PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF LOW SULFATE COALS

The perchloroethylene coal refining process utilizes perchloroethylene (PCE) as its solvent in all phases of the precombustion desulfurization process, including wet grinding, organic sulfur removal, gravitational separation of pyrites and mineral matter, and recovery of elemental sulfur (S₈). The Process is capable of producing compliance coal which emits less than 1.2 lb SO_X/MBTU when burnt, starting from 5 mass percent sulfur Midwestern and Eastern U.S. coals. However, the process efficiency was found to be very strongly dependent upon the degree of weathering or the level of coal oxidation. In this paper, perchloroethylene extraction data of fresh, low-sulfate coals are summarized and critically assessed. The extraction efficiency of the organic sulfur removal ranged from 5 to 30 percent for fresh coals, while that for weathered coals ranged from 30 to 60 percent. This study provides a valuable insight into the chemical reaction mechanism of perchloroethylene desulfurization process.     

Study of physicochemical properties of flutamide-loaded Ocimum basilicum microspheres with ex vivo mucoadhesion and in vitro drug release

Drug which shows extensive first pass effect is difficult task that, needs to be solved by formulators in the pharmaceutical science. The low oral bioavailability (49%) of flutamide may be due to poor wettability, low aqueous solubility and extensive first pass effect. The aim of present investigation was to prepare flutamide loaded microspheres and incorporate it into suppositories for rectal delivery to avoid first pass effect and enhance residence time. Flutamide loaded mucoadhesive microspheres of Ocimum Basilicum mucilage (OBM) were prepared using spray drying and characterized by percent production yield, encapsulation efficiency, particle size, zeta potential, polydispersity index, DSC, SEM, XRPD, in vitro drug release and stability studies. Moreover, ex vivo mucoadhesion was investigated using falling liquid film technique to determine the adhesion of microspheres to sheep rectal mucosa. The microspheres had nearly spherical shape and size about 2.53?μm. The encapsulation efficiency and mucoadhesion of optimized formulation MBF10 were found to be 69.6?±?2.3% and 89.01?±?2.18%, respectively. Percent CDR of optimized flutamide loaded mucoadhesive microspheres was found to be 88.7?±?1.3 at 7?h. In conclusion, OBM microparticles based suppository could be used to deliver drug through rectal delivery.     

Low-temperature synthesis of large-area CNx nanotube arrays

Well-aligned nitrogen-doped multiwall carbon nanotube arrays have been successfully grown over large areas on quartz and silicon wafers by floating-catalyst chemical vapor deposition at low temperatures (600 degrees C). These nitrogen-including nanotubes, derived from pyridine-ferrocene mixtures, have smaller outer diameters but larger inner diameters compared with carbon nanotubes grown from a xylene-ferrocene mixture under similar conditions. The N-doped nanotubes exhibit bamboo-like structures in the core. Elemental analysis and electron energy loss spectroscopy analysis show that the as-prepared nanotubes contain as much as 2.62 wt.% N, with most of the N concentrated in the inner few shells of the nanotube. Such large-scale arrays of well-aligned N-doped nanotubes on silicon wafers have a current density as high as 23.8 mA/cm2 at an applied electric field of 17 V/micron, which can be further improved by patterning the tubes and coating the silicon substrate with a conductive thin metal film for the fabrication of flat panel displays.     

EFFECT OF PYRITIC SULFUR AND MINERAL HATTER ON ORGANIC SULFUR REMOVAL FROM COAL

The perchloroethylene coal cleaning process uses perchloroethylene as the solvent to remove both organic and inorganic forms of sulfur without any significant loss to its calorific value. The process removes these forms of sulfur in two sequential unit steps. The objective of this investigation was to determine the exact sequence of operations in the Process. Hence, organosulfur was removed before and after depyriting and demineralizing the coal. The extent of total sulfur as well as organic sulfur removal were compared in both cases. It was found that the desulfurization is more efficient when organosulfur is extracted before pyritic sulfur and not vice versa, in the sequential removal of organic and inorganic forms of sulfur. The data presented in this paper reestablishes a fact that the mineral matter content in coal is quintessential to its organosulfur extractability.     

KINETICS OF PERCHLOROETHYLENE EXTRACTION DESULFURIZATION OF COALS

The perchloroethylene coal cleaning process selectively removes the organic sulfur from coal via a hybrid mechanism of chemical reaction and physical solvation It was found that the chemical reaction was catalyzed by the inorganic species present in the coal. In this paper, a kinetic study was experimentally carried out to determine rate constants of the reaction. It was confirmed that the extent of organosulfur extraction depended strongly on the type of coal, and also that there is a critical extraction time which is required as the minimum time for each type of coal. Isothermal batch kinetic studies were done for various types of coal. A relation was established between the type of coal and its kinetics and hence the minimumtime for extraction.     

