Urea-assisted water electrolysis in an alkaline environment effectively treats urine-rich wastewater and prevents the release of ammonia gas and nitrate pollution into groundwater and drinking water; these contaminants typically result from the discharge of untreated urea into rivers and lakes. On the other hand, Urea-assisted water electrolysis is an efficient method for electrochemically producing hydrogen from water, while simultaneously cleans urea-polluted water. During this process, urea is oxidized at the anode to produce N? and CO?, while pure hydrogen is produced at the cathode and can be easily collected as a valuable green fuel. Compared to conventional water splitting, this method requires 70% less thermodynamic energy to produce H?. Expanding this technology to industrial applications, such as treatment of wastewater plants and farms, could prevent health problems and costs associated with toxic gas emissions, and contribute to the emerging hydrogen economy. In this thesis, two nickel-based bifunctional catalysts were synthesized, and their feasibility for use in the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) was investigated due to their superior electrocatalytic performance. In Chapter 1, an introduction to Urea-assisted water electrolysis and its importance is provided. In Chapter 2, a cerium-nickel bimetallic metal-organic framework (NiCe-MOF) was synthesized on nickel foam (NF) via a solvothermal method to enhance its conductivity and electrochemical properties. The prepared nanocomposite was characterized using various techniques, including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and Field emission scanning electron microscope (FESEM). The structure of NiCe-MOF/NF was thereby determined. The electrocatalytic performance of the modified electrode toward UOR in an alkaline solution containing 0.5 M urea was evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and other electrochemical methods. Compared to stepwise-modified electrodes, the urea oxidation current on NiCe-MOF/NF was substantially increased and exhibited high stability after 200 potential cycles between 0.0 and +0.8 V. Furthermore, chronopotentiometry (CP) performed at a constant current density of 20 mA cm?² showed a very small potential drop for NiCe-MOF/NF over 20 h, confirming its excellent stability. On the other hand, linear sweep voltammetry (LSV) studies showed excellent electrocatalytic performance towards HER (in KOH, 1 M), with an overpotential of 145 mV at a current density of 10 mA cm?². Furthermore, CP stability tests demonstrated good stability of the proposed catalyst during 20 h of HER operation. The fabricated two-electrode cell, consisting of (-)NiCe-MOF/NF?NiCe-MOF/NF(+), required only 2.22 V to reach a current density of 100 mA cm?² and exhibited excellent stability, with just a slight voltage drop after 20 h of Urea-assisted water electrolysis. The superior electrochemical performance toward urea oxidation and hydrogen evolution was attributed to the effective synergy between nickel and cerium within the MOF structure. In Chapter 3, a chalcogenide was employed in the preparation of an efficient bifunctional electrocatalyst for H2

The ongoing global shift towards sustainable energy paradigms has intensified the focus on electrochemical water-splitting technologies as a pivotal route for generating 'green hydrogen. This cutting-edge method is integral to mitigating the global imperative of replacing fossil fuel-derived energy systems and substantially curbing CO? emissions. As the energy landscape evolves towards cleaner and more sustainable alternatives, water electrolysis has emerged as one of the most viable strategies for hydrogen production, owing to its scalability and environmental benefits.   Chapter 1 offers a thorough exploration of the core principles underpinning water electrolysis, examining the fundamental electrochemical processes responsible for the dissociation of water molecules. Furthermore, it presents an exhaustive analysis of the most efficacious catalysts, emphasizing those that have exhibited remarkable performance in improving electrolysis efficiency, durability, and operational stability. This chapter aims to lay the groundwork for a deeper understanding of the intricate nature of electrochemical water-splitting and underscores the indispensable role of catalysts in optimizing the entire process, thereby contributing to the overarching objective of achieving a carbon-neutral energy future. In Chapter 2, zeolitic imidazolate framework-67 (ZIF-67) was employed as a precursor for the synthesis of Co3S4 via a simple sulfidation technique. The resultant Co3S4 nanostructures were effectively immobilized on the surface of NiTe2 nanoflowers (denoted as NiTe2 NFs@Co9S8/NC nanocomposite), and their catalytic efficiency in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting was extensively investigated. The synthesized NiTe2 NFs@Co9S8/NC nanocomposite demonstrated impressive electrocatalytic performance, exhibiting overpotentials as low as 146 mV for HER and 260 mV for OER at a current density of 50 mA cm-2 in a 1.0 M KOH electrolyte. The integrated alkaline electrolyzer, containing NiTe2 NFs@Co9S8/NC, achieved a low cell voltage of 1.51 V at 10 mA cm-2, significantly enhancing the water-splitting process and maintaining robust stability for 30 hours. This exceptional electrocatalytic activity is attributed to the efficient electron transfer facilitated by the NiTe2 nanoflowers framework, the abundant accessible active sites within the Co3S4, and the synergistic interactions between the composite components. The results from this chapter not only emphasize the potential of NiTe2 NFs@Co9S8/NC nanocomposite for efficient water splitting applications but also outline a promising approach for the development of effective, non-precious metal catalysts for energy conversion and storage, fostering the advancement of scalable and sustainable energy technologies.   

