Sharif Digital Repository

Bimetallic nanoparticles with unique structure, synergistic effect between two metals, and the tunable physical/chemical properties have been used for catalysis. Various methods exist for the staibility, and improvement of the catalytic performance of nanoparticles. In this thesis, different co-catalysts were applied to increase tha staibility, and activity of nanoparticles and metal oxides. In this way, Ni-based bimetallic nanoparticles including CuNi, CoNi, and AgNi, and AgPt with different concentrations were synthesized on the cerium oxide nanorods derived from cerium metal-organic frameworks and magnetic graphene oxide nanosheets, respectively and characterized. The catalytic... 

Freeze desalination as a water refining method has attracted a lot of attention due to its potential in lowering process energy consumption compared to other methods. This method is based on the fact that the dissolved salt is drained from the saline water during its freezing. The current study conducts a parametric study on freezing saline water in a cylindrical container to investigate the impact of geometric and functional factors affecting the desalination quality. This has been done by examining the aforesaid factors in the form of dimensionless parameters such as thermal Grashof number, solutal Grashof number, and Jacob number. In addition, in order to improve the desalination, a novel... 

In the past decades, hydrogels have been used as an adsorbent with high potential to remove pollutants in water. Hydrogels are three-dimensional polymer networks that have the ability to absorb and store water and water-soluble compounds due to the presence of hydrophilic functional groups in their structure. Different particles with unique characteristics can be used to increase the efficiency of hydrogel absorption. Based on the type of pollutant, hydrogels are divided into three different forms, including particles, films and nanocomposites. In this research, the absorption effect of metal cations as well as the absorption kinetics of polyvinyl pyrrolidine-based hydrogels, sodium... 

Chlorinated hydrocarbons such as trichloroethylene form a kind of dense non-aqueous phase liquid contaminants in groundwater and soil that are so difficult to remediate. In recent years, many field research has been demonstrated application of nano scale zero valent iron can degrade these contaminants.
In this research, nZVI particle synthesized by liquid phase reduction method. Nickel (25%wt ) has been added to increase the reduction rate and also reduce intermediate pollutions. However, the combination of a noble metal to nZVI, leads to more rapid oxidation and tendency to agglomeration. So nZVI particles coated by applying a water soluble-starch solution (0.4%wt) as a stabilizer. The... 

Biological layers are one of the main problems related to water transfer with pipe lines which are formed through time in the inner surface of the pipes by the water nutrients. Hence, the inner surfaces in the pipe lines and water refineries should be made in order not to let these biological layers to be made. The reason is that when the biofilm is formed on these surfaces, the traversing water is polluted. Dredging of these pipes is not only necessary in most of the countries in the world and needs huge amounts of water but is also very complex and expensive.In this research, nanomaterials, namely ZnO, T〖iO〗_2،S〖iO〗_2 have been used to cover the surface of concrete and steel pipes (The... 

to achieve a stable elimination of colloidal suspended particles, polymer flocculants such as polyacrylamide and its derivative have been more used. To improve the performance of removing turbidity, reducing settling time, and better dewatering from sediments, hydrophobic styrene monomer copolymerized with acrylamide monomer. In this study the copolymer of acrylamide and styrene was synthesized by inverse emulsion polymerization, then this copolymer undergoes hydrolysis to form anionic groups on the polymer backbone. FT-IR, H NMR, and TGA analyses were carried out to investigate the structure of the copolymer. To evaluate flocculation, turbidity tests, zeta potential, and sedimentation rate... 

Fresh water has always been one of the basic needs of human. Thus using different methods for water purification becomes more important in recent years. In classic methods such as distillation chamber and thermal method, water flux was always low and salt rejection wasn’t satisfactory. So investigating new methods such as nanofiltration becomes more important. This method has high efficiency and good water flux in compare with old methods. One of the useful materials in nanofiltration is grapheme oxide (GO). GO sheets make an array of nanochannels and this membrane improves filtration and water flux. Different parameters affect water flux and salt rejection in this membrane. Restructuring... 

World population is increasing with a rapid paste while the availability of freshwater is becoming more scared. There is a severe lack of fresh water in the world today. Desalination of seawater is one of the significant options in hand to solve this problem. In this research a hybrid solar collector- high efficiency water purification system is introduced which can help to solve this problem with an interesting economic outlook. Renewable energies and desalination plants are two different technologies, which can be combined in various ways. The interface between the renewable energy system and the desalination system is met at the place/subsystem where the energy generated by the renewable... 

In this study three type of nanofiltration membranes were prepared from PVC for water softening; (i) asymmetric PVC nanofiltration membrane, and two different thin film composite (TFC) membranes: (ii) polyamide (PA)/PVC composite membrane (iii) poly vinyl alcohol (PVA)/PVC composite membrane. Asymmetric nanofiltration membranes were prepared by phase inversion. The effect of PVC concentration, solvent (THF) and additive (PVP) on morphology and performance were studied by scanning electron microscopy (SEM) and measuring pure water flux and salt rejection. Increasing PVC concentration decreased pure water flux and increased salt rejection. Adding tetrahydrofuran(THF) decreased the pure water... 

In this study preparation of polymeric membrane for grey water treatment is examined. Grey water is the wastewater that is produced by household activities such as baths, showers and sinks. These sources make 50 to 80 percent of total household wastewater. Because of low contamination of these kind of wastewater, they can be treated with Nanofiltration membrane process. Membrane used for treatment is thin composite polyamide membrane. This membrane is made with interfacial polymerization reaction of Piperazine and m-phenylenediamine as amine monomer and trimesoyl chloride as chloride acid monomer on a Polysulfone ultrafiltration membrane. In order to promote the flux, Polyethylene glycol is... 