EFFECT OF SOLVENT-TO-COAL RATIO ON ORGANOSULFUR EXTRACTABIL1TY IN THE PERCHLOROETHYLENE ORGANODESULFURIZATION PROCESS

A novel reaction-extraction model for removal of organosulfur compounds from coal by the Perchloroethylene Organodesulfunzation Process has been proposed. The model treats the coal as a reactant to observe the effect of slurry composition on the rate of “lock-up” reaction where the liberated organosulfur species from coal re-enters the coal organic matrix. A series of batch organodesulfunzation extractions were conducted to observe the effect of solvent-to-coal ratio on the extent of organosulfur removal. Based on this data, kinetic parameters for the organosulfur “liberation” and “lock-up” reactions were simulated using the model. The ratio of first-order rate constant of “lock-up” reaction to that of the “liberation” reaction was found to be 4.03. Optimal design parameters and operating conditions have been obtained for a wide range of PCE-to-coal ratio for Indiana 5 coal. Mathematical models representing the optimal slurry composition as a function of the ratio of rate constants, extraction capacity, and the corresponding extraction performance have been developed. This study is very significant from the point of view of reaction and process engineering, which in turn assist in achieving an optimal and economical equipment design.     

STATISTICAL ANALYSIS OF ORGANOSULFUR EXTRACTION DATA OF OHIO 5/6 COAL USING THE PERCHLOROETHYLENE COAL CLEANING PROCESS

The perchloroethylene coal cleaning process removes both organic and pyritic forms of sulfur using perchloroethylene as the solvent medium. The effect of process variables including temperature, extraction time, solvent to coal ratio and particle size of coal has been studied by a systematic 2⁴ full factorial experimental design with a single replicate. The process was found to be strongly dependent on the type of coal. Hence, this variable was controlled by choosing one single type of coal, i.e., Ohio 5/6 (1:1 mixture of Ohio 5 and Ohio 6 coals) throughout this entire investigation. The significant effects and interactions have been quantified by F-tests. The estimates of significant effects have been obtained by Yates algorithm. Residual probability and normal probability plots have been obtained to test model adequacy. Finally, a computational model has been developed to predict the organosulfur extraction efficiency of this coal at various values of process variables. The parity plots conclude that the model has a good interpolational predictive capability.     

SELECTIVE REMOVAL OF ORGANIC SULFUR FROM COAL BY TRICHLOROETHANE EXTRACTION

Desulfurization of coal involves removal of both organic and inorganic forms of sulfur. In this paper, the process feasibility of organic desulfurization of coal using 1,1,1-trichloroethane (TCA) as the solvent, is established. Sulfur solubility curve in tnchloroethane was obtained. The process conditions of this novel process were critically assessed. From the solubility curve it was concluded that the process should be carried out at or near the normal boiling point of the solvent. Comparisons between the TCA extraction and the perchloroeihylene (PCE) process have been presented. Since the boiling point of tricbloroethane is quite low, the process conditions are very mild in comparision to the PCE process. It was found that the TCA process is capable of removing organosulfur from coal more selectively than the PCE process. The sulfur containing organic species in the extract obtained from     

Electrochemical studies of kerosene-pyrolysedcarbon films

Polycrystalline thin films of conducting carbon are deposited on alumina substrates by the pyrolysis of kerosene vapour at 1000C for 2h in argon atmosphere. Preliminary structural analysis is done by XRD, laser-Raman, FTIR and SEM studies. The electrochemical behaviour of as-grown conducting carbon films was investigated in various electrolytes at different pH and the performance was compared with that of platinum and glassy electrodes. The electrochemical window of the kerosene carbon electrode in 100mm H2SO4 was found to be 2.91V which is greater than that of glassy carbon (2.79V) and platinum (2.02V). Cyclic voltammetry reveals that Pt electrode has almost an equal tendency towards hydrogen and oxygen evolution, whereas glassy carbon favours hydrogen evolution and kerosene carbon favours oxygen evolution. It is suggested that the kerosene carbon electrode can be used as an oxygen electrode more efficiently. Unlike diamond films or glassy electrodes, kerosene carbon thin films are of low cost and good stability; they are also easy to grow on various ceramic substrates of any size. Moreover, these electrodes are very economical and promising for application in chlor-alkali industry.