Abstract  The addition of oxygen-bearing compounds to diesel fuel considerably reduces particulate emissions. TGME and DBM have been identified as possible diesel additives based on their physicochemical characteristics and performance in engine tests. Although these compounds will reduce particulate emissions, their potential environmental impacts are unknown. As a means of characterizing their persistence in environmental media such as soil and groundwater, we conducted a series of biodegradation tests of DBM and TGME. Benzene and methyl tertiary butyl ether (MTBE) were also tested as reference compounds. Primary degradation of DBM fully occurred within 3 days, while TGME presented a lag phase of approximately 8 days and was not completely degraded by day 28. Benzene primary degradation occurred completely by day 3 and MTBE did not degrade at all. The total mineralized fractions of DBM and TGME achieved constant values as a function of time of approximately 65% and approximately 40%, respectively. Transport predictions show that, released to the environment, DBM and TGME would concentrate mostly in soils and waters with minimal impact to air. From an environmental standpoint, these results combined with the transport predictions indicate that DBM is a better choice than TGME as a diesel additive.

Abstract  The appropriate combination of viscosifier and coviscosifier is a very important factor in the control of the viscosity and adhesion properties of chemical decontamination gels. A chemical decontamination gel was prepared by adding gelling agents composed of a pyro Si viscosifier and PEG-based non-ionic coviscosifier (tripropylene glycol butyl ether and tripropylene glycol dodecyl ether) into a Ce(IV) solution stabilized in concentrated nitric acid. The decontamination and rheological behaviours, along with the drying behaviours of a chemical gel for SUS 304 metallic surfaces contaminated with Co and Cs radionuclides were investigated. A chemical gel containing a 0.5 wt % tripropylene glycol dodecyl ether coviscosifier was more effective in terms of the rheological and drying-detachment properties and the radionucleide decontamination effectiveness in particular, compared to tripropylene glycol butyl ether.

Abstract  A solid-phase microextraction (SPME) device was used as a diffusive sampler for airborne propylene glycol ethers (PGEs), including propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and dipropylene glycol monomethyl ether (DPGME). Carboxen-polydimethylsiloxane (CAR/PDMS) SPME fiber was selected for this study. A polytetrafluoroethylene (PTFE) tubing was used as the holder, and the SPME fiber assembly was inserted into the tubing as a diffusive sampler. The diffusion path length and area of the sampler were 0.3 cm and 0.00086 cm(2), respectively. The theoretical sampling constants at 30°C and 1 atm for PGME, PGMEA, and DPGME were 1.50 × 10(-2), 1.23 × 10(-2) and 1.14 × 10(-2) cm(3) min(-1), respectively. For evaluations, known concentrations of PGEs around the threshold limit values/time-weighted average with specific relative humidities (10% and 80%) were generated both by the air bag method and the dynamic generation system, while 15, 30, 60, 120, and 240 min were selected as the time periods for vapor exposures. Comparisons of the SPME diffusive sampling method to Occupational Safety and Health Administration (OSHA) organic Method 99 were performed side-by-side in an exposure chamber at 30°C for PGME. A gas chromatography/flame ionization detector (GC/FID) was used for sample analysis. The experimental sampling constants of the sampler at 30°C were (6.93 ± 0.12) × 10(-1), (4.72 ± 0.03) × 10(-1), and (3.29 ± 0.20) × 10(-1) cm(3) min(-1) for PGME, PGMEA, and DPGME, respectively. The adsorption of chemicals on the stainless steel needle of the SPME fiber was suspected to be one of the reasons why significant differences between theoretical and experimental sampling rates were observed. Correlations between the results for PGME from both SPME device and OSHA organic Method 99 were linear (r = 0.9984) and consistent (slope = 0.97 ± 0.03). Face velocity (0-0.18 m/s) also proved to have no effects on the sampler. However, the effects of temperature and humidity have been observed. Therefore, adjustments of experimental sampling constants at different environmental conditions will be necessary.

Abstract  PPG-2 methyl ether, PPG-3 methyl ether, and PPG-2 methyl ether acetate are used in cosmetics as fragrance ingredients and/or solvents at concentrations of 0.4% to 2%. Propylene glycol ethers are rapidly absorbed and distributed throughout the body when introduced by inhalation or oral exposure, but the inhalation toxicity of PPG-2 methyl ether vapor, for example, is low. Aerosols, such as found with hair sprays, produce particle sizes that are not respirable. Because these ingredients are highly water-soluble, they are likely to be absorbed through the human skin only at slow rates, resulting in low blood concentrations and rapid removal by the kidney. These ingredients are not genotoxic and are not reproductive or developmental toxicants. Overall the data are sufficient to conclude that PPG-2 methyl ether, PPG-3 methyl ether, and PPG-2 methyl ether acetate are safe as used in cosmetics.

Abstract  Desalination via forward osmosis using draw agents whose regeneration is aided via liquid-liquid phase separation has gained much attention in recent years. In the present study, mixtures of two different glycol ethers, tripropylene glycol methyl ether and tripropylene glycol n-butyl ether, have been studied as potential draw agents. Water activity, viscosity and diffusion coefficient of draw solutions have been measured at different mixture compositions, concentrations and temperatures. Osmotic pressures of these draw solutions decreases strongly with increasing temperature. Forward osmosis experiments performed with these draw solutions reveal appreciable initial loss of trans-membrane water flux, reverse solute flux and severe concentration polarization.