  In the present thesis, thepossibility of using different nanomaterials in fabricating effectiveimmunosensors for rapid diagnosis of prostate cancer has been studied, followedby the construction of the corresponding devices.In Chapter 1, we mainlyfocused on the theoretical information about electrochemical biosensors andimmunosensors based on nanoparticles and nanocomposites.In chapter 2, reports the fabrication of a sensitivelabel-free immunosensor for PSA based on the Au  / polyhedral hollow Co-Cu bimetallicsulfide Nanostructure using differential pulsevoltammetry (DPV) and electrochemical impedancespectroscopy (EIS).Chapter 3, we introduced a novel-typeelectrochemical immunosensor for the quantitative detection ofprostate-specific antigen (PSA) using square wave voltammetry and amperometric measurements.The results on the applicability of gold nanoparticles/ hollowcobalt-based sulfide polyhedral as a modifier and silver nanowires@ZIF-67nanocomposite (Ag NWs@ZIF-67) as a label in the immunosensor are reported. .

   Abstract The presence of heavy metals in drinking water has harmful and harmful effects on human health. Iron is one of the metal ions whose amount affects the water quality. The world health organization has stated that the amount of iron in drinking water is 0.3 mg/L. If iron concentration is increased, it will give an unpleasant taste to the water and higher concentrations indicate the presence of industrial effluents and factory wastewaters. In the first part of this research, a simple and selectable colorimetric method was used to measure Fe(II) and Fe(III) ions. In the first work, in order to detect Fe(II) in water samples of different regions, paper colorimetric sensors based on nanocellulose and phenanthroline and also colorimetric sensors in the glass substrate were used.The recorded images of samples were analyzed with Image Analyzer software to abtain RGB indices. Their plotted curve was linear in the concentration range, 1.0×10-5-1.0×10-3 M with detection limit, 8.75×10-6 M. The relative standard deviation of this method was less than 2% and the relative error was less than 20% for all four samples. In the second work, carbon dots were used to reduce Fe(II) to Fe(III) and form red complex. The plotted curve was 1.0×10-5-1.0×10-3 M, and the detection limit was linear 6.5×10-6 M. The relative standard deviation was less than 1.5% and the relative error for Moallem neighborhood water was 9.1%, Chambashir and Taqbostan rivers were 21.4% and 7.7%. Also the proposed method was used to measure the amount of iron in the rock samples. In the first sample, the percentage of iron was 0.11 % and in the second sample was 0.44 %. The relative error was 25% for the first and 3.3% for the second sample. Also the proposed method was used to measure the amount of iron in the rock samples. In the first sample, the percentage of iron was 0.11 % and in the second sample was 0.44 %. The relative error was 25% for the first and 3.3% for the second sample. Sulfite is one of the most common methods of preserving dried foods. In addition to long-term storage, sulfite is also effective in preserving food color. The world health and food and agriculture organization have determined acceptable daily intake of sulfite for adults 0.7 mg/kg body weight and the allowable amount of sulfite in food is 10 ppm. In the second part of this study, the observed color change due to the reduction of   Fe(III) to Fe(II) and formation of red iron(II) complex with phenanthroline were used to identify and measure sulfite. In the first work, a paper sensor was used to detect and measure sulfite in food samples such as plums, apricots and raisins. The recorded images of samples were analyzed with Image Analyzer software to abtain RGB indices. The plotted curve was linear in the concentration ranges of 1.0×10-5-1.0×10-4 M and 3.0×10-4-1.0×10-2 M. The detection limit was 4.5×10-6. The relative standard deviation for all three samples was less than 2% and the relative error for was less than 15 %. In the second work, paper sensor was used to detect sulfite colorimetric in gas phase (sulfur dioxide). Hydrochloric acid was used to form the gas and to prevent the gas from leaving the adhesive tape. After 5 minutes the color change was observed and the rgb digital images recorded from the samples were obtained. The plotted curve 1.0×10-4-1.0×10-1 M linear and the detection limit was 9.0×10-5. The percentage of relative error was less than 10% for the samples.   

