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A magnetic solid-phase extraction method coupled with gas chromatography was proposed for the determination of polycyclic aromatic hydrocarbons in the environmental water samples. The magnetic adsorbent was prepared by incorporating Fe3 O4 nanoparticles, multi-walled carbon nanotubes, and polypyrrole. The main factors affecting the extraction efficiency including the amount of the sorbents, desorption conditions, extraction time, salt concentration, and sample solution pH were investigated and optimized. Under the optimum conditions, good linearity was obtained within the range of 0.03-100 ng/mL for all analytes, with correlation coefficients ranging from 0.9942 to 0.9973. The method detection limits (S/N = 3) were in the range of 0.01-0.04 ng/mL and the limits of quantification (S/N = 10) were 0.03-0.1 ng/mL. Repeatability of the method was assessed through five consecutive extractions of independently prepared solutions at concentrations of 0.1, 10, and 100 ng/mL of the compounds. The observed repeatability ranged 3.4-10.9% depending of the compound considered. The proposed method was successfully applied in the analysis of PAHs in environmental samples (tap, well, river, and wastewater). The recoveries of the method ranged between 93.4 and 99.0%. The procedure proved to be efficient and environmentally friendly.

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In this work, carbon nanotubes (MWCNTs) were utilized as efficient adsorbents for pantoprazole (PP) removal. We used MWCNTs that were synthesized using the chemical vapor deposition process. The physical characteristics of MWCNTs were described by Brunauer-Emmett-Teller (BET) contact area, surface functional group analysis by the point of zero charge (pHPZC), Fourier transform infrared (FTIR) analysis, Scanning electron microscope (SEM), X-ray diffraction (XRD), and Transmission electron microscopy (TEM). The single-point BET surface area of the MWCNTs was found to be 98.7 m 2 g -1 , with the median pores' diameter of 30.9 nm and an average pore(s) volume of 0.764 cm 3 g -1 . Effective parameters on the PP removal including, pH, contact time and initial amount of adsorbents were optimized, revealing maximum PP removal at pH=6.0 after 25.0 min when 0.026 g MWCNTs. The pseudo second-order kinetic model for adsorption of PP on the surface of both adsorbents revealed the high value of correlation coefficient, indicating the high ability of the pseudo second-order model for representation of experimental results. Adsorption equilibrium studies indicated that the Freundlich isotherm efficiently represented MWCNTs adsorption data. The thermodynamic parameters (Gebbs free energy, enthalpy, and entropy) of adsorption process were calculated. Results had shown that adsorption of PP on the MWCNTs is feasible, spontaneous, and exothermic process in the temperature range of 25-76 °C.

In this research, electric field gradient (EFG), which is the first derivative of electric field, is applied for evaluation of aromaticity of 89 cyclic organic compounds. In our calculations, DFT procedure (b3lyp) with basis set 6-311++G has been employed, and the obtained electronic structures and frequency test has been done for optimized geometries. The aromaticity evaluated for these compounds by EFG procedure is successfully compared with other well-known indices in literature, especially with nuclear independent chemical shift (NICS). These comparisons show that EFG method of assessment of aromaticity can be used as a rather valid procedure for this purpose. Flexibility and simplicity of EFG make this method a rather easy procedure for assessment of aromaticity. Since EFG method of aromaticity evaluation does not need specific programming and it can be done by known software such as Gaussian, therefore, the availability for everyone to calculate desired aromaticity by this method is one of attractive feature of it similar to NICS.