Essay Example on Size variation in the range of macro to Nano









Size variation in the range of macro to nano can bring difference in electrical chemical and magnetic properties of any materials Hence technical properties of nanoparticles are significantly different from their bulk counterpart which makes them commercially and technologically important Nanoparticles of ferrites are widely explored in making the recording devices permanent magnets electric motors automotive traction because of its high coercivity and saturation magnetization These properties can be modified by changing their chemical composition and micro structural characteristics which can be controlled during fabrication and synthesis processes Ferrite nanoparticles are also applied in chemical reactions due to their catalytic photo catalytic and photo electrochemical properties 270 271 Among the ferrites cobalt ferrites are known for their efficient separation after the completion of reactions reusability and magnetic recyclability Moreover high coercivity and moderate magnetization properties of cobalt ferrite make it as a well known hard magnetic material also These properties along with their great physical and chemical stability create CoFe2O4 nanoparticles suitable for magnetic recording applications such as audio and video tape and high density digital recording disks etc 272 274 Cobalt ferrite and nickel ferrite have high and low magneto crystalline anisotropy constant respectively 275 277 

Mixing of this two spinel ferrite will reveal exciting properties since it is a combination of two centrosymmetric magnetic materials This difference in magneto crystalline anisotropy constant introduces complexity in NixCo1 xFe2O4 materials and further the mixing of these two ferrites with suitable proportion has been found to produce materials with zero value of anisotropy constant which can generate intrinsic properties in the final materials 278 Population growth urbanization industrialization increased living standards and poor wastewater management strategies are responsible for release of contaminated wastewater into aqua ecosystem Dye and pigment industrial sectors are considered to be a main concern to the environment because of release of colored waste waters in the environment Further eutrophication can originate dangerous byproducts through oxidation hydrolysis or other chemical reactions which are taking place in the wastewater 279 282 Among these the presence of biologically and chemically stable toxic dyes and nitroaromatic compounds in wastewaters are of great concern as it is difficult to remove them by natural degradation processes 283 284 and have carcinogenic and mutagenic effects towards biosphere Further phenol and its derivatives constitute is also an important class of water pollutants because of their stability in water Nitrogen containing phenols are also of great concern not only because they cause severe health problems but at the same time they are significant poisons for catalysts 285 286 

Because of its significant water solubility it may also be found in ground water wells and surface waters Hence The successful removal of these hazardous contaminants or their transformation in to some helpful products before discharge is of utmost practical importance to achieve drinking water quality Hence the treatment of the effluents containing 4 nitrophenol becomes more inevitable Few treatment techniques which includes photocatalytic degradation 287 288 ozonation 289 290 Fenton process 291 and electrochemical method 292 etc are implemented for the degradation process But the utilization of ferrites as catalyst for the removal degradation or transformation of such contaminants is green inexpensive and facile method but not in practice Feng et al have been employed copper ferrite nanoparticles as catalyst for the reduction of 4 nitrophenol in the presence of NaBH4 as reducing agent and more than 95 conversion is achieved Sodium borohydride is a mild agent and the reaction can be conducted in an aqueous medium also The comparative catalytic efficiency of MFe2O4 M Cu Ni and Zn nanoferrites has been evaluated for the reduction of nitrophenols NP in the presence of NaBH4 as the reducing agent 294 295 From the research it was found that 50 equivalents of NaBH4 is the optimal amount In the present study Co1 xNixFe2O4 nanoparticles are synthesized from an aqueous solution containing metal nitrates urea and deionized water using a microwave via solution combustion method followed by crushing 

This method does not require the addition of any other chemicals to the solution and it has the advantages of simplicity low cost lack of by product formation and an environmentally friendly operation In a microwave oven microwave energy is absorbed due to the interaction of microwave radiation with the material and converted to thermal energy uniformly throughout a reaction container MCM technique have been rapidly developed over the other methods due to the reason that the microwave energy interacts with the reactants at the molecular level as a result of rapid heating of materials faster kinetics homogeneity higher yield better reproducibility of the products are observed To evaluate catalytic activity of the prepared materials degradation of 4 nitrophenol has been chosen as the representative member of the pollutant group because of its environmental importance In the first part of the work the textural and morphological characteristics of the prepared Co1 xNixFe2O4 nanoparticles are studied with various techniques to verify the particle size and distribution as well as to explore other parameters of interest The degradation kinetics of 4 NP in aqueous Co1 xNixFe2O4 nanoparticles suspensions was investigated in presence of NaBH4 as the reducing agent

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