Search

In order to meet increasingly stringent total nitrogen limits, supplemental carbon must be added to improve the performance of the biological nutrient removal process. An industrial by-product that contained ethylene glycol and propylene glycol was used as a substitute carbon source for methanol in this study. The objectives of this study were to investigate the efficiency of using the glycol mixture as carbon source, including the calculation of denitrification rate and yield at two different initial concentrations of glycols. Possible inhibition effect on nitrification was also investigated. Three SBR reactors were operated by adding methanol, a low dosage of glycol, and a high dosage of glycol into the reactors. The low dosage glycol reactor exhibited the best performance, with the highest denitrification rate of 11.55 mg NOx-N/g MLVSS"h and the lowest yield of 0.21 mg VSS/mg COD. Small nitrite accumulation was observed in the low dosage glycol reactor (COD=185"•15 mg/L), but effluent quality was not influenced. Excess glycol in the reactor caused deteriorated performance. The high dosage glycol reactor (COD=345"•20 mg/L) performed with the lowest denitrfication rate of 8.56 mg NOx-N/g MLVSS"h and the highest yield of 0.55 mg VSS/ mg COD. The reactor with the high dosage of glycol also inhibited the lowest nitrification rate of 1.15 mg NH3-N oxidized/g MLVSS"h, which indicated that excess glycol may cause nitrification inhibition.

Air monitoring was performed on an aircraft deicing fluid collection system at the Cincinnati/Northern Kentucky International Airport (CNKIA). The goal of the study was to determine employee exposure to ethylene glycol and the target compounds of decomposition as maintenance was performed on the system. The maintenance work involved performing confined space entries to repair and maintain various diversion chambers, pump stations and storage tanks used to collect and convey spent aircraft deicing fluid. The collected deicing fluid during the period of the study was primarily ethylene glycol based. The study included low flow area air sampling of selected diversion valve pits, pump stations and storage tanks for the presence of ethylene glycol as well as ethanol, formaldehyde, and acetaldehyde which are suspected end products of decomposition of ethylene glycol. The study also included the collection of weekly samples using Draeger Tubes to test for ethylene glycol. Samples were collected in the spring, summer and winter months. The results of the study revealed that the target compounds of decomposition were detected in various concentrations throughout the sample study. All results for the decomposition compounds were well below established regulatory and recommended levels. The weekly analysis for ethylene glycol revealed the potential for exposure to ethylene glycol at the diversion valves and to a lesser extent at the deicing pad pump stations during periods of heavy deicing. Ceiling limits for ethylene glycol at deicing fluid collection valves appear to be exceeded during periods of deicing fluid use greater than 750 gallons per day.

The objective of this study was to determine the effect of molecular weight on the function of polyethylene glycols (PEGs) as lubricant sparing binders in tabletting technology. Compression-force and ejection-force profiles were obtained using an instrumented Manesty D3B rotary tablet press. In order to determine the lubricating mechanism of PEGs, after storage in controlled settings, PEGs of different molecular weight were compressed. PEG-8000 resulted in compacts with the greatest crushing strength, PEG-3350 next, and PEG-20M last. Scanning electron microscopy showed, while PEG-20M compacted by plastic deformation, both PEG-3350, and PEG-8000 had compacted by brittle fracture, with evidence of melting during compression. It was concluded that lubrication properties of PEG-20M was due to its plastic deformation properties. PEGs were also studied for their binding mechanism. A full factorial experimental design using three binder levels and three compression forces, using 0.5% magnesium stearate was utilized. Low-shear wet granulation, high-shear wet granulation, and roller-compaction were utilized using acetaminophen as the model drug. Tablets with a target weight of 310 mg were compressed using 9-mm shallow concave punches at 19 RPM. ANOVA was used to analyze the results based on the PEG molecular weight, levels, and compression force (P < 0.05). PEG-20M proved to be the superior binder to all other polyethylene glycol binders using all three manufacturing methods, and comparable or superior to povidone. PEG-20M produced tablets with lower friability than PEG-8000 and PEG-3350. It also resulted in tablets with the highest dissolution rate for acetaminophen, including the reference binder. PEG-20M resulted in tablets with acceptable friability using low-shear and high-shear wet granulation, and roller compaction with significantly lower tablet ejection forces than other polyethylene glycols or povidone. It was concluded that PEG-20M is a unique molecule, with higher porosity, and flexibility than lower molecular weight PEGs. It is only a better binder than other PEGs, but also enhances the dissolution of acetaminophen, a poorly soluble drug (channeling agent). Under the conditions studied, PEG-20M had the best "binder efficiency", granule size flow and homogeneity, and tablet crushing strength friability and dissolution results.

The synthesis and characterization of poly(ethylene glycol methyl ether)-b-poly(imino-1,2-ethanediyl)('+), its precursors and derivatives are described. Poly(ethylene glycol methyl ether) was tosylated and the tosylate was used to initiate the polymerization of 2-methyl-2-oxazoline. The resulting block copolymer, poly(ethylene glycol methyl ether)-b-poly (acetylimino)-1,2-ethanediyl *, was separated by fractional precipitation and characterized by gel permeation chromatography and thin layer chromatography. Thus, the (acetylimino)-1,2-ethane- diyl block copolymer was free from the contamination of the poly- meric initiator residue. Poly(ethylene glycol methyl ether)-b-poly (acetyl-imino)1,2-ethanediyl was hydrolyzed to give poly(ethylene glycol methyl ether)-b-poly(imino-1,2-ethanediyl hydrochloride). This hydrochloride salt was characterized by both potentiometric titration and dilute solution viscosity measurements. Interaction of the charged sites were understood in this linear polyelectrolyte. The imino-1,2-ethanediyl backbone polynucleotide analog was prepared by grafting 2-(thymin-1-yl)propionic acid onto the imino-1,2-ethanediyl copolymer. This polynucleotide model compound was soluble in water up to about 0.01 g/10 ml. Hypochromicity as deter- mined by UV absorption indicated that local ordered conformations were present in this model compound. Interactions between the imino-1,2-ethylanediyl backbone polynucleotide analog and poly-A in aqueous solutions were also studied by UV spectroscopic method. Interactions were only observed in neutral water. (l) N-Cbz-Alanine, (L) N-Cbz-phenylalanine, (L) N-Cbz-O-t-Bu-serine and (L) N-FMOC-proline were grafted onto poly(ethylene glycol methyl ether)-b-poly(imino-1,2-ethanediyl) by coupling the protected amino acids and the polyamine with either N,N-dicyclo- hexylcarbodiimide (DCC) or diethylcyanophosphate (DEPC). The DCC route was able to give some optically active products whereas the DEPC route failed to give any optically active grafted polymer. The removal of the FMOC group was easier than the removal of the Cbz group. ('+)Also named as poly(ethylene glycol methyl ether)-b-poly(ethylenimine). *Also named as poly(ethylene glycol methyl ether)-b-poly(N-acetyl ethylenimine).