The N-doped rGO/NiFe2O4@Ti-doped ZnO as a novel ternary nanocomposite with magnetic recyclable was obtained by a facile and low-cost hydrothermal method. The structure, morphology, and optical as well as magnetic properties of synthesized nanocomposite were analyzed using the X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), Raman spectroscopy, Emission scanning electron microscopy (FESEM) with Energy dispersive spectra, Transmission electron microscopy (TEM), UV-vis diffusive reflectance spectra, and Vibrating sample magnetometer (VSM). The photocatalytic activity was determined by the degradation of Methylene blue (MB) and Methylene orange (MO) dyes under visible light... 

One of the most efficient and effective methods of water and wastewater treatment is the use of membranes and can be a good alternative to traditional methods such as adsorption, chemical coagulation and .... One of the limitations of this method is membrane fouling, which limits its use in industry.In this study, ultrafiltration membrane made by phase inversion method from a combination of PVDF and SPES polymers and surface modified with hyperbranched polyethylene imine and its performance in cationic coating paint purification was investigated. Also, the performance of this membrane has been investigated by calculating the separation rate, pure water flux, contact angle and specifications... 

One of the major environmental problems in recent years is the presence of micropollutants that cause many problems for the environment and living organisms. Diclofenac is one of the micropollutants and endocrine disruptors. Conventional treatment methods do not have the ability to effectively remove pharmaceutical pollutants and micro-pollutants, and finding a suitable approach to remove these pollutants is of great importance. In recent years, biological methods such as the use of enzymes and molds have received attention, but due to the relative removal of pollutants, these methods have been combined with membrane technology to improve the level of pollutant removal and increase the... 

Water is one of the world’s most valuable resources, yet it is under constant threat due to climate change, explosive population growth, and waste. One of the most promising efforts to stem the global water crisis is river contaminated, water reclamation and reuse. This study was carried out to investigate in the water quality “S. H. C.” using treatment techniques. Research project was to check out which method give maximum removal of TOC, COD and coliform, fecal coliform and TSS where this parameters exceeded the permissible limits and therefore “S. H. C.” water was contaminated by these parameters. After carrying out the study more from 8 month on water treatment "S. H. C." we get the... 

Novel zeolite-based micromotors consisted of silver-exchanged zeolite core and three different partial catalytic coatings (Mg/Au, Pt and Ag) were synthesized to eliminate the biological and chemical contamination from water in a fast and efficient way. These engines are benefited by the adsorption capacity and antibacterial activity of silver-zeolites in combination with the autonomous propulsion of catalytic micromotors. The remarkable bactericidal capacity of these particles relies on reactive silver ion released from zeolite and accordingly, increased chance of contact with bacteria during movement. These motors showed rapid killing of bacteria and effective elimination of the Pseudomonas... 

Contaminants in drinking water, including microbial contaminants, have a great impact on the health of people in the community and can seriously threaten public health. In recent years, diseases caused by pathogenic bacteria due to the consumption of contaminated water have led to many deaths. As a result, water treatment has been one of the most important human concerns. Among the new water treatment technologies, metal-organic(MOF) frameworks are a new generation of porous materials that have properties such as high surface area, water stability and functionality due to their dual structure. As a result, they are widely used today in various scientific fields, including water purification.... 

Nowadays capacitive deionization (CDI) has attracted a lot of attention for water treatment. CDI is an emerging water treatment technology that uses electrophoretic driving forces for desalination of water. During the CDI process, ions are adsorbed onto the surface of electrodes by applying a low voltage electric field (DC<2V). In addition, the regeneration of the electrodes contains desorption of the electrosorbed ions from the surface of the electrodes to the water in the absence of the applied electric field. In the mechanism of CDI, separation and accumulation of ions in the electric field are the main processes and no additional chemicals are required in this technology. Therein,... 

Membranes are one of the best water and wastewater treatment methods that could successfully replace other less-effective conventional techniques such as adsorption, coagulation, etc. Moreover, relative to other techniques, the quality of the water produced by membrane separation is very high compared to others. One of the main drawbacks of membrane treatment is fouling of the surface and internal pores of the membranes restricting its widespread application in the industry.In this study, TiO2@MIL-88A (Fe) photocatalyst and polyacrylonitrile membrane were modified with this photocatalyst to remove humic acid under visible light irradiation inside the PMR photocatalytic reactor was... 

Microalgae is a major problem in water resources due to its adverse influence on water treatment process and water quality like color, odor and taste. In addition microalgae removal is an important process in food and pharmacy industry. Electrocoagulation is a potential method for microalgae removal. Another method for microalgae recovery is membrane treatment. This study is focusing on using both methods separately and simultaneously. To achieve this, the removal of Chlorella Vulgaris, a fresh water microalgae, was used in experiments. In first phase the experiments were solely on electrocoagulation and the effect of several parameters including current density, electrocoagulation duration,... 

Statistics show that plastic production in the world is increasing, with 335 million tonnes in 2016 reaching 367 million tonnes in 2020. Since the presence of plastics in the dimensions of micro and nano, especially in aquatic environments can have adverse effects on human health and other living organisms, it has raised major environmental concerns. Therefore, it is necessary to think of measures to remove them and develop efficient methods for eliminating and decomposing microplastics. Recently, the advanced oxidation processes have attracted much attention because of the ability to eliminate recalcitrant compounds. In this study, electrochemical techniques and Fenton-based techniques for...