فهرست مطالب saeid khodadoust

In the present work, a copper nanowire loaded on activated carbon (Cu-NW-AC) was fabricated and applied as an effective adsorbent for the removal of bromophenol blue (BPB) dye from aqueous solutions and then the percentage of removal was evaluated by UV–Vis spectrophotometer. The synthesized adsorbent was characterized and identified using techniques like Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET). The effective parameters of the removal process were investigated and optimized by experimental design methodology (EDM) based on response surface methodology (RSM) as a powerful optimization method. EDM is a unique method for following the effects of different factors on the removal process simultaneously. Analysis of variance (ANOVA) was used based on p-values and F-tests to investigate the accuracy and reliability of the used method. The optimized parameters were obtained as BPB concentration of 15 mg L-1, ultrasonic irradiation time of 14 min, adsorbent dosage of 0.018 g and pH= 5.5 under the desirability function. To evaluate the adsorption mechanism and calculation of maximum adsorption capacity, different adsorption isotherms were studied and according to the results, the Langmuir isotherm model showed the highest compatibility due to its higher R2 (0.9905). Also, the proposed adsorbent represented good adsorption capacity (123.45 mg g-1).

Organophosphates are the basis of many pesticides and chemical warfare agents. Organophosphorus pesticides (OPPs) are a class of chemicals that generally act as cholinesterase inhibitors and have been widely used in agriculture due to their high efficiency as insecticides. The main purpose of this study is to present a new method for extracting diazinon toxin from ambient water.

In this research NiZnS nonmaterial supported on the activated carbon synthesized and characterized with various method including XRD, FT-IR and TEM. Then these nanomaterials with 45 nm average particle size was applied for extraction of diazinon pesticide based on dispersive nano solid material-ultrasound assisted microextraction (DNSUAME) from environmental water samples prior to HPLC-UV. The optimum effective variables on the extraction yields were investigated by central composite design.

The optimized DNSUAME combined with HPLC-UV allowed quantification of trace levels of diazinon in the water samples. The advantages of the proposed method based on the new nanomaterial include simple, and inexpensive synthesis method; rapid and convenient extraction operation, feasibility for large-volume samples, high sensitivity, and precision and accuracy in preconcentration and determination of diazinon. 

At optimum conditions values of variables set as 15.5 mg of NiZnS-AC, 5.5 min vortex and 5.5 min sonication time. At optimum conditions method has linear response over 0.001-10 µgmL-1 with detection limit 0.0005 µgmL-1 with relative standard deviations (RSDs) less than 6 % (n=6).

Antioxidants are molecules which able to control free radicals and prevent the oxidants of other molecules considering undesirable effects of synthetic anti oxidant. In recent years using of natural anti oxidant gets the great importance. The secondary metabolisms of plants are rich sources of phenol and flavonoids considered as the most important natural antioxidant.  

In this research, the optimization process of phenolic and flavonoids from Adiantum capillus-veneris L. carried out by ultrasound-assisted extraction (UAE) and central composite design (CCD).

Optimization process were performed with four indepent variables including, plant powder (0.1-0.9 g), volume of solvent (5-17 ml), sonication time (5–25 min) and temperature of ultrassonic bath (20-60 ºC) on five levels including 26 test with 2 repetition on central point. The total phenolic content and total flavonoid content, respectively, were accounted by using foline-ciocalteu and aluminum chloride colorimetric method.

At optimum conditions values of variables set at 0.7 g of plant powder, 16 ml of extraction solvent, 20 min for ultrasound waves and 40 ºC for ultrasonic bath.

The results show that the quadratic mathematical model has acted with high accuracy to predict the optimal values of the studied parameters. Under these conditions, the extraction efficiencies for total phenol and flavonoid compounds were 9.46 mg/g and 5.22 mg/g, respectively.

The potential of biochar for pollutant removal from aqueous solution greatly depends on biochar characteristics and its production conditions. The objective of this research was to investigate the efficiency of phosphorous adsorption from aqueous solution by date wood and sugarcane bagasse biochars produced at different pyrolysis temperature. For this purpose, biochars were produced at different temperatures (250, 400, 550 ˚C) and their physio-chemical characteristics were measured. Batch experiments performed to evaluate equilibrium and kinetics phosphate adsorption on biochars surface. Then, experimental data of phosphate adsorption were analyzed using the kinetic (Pseudo First-order, Pseudo second-order, and intra-particle diffusion) and the adsorption isotherm (Langmuir, Freundlich) models. In addition, the effect of various initial phosphate concentrations (25–500 mg L-1) and solution pH was investigated. The results indicated that the removal efficiency of sugarcane bagasse biochars was more than the date wood and increased with increasing of pyrolysis temperature. The sugarcane bagasse biochar produced at 550 ˚C, had maximum phosphorus adsorption from aqueous solution (46.94 mg g-1). Freundlich model showed the best fit for experimental data of phosphate adsorption onto biochar with R2=0.96 and RMSE=0.004. The results also revealed that Pseudo second-order kinetic model (R2 = 0.99) had the best fit for phosphate adsorption data. According to the results of this study, it can be concluded that the sugarcane bagasse biochar produced at 550 ˚C has high efficiency for removal phosphate from aqueous solution.