Filtration, liquid fraction

Purification of poloxamers has been extensively investigated due to their use in medical applications, the intention often being to remove potentially toxic components. Supercritical fluid fractionation and liquid fractionation have been used successfully to remove low-molecular weight impurities and antioxidants from poloxamers. Gel filtration, high-performance liquid chromatography (HPLC), and ultrafiltration through membranes are among the other techniques examined [5]. 

Oleic acid may be obtained from glycerol trioleate, present in many liquid vegetable and animal nondrying oils, such as olive, cottonseed, lard, by hydrolysis. The crude oleic acid after separation of the water solution of glycerol is cooled to fractionally crystallize the stearic and palmitic acids, which are then separated by filtration, and fractional distillation under diminished pressure. Oleic acid reacts with lead oxide to form lead oleate, which is soluble in ether, whereas lead stearate or palmitaie is insoluble, prom lead oleate oleic add may be obtained by treatment with IL 5 (lead sulfide, insoluble solid, formed). With sodium oleate, a soap is formed. Most soaps are mixtures of sodium stearate, palmitate. and oleate. 

The pressure vessel is heated with agitation at 100° for 4 hours and at 130° for 6 hours. The vessel is allowed to cool to room temperature and the volatile by-products [Caution Toxic (Note 4)] are vented. The crude, fuming, liquid product (Note 5) is poured into a stirred suspension of 10 g. of finely divided sodium fluoride in 60 ml. of pentane (Note 6), the mixture is filtered, and the filtrate is fractionated through a 6-in. Vigreux column. 1,1,1-Trifluoroheptane is collected at 100-101°/760 mm., 1.3449. The yield is 21.7-24.6 g. (70-80%). 

The liquid fractions after pretreatment were fermented using baker s yeast (Jastbolaget AB, Rotebro, Sweden) to determine the toxicity of the samples. Fermentation was carried out in 25-cm3 glass flasks, sealed with rubber stoppers and equipped with cannulas for removal of produced broth C02. The volume of the fermentation broth was 20 cm3 (18.5 cm3 of filtrate, 0.5 cm3 of nutrients, and 1 cm3 of inoculum). 

Chipped Norway spruce, Picea abies, was used in a two-step hydrolysis process in which H2S04 was used as catalyst. The conditions and procedures were as previously reported (22). The solid fraction was removed by filtration after hydrolysis, and the liquid fraction, hereafter referred to as the hydrolysate, had a pH of 1.9. 

The principle mattix for assessing compliance with respect to Environmental Quality Standards (EQS) for priority substances is whole water or for metals, the liquid fraction obtained by filtration of the whole water sample. Whole water is a synonym for the original water sample and shall mean that suspended particulate matter (SPM) and the liquid phase have not been separated. 

For any intracellular product, the cells first mest be harvested from the fermentation broth and lysed, or broken open, to relentu their contents. The liquid fraction, which contains the product, must than be separated from the cells. Cellular debris can be removed by either filtration or centrifugation, or a combination of both. Crossflow filtration, using microporous media or ultrafiluaiion membranes, has been shown to be extremely effective for this step, hot problems with membrane blockege have been reported. 

Northcote, D. H. Carbohydrates and Mucoid Substances, in "The Separation of Biological Materials, Brit. Med. Bull. 22, 180 (1966) (Partition, thin-layer, gas-liquid, absorption, and ion-exchange chromatographies electrophoresis gel filtration and fractional precipitation),... 

The size of the beads is critical, and the crystallizer tank is specially designed to allow fat to be introduced as droplets through a specially designed distributor at the bottom. The temperature and rate of addition are adjusted to maintain the temperature of the beads that form. The temperature of the mix is held until the crystallization has reached equilibrium, and then the mix is transferred to a membrane filter press. The aqueous phase is separated from the fat beads using low pressure, and then the liquid fraction of the fat is squeezed from the beads by increasing the pressure. Unlike conventional batch crystallization from the melt, where the crystallization may not have reached equilibrium by the time the crystals are filtered, this process allows the crystals to reach equilibrium before filtration. The result is a more efficient separation than that achieved by conventional filtration. 

Cross-flow filtration allows the olein fraction to be recovered continuously. However, this type of filtration only concentrates the crystal slurry and does not separate the crystals. There is a tendency for the smaller, needle-like crystals to pass through the filter medium, contaminating the liquid fraction. Complete separation of the fractions still requires conventional filtration such as with a membrane filter. 

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