   In recent years, electrochemical methods with the help of modified electrodes have become widely popular as simple, cheap, and accurate methods with high sensitivity in measuring drugs. This thesis presents the development, electrochemical characterization, and analytical application studies of two voltammetric sensors developed for the widely used drug Naproxen (NAP). In this thesis, low-cost electrode modifiers developed from anion-doped transition metal compounds and their composites with carbon nanotubes have been investigated. The thesis is divided into three chapters.

Sodium dithionite (Na?S2O4) is a highly reactive white crystalline powder with a sulfur smell. And in particular, it Is used as a strong reducing and bleaching agent in many applications, including biological sciences, textiles, papermaking, and food industries. Lead or silver.The purpose of this research was to measure sodium dithionite in flour and bread samples using silver nanoparticles functionalized with black mulberry. Flour and bread samples purchased from bakeries all over the city were examined. The linear range and detection limit were 0.2 to 5.6 mg and 0.1 liter/mg, respectively. The correlation coefficient (R2=0.958) was close to was 1 and the measurement error of the method is less than 20%.Determination of water hardness is of vital importance for potable water. And also for water used in industrial purposes. Hard water creates a cloudy and undesirable layer on hair, cloth, and glassware.Water hardness is generally caused by barium ions, iron ions, strontium ions, zinc ions, calcium ions, and magnesium ions. Traditionally, total hardness is defined as the sum of the concentrations of calcium ions and magnesium ions in milligrams per liter of calcium carbonate (CaCO? ) is defined.In this method, due to the non-specific but selective behavior of silver nanoparticles synthesized with these ions, successfully to determine the total hardness of water, this is the same event that occurs in standard titrimetry, it is possible to determine the hardness of silver nanoparticles prepared All the water used. The color changes of silver nanoparticles in the presence of different water samples were confirmed, which Is a good indicator of the hardness of the whole water samples. This method was used quantitatively and semi-quantitatively to determine the hardness of all water samples.Next, PLS was used for the first time to directly determine the total hardness of water samples.Sodium hydrogen carbonate or sodium bicarbonate with the formula (NaHCO?) is one of the sodium salts combined with carbonic acid, where only one acidic hydrogen of this compound is replaced by sodium. This composition Is odorless and tasteless, it has a slightly pungent effect and is in the form of a white or crystalline powder, and it is called baking soda. Bicarbonate is moisture absorbent and deodorizer. Sodium hydrogen carbonate is also used to make bread dough porous.In this work, to measure sodium bicarbonate, silver nanoparticles were first synthesized from black mulberry quantum dots. The linear range obtained from the method is 2 to 6.5 mg and the limit of detection is 0.1 liter/mg, the measurement error The method for the real sample is 15%.Keyword: sodium dithionite, sodium bicarbonate, baking soda, flour, bread, silver nanoparticles, quantum dots, water hardness, colorimetry 

AbstractDue to the reduction of water resources all over theworld, it is very important to investigate the removal of all kinds ofpollutants from surface and underground water. Therefore, the aim of this studywas to investigate the absorption of methylene blue dye from the aqueoussolution prepared in the laboratory using zeolite improved with manganese. Forthis purpose, the base material (zeolite) was first synthesized and calcinedusing chemical deposition technique. Then, in the next step, manganese element wasdoped in the synthetic zeolite structure using the doping process. Thesynthesized materials were analyzed and morphologically examined using XRD,FTIR, TGA, BET, EDX, Maping and SEM analyses. The results showed that thesynthetic material was correctly synthesized and also the material was on anano scale. In the next step in this study, the absorption tests were measuredand analyzed to determine the effective parameters on the absorption efficiencyof the dye, such as the amount of nanoabsorbent material, pH, temperature,time, and the initial concentration of the dye. The results showed that thebest absorption performance is in the amount of 45 mg of adsorbent, pH equal to11, temperature equal to 70 degrees centigrade, time equal to 12 minutes and initialconcentration of colored substance equal to 10-9   Molar has happened.Key words: optimization, kinetics, nanoadsorbent, zeolite, manganese, magnesium, color.  

