Phosphoric acid pretreatment

Effect of Propane to Oxygen Mole Ratio in Feed. Table IV gives the results for the propane and oxygen mole ratio ranging from 2 to 8. Stainless steel Reactor VII was used for these experiments after the phosphoric acid pretreatment the reaction temperature was 430°C. The product gas was cooled in the Liebig condenser at 2°C., and the condensate was analyzed. 

Most seed oils contain 0.2-0.8% nonhydratable phospholipids (5), specifically the magnesium (Mg) and calcium (Ca) salts of phospholipids, which cannot be removed by water degumming. For many years, a common way for nonlecithin producers to degum edible oil was to treat the oil with 0.02-1% of concentrated phosphoric acid at 70-90°C, after water degumming. Then, without the removal of any precipitated solids, the oil is caustically refined. Phosphoric acid chelates the Ca and Mg in the oil so that the nonhydratable phospholipids are converted into the hydratable form. The phosphoric acid pretreatment produces a darker lecithin with lower purity (5). 

W. J. Russell, R. Rosty, K. M. Adelson, M. J. Bodnar, R. F. Wegman, E. A. Gamis, and D. W. Levi, Use of Stressed Durability Testing to Evaluate Polyhydric Alcohol-Phosphoric Acid Pretreatment of Steel for Adhesive Bonding, Technical Report ARSCD-TR-83014, U.S. Army Research and Development Center, Dover, New Jersey (October 1983). 

Ishola, M. M., Taherzadeh, M. J. Effect of fungal and phosphoric acid pretreatment on ethanol production from oil pahn empty fruit bunches (OPEFB). Bioresource Technology 2014, 165, 9-12. 

Zhang J, Zhang B, Zhang J, Lin L, Liu S, Ouyang P (2010) Effect of phosphoric acid pretreatment on enzymatic hydrolysis of microcrystalline cellulose. Btotechnol Adv 28 613-619... 

Rider and Amott were able to produce notable improvements in bond durability in comparison with simple abrasion pre-treatments. In some cases, the pretreatment improved joint durability to the level observed with the phosphoric acid anodizing process. The development of aluminum platelet structure in the outer film region combined with the hydrolytic stability of adhesive bonds made to the epoxy silane appear to be critical in developing the bond durability observed. XPS was particularly useful in determining the composition of fracture surfaces after failure as a function of boiling-water treatment time. A key feature of the treatment is that the adherend surface prepared in the boiling water be treated by the silane solution directly afterwards. Given the adherend is still wet before immersion in silane solution, the potential for atmospheric contamination is avoided. Rider and Amott have previously shown that such exposure is detrimental to bond durability. 

Care must be taken here not to confuse acid cleaners with the high-strength, phosphoric acid-based chemical polishes and chemical brighteners, which are used specifically to obtain the surface finish which such materials produce. Also in the category of acid cleaners could be considered the lightweight alkali-metal phosphating cleaner-coater solutions, but a discussion on such materials is best left to specialist publications on metal pretreatment chemicals. 

Etch primers are widely used. They are mostly based on polyvinyl butyral and contain chromates and phosphoric acid. They are said to act both as primers and as etching solutions because it is believed that the chromates and phosphoric acid form an inorganic him, which provides adhesion, while oxidised polyvinyl butyral provides an organic him. For direct application to new galvanised steel, the best known primers are based on calcium orthoplumbate pigment and metallic lead, but these are now less used for environmental reasons. Zinc-dust paints and zinc-phosphate pigmented paints are also used, but the trend is to use pretreatments to assure good adhesion. 

Etch primers partially fulfil the roles of both pretreatment and primer. They contain phosphoric acid for surface passivation and are based on polyvinyl butyral ... 

Cellulase enzyme complexes consist of three major types of proteins that synergistically catalyze the breakdown of a cellulosic substrate. Because the enzymes are strictly substrate-specific in their action, any change in the structure or accessibility of the substrate can have a considerable influence on the course of the hydrolysis reaction. A pretreatment method based on exposing cellulosic substrate to phosphoric acid solution [9] and addition of the nonionic... 

Progress has recently been made at successfully retarding this adhesion strength loss mechanism for the case of aluminum oxide through the use of a phosphoric acid anodizing pretreatment or special inhibitors86). These pretreatments are analyzed in Section 6.2. 

When liquid samples such as serum, plasma, milk, or honey are not to be extracted using direct liquid-liquid partitions with organic solvents but through use of solid-phase extraction or matrix solid-phase dispersion techniques, dilution with water (323, 324), phosphate buffer saline (325), or phosphoric acid (326, 327) is often the only sample preparation procedure applied. Milk analysis sometimes requires further pretreatment for fat removal (328). Centrifugation at about 7000g at 4-10 C for 20 min is the usually applied procedure for making the fat floating on top of milk readily eliminated. 

