Glassy phosphate

Glassy phosphates (sodium polymetaphosphate [50813-16-6] sodium hexametaphosphate [10124-56-8J) vary in composition, depending upon the... 

Glassy phosphates (sodium polymetaphosphate, sodium hexametaphosphate) vary in composition, depending on the manufacturing process. They exert a powerful sequestering and suspending effect combined with a low-solution pH, about 6 or 7, and tend to hydrolyze or revert in aqueous solution and heat to pyrophosphates and orthophosphates. 

Ilexaphos [FMC], TM for a glassy phosphate of high molecular weight having superior water-softening properties. 

Another form of continuous application is by the nse of slightly soluble forms of solid inhibitors. The inhibitor (such as glassy phosphate or silicate in the form of a cartridge) is installed in a flow line where the inhibitor is continuously leached out by passage of fluid through the cartridge. Inhibitors in the form of sticks or pellets are used in oil and gas wells to supply inhibitor continuously by their natural slow dissolution (Fan et al. 2011). 

Low-melting-point vitreous enamels for aluminium utilise as much as 30-40% P2O5 in their formulations [67]. The formation of protective films on metal surfaces (Section 12.7) in some cases involves the formation, in part, of glassy phosphate phases. These can be for corrosion protection or electrical insulation [68]. 

It is known that a solid orthophosphate passes through an amorphous phase transition when being converted to a polyphosphate. It has been emphasized in the chapter devoted to phase chemistry that a melt or a solid glassy phosphate is a solution. In the case of a dissolved salt a reaction is seldom considered to be a phase transition, because there is no change of phase. 

Sodium-zinc molecularly dehydrated glassy phosphate inhibitor is used... 

Azathymidine was first prepared by Prusoff " and the procedure was described in more detail by Hall and Haselkorn. The nucleoside was prepared here in the form of a glassy solid, but with dibenzyl-phosphochloridate it yielded a mixture of nucleotides from which crystalline 3 -phosphate, 5 -phosphate, and 3, 5 -diphosphate were prepared. 

There is a wide variety of phosphates available and they are commonly produced in glassy, crystalline, amorphous powder and liquid forms. Figure 10.1 shows two common phosphate types. 

Figure 10.1 Types of phosphate structures, (a) Where x = 12 to 14, the structure represents sodium polyphosphate, a phosphate typically used in HW heating and industrial steam boiler formulations. The structure is ill defined and described as glassy rather than crystalline. Where x = 2, it represents sodium tripolyphosphate, (b) This is the structure where effectively, x = 0, and represents trisodium phosphate (sodium orthophosphate), which is commonly supplied in either crystalline or anhydrous powder form and used as an alkalinity booster, boiler boil-out cleaner, and metal surfaces passivator.

Condensed phosphates are indirectly manufactured derivatives of phosphorous acids, having less water than orthophosphoric acid (two molecules of phosphoric can be written P205 3H20, which indicates the source of the condensation reaction). Condensed phosphates are typically available in either crystalline or glassy forms. 

Figure 3.20 Cyclic voltammogram of COx/SWNT/glassy carbon in pH 7.0 phosphate buffer/0.1 M KCI (solid curve) FAD/SWNT/ glassy carbon in pH 7.0 phosphate buffer/0.1 M KCI (dotted curve). Scan rate 50mV/s. Reprinted with permission from Ref [135]. Copyright, 2002, Institute of Physics publishing.

---