الفهرس 
Water contaminationOnly 14 pages are availabe for public view
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Abstract
The processes of coagulation, adsorption, and advanced oxidation are the most commonly used methods in water treatment, whether for drinking or other industrial purposes. Graphene oxide (GO) is used in many applications due to its characteristic properties and high ability to eliminate various pollutants, either as an adsorbent or a catalyst. The present study aims at improving the quality of water by removing many natural and industrial pollutants existing in raw surface water collected from El-Kased conduit, Tanta City, Egypt, using nanomaterials such as GO as an alternative coagulant to alum, the most abundant material used in water treatment, to reduce the proportion of aluminum released in water after treatment. The effect of chitosan (as a coagulant aid) on the coagulation efficiency of GO was also investigated. In addition, the nanocomposite of copper oxide and iron oxide (CuO/α-Fe2O3)was also used to remove industrial dyes and heavy metals. The thesis contains three main sections: The first section comprises an introduction and literature survey of the natural and industrial pollutants present in surface water and the different techniques used in treating them. It also contains a description of the process of coagulation/flocculation and various coagulants used in this process. It also includes information about the process of 310 advanced oxidation. This section also presents an overview of GO, its properties, its preparation methods, and its application in removing water pollutants by adsorption. The second section describes the materials used in this study: their sources, preparation of the required solutions, as well as the devices and methods used to study the properties of prepared nanomaterials and the characteristics of water before and after the treatment process. The third section comprises the results and discussion. It contains the results of characterization of the GO and CuO/α-Fe2O3 using many characterization techniques such as FTIR, X-ray powder diffraction, UV-Visible spectrophotometry, transmission, and scanning electron microscopy techniques. It divided into three parts. The first part contains the coagulation results of GO for removing the turbidity and other substances or organisms suspended in the collected surface water. GO has proved an excellent ability to remove natural and artificial turbidity from surface water with efficiency exceeding 90% in a wide range of pH at all levels of turbidity. Remarkably, GO showed excellent ability to remove HB and FCB reaching 98.75% and 96% at a dosage of 40 mg/L. The coagulation effectiveness of GO was strongly affected by water alkalinity. Besides, GO did not show any significant effect on the characteristics of raw 311 surface water such as alkalinity, TDS, hardness, COD, and chloride and nitrogen content (NO2, NO3, and NH3) after the treatment. The recycling applicability of GO following coagulation/flocculation makes it economically efficient. As well, after the treatment process, there is no residual of GO in the neutral and alkaline media but in acidic media, traces of GO are detected in treated water which increase by increasing the acidity. In comparison, alum which is the most commonly used coagulant in water treatment, leaves traces of aluminum at all pH values. Thus, GO is superior to alum in that respect. The effect of chitosan as a coagulant aid on the coagulation efficiency of GO as a main coagulant was also studied. Chitosan has shown an excellent ability to improve the coagulation ability of GO. It was found that the addition of small doses of chitosan to GO reduced the required dosage of GO in the coagulation process, and also increased the sedimentation speed of the formed flocs to less than 10 minutes to reach standard levels of turbidity. The efficiency of the removal of turbidity and algae was 99% or more in a wide range of pH range (pH 4 -10), where the efficiency increase in the acid media than in alkaline ones. In addition, the binary coagulation system (GO/CS) showed no effect on the chemical characteristics of water. However, it reduced the values of COD and DOC. The dual system (GO/CS) 312 showed a high ability to remove dyes by coagulation. The removal efficiency was 100% for direct brown (DB2) and 80% for the methylene blue (MB). For heavy elements, the removal efficiency was 60% for lead ions and more than 40% for nickel ions. Sludge resulting from the coagulation/flocculation process was also reused as an adsorbent composite in removing more dyes and heavy metals showing high efficiency and capacity in the removal. This makes it superior to many other materials used in removing the same pollutants. On the other hand, the secondary materials resulting from chlorine application in water purification process were investigated in the presence of GO and (GO/CS). Trihalomethane (THM) compounds were selected, representing the largest percentage of secondary materials resulting from the chlorination process. The results showed that the use of GO as a coagulant with chlorine as a water disinfectant was safe until the concentration of 4 mg/L of chlorine. The GO then began to interact with the free chlorine. However, THM secondary materials did not exceed the approved permissible limits. In the case of the binary (GO/CS) system, chitosan worked to protect GO from the interaction with chlorine free in treated water. The second part presents the results of the catalytic oxidative degradation of various organic dyes (DV4, MB, RhB) using 313 CuO/α-Fe2O3 as catalyst and H2O2 as oxidant. The obtained data were found to fit with the first-order kinetics with respect to dyes concentration. Different parameters such as initial dye concentration, initial H2O2 concentration, catalyst dose, contact time, and pH have been used to optimize the oxidation reaction conditions. The reaction rate was found to increase by increasing H2O2 concentration, catalyst dose, contact time and temperature. Study of pH effect, the results showed that the acidic media were optimal for DV4 and RhB, while the alkaline one was optimal for MB. The results also verify the complete degradation of dyes into simple inorganic products. The highest TOC removal efficiency of more than 60% mineralization was obtained. The thermodynamic activation parameters of the oxidative degradation reaction were determined with an endothermic nature of the catalytic reaction. The mechanism of the oxidative degradation of the studied dyes was proposed that is based on holes and free radicals generated by the catalytic reaction between the nanocomposite and H2O2. For the stability of the catalysts, it has been shown to be excellent for reuse more than five times. The third part contains the results of the uptake of lead ions from water using CuO/α-Fe2O3 nanocomposite by adsorption that showed high efficiency in removing lead ions from water. The effect of many 314 factors on the adsorption capacity of the nanocomposite has been studied. When analyzing the adsorption results and applying the Langmuir and Freundlich equations, it was found that the adsorption process follows the Freundlich equation. The use of different techniques such as clotting, adsorption and catalytic oxidation using various nanomaterials in this study may contribute to improve the quality of treated water.