چكيده فارسي :
Abstract: Organic dyes is one of the major groups of pollutants widely used in textile, plastic, medicine and many other industries, while the hazardous effects of organic dyes in waste water have been a major concern and now a major threat in the environment due to the substantial pollution problems caused by them. These industries exhausted large quantity of high content color effluents, which are generally more toxic and resistant to destruction by conventional methods. A necessary criterion in the use of these dyes is that they must be highly accumulated in water and stable in light during washing. The accumulation of these dyes in the water bodies causes eutrophication, reduces the reoxygenation capacity and makes severe damage to the aquatic organisms by hindering the infiltration of sunlight [1]. They must also be resistant to microbial attack. Therefore, they are not readily degradable and are typically not removed from water by wastewater treatment systems and conventional methods like adsorption, ultrafiltration, chemical and electrochemical methods [2]. The superiority of photocatalytic degradation by nanocatalyts in wastewater treatment is due to its advantages over the conventional methods, such as quick oxidation, no formation of polycyclic products and oxidation of pollutants. It is an effective and rapid technique in the removal of pollutants from wastewater [3]. In this research a novel strategy of utilizing supramolecular polymerization for fabricating nitrogen doped porous graphene. Melamine-cyanurate solves restacking problems of graphene sheets by creating spaces between layers. In addition, it acts as a wealthy source of nitrogen which can like trapping centers. Phosphotungstic acid anchored to the trapping centers of melamine-cyanurate and penetrated in situ between graphene sheets. The designed catalyst characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) , X-ray diffraction, vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy(FT-IR). The heterogeneous catalytic system was investigated for the reduction of 4-nitrophenol, methylene blue and methyl orange in the presence of NaBH4 as a reducing reagent in an aqueous medium at 25 °C. The catalytic reaction followed pseudo-first-order reaction kinetics, as monitored using UV-visible spectroscopy. The results show that the reactivity of new prepared heterogeneous catalyst is similar to a homogeneous catalyst.
