A direct and indirect calibrated B3LYP/6-311++G (d, p) method predicted the aqueous phase redox potential of dobutamine as 0.850 V Respectively. The electronic densities of dobutamine calculation at oxidation and reduction state in HOMO and LUMO proved that energies of dobutamine LUMO in oxidation form are lower than dobutamine LUMO in reduction. Therefore, the electron transfer from HOMO to LUMO in dobutamine oxidation form is easier than in dobutamine reduction form. The experimental E° was obtained using cyclic voltammetry at activated glassy carbon electrode as 0.79V versus SHE. The results show that there is a satisfactory agreement between the experimental and computational standard potential value of dobutamine.

Recently, different significant efforts have been made to fabricate an effectively modified electrode for replying to the growing requests for enhanced performance electrodes for electrochemical sensors. Herein, we introduced an organic material along with a composite of the zinc sulfide (ZnS) particles distributed in the substrate of carbon nanotubes (CNTs)/reduced graphene oxide (RGO) nanosheets by using an inexpensive, simple, and one-step fabrication method, as an effectively modified electrode for the determination of hydrazine as an analyte. This electrode represents a great electrochemical performance with a large linear range (0.01 μM-60.0 μM) and a proper limit of detection value (0.006 µM) for determination of hydrazine. Good recovery percentage values for the proposed sensor confirm its excellent ability to measure hydrazine.

A quantitative Structure-Activity Relationship (QSAR) model was applied to the prediction of the antimicrobial activity of 22 derivatives 2, 4, 6-s-triazine as anti-malarial agents. The antimicrobial activity of 22 2, 4, 6-s-triazine derivatives were modeled with the descriptors of quantum-chemical calculations with density functional theory (DFT) method at B3LYP/6‒31G level and topological descriptors. This study was conducted using the multiple linear regressions (MLR), the partial least square analysis (PLS) and the principal component regression (PCR) method. Results displayed that the MLR method predicted of antimicrobial activity good enough. The best model, with six descriptors was selected. Also it indicates very good consistency towards data variations for the validation methods. The predicted values of antimicrobial activity are in suitable agreement with the experimental results. The obtained results suggested that the PLS method could be more helpful to predict the antimicrobial activity of 2, 4, 6-s-triazine derivatives. This study to be usable to predict the activity of other derivatives in the same groups.

In this research, Sistan sand was used as a natural and inexpensive sorbent for removal of cephalexin and tetracycline antibiotics from water and wastewater samples. For a concentration 60.0 mg L-1 of cephalexin, optimum removal conditions were: pH of the sample 3.0, adsorbent amount 1.0 g, contact time 20.0 min, added amount of sodium chloride to adjust the ionic strength of the solution 7.0 g L-1. Langmuir isotherm was the best fitted model for this adsorption process and adsorbent capacity was calculated to be 0.26 g g-1. This adsorbent was able to remove up to 68.1% of cephalexin from wastewater. In case of tetracycline, for a 90.0 mg L-1 of the analyte, the optimum adsorption conditions were achieved at pH 8.0, 1.0 g of sorbent, contact time of 35.0 min and ionic strength of the solution as sodium chloride of 7.0 g L-1. The isotherm was best in agreement with Freundlich model. Adsorbent capacity was 0.76 g g-1 and up to 76.2% of this antibiotic could be removed from wastewater.

In this study, a novel and convenient electrochemical sensor was fabricated by using dripping well-dispersed graphene oxide nanosheets, electropolymerization of poly glycine (p-Gly) and in situ plating of metallic copper nanoparticle film methods, successively. This sensor was further employed to investigate the electrochemical behavior of hydrazine. Scanning electron microscopy and energy dispersive X-ray spectrometry were used for the characterization of the prepared film. Anodic peak potential of hydrazine oxidation at the surface of modified electrode shifts by about 150 mV toward negative values compared with that on the bare electrode. The kinetic parameters such as the electron transfer coefficient (α) and charge transfer rate constant (k) for the oxidation of hydrazine was determined utilizing cyclic voltammetry (CV). The diffusion coefficient (D) of hydrazine was also estimated using chronoamperometry. The dynamic detection range of this sensor to hydrazine was 5- 60 and 80- 150 µM at the modified electrode surface using an amperometric method. The detection limit and quantitation are 5.33 µM and 17.77 µM, respectively. A new voltammetric method for determination of hydrazine was erected and shows good sensitivity and selectivity, wider linear relationship, very easy surface update and good stability.

This research aimed to develop a novel sensing platform for hydrogen peroxide (H2O2) quantification in the milk samples. The proposed sensor was fabricated using a glassy carbon electrode modified with Fe-Cu layered double hydroxide (LDH)/magnetic Fe3O4 nanoparticles (FeCu-LDH@Fe3O4/GCE). The resulting sensor was characterized using field emission scanning, electron microscopy, x-ray diffraction, and infrared spectroscopy, with the addition of the electrochemical methods. After optimization of affecting parameters, the FeCu-LDH@Fe3O4/GCE exhibited a high electrocatalytic activity for H2O2 electroreduction; and high cathodic peak currents were obtained. The proposed electrode also illustrated a wide linear dynamic domain in the range of 2 to 400 µM; and low limit of detection was calculated to be 0.6 µM.

