زمینه و هدف: جداسازی و اندازه گیری مقادیر ناچیز یون های کبالت در نمونه های حقیقی به جهت سمیت آن، برای انسان اهمیت زیادی دارد که در تحقیق حاضر از نانو سلولز اصلاح شده به عنوان جاذب استفاده شده است. نانو سلولز به روش هیدرولیز اسیدی سنتز و با 2- ( 5- برمو -2- پیریدیل آزو ) 5- ( دی اتیل آمینو ) فنل) Br-PADAP 5-) اصلاح شد. به کمک میکروسکوپ الکترونی عبوری (TEM) اندازه نانو فیبرهای سلولزی تعیین شد. بعد از اصلاح نانو جاذب با PADAP 5-Br-، از نانوکامپوزیت اصلاح شده آنالیز وزن سنجی حرارتی (TGA) صورت گرفت و همچنین برای تعیین مقدار سطح قبل و بعد از اصلاح جاذب از تکنیک BET استفاده شد. در کار حاضر هدف اصلاح سطح نانو سلولز با لیگاند 5-Br-PADAP جهت استفاده از آنها برای استخراج و پیش تغلیظ مقادیر ناچیز یون های کبالت قبل از اندازه گیری آن توسط طیف سنجی جذب اتمی شعله ای در نمونه های حقیقی می باشد.روش بررسی: حجم معینی از یون کبالت را داخل لوله آزمایش حاوی نانو جاذب اصلاح شده ریخته و به آن محلول بافر با 9pH= اضافه کرده و به مدت 15 دقیقه درون شیکر و سپس سانتریفیوژ قرار داده و در مرحله بعد محلول رویی را دور ریخته و 1 میلی لیتر HCl جهت بازیابی یون کبالت افزوده و 10دقیقه داخل شیکر و سپس سانتریفیوژ قرار داده و جذب محلول رویی توسط دستگاه جذب اتمی شعله ای خوانده شد.نتایج به دست آمده نشان می دهد که نانو سلولز اصلاح شده، برای اندازه گیری یون کبالت در غلظت های پایین بسیار حساس و گزینش پذیر عمل می کند و تحت تاثیر پارامتر های مختلفی مانند pH، مقدارجاذب، زمان استخراج و نوع حلال شوینده قرار می گیرد.یافته ها: منحنی کالیبراسیون در گستره 500-10 نانو گرم بر میلی لیتر خطی بود و حد تشخیص روش 3/4 نانوگرم بر میلی لیتر و انحراف استاندارد نسبی (RSD) روش 8/1 % به دست آمد. همچنین دارای فاکتور پیش تغلیظ و غنی سازی بالا می باشد.بحث ونتیجه گیری: روش پیشنهادی جهت اندازه گیری مقادیر ناچیز یون های کبالت با روش افزایش استاندارد در نمونه آب های طبیعی نظیر آب دریا، رودخانه، آب چاه ، آبندان و آب شهری توسط دستگاه طیف سنجی جذب اتمی با نتایج رضایت بخش مورد استفاده قرار گرفت. پرونده مقاله

In order to produce biodiesel from waste cooking oil and optimize its yield, a two-stage process of esterification/ transesterification has been used in this study. First, we used the acidic catalysts H2SO4 in order to diminish the content of free fatty acid (FFA) in oil that caused reducing the oil acidity from 6.1% to 0.57% through esterification. Then, the biodiesel was produced by transesterification of resulted oil using heterogeneous CaO nanoparticles as catalyst. At each stage, the best possible conditions have been determined by applying Taguchi methodology for each major variable, including time, temperature, alcohol/oil molar ratio, and the amount of catalyst. The optimum conditions for esterification are achieved at 80°C temperature, 120 minutes time, 6:1 molar ratio of alcohol/oil, and H2SO4 content of 1% (w/w oil). The optimum condition for transesterification were found in 100 °C temperature, 90 minutes time, 8:1 molar ratio of alcohol/oil, and 3% (w/w oil) of CaO nanoparticles as catalyst. After applying full optimization of these two stages, the yield of the produced biodiesel has achieved 96.4%. پرونده مقاله

