تهیه الکترودهای اصلاح شده بر پایه نانوذرات هیدروکسیدهای دوگانهی لایهای و کاربردهای الکتروتجزیهای آنها
Preparation of modified electrodes based on layered double hydroxides nanoparticles and their electroanalytical applications
/رقیه امینی
: شیمی
، ۱۳۹۷
، راشدی
۲۱۳ص
چاپی - الکترونیکی
دکتری
شیمی تجزیه
۱۳۹۷/۰۶/۱۸
تبریز
یکی از مسائل مهم در مهندسی آب و فاضلاب تعیین ضریب زبری و اصطکاک در لوله ها است .در تحلیل مسائل توزیع سرعت، تنش برشی، انتقال رسوب و افت فشارنیاز به دانستن ضریب اصطکاک از ضروریات حل مسئله میباشد .روش های استاندارد برای محاسبه ضریب اصطکاک عموما نیاز به محاسبات مکرر داشته، و هزینه های محاسباتی بالایی را در شبکه های لوله کشی بزرگ برجا می گذارد .به همین دلیل استفاده از روشصهایی که کارایی تخمین دقیقصتر این پارامتر را داشته باشند، ضروری است .در تحقیق کنونی ضریب زبری در لولههای فاضلابصرو با شرایط بستر متفاوت شامل بستر صلب و بستر رسوبگذاری شده، با استفاده از روش ماشین بردار پشتیبان ((SVM و برنامهریزی بیان ژن ((GEP تخمین زده شد و نرخ تأثیر پارامترهای ورودی در هر حالت مورد تجزیه و تحلیل قرارگرفت .مقایسه نتایج حاصل از روش رگرسیون ماشین بردار پشتیبان و برنامهریزی بیان ژن با روابط کلاسیک، قابلیت و کارایی بالای روش ماشین بردار پشتیبان و برنامهریزی بیان ژن را نسبت به مدلهای کلاسیک نشان داد .یکی از قابلیت های برنامه ریزی بیان ژن ارائه فرمول صریح برای ضریب زبری می باشد .همچنین مشاهده گردید که در حالت بستر صلب مدل با پارامترهای ورودی شامل عمق نسبی جریان، اندازه بدون بعد ذرات، عدد فرود معین ودبی رسوب (Cv, Frm, Dgr, d۵۰/y) و در حالت بستر رسوبگذاری شده مدل با پارامترهای ورودی عرض نسبی بستر رسوبی، عدد فرود معین و عمق نسبی بستر رسوبی و دبی رسوب ((Cv, ys/D ,Frm ,Wb/y۰ نتایج مطلوبصتری را ارائه میصدهند .آنالیز سری داده ها به صورت جداگانه منجر به جوابصهای دقیقصتری نسبت به تر کیب دادهصها می گردد و ترکیب کردن داده ها از کارایی مدل می کاهد .نتایج به دست آمده برای ضریب دارسی وایسباخ در مقایسه با ضریب مانینگ از دقت بالاتری برخوردار است
This study contains five sections: In the first section, hexacyanoferate(III) intercalated Ni-Al layered double hydroxide was synthesized by coprecipitation method. The as-prepared LDH structurally and morphologically was characterized using Xray diffraction, Fourier transform IR, scanning electron microscopy and energy dispersive Xray analysis (EDX) techniques. The electrochemical behavior of as-synthesized nanoparticles modified glassy carbon electrode was investigated. The modified electrode was applied for mediated oxidation of acetaminophen. Some variables affecting the electrochemical behavior of acetaminophen were studied. The electrocatalytic response of the modified GC electrode was linear in the PC concentration range 31500 M, with a detection limit of 0.8 M, using hydrodynamic amperometry. The fabricated sensor was successfully applied to determination of acetaminophen in various pharmaceutical preparations such as tablets, oral solution, and oral drops and human serum sample. In the second section, mercaptoacetic acid was intercalated in MgAl layered double hydroxide using ion exchange method. The synthesized nanoparticles were characterized using different techniques. The as-synthesized nanoparticles modified glassy carbon electrode was used for the determination of trace mercury using square wave anodic stripping voltammetry. Several variables affecting the stripping peak current of Hg(II) such as the type and concentration of supporting electrolytes, pH value, deposition potential and deposition time, were carefully optimized. The effects of some potentially interfering ions were also investigated. Under optimal conditions, the proposed sensor exhibited a wider linearity range from 2.0 to 800 nM Hg(II) with a detection limit of 0.8 nM. Finally, this newly prepared sensor was successfully applied to determination of Hg(II) in water samples. In the third section, Ag nanodendrites (AgNDs) were electrodeposited on the surface of a Zn-Al layered double hydroxidemodified glassy carbon electrode. Investigation of the modified electrode surface with various techniques revealed that AgNDs were successfully synthesized on Zn-Al LDH surface. Voltammetric measurement of double layer capacitance was used to evaluate the real surface area of the modified electrode. Excellent electrocatalytic activity, high stability, and good repeatability make this sensor a good candidate for pyrazinamide determination. Using differential pulse voltammetry technique, the calibration plot was obtained with two linear dynamic ranges (0.985 and 85520 M) and the detection limit of 0.72 M. The fabricated sensor was used for the determination of pyrazinamide in commercial pharmaceutical tablets and biological fluids. In the fourth section, the poly(tyrosine) film modified glassy carbon electrode was fabricated. The electropolymerization parameters of poly(tyrosine) were discussed in detail. Afterwards, Co-Al layered double hydroxide nanoparticles were drop casted on the poly(tyrosine) modified electrode. The morphology and chemical composition of the modified eleectrode was illustrated by scanning electron microscopy and energy dispersive Xray analysis techniques. The fabricated electrode indicated excellent electrocatalytic activity toward the reduction of diazepam. The calibration plot of diazepam obtained via differential pulse voltammetry technique consists of two linear segments in the concentration ranges of 0.210 and 1060 M. The limit of detection was found to be 0.078 M. The proposed method was applied for determination of diazepam in the pharmaceutical tablets and human plasma samples. In the last section, a nanocomposite of Zn-Al layered double hydroxide and nickel cobaltite was synthesized. Crystalline structure of the nanocomposite was studied by X-ray diffraction technique. The nanocomposite modified glassy carbon electrode surface was investigated by scanning electron microscopy and energy dispersive Xray analysis techniques. Electrochemical behavior of pyridoxine on the fabricated electrode was studied. The fabricated sensor via differential pulse voltammetry technique exhibited linear range of 0.2200 M and the detection limit of 0.086 M for pyridoxine. The fabricated sensor was applied for the determination of pyridoxine in pharmaceutical tablet and human plasma samples
Preparation of modified electrodes based on layered double hydroxides nanoparticles and their electroanalytical applications