   Electrochemical sensors are known for their numerous advantages such as simplicity, low cost, high selectivity and high sensitivity. Hence, they have become powerful tools direction measuring various samples including foodstuffs, environment, disease diagnosis, medical surveys and security systems. Electrochemical sensors are >     In the first chapter of this section, a brief introduction of sensor and its types, voltammetric techniques, chemically modified electrode, materials used for electrode correction, check of studied analytes and research history is provided.    In the second chapter, a sensitive and selective voltammetric sensor which based on glassy carbon electrode modified with zirconium oxide-porous carbon/reduced graphene oxide (rGO) nanocomposite for the detection of ascorbic acid (AA) is presented. The platform was obtained by calcination of a metal-organic framework (MOF) attached to graphene oxide. Different methods were used for surface characterization. The electrochemical behavior of prepared electrode for the determination of ascorbic acid was systematically investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Compared with the bare glassy carbon electrode (GCE), ZrO2-PCs/rGO/GCE exhibits much higher electrocatalytic activities toward the oxidation of ascorbic acid (AA) with increasing of peak currents and decreasing of oxidation overpotentials. Under optimum conditions, the modified electrode exhibits linear response to ascorbic acid in the range 1.49×10-1-9.8×10+3?M, with detection limit (S/N = 3) calculated to be 5.2×10-2 ?M. The electrochemical sensor presented the advantages of high selectivity, excellent reproducibility (RSD %= 0.379%) and repeatability (RSD %= 0.162%) and long-term storage stability. In addition to this ZrO2-PCs/rGO/GCE sensor was practically applied for the routine analysis of AA in various food and pharmaceutical samples. In the third chapter, by the method of carbonization of a metal-organic framework (MOF), porous carbon nanocomposite containing zirconium oxide (ZrO2-PCs) was prepared, which was proposed for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The morphology and structure of ZrO2-PCs obtained was characterized by different methods. In addition, the electrode modified with nanocomposite was studied by various electrochemical methods, i.e., cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) to investigate the electrochemical behavior. ZrO2-PCs/GCE showed high selectivity and excellent electrocatalytic activity to discriminate the three biomolecules. At the optimized conditions, wide linear range 1×100-6×10+3, 5×10-1-2.21×10+2, and 5×10-1-2.71×10+2µM of towards AA, DA, and UA in ternary mixture were observed, respectively. The modified electrode offers superior anti-interference capability, good repeatability (RSD %= 2 AA, 2.22 DA, 4.71UA) and reproducibility (RSD %= 2.59 AA, 4.48 DA, 1.37UA) and long-term stability. In addition, ZrO2-PCs/GCE was successfully used for the simultaneous measurement of AA, DA and UA in real samples.

در مطالعه ديناميك مولكولي (MD)، فرآيند اكسيداسيون تركيبات مبتني بر بنزيميدازول و بنزوتيازول در دماهاي اوليه مختلف توضيح داده شده است. فرآيند اكسيداسيون در سيستم هاي اتمي تعريف شده توسط دما، انرژي پتانسيل، انرژي پيوند، انرژي برهمكنش و تعداد محاسبه پيوند بين اتمي گزارش شده است. خروجي‌هاي MD دما و انرژي پتانسيل سيستم‌هاي تعريف‌شده را نشان مي‌دهند كه پس از 10 ns به نسبت محدود همگرا شده‌اند. براي شبيه‌سازي فرآيند تعادل در گروه NPT تحقيقاتي ما با استفاده از Nose-Hoover barostst اجرا شد. علاوه بر اين، محاسبات ما نشان مي دهد كه فرآيند اكسيداسيون با حداكثر شدت پس از 10 ns رخ مي دهد. همچنين نتايج MD نشان داد كه افزايش دماي اوليه در فرآيند اكسيداسيون تركيبات بنزيميدازول و بنزوتيازول پارامتر مهمي است و با بزرگ شدن اين پارامتر فيزيكي تا 375 كلوين، تعداد پيوندهاي بين اتمي به 1175 پيوند افزايش مي‌يابد كه اين تغيير پيوند نشان مي‌دهد كه فرآيند اكسيداسيون با شدت بيشتري رخ مي‌دهد. .  

