Ambient Processes

Cooling is routinely appHed, either with ambient process water if THF is the solvent or with chilled brine if diethyl ether is used. Since Grignard reagents are particularly reactive with water, Hquid hydrocarbon coolants may be preferred, to eliminate the risk that could arise from a cooling-system leak. 

Morawska L, Ristovski Z, Jayaratne ER, Keogh DU, Ling X (2008) Ambient nano and ultrafine particles from motor vehicle emissions characteristics, ambient processing and implications on human exposure. Atmos Environ 42 8113-8138... 

It should be stable at above ambient processing temperatures, typically 45-65°C. 

Zhang M, Wexler A, Zhu Y et al (2004) Evolution of particle number distribution near roadways. Part II the road-to-ambient process. Atmos Environ 38 6655-6665... 

Density measurements were carried out on crushed glass pieces obtained fiom the same sample set as used for FTIR and UV-Vis spectroscopy measurements by the Archimedes method. Deionized water with a few drops of surftictant was used as the weighing mediuiiL A wire mesh, hung fiom a support fiame connected to a balance, was used to suspend the samples in the water. A thermometer was clipped to the water beaker to continuously monitor the water bath temperature. Sis glass samples were used fiom two different batches at each condition, vacuum and ambient processing, for tbe density measurement... 

Assuming a density of 2.5 x 10 kg/m, the dissolved water concentration (in mass fraction) calculated using Eq. (1) was found to be 0.0237 0.0027% in the ambient processed glass and 0.0194 0.0015% in the vacuum processed glass. The density of both ambient and vacuum processed glasses was assumed to be the same for this calculation. This assumption is reasonable as will be shown below. The dissolved water concentration values obtained in this work are in reasonable agreement with those found by Fenstermacher et al. [2] and by Jewell et al. [3]. 

The adsorption literature often classifies the adsorptive processes in terms of (a) Pressure Swing Adsorption (PSA) when the adsorption step is carried out at a super-atmospheric pressure level and the lowest desorption pressure is ambient (Processes A, D, E, F, G), (b) Vacuum Swing Adsorption (VSA) when the adsorption step is carried out at near-ambient pressure level and the lowest desorption pressure is sub-ambient (Processes H, I) and (c) Pressure Vacuum Swing Adsorption (PVSA) when the adsorption step is carried out at a super-atmospheric pressure level and the lowest desorption pressure is sub-atmospheric (Processes B, C). 

Contamination from the processing gas can come from an impure gas source or contamination from the distribution line. Distribution lines for gases should be of staiidess steel or a fluoropolymer to reduce contamination. Gases can be purified near the point of use using cold traps to remove water vapor or purifiers to remove reactive gases. Purifiers may be hot metal chips (e.g. Ti) or cold catalytic luckel surfaces and should be sized to match flow requirements. Reactive gases can come from the ambient processing environment around the system. 

Figure 6.6 Photograph of rubber crumb groimd using an ambient process. Reproduced with permission from Smithers Rapra Technology Ltd, Shawbury, UK. 2006, Smithers Rapra Technology Ltd...

Chem. Descrip. 40% Silicone polyether copolymer in cyclopentasiloxane Uses Emulsifier for antiperspirants, creams and lotions, pigmented disps, sunscreens, color cosmetics, hair care prods., conditioners Features Wash-off resistant ambient processing can be used in cl. prods, Properties Opaque liq. vise. 10,000-50,000 cP f.p. < -40 C flash pt. 77 C 40% act. 

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