Sago starch polymer is widely used in food, pharmaceutical, textile, etc industries. Their combination with other materials such as sorbitol and glycerin increases their mechanical properties. Mechanical properties are important for edible films. Mechanical tests of the films were performed in accordance to the standard methods. In this regard, the use of various herbal extracts can greatly improve the efficiency of the packaging.In the research biofilm based on the sago starch incorporated with the Abelmoschus esclentus alcoholic extract (2, 4, and 6 grams) and Sorbitol/glycerol was used as a plasticizer and films were prepared under controlled conditions by the casting method using nano zinc oxide and nano zincoxide -Cds5% its properties the mechanical tensile strength (TS) and elongation at break (EAB) and mechanical properties were evaluated with a decrease in the content of the extract. The best results for the concentration of 2gram extract mixed with 0.01gram nanoparticle zinc oxide-Cds5%. Which is the lowest tensile strength and highest elongation at break. پرونده مقاله

The first study on the high efficiency of nanometer-sized magnetic nanoparticles (Fe3O4) coated with sodium dodecyl sulfate (SDS) and dithiooxamide as a new sorbent solid phase extraction has been reported. Modified magnetic nanicomposites was used to preconcentrate and separate Co (II) ions in food and environmental water samples. Magnetic nanoparticles were prepared by chemical precipitation of Fe (II) and Fe (III) salts from aqueous solution by ammonia solution. These magnetic nanoparticles and nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo gravimetric analysis (TGA) and elemental analysis CHNS. A micro sample introduction system was employed for the nebulization micro-volume of diluted solution into flame atomic absorption spectrometry (FAAS). The extraction conditions were optimized by selecting the appropriate extraction parameters including the amount of nanosorbent, pH value, volume of dithiooxamide and condition of eluting solution. The detection limit of this method for Co (II) ions was 1.21 ng ml-1 and the R.S.D. was 0.9% (n=6). The advantages of this new method include rapidity, easy preparation of nanosorbents and a high preconcentration factor. The proposed method has been applied to the determination of Co (II) ions at trace levels in real samples such as, kiwi, orange, cucumber, apple, green pepper, honey, potato, tap water, river water and sea water with satisfactory results. پرونده مقاله

The present work deals with a simple, inexpensive, sensitive, high performance and economic technique for extracting and preconcentrating trace quantity of PAHs compounds through glass foam modified with CTAB surfactant. Solution desorption was employed subsequently for transferring the extracted PAHs into a gas chromatography-mass spectrometry’s injection port. BET, TGA, and FT-IR were used to characterize glass foam and CTAB/glass foam. Operative parameters in PAHs extraction and preconcentration such as amount of sorbent, pH, recovery solvent type, ionic power of solution, contacting time, and recovery time were enhanced to quantitatively determine PAHs. Analytical statistics of merit including limit of detection, accuracy, and linear range were determined to prove the suitability of our suggested technique. The CTAB/glass foam represented higher sensitivity to detect very lower concentration of PAHs such as phenanthrene, fluorene, pyrene and anthracene at ng mL-1 level with high accuracy for drinking water samples. پرونده مقاله

In the present study, trace amount of nickel (II) ions in real samples has been separated, preconcentrated and determined by a synthesized nanocomposite. Our suggested nanocomposite was prepared by immobilization of 2-aminopyrimidine on nanocellulose. The properties of nanocomposite were characterized by TEM, TGA, elementalanalysis CHNS, EDS, and BET techniques. The effective factors such as pH, nanocomposite amount, extraction time, eluent type, ionic strength and sample volume were optimized for quantitative determination of nickel (II) ions. The linear range of the calibration graph was between 5 and 500 ng mL−1 with limit of detection (LOD) 2.33 ng mL−1. Relative standard deviations (RSD) were 2.33%. Modified nanocellulose was used for measurement of the trace amounts of Ni (II) ions in the real samples such as human blood and urine with suitable fallouts. پرونده مقاله