Nitrogen Recovery with Membranes

Nitrogen Recovery with Membranes 2.2.3.1 Physical Principle... 

Figure 8.25 Nitrogen recovery as a function of product nitrogen concentration for membranes with selectivities between 2 and 20...

Figure 7.2.2. (a) Oxygen mole fraction in permeate vs. stage cut for a membrane having oo -nj = 6.0. (b) Two permeators in series operation with recycle of permeate from the second permeator to die f. (c) Fractional nitrogen recovery vs. residual oxygen mole fraction in NBA for different membrane selectivities. (part(c) after Baker (2004).)... 

Reszka et al. [168] used ultrahltration to separate free mitoxantrone from PBCA nanoparticles. The particle suspension was passed through a cellulose nitrate membrane with a pore size of 20 nm with magnetic stirring and pressurized nitrogen. The filtrate obtained was analyzed for free drug content. Recovery of the particles is not possible with... 

The cardioprotective effect of melatonin is demonstrated in several studies in in vivo and ex vivo experimental rat models or cardiomyocytes, as reviewed by Reiter.30 Melatonin administration in perfused rat hearts subjected to ischemia and reperfusion increased postischemic recovery of function, reduced the duration of ventricular tachycardia and ventricular fibrillation and this was associated with decreased lipid peroxidation products and OH radical formation, indicating an antioxidant effect of melatonin.31 Furthermore, in pinealectomized rats, occlusion of the left coronary artery followed by reperfusion resulted in significant increase in infarct size than in intact animals.32 Melatonin acts as scavenger of oxygen or nitrogen based reactants, stimulates antioxidant enzymes, stabilizes cellular membrane, increases the efficiency of oxidative phosphorylation, reduces leukocyte recruitment and adhesion molecule expression and reduces homocysteine induced damage (reviewed by Duncker33). 

Within a relatively short period after their commercialization, membranes for gas separation have been utilized in a wide variety of applications. Among these applications are recovery of hydrogen from purge streams such as encountered in ammonia plants, retrofit chemical plants and from hydroprocessors in refineries. Membrane systems have been introduced into oil fields for C02 recovery from well-head gas in enhanced oil recovery, and they have been used to separate oxygen from nitrogen in air. Also, they have been utilized in combination with other recovery systems, such as cryogenic and adsorption, to both reduce cost and increase efficiency. 

The recovery of hydrocarbon monomers from ethylene in polyethylene and polypropylene plants is actually the largest application of vapor separation membranes. After the production of the polyolefin resin, there are unreacted monomer and hydrocarbon solvents dissolved in the resin powder that must be separated in order to reuse the polymer. The traditional application involves stripping with hot nitrogen in a column known as a degassing bin. The values of nitrogen and monomer are both high therefore, the recovery and reuse of these components are of great interest. For this purpose, a membrane operation is profitably used. It consists of two membrane units in series where the off-gas... 

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