|
Berger & CO.
<br />350 Sansome St.-
<br />San
<br />t,San F:i+ancisco, Ca. 04104
<br />(415) 956--100
<br />Introduction
<br />SOC!, -I!•` •.1ntC;• , '. .; r:.Ilt (s.:,,n);:n r :71 •.
<br />So:!n.r =,r..;�h•.r,,l:a:< Gra'.a .
<br />soditin,.••.;,•,,rl(• .1t,. !.U)Ir t•1• .. Dili,+; tjr.rt!+ •.rr
<br />.hlt.la� ,1+.• ntontl,,.,
<br />Set,l. .l ;�,-!. i•'•, 1I`+',,1+•, i,l Y.h,t l• I!'1 I.'.'.r(- l, :n•r •.
<br />a$(' 1' 1` ;'•t.,;)!:,•'•it!t.lit. attd If t'+„'•ir!t.1.t+' (11,jrY111
<br />pht•sl:',,+lr`) 5'Ills Of IN' aodl. Il,f'.lt. ana 110.10”,
<br />TheN ,tic ;,+ntt'hrtWy t1CSCr,bet! .l1 �, nty)IU>. phl,sj+►tales
<br />atilt( :1 �I tho. wrn:rlClutic ,',Ih1 r lyheti rtl
<br />C011j? •lir•,: 1!`i i)IJSSy Sof!,lrnl Phosph.11v!' confolill
<br />:v11h ;rt++ mnlort:l,u structure Of thr` %odium poly
<br />ONa ONO
<br />( I I
<br />NaO•—P—O —P—C)`--P--ONa
<br />11 it 0 O 0
<br />-'(n.2)
<br />in which the value of n may be high, especially in the
<br />crystalline Kurrol and Maddrell salts
<br />In soder^,. hexametaphosphate. the average value of n
<br />is about 12
<br />DronuL,s —
<br />also manufacture two closely related
<br />Pl,,,s:)r..irr Macs 627 (62- 63%P.0,) with an n value
<br />P/nc W1:.l-W Glass o9(1 (69-7nM�'?05) with an n value
<br />Properties
<br />Appeatance
<br />Sodrlrm ate•.+•r,1•t,tp!tu�jthatc 1s sold as a fine white
<br />pu"%Ae• or as n!assti' chips Both forms arc hydroscopic
<br />•+nd .1 „ulr! he sintea 1n Closed conl.uners
<br />Melting Point
<br />SoClurtl he>+ernetaphosphatc melts when heated above
<br />600'C anrt will then dissolve most metallic oxides.
<br />This t`rl-pNt%- !las been used for a tong time In qualitative
<br />anal) s's 11• tri` mlcrnrosmlc salt head test.
<br />Aqueous Solutions
<br />Sodium her,antot ,rj)lt,a;.l+;,i� rs rr.1l)rl� �.,Iubh1 u) wales
<br />but ,r+s:,lu(,tr+ .n ot_la nn hqurds It ,,is 11,; true solubility
<br />11m1b drtd t,i•ry concentrated aqueous solutluns_ up to
<br />500,. o:t r•,,s+1q be prepaled To 1)'epkle bloCk solwtlons
<br />chip SHNIP ,ho:,ld be put into a r1oil, bag Int mct;ll or
<br />the, pro ernes
<br />r
<br />an(, toPPh(,u�
<br />a cof'
<br />rie I' lOSPI)td to
<br />j)l.rSlrCs f,.1!,►rt ;rnmt`,1,.1Ir1� 1)1•1,:.-, It,t• Irl,,. r• 1
<br />t, r,
<br />, illy Ill s%'lu, h 11 1!. 11+ hl' (li•.S„l+r•r) Ilu+ 11 ,••lt ,111:
<br />'141)111.11 whit I. It,rm, l%,ll 1.111 1+•
<br />vt•SSr•1 dnd 1111• ,�•hrtlr '.hntrllt f+r• rrt,xr,,1 vda r .,!! Iltr•
<br />!,r)11H Ital. d:.:.n!vcr) �'V.tlrt .11 jer,l;,r:raturr, u1 t ' ;rr•C
<br />(10-1•I) n,;ty I,r ,r.pr1 1111 tlr.!•ul�lru; r,ll!,11' I>,,l j,py
<br />w.tter ;'„ ;;tri hn ,,vnrtir C1 a'. U!. u•,c+ r nn l;t,r::j nh,)ut St,rnC
<br />ItydIoIy!1
<br />Powdered sudrum hexamel.rj lry ;,h.11r 1:, most cusrh
<br />dissolved by adding it gradually, will, Shrung to .%arm
<br />%eater 1he pov det Is not rerommended for mak,ng
<br />very concentrated solutions
<br />Dilute (0 25%) solutions have a pH value of iibout 2 2
<br />and this should be raised by the addition of an alkali If
<br />sodium hexametaphosphate is to be used In conjunction
<br />with soap.
<br />Sodium hexametaphosphate solutions are only slightly
<br />buffered ; this is of value in some textile operations. as
<br />SHMP can be added to processing baths without caus-
<br />ing any appreciable change in the pH value of the liquor.
<br />Concentrated solutions should be stored in vessels
<br />made of stoneware, glass or other- corrosion resisting -'-
<br />material, such as stainless stee!. plastics -lined steel or
<br />Monet. The more dilute solutions (up to 10%). which
<br />are used as stock solutions in water treatment applica- •
<br />tions, can be kept in steel vessels if sufficient alkali
<br />(sodium carbonate or caustic soda) is added to make
<br />the solutions alkaline to phenolphthalein (pli 8 5 or
<br />above).
<br />Conversion into other Phosphates
<br />Sodium hexametaphosphate in solution is converted
<br />into phosphates of shorter chain length, by hydrolysis.
<br />The rate of conversion will vary according to temperature
<br />and pH of the solution but. as a general guide, we can
<br />say that hydrolysis to orthophosphate is most rapid in
<br />acid solution and slowest at about pH9. At pH9 and
<br />100'C. hydrolysis will convert 20% of the glassy
<br />phosphate to orthophosphate in 2 hours. whereas at
<br />20'C we would expect this amount of hydrolysis to
<br />require many months. This change is of importance In
<br />considering the time of storage of SHMP solutions and
<br />also in some of its applications: the lower poly-
<br />phosphates retain to some extent the properties of the
<br />original sodium hexametaphosphate.
<br />A valuable use is made of the conversion to ortho-
<br />phosphate, which is required for the final conditioning
<br />of boiler water. because it precipitates as non- adherent
<br />sludge any calcium Introduced vvith the feed water. It
<br />1 4
<br />
|