Current Issue : July - September Volume : 2013 Issue Number : 3 Articles : 6 Articles
With the advance technology and the increase in the population, plastics product were found one of the part in every aspect of our life. Plastics are a broad name given to different polymers with high molecular weight, which also can be possible degraded by various processes. Plastics have wide range of application in each and vary aspect of our life. Every one using different kind of plastics materials every day because of it’s easily available and low cost of production. But Plastics material remain in nature for decades. One of the ways to solve such a problem is to find out ways for degradation of Plastics. Degradation means change in polymer properties due to chemical, physical or biological reactions resulting in bond scissions and subsequent chemical transformation. A biodegradable plastic is an innovation means of solving the plastics disposal problem from the standpoint of development of new materials. In view of facts concerning plastic bio degradation, in this paper, An attempt has been made to take a short review on degradation, types of degradation, biodegradation, mechanism of biodegradation and its applications....
A new residence-time distribution (RTD) function has been developed and applied to quantitative dye studies as an alternative to the traditional advection-dispersion equation (AdDE). The new method is based on a jointly combined four-parameter gamma probability density function (PDF). The gamma residence-time distribution (RTD) function and its first and second moments are derived from the individual two-parameter gamma distributions of randomly distributed variables, tracer travel distance, and linear velocity, which are based on their relationship with time. The gamma RTD function was used on a steady-state, nonideal system modeled as a plug-flow reactor (PFR) in the laboratory to validate the effectiveness of the model. The normalized forms of the gamma RTD and the advection-dispersion equation RTD were compared with the normalized tracer RTD. The normalized gamma RTD had a lower mean-absolute deviation (MAD) (0.16) than the normalized form of the advection-dispersion equation (0.26) when compared to the normalized tracer RTD. The gamma RTD function is tied back to the actual physical site due to its randomly distributed variables. The results validate using the gamma RTD as a suitable alternative to the advection-dispersion equation for quantitative tracer studies of non-ideal flow systems....
In an earlier work the author had studied the degradation kinetics of polyethylene terephthalate (PET), polytrimethylene\r\nterephthalate (PTT), and polybutylene terephthalate (PBT) under nonisothermal conditions in air and N2 at heating rates of\r\n5, 10, 15, and 20?C/min. In this paper the kinetic degradation parameters of PET, PTT, and PBT were estimated using the Coats-\r\nRedfern method for two different weight loss regions ranging from 2ââ?¬â??8% (Zone I) and 8ââ?¬â??40% (Zone II). A comparative analysis\r\nof the enthalpy-entropy compensation effect for these polyesters in air and N2 is presented. A linear relationship was found to exist\r\nbetween entropy and enthalpy values. The following criteria were applied to establish an enthalpy-entropy compensation effect and\r\nto check the presence of an isokinetic temperature: (a) Exnerââ?¬â?¢s plot of log k3T1 versus log k3T2 , and (b) Krug et al. linear regression\r\nof ?H versus ?G. By the use of the latter two methods, varying isokinetic temperatures were obtained. These temperatures were\r\nnot in the range of the experimental work conducted, indicating that these systems do not display compensation phenomena....
Reactive crystallization designed to separate nickel or copper ion from effluents has been advanced for applying to actual industrial wastewater containing impurities. In the primary reaction of this method, metal sulfate solution reacts with sodium carbonate solution in a semibatch crystallizer. In the present study, during the process of nickel or copper ions incorporation, inhibitory effect on seed growth of impurities, like cobalt, manganese, zinc, and borate and phosphate ions, was investigated. Through the 8-hour reactive crystallization, obtained particles� characters and metals removal efficient were examined. Considering analyses data on metal component ratio in produced crystals, metal ions initial uptake rate was found to be different by the kind of seeds and impurities. And the centrifugation was performed against obtained crystals aimed for examining target metal purity improvement. The results indicated that copper components can incorporate and remove other metal ions easily. In addition, when the anions are used as impurities, depending on the kind of anions, the effect of damaging the surface of seeds or producing many fine particles has been confirmed....
The food additive named polyglycerol polyricinoleate (PGPR) and identified with the code E-476 (PGPR) is used as emulsifier in tin-greasing emulsions for the baking trade and for the production of low-fat spreads. However, the main application of PGPR is in the chocolate industry, where, besides its action as an emulsifier, it also has important properties as a viscosity modifier and thus improves the moulding properties of the molten chocolate. An additional property of PGPR in chocolate is its ability to limit fat bloom. Known chemical methods for preparing this emulsifier involve long reaction times and high operating temperatures, which adversely affect the quality of the final product leading to problems of coloration and odors that could make it inadvisable for the food industry. As an alternative, the enzymatic synthesis of PGPR by the catalytic action of two lipases has been developed. The enzymes act in mild reaction conditions of temperature and pressure, neutral pH, and in a solvent-free system, which makes the process environmentally friendly and avoids side reaction, so that the product has a higher purity and quality....
Zeolites have been shown to be useful catalysts in a large variety of reactions, from acid to base and redox catalysis. The particular properties of these materials (high surface area, uniform porosity, interconnected pore/channel system, accessible pore volume, high adsorption capacity, ion-exchange ability, and shape/size selectivity) provide crucial features as effective catalysts and catalysts supports. Currently, new applications are being developed from the considerable existing knowledge about these important and remarkable materials. Among them, those applications related to the development of processes with less impact on the environment (green processes) and with the production of alternative and cleaner energies are of paramount importance. Hydrogen is believed to be critical for the energy and environmental sustainability. It is a clean energy carrier which can be used for transportation and stationary power generation. In the production of hydrogen, the development of new catalysts is one of the most important and effective ways to address the problems related to the sustainable production of hydrogen. This paper explores the possibility to use zeolites as catalysts or supports of catalysts to produce hydrogen from renewable resources. Specifically, two approaches have been considered: reforming of biomass-derived compounds (reforming of bioethanol) and water splitting using solar energy. This paper examines the role of zeolites in the preparation of highly active and selective ethanol steam reforming catalysts and their main properties to be used as efficient water splitting photocatalysts....
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