   AbstractIn wastewater treatment, a variety of efficient issues such as theeco-friendly and cost-effective nanomaterials have been developed to have theunique functionalities for the potential decontamination of industrial effluents,surface water, ground water and drinking water. Amongorganic contaminants, the dyes are considered to be the serious pollutants dueto their toxicity. Conventional water treatment processes are very diverse andinclude physical decolorization techniques (such as, sedimentation, filtration,adsorption, and reverse osmosis), chemical decolorization techniques (such as,neutralization, recovery, chemical oxidation and ion exchange methods), andbiological decolorization techniques.Among the various kind of photocatalytic semiconductors, the metaltungstates have grabbed the considerable attention. In this research, the binary nanocomposite of cobalttungstate/reduced graphene oxide hasbeen synthesized by the hydrothermal method. One of the problems that limited the use of thesenanoparticles in the photocatalyst process is the rapid recombination ofelectrons and hole. Therefore, present research has focused on the modification of cobalt tungstate/reduced graphene oxideby adding nickelhydroxide. The results showed that the structure of the Co/Ni/RGO had asuitable photocatalytic activity in the destruction of the direct red 16(DR16). The maximum photodegradation efficiency of DR16 were obtained at concentration of 5 ppm, pH of solution,catalyst loading 2 g/L and irradiationtime 60 minutesconditions.   The catalyst was foundto be reusable, even after several runs and its catalytic activity was almostthe same as that of freshly used catalyst. The amount of the recovered catalyst(wt.%) was measured after each run. The results showed that weight losses ofthe catalyst during the operation was negligible. The synthesized photocatalystwas characterized by using the Fourier transform infrared, scanning electronmicroscopy, X-ray diffraction, Transmission electronmicroscopy, X-ray photoelectron spectroscop, electron dispersive X-ray, diffuse reflectance spectra, andphotoluminescence.

   In the first stage of this study, high-rate simultaneous carbon, nitrogen, phosphorus (CNP) removal from soft drink wastewater (SDW) in a jet loop-air lift membrane bioreactor was modeled and optimized. For this purpose, the effect of four independent factors including hydraulic retention time (HRT) (8-16 h), anaerobic volume to total working volume ratio (VAn/VT) (0.04-0.12), air flow rate (AFR) (3.5-5.5 l/min), and influent nitrogen concentration (150-300 mg/l) on the bioprocess performance were evaluated. Chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) removal efficiencies were 97%, 63%, and 81%, respectively, at optimum conditions (HRT: 14h, VAn/VT: 0.06, AFR: 5.5 l/min, influent nitrogen: 225 mg/l). As a result in this step, it can be noted that HRT and AFR had direct positive effect on biological CNP removal while VAn/VT had direct negative effect. Influent nitrogen concentration had no direct effect on COD and TP removal efficiencies but had direct negative effect on TN removal efficienciy. In the second stage, for water reuse with a high quality from SDW, jet loop-air lift bioreactor was coupled with membrane dead-end set up. For this purpose, reactor effluent at optimum condition was post treated by an optimal ultrafiltration membrane modified by boehmite-tannic acid-graphene quantum dot (BM-TA-GQD) as a hydrophilic nanoparticle. The modified mixed matrix membrane (MMM) showed an improvement in hydrophilicity (contact angle reduction from 75.45 to 59.38) and antifouling properties (reversible resistance (Rr) from 8.8 to 41.78 % and flux recovery ratio (FRR) from 44.58 to 71.35 %) in comparison to bare membrane. As a conclusion, the combination of the jet loop-air lift bioreactor and selected membrane (0.5% wt. of BM-TA-GQD) can be considered as an effective and low-cost approach for water reuse with a high quality.