Ethylene removal

An estimate for the G value for ethylene removal by ionic reactions can be made from the ion intensities of the 5-torr spectrum. First, the total intensity of accounted ions is set equal to unity. Then we multiply the intensities of the given ions by the number of ethylene molecules used up in their formation. Some of the weighing factors used were ... 

By keeping ethylene concentrations to less than 0.8 ul/1 of air, stem-end decay caused by a species of Fusarium, green mold, loss of orange flavor, and development of off-flavors were minimized. Other volatiles present with and without the ethylene absorber apparently had no effect on quality. Ethylene, produced in copious quantities by rots, enhances respiration and senescence of healthy fruit within the storage facility (281). The importance of ethylene removal has been illustrated also in recent storage studies of lemons in Australia (282, 283, 284, 285). 

Manufacturers of some of these products do not claim to remove ethylene specifically but to confer freshness on packaged produce. Some claims include both ethylene removal and favourable gas balance, whereas others include beneficial effects of emission of far-infrared radiation (Abe, 1990 Labuza and Breene, 1989). 

Stow J (1988) The effect of high carbon dioxide pre-treatments and ethylene removal on the storage performance of apples Cox s Orange Pippin. Sci Hortic 35 89-97... 

The levels of antifungal diene in the pericarp of whole avocado fruits could be increased by exposure to ethylene (40 pl/1) during 3 h. The diene content of the extracted pericarp increased by 50% 6 h after ethylene removal. Similar results were obtained at 35°C. 

The active or intelligent packaging has various modes of action such as removal, Oj barrier, water removal, gas indicator, ethylene removal, CO release, antimicrobial properties, and so on. Recently, new films known as time temperature indicators have also been introduced for commercial application. 

Suslow, T. Performance of zeolite based products in ethylene removal. Perishable Handhng Q., 92, 32-33 (1997). 

Zagory, D. Ethylene-Removing Packaging. M. L. Rooney (Ed.), Active Food Packaging, Black-ie Academic and Professional, London, pp. 38-54 (1995). 

Elsgaard L (1998) Ethylene removal by a biofilter with immobilized bacteria. Appl Environ Microbiol 64 4168-4173... 

In summary, the 5 nanoporous crystalline phase of SPS presents high ethylene solubility and low ethylene diffusivity, which can also be controlled by the orientation of the crystalline phase, associated with negligible water uptake. These features make polymeric materials presenting the 5-nanoporous crystalline phase of SPS suitable for ethylene removal and storage and, due to its chemical and mechanical properties, it can be considered suitable candidates as (also repeated use) produce packaging. 

Albunia, A. R., Minucci,T., Guerra, G. Ethylene removal by sorption from polymeric crystalhae frameworks./. Mater. Chem., 18,1046-1050 (2008). 

Condensation polymerization differs from addition polymerization in that the polymer is formed by reaction of monomers, each step in the process resulting in the elimination of some easily removed molecule (often water). E.g. the polyester polyethylene terephthalate (Terylene) is formed by the condensation polymerization (polycondensation) of ethylene glycol with terephthalic acid ... 

The first column removes ethane which, after treatment for storage, may be used as feed for an ethylene plant. The heavier hydrocarbons pass to the next fractionating... 

There are two additive terms to the energy, POP and TORS, that have not been mentioned yet because they are zero in minimal ethylene. The POP term comes from higher-energy conformers. If the energy at the global minimum is not too far removed from one or more higher conformational minima, molecules will be distributed over the conformers according to the Boltzmann distribution... 

Prepare a saturated solution of sodium sulphide, preferably from the fused technical sodium polysulphide, and saturate it with sulphur the sulphur content should approximate to that of sodium tetrasulphide. To 50 ml. of the saturated sodium tetrasulphide solution contained in a 500 ml. round-bottomed flask provided with a reflux condenser, add 12 -5 ml. of ethylene dichloride, followed by 1 g. of magnesium oxide to act as catalyst. Heat the mixture until the ethylene dichloride commences to reflux and remove the flame. An exothermic reaction sets in and small particles of Thiokol are formed at the interface between the tetrasulphide solution and the ethylene chloride these float to the surface, agglomerate, and then sink to the bottom of the flask. Decant the hquid, and wash the sohd several times with water. Remove the Thiokol with forceps or tongs and test its rubber-like properties (stretching, etc.). 

A solution of a-lithiomethoxyallene was prepared from nethoxyal lene and 0.20 mol of ethyllithiurn (note 1) in about 200 ml of diethyl ether (see Chapter II, Exp. 15). The solution was cooled to -50°C and 0.20 mol of ethylene oxide was added immediately. The cooling bath was removed temporarily and the temperature was allowed to rise to -15 c and was kept at this level for 2.5 h. The mixture was then poured into 200 ml of saturated ammonium chloride solution, to which a few millilitres of aqueous ammonia had been added (note 2). After shaking the layers were separated. The aqueous layer was extracted six times with small portions of diethyl ether. The combined ethereal solutions were dried over sodium sulfate and subsequently concentrated in a water-pump vacuum. Distillation of the... 

Diols that bear two hydroxyl groups m a 1 2 or 1 3 relationship to each other yield cyclic acetals on reaction with either aldehydes or ketones The five membered cyclic acetals derived from ethylene glycol (12 ethanediol) are the most commonly encoun tered examples Often the position of equilibrium is made more favorable by removing the water formed m the reaction by azeotropic distillation with benzene or toluene... 

Ester interchange reactions are valuable, since, say, methyl esters of di-carboxylic acids are often more soluble and easier to purify than the diacid itself. The methanol by-product is easily removed by evaporation. Poly (ethylene terephthalate) is an example of a polymer prepared by double application of reaction 4 in Table 5.3. The first stage of the reaction is conducted at temperatures below 200°C and involves the interchange of dimethyl terephthalate with ethylene glycol... 

The rate of this reaction is increased by using excess ethylene glycol, and removal of the methanol is assured by the elevated temperature. Polymer is produced in the second stage after the temperature is raised above the melting point of the polymer, about 260°C. 

The ethylene glycol liberated by reaction (5.L) is removed by lowering the pressure or purging with an inert gas. Because the ethylene glycol produced by reaction (5.L) is removed, proper stoichiometry is assured by proceeding via the intermediate, bis(2-hydroxyethyl) terephthalate otherwise the excess glycol used initially would have a deleterious effect on the degree of polymerization. Poly(ethylene terephthalate) is more familiar by some of its trade names Mylar as a film and Dacron, Kodel, or Terylene as fibers it is also known by the acronym PET. 

Furfuryl alcohol is used alone or in combination with other solvents for various cleaning and paint removing operations. The ethylene oxide adduct of furfuryl alcohol is especially useful in this type of appHcation (80—83). 

---