Pretreatment of Stainless Steel Reactor. Since quartz is unsuitable for fabricating an industrial reactor, we tested stainless steel (SUS 27) reactors. One of these was treated with 30% phosphoric acid solution for 12 hours at room temperature and then washed thoroughly (Reactor VII) and other was untreated and unaged (Reactor VI). Oxidations were carried out at 430°C. with a propane/oxygen mole ratio of 3 and at various flow rates. 

As described in Figure 3.7, TRU separation is performed by implementing the DIDPA process on pretreated PUREX raffinates. A front-end denitration step by formic acid is thus required to reduce the nitric acid concentration of the feed down to 0.5 M to allow the TRU elements to be extracted by the cation exchanger di-fvo-dccyl-phosphoric acid (DIDPA). This preliminary step, however, induces the precipitation of Mo and Zr (and thus the potential carrying of Pu), which requires filtration steps. The TRU and Ln(III) elements are coextracted by a solvent composed of the dimerized DIDPA and TBP, dissolved at 0.5 and 0.1 M, respectively, in n-dodecane. The An(III) + Ln(III) fraction is back-extracted into a concentrated 4 M nitric acid solution, whereas Np and Pu are selectively stripped by oxalic acid. 

C2-C6 carboxylic -acids ChromosorbW pretreated with phosphoric acid [599]... 

We have also studied the use of paper as the source of cellulose (1) and we have learned that if the paper is pretreated with acid, yields of ca. 5% levoglucosenone (2) can be obtained. The paper was preacidified following the procedure of Shafizadeh and Chin.9 A quantity of 25 g of paper from a newspaper was shredded into strips which were then cut by hand into smaller pieces. To a 1000-mL single-neck round-bottom flask were added the shredded paper, 180 mL of water, and 0.8 g (3.2% of the weight of the paper) of 88% phosphoric acid. The mixture was heated for 3 hours at 60-70°C and then the water was removed by using a rotary evaporator (4 hr). The preacidified paper was then mixed with 25 g of soy oil and the mixture was pyrolyzed in a 500-mL round-bottom flask the yield as determined by GC using octyl alcohol as the internal standard was ca. 5%. 

Titanates are valuable in other paint applications. Corrosion-resistant coatings have been described for tinplate, steel, and aluminum (440—444). Incorporation of phosphoric acid or polyphosphates enhances the corrosion resistance. Because titanates promote hardening of epoxy resins, they are often used in epoxy-based paint (445). Silicones (polysiloxanes) are often cured by titanates. Pigments, eg, Ti02, Si02, Al O and Zr02, are frequently pretreated with titanates before incorporation into paints (441,446). In these applications, the Ti(OR)4 compounds are often mixed with Si(OR)4, Al(OR)3, Zr(OR)4, and other metal alkoxides (12). 

One very beneficial chemical pretreatment treatment for aluminum substrates is phosphoric acid anodization (PAA), which provides an oxide coating that is inherently hydration-resistant. Its stability is due to a layer of phosphate incorporated into the outer A1203 surface during anodization. 

There are many considerations that must be taken into account when choosing a particular carbon, or carbon structure, as an electrocatalyst support. In hot phosphoric acid at cathodic potentials, the carbon surface is capable of being oxidized to carbon dioxide. The degree of oxidation will depend on the pretreatment of the carbon (for instance, the degree of graphitization), on the carbon precursor, and the provenance. There are two important parameters that will govern the primary oxidation rate for any given carbon material in an electrochemical environment. These are electrode potential (the carbon corrosion is an electrochemical process and therefore will increase rapidly as the electrode potential is raised) and temperature. 

Crude Oil Conditioning—Crude oils with high levels of phosphatides and trace metals are usually treated with food-grade phosphoric acid for 4 to 8 hours before refining. The purpose of the acid pretreatment is to (1) help precipitate phosphatidic materials (2) precipitate natural calcium and magnesium as insoluble phosphate salts (3) inactivate trace metals, such as iron, copper, and others that may be present in the oil (4) reduce the neutral oil losses and (5) improve the color and flavor stability of the finished deodorized oil. 

Hydrolysis of phosphatides and pigments in the crude oil miscella requires an acid pretreatment, which usually varies between 100 ppm and 500 ppm by weight of the oil, depending on the quality of the crude oil. An acid such as phosphoric or glacial acetic has been found effective in improving oil quality and reducing refining losses. Phosphoric acid is used more commonly because of its less corrosive properties and its availability. The acid is mixed with the miscella in a static mixer to provide an intimately dispersed acid phase that immediately reacts with the crude miscella. 

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