In this study, polymer/silica hybrid composites were developed using grafting techniques for potential applications as adsorbent, heterogeneous catalyst, and ion exchange resin. Two commonly used grafting techniques i.e., radiation-induced grafting and emulsion graft polymerization have been explored to modify the surface of the commercially available silica microparticles with different monomers to fabricate composite materials for environmental applications. The mesoporous silica particles with high surface area, tunable pore size, and narrow pore size distribution were modified by treating with vinyltriethoxysilane to introduce polymerizable vinyl functionality on the particle surface for in-situ polymerization of various monomers to achieve polymer/silica hybrid composites. Silica/poly(acrylonitrile) and silica/polystyrene hybrid composites were fabricated by in-situ grafting of acrylonitrile (AN) and styrene (St), from surface of the modified silica (MS) microparticles, respectively. Radiation induced grafting was achieved by using the Co-60 irradiator. Systematic and detailed studies have been carried out to investigate the influence of various grafting parameters, i.e., gamma absorbed dose and monomer concentration, on the grafting of acrylonitrile. Under the optimized conditions of 1:12 silica to monomer ratio (w/v) and 20 kGy absorbed dose, afforded the highest grafting (748 %, the value indicates the % increase in weight of the silica particles after the AN grafting). Radiation induced grafting in a solvent free system provided eco-friendly route by avoiding hazardous organic solvents. The emulsion graft polymerization AN was carried out with potassium persulfate as initiator and tween 80 as surfactant in aqueous medium. Systematic investigations were carried out to elucidate the effect of monomer, initiator, and surfactant concentration on the grafting. The optimized conditions were found to be 6% monomer, 0.15 % initiator, and 1 % surfactant concentration that afforded the highest grafting (296 %). The nitrile (-CN) groups of the grafted poly(acrylonitrile) were converted into amidoxime functionality by treating with hydroxylamine. The emulsion grafting route is free from the requirements of using higher monomer concentration, costly organic solvents, and special equipment. In 2nd study, styrene was grafted onto modified silica particles to afford silicagrafted- styrene composite via radiation induced grafting and subsequent sulfonation of the grafted polystyrene. The effect of grafting conditions, such as absorbed dose, monomer concentration, and the type of solvent used was investigated in detail. The structural and morphological investigations of the hybrid composites were carefully performed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET) nitrogen adsorption-desorption isotherms. The amidoxime grafted silica materials prepared were evaluated as adsorbent for Cu(II) ions from the aqueous solution and were found to have higher loading capacities of 172 mg/g and 130 mg/g, respectively, for radiation-induced and emulsion grafted samples. The hybrid materials after loading with Cu(II) ions were also employed as heterogeneous catalyst for the reductive degradation of methylene blue (MB) in the presence of NaBH4 as reductant. The reduction process followed pseudo-first-order kinetics and the rate constant (k) was calculated 0.6224 min-1. The hybrid catalyst was found to be highly effective for the degradation of MB and can be easily recovered and reused several times with no appreciable loss of catalytic activity. The ion exchange capacity (IEC) of the fabricated silica-grafted-sulfonated styrene composite resin was evaluated by ion exchange titrations (back titration method). The IEC was found to be in the range of 0.43-2.97 meq/g depending on the degree of grafting. The facile fabrication method and high IEC value could lead to potential application of the fabricated resin in ion exchange resin in waste water treatment and metal recovery.
It goes without saying that peace has been a hot issue in the past; it is, still, a vital topic of discussion today, and it seems to continue to draw the attention of people in the future. We witness wars and destructions in several parts of the world. This has led to killings of millions of people, left innumerable number of families broken and displaced millions of people. We need to address it earnestly. The author of this dissertation has specified this topic with reference to the Holy Qur’ān, because being the book of Allāh Almighty, it means to us as the final constitution, the ultimate torchlight for our guidance, and a great blessing to the whole world. Peace means to be free from the calamities in this world and in the hereafter. Usually, peace is used to imply an opposition to war and violence between the nations. Peace is a virtue and it means absence of evil, and, therefore, it is always praiseworthy. The author of this paper deals with this topic by dividing it into six sections. These are, ‘The Peace’ as one of the divine names of Allāh Almighty; Peace equals good; Peace is praiseworthy; Peace in the sense of conciliation and security; Peace in the sense of customary Islamic salutation; and Refutation of the objection that Islām was spread by sword.
Safety and availability are prime factors for nuclear power plant operation. Safe operation requires a well-built backup of safety systems for saving plant capital cost, environment and the public. The backup system is maintained with the use of active and passive safety systems in the form of engineered safety features. Traditionally, active safety systems have been utilized for counteracting accidental conditions. These systems require proper and timely operator actions, which is some time misleading. Now a day, passive safety systems are becoming more popular due to their dependence on forces of nature for operation and actuation. Passive operations include, under gravity flow, natural recirculation of fluid and nitrogen gas pressure. For such type of systems, when certain conditions are met and the passive operation is started automatically. Therefore, world nuclear community has started using passive safety systems in the present nuclear power plant technology due to the simplicity in operation, maintenance and safety enhancement. This thesis concentrates on the augmentation of passive safety features in small scale pressurized water reactor design. The research was started with the study and simulation of a small scale reference power plant. The scope of simulation includes safety systems including necessary nuclear and conventional island. The individual process systems and related electrical systems are simulated and integrated within the frame work of their respective instrumentation and control to form a standalone simulated model for a reference power plant. Using this model, design basis accident has been modeled and the response of the safety systems together with related primary systems has been observed. Satisfactory results have been experienced in this regard. The research was extended by designing and simulating a passive safety injection system. This proposed system consists of many passive components and functions in place of an existing safety injection system for mitigating loss of coolant accidental condition. The use of proposed passive system has been suggested only for intermediate type pipe breaks because for small breaks, the depressurization is slow and only high pressure charging system is utilized whereas for larger breaks, the depressurization is very fast and low pressure safety injection system is actuated rapidly. Therefore, in a simulation test run this proposed system has been tested and verified for intermediate coolant loss accident. It has been found that the response of the proposed passive system is satisfactory and it keeps all necessary safety parameters within range. Through this research, it is concluded that the proposed passive system could be a potential candidate for handling intermediate type breaks representing loss of coolant accidents in small scale pressurized water reactors. For other accidental conditions of the plant like steam generator tubes rupture and steam line break, the use of conventional way of accidental management has been suggested. Keywords: Advance NPP, Passive safety, Analysis, LOCA, Reliability