In this work, Zinc oxide nanoparticles (ZnONPs) were utilized as a potential adsorbent for the adsorption of Reactive Blue 25 (RB25) and Reactive Blue 49 (RB49) dyes from aqueous solutions. ZnONPs adsorbent was synthesized by precipitation method and characterized using XRD, TEM, SEM, and N2 adsorption /desorption techniques. The effect of various parameters including solution pH, shaking time, adsorbent amount and initial concentration of the dyes on the adsorption efficiency was studied. The experimental adsorption data analyzed with various kinetic and isothermal methods. The adsorption kinetic study revealed that the adsorption process followed pseudo-second-order kinetic model. Additionally, adsorption isotherm studies indicated that adsorption equilibrium data were well fitted to Langmuir model and accordingly, the maximum adsorption capacity of the adsorbent for RB25 and RB49 found to be 34.36 and 34.60 (mg/g), respectively. From this study, ZnONPs is suggested as an effectual adsorbent for the removal of dyes from aqueous samples.

The aim of the present study was to develop electrochemical sensors based on pencil graphite electrode modified with green-caped ZnO, CdO nano particles and potassium tetra chloroplatinate (II), for a simple and fast simultaneous microextraction and determination of Aspirin (ASA) and Ibuprofen (IBU). The nanoparticles were initially synthesized by the use of four vegetable extracts including garlic, onion, green onion and cabbage. The fabricated nanoparticles and platinum were then deposited on the surface of a pencil graphite electrode and was used as a working electrode in a three electrodes system. The Taguchi experimental design was employed for investigating the effects different parameters. For this purpose, a Taguchi L16 orthogonal array (OA) design was applied and the results were confirmed by the ANOVA test. The electrochemical behavior of ASA and IBU at the modified electrodes, were studied. The calibration curves were linear in the range of 5.17to 134.0 µg.mL-1 and 3.13 to 231.0 µg.mL-1 for ASA and IBU respectively. The limits of detection for ASA and IBU was calculated to be 0.50 and 0.42 µg.mL-1 respectively. The modified sensor showed good performance for simultaneous analysis of ASA and IBU in biological and pharmaceutical samples.

Two new organic hybrids of phosphomolybdic acid (PMA) were prepared by means of hexamine (HMT) and HMT-Ni2+ complex. The effects of hybridization of HMT and Ni2+ were investigated on the photocatalytic activity of PMA. Characterization of hybrids were carried out by elemental analyses, Fourier transform infrared spectroscopy, powder X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The band gaps of PMA, phosphomolybdate-hexamine (PMA-HMT) and phosphomolybdate-hexamine-nickel (PMA-HMT-Ni) were determined from the diffuse reflectance spectra using the Tauc plots. Dye adsorption and photocatalytic properties of PMA-HMT and PMA-HMT-Ni hybrids were examined by studying the decolorization of model dyes methylene blue (MB), rhodamine B (RhB) and mixtures of MB and methyl orange (MO) solutions. The results show that the band gap of PMA-HMT-Ni is narrower and hence, its photocatalytic activity is higher for the degradation of dyes under sunlight irradiation. Mechanism of photodegradation was studied by adding scavengers. Removal is via combination of adsorption and then photocatalytic degradation through oxidation by radicals.

Herein, the date palm pollen (DPP) grain was used as an amikacin (AMK) delivery vehicle for the first time. The AMK-loaded DPP was characterized using scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, and surface area (BET) analysis. The pore size of DPP was obtained 80–200 nm that was favorable to the drug uptake. The effects of pH and temperature were studied on the AMK loading in DPP. The study of drug release kinetics in phosphate buffer pH 7.4 at 37 oC suggested that the best kinetic model was the Higuchi equation. The antibacterial activity of AMK-loaded DPP (AMK-DPP) was investigated on Staphylococcus aureus and Escherichia coli bacteria by the agar-well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for AMK were also carried out by using broth dilution method. The similarity of the results between MIC and MBC is considerable. However, an intense reduction in the MBC was observed after AMK loaded on palm pollen. Moreover, the AMK-DPP was utilized to improve the effectiveness of AMK against the dangerous forms of antibiotic-resistant bacteria. In general, AMK-DPP shows to be a new favorable method allowing in the management of Gram-positive and Gram-negative bacterial infections and may be further evaluated in in-vivo experiments.

In this paper, graphitic carbon nitride (g-C3N4) was prepared by direct pyrolysis of melamine and then used to synthesize P-doped graphitic carbon nitride nanosheets with ultrasound in phosphoric acid. This simple method helps increase the trapping of light, change the electronic property of g-C3N4 and prevent charge recombination in the as-prepared photocatalyst. The useful features of this method to prepare P-doped g-C3N4 nanosheets are its simplicity, short synthesis time, economical and environmentally friendly. The present study demonstrates the ability of phosphoric acid to synthesize P-doped g-C3N4 nanosheets with ultrasound, which leads to an increase in photodegradation of Tartrazine under visible light.