فهرست مطالب عباس افخمی

Toluene, benzene, xylene, and ethylbenzene (BTEX) belong to the class of monocyclic aromatic hydrocarbons and are identified as toxic volatile compounds due to their harmful properties. The reliable biomarkers for occupational exposure to these toxic compounds are hippuric acid (HA), trans,trans-muconic acid (tt-MA), mandelic acid (MA), and methylhippuric acid (MHA), which correlate with toluene, benzene, ethylbenzene, and xylene, respectively.

A novel magnetized imine-linked covalent organic framework (Fe3O4@TFPA-Bd) was synthesized, marking its inaugural use as a sorbent in microextraction by packed sorbent (MEPS). The synthesis of Fe3O4@TFPA-Bd was executed in a straightforward and efficient manner, using Fe3O4 nanoparticles as the magnetic core and benzidine (Bd) and Tris (4-formyl phenyl) amine (TFPA) as the structural building blocks. This newly produced sorbent was tested for the microextraction of hippuric acid (HA), mandelic acid (MA), trans, trans-muconic acid (tt-MA), and m-methyl hippuric acid (m-MHA) from urine samples, which were then analyzed using high-performance liquid chromatography (HPLC). In order to optimize the extraction performance, parameters like sample volume, elution volume, extraction cycles, pH, and sample solution temperature were thoroughly adjusted. The synthesized adsorbent underwent thorough characterization via scanning and transmission electron microscopy (SEM and TEM), Fourier transforms infrared spectrometer (FTIR), and X-ray diffraction (XRD).

The developed method showcased promising attributes: low detection limits (0.02 µg/ml for tt-MA, S/N=3), low quantification limits (0.06 µg/ml for tt-MA, S/N=10), a solid linear range (0.5-320 µg/ml for MA, R > 0.99), and commendable intra- and inter-day precision (2.4%-4.3% and 3.1%-7.8%, respectively) for volatile organic compound (VOC) biomarkers. Furthermore, the method demonstrated recoveries in the 81-87.5% range for spiked samples, indicating its practicality and effectiveness.

The developed procedure was suitable for the determination of BTEX biomarkers from urine samples and can be an alternative to previous methods.

Long-term drinking of nitrate-contaminated water poses a serious risk to human health. The present study explores the possibility of enhancing the adsorption capacity of graphene oxide via activation with hydrochloric acid for nitrate removal from aqueous solutions. Experiments were performed in a batch reactor in which such major factors as pH, reaction time, and concentrations of both graphene oxide (GO) and activated graphene oxide (AGO) were used as variables. Nitrate removal efficiency was investigated using the One-Way ANOVA statistical test and SPSS-16 software. The chemical composition and solid structure of the synthesized AGO were analyzed using FE-SEM coupled with energy dispersive spectrometry (EDS). The micropore volumes of the samples were determined using the BET and BJH. The predominant composition (52%) of the synthesized AGO was C and its mean pore diameter was 26.896 nm. The maximum adsorption capacity of AGO was estimated at 3333.33 mg/g. Based on the results, the AGO nano-structure may be recomended as a new means for nitrate removal from aqueous solutions.

Increasing water resources pollution by heavy metals cause serious environmental and health concerns in the world. Selenium blood levels of >100 𝜇g/dl can result in selenosis. Atomic absorption spectroscopy is the most common method for selenium detection. This technique has several disadvantages such as high equipment and operational costs، time-consuming and the need for quality control of the test method. In this study، the HMS) Hexagonal mesoporous silica (activated by 4- (2-pyridylazo) -resorcinol (PAR) was used for spectrophotometric determination of selenium. The qualitative detection was done by colour change of sediment from orange to pink in water samples and the quantitative detection by a spectrophotometer. Various parameters such as pH، the initial concentration of the selenium، contact time، and the indicator doses were also examined. The results of this study showed that the qualitative and quantitative detection of selenium are better done with increasing the contact time. The best condition for selenium detection was observed at pH =10. Increasing the indicator doses had no significant effect on the identification process. Increasing initial concentration of selenium increased the pink colour formation and consequently enhanced accuracy of qualitative and quantitative detection. This study is a basic and applied research. The HMS sensor activated by 4- (2-pyridylazo) -resorcinol (PAR) can be used as an inexpensive and rapid indicator for quantitative (spectrophotometry) and qualitative (colour change) detection of selenium in water and wastewater in research and administrative unites.

Bearing organic and inorganic pollutants, colored wastewater are an important source of environmental pollution. Removal dyes from dyestuff can be accomplished by various methods such as coagulationflocculation, Fenton regent, ozonation and so on. This work investigated metallic iron as an efficient and inexpensive material for treatment of colored wastewater. Parameters such as pH (3,, , 9 and 11), contact time (15, 30, 45, 60, 75, 90, 105 and 120 min), iron powder concentration (0.5, 1, 1.5 and 2 g/L) and initial dye concentration (25, 50, 75 and 100 mg/L) were studied. In addition, experimental data were fitted on pseudo- first order, pseudo-second order and modified pseudo-first order kinetic models. Result showed that dye removal was increased by increasing iron mass and contact time. While decreased by increasing pH of solution. Increasing initial dye concentration of AO7, has increased removal efficiency, while it was decreased by increasing initial dye concentration of RB5. In addition, results showed that pseudo-first order model best describe removal of AO7 (r2> 0.9708) and RB5 (r2>0.9776) by metallic iron. We concluded that metallic iron can be used as an effective an inexpensive matter for treatment of dyestuff waste.

Groundwater treatment by nano particles has received increasing interest in recent years. Chromium is a commonly identified contaminant in soils and groundwater. Zero-valent iron, as a natural reduction agent can be used in controlling of contaminated sites. The aim of this research is investigation of hexavalent chromium removal from aqueous solutions by using of iron nano particles the effective parameters. In this research the synthesized of the iron nano particles has performed by addition of NaBH4 to FeCl3·6H2O solution and Cr(VI) reduction efficiency in Batch system was studied. Also the impact of the important field parameters including pH, initial chromium concentration, nano zero valent iron concentration and retention time were investigated.The results of this research showed that synthesized particles were in nano scale. In pH=3, chromium inlet concentration of 10 mg L-1, nano zero valent iron concentration 0.5 g L-1 and 2 minute retention time, 100% of Cr(VI) was removed.The concentration of nano zero valent iron had significant effect on the reduction of Cr(VI).The reaction occurred in a wide range of pH value and the reaction efficiency increased significantly with decreasing initial pH. The significant removal efficiency, high rate of process and short reaction time were showed that iron nano particles have significant potential in removal ofCr(VI) from contaminated water.